// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *
 * Procedures for interfacing to the RTAS on CHRP machines.
 *
 * Peter Bergner, IBM   March 2001.
 * Copyright (C) 2001 IBM.
 */

#define pr_fmt(fmt)     "rtas: " fmt

#include <linux/bsearch.h>
#include <linux/capability.h>
#include <linux/delay.h>
#include <linux/export.h>
#include <linux/init.h>
#include <linux/kconfig.h>
#include <linux/kernel.h>
#include <linux/lockdep.h>
#include <linux/memblock.h>
#include <linux/mutex.h>
#include <linux/nospec.h>
#include <linux/of.h>
#include <linux/of_fdt.h>
#include <linux/reboot.h>
#include <linux/sched.h>
#include <linux/security.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/stdarg.h>
#include <linux/syscalls.h>
#include <linux/types.h>
#include <linux/uaccess.h>
#include <linux/xarray.h>

#include <asm/delay.h>
#include <asm/firmware.h>
#include <asm/interrupt.h>
#include <asm/machdep.h>
#include <asm/mmu.h>
#include <asm/page.h>
#include <asm/rtas-work-area.h>
#include <asm/rtas.h>
#include <asm/time.h>
#include <asm/trace.h>
#include <asm/udbg.h>

struct rtas_filter {
        /* Indexes into the args buffer, -1 if not used */
        const int buf_idx1;
        const int size_idx1;
        const int buf_idx2;
        const int size_idx2;
        /*
         * Assumed buffer size per the spec if the function does not
         * have a size parameter, e.g. ibm,errinjct. 0 if unused.
         */
        const int fixed_size;
};

/**
 * struct rtas_function - Descriptor for RTAS functions.
 *
 * @token: Value of @name if it exists under the /rtas node.
 * @name: Function name.
 * @filter: If non-NULL, invoking this function via the rtas syscall is
 *          generally allowed, and @filter describes constraints on the
 *          arguments. See also @banned_for_syscall_on_le.
 * @banned_for_syscall_on_le: Set when call via sys_rtas is generally allowed
 *                            but specifically restricted on ppc64le. Such
 *                            functions are believed to have no users on
 *                            ppc64le, and we want to keep it that way. It does
 *                            not make sense for this to be set when @filter
 *                            is NULL.
 * @lock: Pointer to an optional dedicated per-function mutex. This
 *        should be set for functions that require multiple calls in
 *        sequence to complete a single operation, and such sequences
 *        will disrupt each other if allowed to interleave. Users of
 *        this function are required to hold the associated lock for
 *        the duration of the call sequence. Add an explanatory
 *        comment to the function table entry if setting this member.
 */
struct rtas_function {
        s32 token;
        const bool banned_for_syscall_on_le:1;
        const char * const name;
        const struct rtas_filter *filter;
        struct mutex *lock;
};

/*
 * Per-function locks for sequence-based RTAS functions.
 */
static DEFINE_MUTEX(rtas_ibm_activate_firmware_lock);
static DEFINE_MUTEX(rtas_ibm_lpar_perftools_lock);
DEFINE_MUTEX(rtas_ibm_physical_attestation_lock);
DEFINE_MUTEX(rtas_ibm_get_vpd_lock);
DEFINE_MUTEX(rtas_ibm_get_indices_lock);
DEFINE_MUTEX(rtas_ibm_set_dynamic_indicator_lock);
DEFINE_MUTEX(rtas_ibm_get_dynamic_sensor_state_lock);
DEFINE_MUTEX(rtas_ibm_receive_hvpipe_msg_lock);
DEFINE_MUTEX(rtas_ibm_send_hvpipe_msg_lock);

static struct rtas_function rtas_function_table[] __ro_after_init = {
        [RTAS_FNIDX__CHECK_EXCEPTION] = {
                .name = "check-exception",
        },
        [RTAS_FNIDX__DISPLAY_CHARACTER] = {
                .name = "display-character",
                .filter = &(const struct rtas_filter) {
                        .buf_idx1 = -1, .size_idx1 = -1,
                        .buf_idx2 = -1, .size_idx2 = -1,
                },
        },
        [RTAS_FNIDX__EVENT_SCAN] = {
                .name = "event-scan",
        },
        [RTAS_FNIDX__FREEZE_TIME_BASE] = {
                .name = "freeze-time-base",
        },
        [RTAS_FNIDX__GET_POWER_LEVEL] = {
                .name = "get-power-level",
                .filter = &(const struct rtas_filter) {
                        .buf_idx1 = -1, .size_idx1 = -1,
                        .buf_idx2 = -1, .size_idx2 = -1,
                },
        },
        [RTAS_FNIDX__GET_SENSOR_STATE] = {
                .name = "get-sensor-state",
                .filter = &(const struct rtas_filter) {
                        .buf_idx1 = -1, .size_idx1 = -1,
                        .buf_idx2 = -1, .size_idx2 = -1,
                },
        },
        [RTAS_FNIDX__GET_TERM_CHAR] = {
                .name = "get-term-char",
        },
        [RTAS_FNIDX__GET_TIME_OF_DAY] = {
                .name = "get-time-of-day",
                .filter = &(const struct rtas_filter) {
                        .buf_idx1 = -1, .size_idx1 = -1,
                        .buf_idx2 = -1, .size_idx2 = -1,
                },
        },
        [RTAS_FNIDX__IBM_ACTIVATE_FIRMWARE] = {
                .name = "ibm,activate-firmware",
                .filter = &(const struct rtas_filter) {
                        .buf_idx1 = -1, .size_idx1 = -1,
                        .buf_idx2 = -1, .size_idx2 = -1,
                },
                /*
                 * PAPR+ as of v2.13 doesn't explicitly impose any
                 * restriction, but this typically requires multiple
                 * calls before success, and there's no reason to
                 * allow sequences to interleave.
                 */
                .lock = &rtas_ibm_activate_firmware_lock,
        },
        [RTAS_FNIDX__IBM_CBE_START_PTCAL] = {
                .name = "ibm,cbe-start-ptcal",
        },
        [RTAS_FNIDX__IBM_CBE_STOP_PTCAL] = {
                .name = "ibm,cbe-stop-ptcal",
        },
        [RTAS_FNIDX__IBM_CHANGE_MSI] = {
                .name = "ibm,change-msi",
        },
        [RTAS_FNIDX__IBM_CLOSE_ERRINJCT] = {
                .name = "ibm,close-errinjct",
                .filter = &(const struct rtas_filter) {
                        .buf_idx1 = -1, .size_idx1 = -1,
                        .buf_idx2 = -1, .size_idx2 = -1,
                },
        },
        [RTAS_FNIDX__IBM_CONFIGURE_BRIDGE] = {
                .name = "ibm,configure-bridge",
        },
        [RTAS_FNIDX__IBM_CONFIGURE_CONNECTOR] = {
                .name = "ibm,configure-connector",
                .filter = &(const struct rtas_filter) {
                        .buf_idx1 = 0, .size_idx1 = -1,
                        .buf_idx2 = 1, .size_idx2 = -1,
                        .fixed_size = 4096,
                },
        },
        [RTAS_FNIDX__IBM_CONFIGURE_KERNEL_DUMP] = {
                .name = "ibm,configure-kernel-dump",
        },
        [RTAS_FNIDX__IBM_CONFIGURE_PE] = {
                .name = "ibm,configure-pe",
        },
        [RTAS_FNIDX__IBM_CREATE_PE_DMA_WINDOW] = {
                .name = "ibm,create-pe-dma-window",
        },
        [RTAS_FNIDX__IBM_DISPLAY_MESSAGE] = {
                .name = "ibm,display-message",
                .filter = &(const struct rtas_filter) {
                        .buf_idx1 = 0, .size_idx1 = -1,
                        .buf_idx2 = -1, .size_idx2 = -1,
                },
        },
        [RTAS_FNIDX__IBM_ERRINJCT] = {
                .name = "ibm,errinjct",
                .filter = &(const struct rtas_filter) {
                        .buf_idx1 = 2, .size_idx1 = -1,
                        .buf_idx2 = -1, .size_idx2 = -1,
                        .fixed_size = 1024,
                },
        },
        [RTAS_FNIDX__IBM_EXTI2C] = {
                .name = "ibm,exti2c",
        },
        [RTAS_FNIDX__IBM_GET_CONFIG_ADDR_INFO] = {
                .name = "ibm,get-config-addr-info",
        },
        [RTAS_FNIDX__IBM_GET_CONFIG_ADDR_INFO2] = {
                .name = "ibm,get-config-addr-info2",
                .filter = &(const struct rtas_filter) {
                        .buf_idx1 = -1, .size_idx1 = -1,
                        .buf_idx2 = -1, .size_idx2 = -1,
                },
        },
        [RTAS_FNIDX__IBM_GET_DYNAMIC_SENSOR_STATE] = {
                .name = "ibm,get-dynamic-sensor-state",
                .filter = &(const struct rtas_filter) {
                        .buf_idx1 = 1, .size_idx1 = -1,
                        .buf_idx2 = -1, .size_idx2 = -1,
                },
                /*
                 * PAPR+ v2.13 R1–7.3.19–3 is explicit that the OS
                 * must not call ibm,get-dynamic-sensor-state with
                 * different inputs until a non-retry status has been
                 * returned.
                 */
                .lock = &rtas_ibm_get_dynamic_sensor_state_lock,
        },
        [RTAS_FNIDX__IBM_GET_INDICES] = {
                .name = "ibm,get-indices",
                .filter = &(const struct rtas_filter) {
                        .buf_idx1 = 2, .size_idx1 = 3,
                        .buf_idx2 = -1, .size_idx2 = -1,
                },
                /*
                 * PAPR+ v2.13 R1–7.3.17–2 says that the OS must not
                 * interleave ibm,get-indices call sequences with
                 * different inputs.
                 */
                .lock = &rtas_ibm_get_indices_lock,
        },
        [RTAS_FNIDX__IBM_GET_RIO_TOPOLOGY] = {
                .name = "ibm,get-rio-topology",
        },
        [RTAS_FNIDX__IBM_GET_SYSTEM_PARAMETER] = {
                .name = "ibm,get-system-parameter",
                .filter = &(const struct rtas_filter) {
                        .buf_idx1 = 1, .size_idx1 = 2,
                        .buf_idx2 = -1, .size_idx2 = -1,
                },
        },
        [RTAS_FNIDX__IBM_GET_VPD] = {
                .name = "ibm,get-vpd",
                .filter = &(const struct rtas_filter) {
                        .buf_idx1 = 0, .size_idx1 = -1,
                        .buf_idx2 = 1, .size_idx2 = 2,
                },
                /*
                 * PAPR+ v2.13 R1–7.3.20–4 indicates that sequences
                 * should not be allowed to interleave.
                 */
                .lock = &rtas_ibm_get_vpd_lock,
        },
        [RTAS_FNIDX__IBM_GET_XIVE] = {
                .name = "ibm,get-xive",
        },
        [RTAS_FNIDX__IBM_INT_OFF] = {
                .name = "ibm,int-off",
        },
        [RTAS_FNIDX__IBM_INT_ON] = {
                .name = "ibm,int-on",
        },
        [RTAS_FNIDX__IBM_IO_QUIESCE_ACK] = {
                .name = "ibm,io-quiesce-ack",
        },
        [RTAS_FNIDX__IBM_LPAR_PERFTOOLS] = {
                .name = "ibm,lpar-perftools",
                .filter = &(const struct rtas_filter) {
                        .buf_idx1 = 2, .size_idx1 = 3,
                        .buf_idx2 = -1, .size_idx2 = -1,
                },
                /*
                 * PAPR+ v2.13 R1–7.3.26–6 says the OS should allow
                 * only one call sequence in progress at a time.
                 */
                .lock = &rtas_ibm_lpar_perftools_lock,
        },
        [RTAS_FNIDX__IBM_MANAGE_FLASH_IMAGE] = {
                .name = "ibm,manage-flash-image",
        },
        [RTAS_FNIDX__IBM_MANAGE_STORAGE_PRESERVATION] = {
                .name = "ibm,manage-storage-preservation",
        },
        [RTAS_FNIDX__IBM_NMI_INTERLOCK] = {
                .name = "ibm,nmi-interlock",
        },
        [RTAS_FNIDX__IBM_NMI_REGISTER] = {
                .name = "ibm,nmi-register",
        },
        [RTAS_FNIDX__IBM_OPEN_ERRINJCT] = {
                .name = "ibm,open-errinjct",
                .filter = &(const struct rtas_filter) {
                        .buf_idx1 = -1, .size_idx1 = -1,
                        .buf_idx2 = -1, .size_idx2 = -1,
                },
        },
        [RTAS_FNIDX__IBM_OPEN_SRIOV_ALLOW_UNFREEZE] = {
                .name = "ibm,open-sriov-allow-unfreeze",
        },
        [RTAS_FNIDX__IBM_OPEN_SRIOV_MAP_PE_NUMBER] = {
                .name = "ibm,open-sriov-map-pe-number",
        },
        [RTAS_FNIDX__IBM_OS_TERM] = {
                .name = "ibm,os-term",
        },
        [RTAS_FNIDX__IBM_PARTNER_CONTROL] = {
                .name = "ibm,partner-control",
        },
        [RTAS_FNIDX__IBM_PHYSICAL_ATTESTATION] = {
                .name = "ibm,physical-attestation",
                .filter = &(const struct rtas_filter) {
                        .buf_idx1 = 0, .size_idx1 = 1,
                        .buf_idx2 = -1, .size_idx2 = -1,
                },
                /*
                 * This follows a sequence-based pattern similar to
                 * ibm,get-vpd et al. Since PAPR+ restricts
                 * interleaving call sequences for other functions of
                 * this style, assume the restriction applies here,
                 * even though it's not explicit in the spec.
                 */
                .lock = &rtas_ibm_physical_attestation_lock,
        },
        [RTAS_FNIDX__IBM_PLATFORM_DUMP] = {
                .name = "ibm,platform-dump",
                .filter = &(const struct rtas_filter) {
                        .buf_idx1 = 4, .size_idx1 = 5,
                        .buf_idx2 = -1, .size_idx2 = -1,
                },
                /*
                 * PAPR+ v2.13 7.3.3.4.1 indicates that concurrent
                 * sequences of ibm,platform-dump are allowed if they
                 * are operating on different dump tags. So leave the
                 * lock pointer unset for now. This may need
                 * reconsideration if kernel-internal users appear.
                 */
        },
        [RTAS_FNIDX__IBM_POWER_OFF_UPS] = {
                .name = "ibm,power-off-ups",
        },
        [RTAS_FNIDX__IBM_QUERY_INTERRUPT_SOURCE_NUMBER] = {
                .name = "ibm,query-interrupt-source-number",
        },
        [RTAS_FNIDX__IBM_QUERY_PE_DMA_WINDOW] = {
                .name = "ibm,query-pe-dma-window",
        },
        [RTAS_FNIDX__IBM_READ_PCI_CONFIG] = {
                .name = "ibm,read-pci-config",
        },
        [RTAS_FNIDX__IBM_READ_SLOT_RESET_STATE] = {
                .name = "ibm,read-slot-reset-state",
                .filter = &(const struct rtas_filter) {
                        .buf_idx1 = -1, .size_idx1 = -1,
                        .buf_idx2 = -1, .size_idx2 = -1,
                },
        },
        [RTAS_FNIDX__IBM_READ_SLOT_RESET_STATE2] = {
                .name = "ibm,read-slot-reset-state2",
        },
        [RTAS_FNIDX__IBM_RECEIVE_HVPIPE_MSG] {
                .name = "ibm,receive-hvpipe-msg",
                .filter = &(const struct rtas_filter) {
                        .buf_idx1 = 0, .size_idx1 = 1,
                        .buf_idx2 = -1, .size_idx2 = -1,
                },
                /*
                 * PAPR+ v2.13 R1–7.3.32.1
                 */
                .lock = &rtas_ibm_receive_hvpipe_msg_lock,
        },
        [RTAS_FNIDX__IBM_REMOVE_PE_DMA_WINDOW] = {
                .name = "ibm,remove-pe-dma-window",
        },
        [RTAS_FNIDX__IBM_RESET_PE_DMA_WINDOW] = {
                /*
                 * Note: PAPR+ v2.13 7.3.31.4.1 spells this as
                 * "ibm,reset-pe-dma-windows" (plural), but RTAS
                 * implementations use the singular form in practice.
                 */
                .name = "ibm,reset-pe-dma-window",
        },
        [RTAS_FNIDX__IBM_SCAN_LOG_DUMP] = {
                .name = "ibm,scan-log-dump",
                .filter = &(const struct rtas_filter) {
                        .buf_idx1 = 0, .size_idx1 = 1,
                        .buf_idx2 = -1, .size_idx2 = -1,
                },
        },
        [RTAS_FNIDX__IBM_SEND_HVPIPE_MSG] {
                .name = "ibm,send-hvpipe-msg",
                .filter = &(const struct rtas_filter) {
                        .buf_idx1 = 1, .size_idx1 = -1,
                        .buf_idx2 = -1, .size_idx2 = -1,
                },
                /*
                 * PAPR+ v2.13 R1–7.3.32.2
                 */
                .lock = &rtas_ibm_send_hvpipe_msg_lock,
        },
        [RTAS_FNIDX__IBM_SET_DYNAMIC_INDICATOR] = {
                .name = "ibm,set-dynamic-indicator",
                .filter = &(const struct rtas_filter) {
                        .buf_idx1 = 2, .size_idx1 = -1,
                        .buf_idx2 = -1, .size_idx2 = -1,
                },
                /*
                 * PAPR+ v2.13 R1–7.3.18–3 says the OS must not call
                 * this function with different inputs until a
                 * non-retry status has been returned.
                 */
                .lock = &rtas_ibm_set_dynamic_indicator_lock,
        },
        [RTAS_FNIDX__IBM_SET_EEH_OPTION] = {
                .name = "ibm,set-eeh-option",
                .filter = &(const struct rtas_filter) {
                        .buf_idx1 = -1, .size_idx1 = -1,
                        .buf_idx2 = -1, .size_idx2 = -1,
                },
        },
        [RTAS_FNIDX__IBM_SET_SLOT_RESET] = {
                .name = "ibm,set-slot-reset",
        },
        [RTAS_FNIDX__IBM_SET_SYSTEM_PARAMETER] = {
                .name = "ibm,set-system-parameter",
                .filter = &(const struct rtas_filter) {
                        .buf_idx1 = 1, .size_idx1 = -1,
                        .buf_idx2 = -1, .size_idx2 = -1,
                },
        },
        [RTAS_FNIDX__IBM_SET_XIVE] = {
                .name = "ibm,set-xive",
        },
        [RTAS_FNIDX__IBM_SLOT_ERROR_DETAIL] = {
                .name = "ibm,slot-error-detail",
        },
        [RTAS_FNIDX__IBM_SUSPEND_ME] = {
                .name = "ibm,suspend-me",
                .banned_for_syscall_on_le = true,
                .filter = &(const struct rtas_filter) {
                        .buf_idx1 = -1, .size_idx1 = -1,
                        .buf_idx2 = -1, .size_idx2 = -1,
                },
        },
        [RTAS_FNIDX__IBM_TUNE_DMA_PARMS] = {
                .name = "ibm,tune-dma-parms",
        },
        [RTAS_FNIDX__IBM_UPDATE_FLASH_64_AND_REBOOT] = {
                .name = "ibm,update-flash-64-and-reboot",
        },
        [RTAS_FNIDX__IBM_UPDATE_NODES] = {
                .name = "ibm,update-nodes",
                .banned_for_syscall_on_le = true,
                .filter = &(const struct rtas_filter) {
                        .buf_idx1 = 0, .size_idx1 = -1,
                        .buf_idx2 = -1, .size_idx2 = -1,
                        .fixed_size = 4096,
                },
        },
        [RTAS_FNIDX__IBM_UPDATE_PROPERTIES] = {
                .name = "ibm,update-properties",
                .banned_for_syscall_on_le = true,
                .filter = &(const struct rtas_filter) {
                        .buf_idx1 = 0, .size_idx1 = -1,
                        .buf_idx2 = -1, .size_idx2 = -1,
                        .fixed_size = 4096,
                },
        },
        [RTAS_FNIDX__IBM_VALIDATE_FLASH_IMAGE] = {
                .name = "ibm,validate-flash-image",
        },
        [RTAS_FNIDX__IBM_WRITE_PCI_CONFIG] = {
                .name = "ibm,write-pci-config",
        },
        [RTAS_FNIDX__NVRAM_FETCH] = {
                .name = "nvram-fetch",
        },
        [RTAS_FNIDX__NVRAM_STORE] = {
                .name = "nvram-store",
        },
        [RTAS_FNIDX__POWER_OFF] = {
                .name = "power-off",
        },
        [RTAS_FNIDX__PUT_TERM_CHAR] = {
                .name = "put-term-char",
        },
        [RTAS_FNIDX__QUERY_CPU_STOPPED_STATE] = {
                .name = "query-cpu-stopped-state",
        },
        [RTAS_FNIDX__READ_PCI_CONFIG] = {
                .name = "read-pci-config",
        },
        [RTAS_FNIDX__RTAS_LAST_ERROR] = {
                .name = "rtas-last-error",
        },
        [RTAS_FNIDX__SET_INDICATOR] = {
                .name = "set-indicator",
                .filter = &(const struct rtas_filter) {
                        .buf_idx1 = -1, .size_idx1 = -1,
                        .buf_idx2 = -1, .size_idx2 = -1,
                },
        },
        [RTAS_FNIDX__SET_POWER_LEVEL] = {
                .name = "set-power-level",
                .filter = &(const struct rtas_filter) {
                        .buf_idx1 = -1, .size_idx1 = -1,
                        .buf_idx2 = -1, .size_idx2 = -1,
                },
        },
        [RTAS_FNIDX__SET_TIME_FOR_POWER_ON] = {
                .name = "set-time-for-power-on",
                .filter = &(const struct rtas_filter) {
                        .buf_idx1 = -1, .size_idx1 = -1,
                        .buf_idx2 = -1, .size_idx2 = -1,
                },
        },
        [RTAS_FNIDX__SET_TIME_OF_DAY] = {
                .name = "set-time-of-day",
                .filter = &(const struct rtas_filter) {
                        .buf_idx1 = -1, .size_idx1 = -1,
                        .buf_idx2 = -1, .size_idx2 = -1,
                },
        },
        [RTAS_FNIDX__START_CPU] = {
                .name = "start-cpu",
        },
        [RTAS_FNIDX__STOP_SELF] = {
                .name = "stop-self",
        },
        [RTAS_FNIDX__SYSTEM_REBOOT] = {
                .name = "system-reboot",
        },
        [RTAS_FNIDX__THAW_TIME_BASE] = {
                .name = "thaw-time-base",
        },
        [RTAS_FNIDX__WRITE_PCI_CONFIG] = {
                .name = "write-pci-config",
        },
};

#define for_each_rtas_function(funcp)                                       \
        for (funcp = &rtas_function_table[0];                               \
             funcp < &rtas_function_table[ARRAY_SIZE(rtas_function_table)]; \
             ++funcp)

/*
 * Nearly all RTAS calls need to be serialized. All uses of the
 * default rtas_args block must hold rtas_lock.
 *
 * Exceptions to the RTAS serialization requirement (e.g. stop-self)
 * must use a separate rtas_args structure.
 */
static DEFINE_RAW_SPINLOCK(rtas_lock);
static struct rtas_args rtas_args;

/**
 * rtas_function_token() - RTAS function token lookup.
 * @handle: Function handle, e.g. RTAS_FN_EVENT_SCAN.
 *
 * Context: Any context.
 * Return: the token value for the function if implemented by this platform,
 *         otherwise RTAS_UNKNOWN_SERVICE.
 */
s32 rtas_function_token(const rtas_fn_handle_t handle)
{
        const size_t index = handle.index;
        const bool out_of_bounds = index >= ARRAY_SIZE(rtas_function_table);

        if (WARN_ONCE(out_of_bounds, "invalid function index %zu", index))
                return RTAS_UNKNOWN_SERVICE;
        /*
         * Various drivers attempt token lookups on non-RTAS
         * platforms.
         */
        if (!rtas.dev)
                return RTAS_UNKNOWN_SERVICE;

        return rtas_function_table[index].token;
}
EXPORT_SYMBOL_GPL(rtas_function_token);

static int rtas_function_cmp(const void *a, const void *b)
{
        const struct rtas_function *f1 = a;
        const struct rtas_function *f2 = b;

        return strcmp(f1->name, f2->name);
}

/*
 * Boot-time initialization of the function table needs the lookup to
 * return a non-const-qualified object. Use rtas_name_to_function()
 * in all other contexts.
 */
static struct rtas_function *__rtas_name_to_function(const char *name)
{
        const struct rtas_function key = {
                .name = name,
        };
        struct rtas_function *found;

        found = bsearch(&key, rtas_function_table, ARRAY_SIZE(rtas_function_table),
                        sizeof(rtas_function_table[0]), rtas_function_cmp);

        return found;
}

static const struct rtas_function *rtas_name_to_function(const char *name)
{
        return __rtas_name_to_function(name);
}

static DEFINE_XARRAY(rtas_token_to_function_xarray);

static int __init rtas_token_to_function_xarray_init(void)
{
        const struct rtas_function *func;
        int err = 0;

        for_each_rtas_function(func) {
                const s32 token = func->token;

                if (token == RTAS_UNKNOWN_SERVICE)
                        continue;

                err = xa_err(xa_store(&rtas_token_to_function_xarray,
                                      token, (void *)func, GFP_KERNEL));
                if (err)
                        break;
        }

        return err;
}
arch_initcall(rtas_token_to_function_xarray_init);

/*
 * For use by sys_rtas(), where the token value is provided by user
 * space and we don't want to warn on failed lookups.
 */
static const struct rtas_function *rtas_token_to_function_untrusted(s32 token)
{
        return xa_load(&rtas_token_to_function_xarray, token);
}

/*
 * Reverse lookup for deriving the function descriptor from a
 * known-good token value in contexts where the former is not already
 * available. @token must be valid, e.g. derived from the result of a
 * prior lookup against the function table.
 */
static const struct rtas_function *rtas_token_to_function(s32 token)
{
        const struct rtas_function *func;

        if (WARN_ONCE(token < 0, "invalid token %d", token))
                return NULL;

        func = rtas_token_to_function_untrusted(token);
        if (func)
                return func;
        /*
         * Fall back to linear scan in case the reverse mapping hasn't
         * been initialized yet.
         */
        if (xa_empty(&rtas_token_to_function_xarray)) {
                for_each_rtas_function(func) {
                        if (func->token == token)
                                return func;
                }
        }

        WARN_ONCE(true, "unexpected failed lookup for token %d", token);
        return NULL;
}

/* This is here deliberately so it's only used in this file */
void enter_rtas(unsigned long);

static void __do_enter_rtas(struct rtas_args *args)
{
        enter_rtas(__pa(args));
        srr_regs_clobbered(); /* rtas uses SRRs, invalidate */
}

static void __do_enter_rtas_trace(struct rtas_args *args)
{
        const struct rtas_function *func = rtas_token_to_function(be32_to_cpu(args->token));

        /*
         * If there is a per-function lock, it must be held by the
         * caller.
         */
        if (func->lock)
                lockdep_assert_held(func->lock);

        if (args == &rtas_args)
                lockdep_assert_held(&rtas_lock);

        trace_rtas_input(args, func->name);
        trace_rtas_ll_entry(args);

        __do_enter_rtas(args);

        trace_rtas_ll_exit(args);
        trace_rtas_output(args, func->name);
}

static void do_enter_rtas(struct rtas_args *args)
{
        const unsigned long msr = mfmsr();
        /*
         * Situations where we want to skip any active tracepoints for
         * safety reasons:
         *
         * 1. The last code executed on an offline CPU as it stops,
         *    i.e. we're about to call stop-self. The tracepoints'
         *    function name lookup uses xarray, which uses RCU, which
         *    isn't valid to call on an offline CPU.  Any events
         *    emitted on an offline CPU will be discarded anyway.
         *
         * 2. In real mode, as when invoking ibm,nmi-interlock from
         *    the pseries MCE handler. We cannot count on trace
         *    buffers or the entries in rtas_token_to_function_xarray
         *    to be contained in the RMO.
         */
        const unsigned long mask = MSR_IR | MSR_DR;
        const bool can_trace = likely(cpu_online(raw_smp_processor_id()) &&
                                      (msr & mask) == mask);
        /*
         * Make sure MSR[RI] is currently enabled as it will be forced later
         * in enter_rtas.
         */
        BUG_ON(!(msr & MSR_RI));

        BUG_ON(!irqs_disabled());

        hard_irq_disable(); /* Ensure MSR[EE] is disabled on PPC64 */

        if (can_trace)
                __do_enter_rtas_trace(args);
        else
                __do_enter_rtas(args);
}

struct rtas_t rtas;

DEFINE_SPINLOCK(rtas_data_buf_lock);
EXPORT_SYMBOL_GPL(rtas_data_buf_lock);

char rtas_data_buf[RTAS_DATA_BUF_SIZE] __aligned(SZ_4K);
EXPORT_SYMBOL_GPL(rtas_data_buf);

unsigned long rtas_rmo_buf;

/*
 * If non-NULL, this gets called when the kernel terminates.
 * This is done like this so rtas_flash can be a module.
 */
void (*rtas_flash_term_hook)(int);
EXPORT_SYMBOL_GPL(rtas_flash_term_hook);

/*
 * call_rtas_display_status and call_rtas_display_status_delay
 * are designed only for very early low-level debugging, which
 * is why the token is hard-coded to 10.
 */
static void call_rtas_display_status(unsigned char c)
{
        unsigned long flags;

        if (!rtas.base)
                return;

        raw_spin_lock_irqsave(&rtas_lock, flags);
        rtas_call_unlocked(&rtas_args, 10, 1, 1, NULL, c);
        raw_spin_unlock_irqrestore(&rtas_lock, flags);
}

static void call_rtas_display_status_delay(char c)
{
        static int pending_newline = 0;  /* did last write end with unprinted newline? */
        static int width = 16;

        if (c == '\n') {
                while (width-- > 0)
                        call_rtas_display_status(' ');
                width = 16;
                mdelay(500);
                pending_newline = 1;
        } else {
                if (pending_newline) {
                        call_rtas_display_status('\r');
                        call_rtas_display_status('\n');
                }
                pending_newline = 0;
                if (width--) {
                        call_rtas_display_status(c);
                        udelay(10000);
                }
        }
}

void __init udbg_init_rtas_panel(void)
{
        udbg_putc = call_rtas_display_status_delay;
}

void rtas_progress(char *s, unsigned short hex)
{
        struct device_node *root;
        int width;
        const __be32 *p;
        char *os;
        static int display_character, set_indicator;
        static int display_width, display_lines, form_feed;
        static const int *row_width;
        static DEFINE_SPINLOCK(progress_lock);
        static int current_line;
        static int pending_newline = 0;  /* did last write end with unprinted newline? */

        if (!rtas.base)
                return;

        if (display_width == 0) {
                display_width = 0x10;
                if ((root = of_find_node_by_path("/rtas"))) {
                        if ((p = of_get_property(root,
                                        "ibm,display-line-length", NULL)))
                                display_width = be32_to_cpu(*p);
                        if ((p = of_get_property(root,
                                        "ibm,form-feed", NULL)))
                                form_feed = be32_to_cpu(*p);
                        if ((p = of_get_property(root,
                                        "ibm,display-number-of-lines", NULL)))
                                display_lines = be32_to_cpu(*p);
                        row_width = of_get_property(root,
                                        "ibm,display-truncation-length", NULL);
                        of_node_put(root);
                }
                display_character = rtas_function_token(RTAS_FN_DISPLAY_CHARACTER);
                set_indicator = rtas_function_token(RTAS_FN_SET_INDICATOR);
        }

        if (display_character == RTAS_UNKNOWN_SERVICE) {
                /* use hex display if available */
                if (set_indicator != RTAS_UNKNOWN_SERVICE)
                        rtas_call(set_indicator, 3, 1, NULL, 6, 0, hex);
                return;
        }

        spin_lock(&progress_lock);

        /*
         * Last write ended with newline, but we didn't print it since
         * it would just clear the bottom line of output. Print it now
         * instead.
         *
         * If no newline is pending and form feed is supported, clear the
         * display with a form feed; otherwise, print a CR to start output
         * at the beginning of the line.
         */
        if (pending_newline) {
                rtas_call(display_character, 1, 1, NULL, '\r');
                rtas_call(display_character, 1, 1, NULL, '\n');
                pending_newline = 0;
        } else {
                current_line = 0;
                if (form_feed)
                        rtas_call(display_character, 1, 1, NULL,
                                  (char)form_feed);
                else
                        rtas_call(display_character, 1, 1, NULL, '\r');
        }

        if (row_width)
                width = row_width[current_line];
        else
                width = display_width;
        os = s;
        while (*os) {
                if (*os == '\n' || *os == '\r') {
                        /* If newline is the last character, save it
                         * until next call to avoid bumping up the
                         * display output.
                         */
                        if (*os == '\n' && !os[1]) {
                                pending_newline = 1;
                                current_line++;
                                if (current_line > display_lines-1)
                                        current_line = display_lines-1;
                                spin_unlock(&progress_lock);
                                return;
                        }

                        /* RTAS wants CR-LF, not just LF */

                        if (*os == '\n') {
                                rtas_call(display_character, 1, 1, NULL, '\r');
                                rtas_call(display_character, 1, 1, NULL, '\n');
                        } else {
                                /* CR might be used to re-draw a line, so we'll
                                 * leave it alone and not add LF.
                                 */
                                rtas_call(display_character, 1, 1, NULL, *os);
                        }

                        if (row_width)
                                width = row_width[current_line];
                        else
                                width = display_width;
                } else {
                        width--;
                        rtas_call(display_character, 1, 1, NULL, *os);
                }

                os++;

                /* if we overwrite the screen length */
                if (width <= 0)
                        while ((*os != 0) && (*os != '\n') && (*os != '\r'))
                                os++;
        }

        spin_unlock(&progress_lock);
}
EXPORT_SYMBOL_GPL(rtas_progress);               /* needed by rtas_flash module */

int rtas_token(const char *service)
{
        const struct rtas_function *func;
        const __be32 *tokp;

        if (rtas.dev == NULL)
                return RTAS_UNKNOWN_SERVICE;

        func = rtas_name_to_function(service);
        if (func)
                return func->token;
        /*
         * The caller is looking up a name that is not known to be an
         * RTAS function. Either it's a function that needs to be
         * added to the table, or they're misusing rtas_token() to
         * access non-function properties of the /rtas node. Warn and
         * fall back to the legacy behavior.
         */
        WARN_ONCE(1, "unknown function `%s`, should it be added to rtas_function_table?\n",
                  service);

        tokp = of_get_property(rtas.dev, service, NULL);
        return tokp ? be32_to_cpu(*tokp) : RTAS_UNKNOWN_SERVICE;
}
EXPORT_SYMBOL_GPL(rtas_token);

#ifdef CONFIG_RTAS_ERROR_LOGGING

static u32 rtas_error_log_max __ro_after_init = RTAS_ERROR_LOG_MAX;

/*
 * Return the firmware-specified size of the error log buffer
 *  for all rtas calls that require an error buffer argument.
 *  This includes 'check-exception' and 'rtas-last-error'.
 */
int rtas_get_error_log_max(void)
{
        return rtas_error_log_max;
}

static void __init init_error_log_max(void)
{
        static const char propname[] __initconst = "rtas-error-log-max";
        u32 max;

        if (of_property_read_u32(rtas.dev, propname, &max)) {
                pr_warn("%s not found, using default of %u\n",
                        propname, RTAS_ERROR_LOG_MAX);
                max = RTAS_ERROR_LOG_MAX;
        }

        if (max > RTAS_ERROR_LOG_MAX) {
                pr_warn("%s = %u, clamping max error log size to %u\n",
                        propname, max, RTAS_ERROR_LOG_MAX);
                max = RTAS_ERROR_LOG_MAX;
        }

        rtas_error_log_max = max;
}


static char rtas_err_buf[RTAS_ERROR_LOG_MAX];

/** Return a copy of the detailed error text associated with the
 *  most recent failed call to rtas.  Because the error text
 *  might go stale if there are any other intervening rtas calls,
 *  this routine must be called atomically with whatever produced
 *  the error (i.e. with rtas_lock still held from the previous call).
 */
static char *__fetch_rtas_last_error(char *altbuf)
{
        const s32 token = rtas_function_token(RTAS_FN_RTAS_LAST_ERROR);
        struct rtas_args err_args, save_args;
        u32 bufsz;
        char *buf = NULL;

        lockdep_assert_held(&rtas_lock);

        if (token == -1)
                return NULL;

        bufsz = rtas_get_error_log_max();

        err_args.token = cpu_to_be32(token);
        err_args.nargs = cpu_to_be32(2);
        err_args.nret = cpu_to_be32(1);
        err_args.args[0] = cpu_to_be32(__pa(rtas_err_buf));
        err_args.args[1] = cpu_to_be32(bufsz);
        err_args.args[2] = 0;

        save_args = rtas_args;
        rtas_args = err_args;

        do_enter_rtas(&rtas_args);

        err_args = rtas_args;
        rtas_args = save_args;

        /* Log the error in the unlikely case that there was one. */
        if (unlikely(err_args.args[2] == 0)) {
                if (altbuf) {
                        buf = altbuf;
                } else {
                        buf = rtas_err_buf;
                        if (slab_is_available())
                                buf = kmalloc(RTAS_ERROR_LOG_MAX, GFP_ATOMIC);
                }
                if (buf)
                        memmove(buf, rtas_err_buf, RTAS_ERROR_LOG_MAX);
        }

        return buf;
}

#define get_errorlog_buffer()   kmalloc(RTAS_ERROR_LOG_MAX, GFP_KERNEL)

#else /* CONFIG_RTAS_ERROR_LOGGING */
#define __fetch_rtas_last_error(x)      NULL
#define get_errorlog_buffer()           NULL
static void __init init_error_log_max(void) {}
#endif


static void
va_rtas_call_unlocked(struct rtas_args *args, int token, int nargs, int nret,
                      va_list list)
{
        int i;

        args->token = cpu_to_be32(token);
        args->nargs = cpu_to_be32(nargs);
        args->nret  = cpu_to_be32(nret);
        args->rets  = &(args->args[nargs]);

        for (i = 0; i < nargs; ++i)
                args->args[i] = cpu_to_be32(va_arg(list, __u32));

        for (i = 0; i < nret; ++i)
                args->rets[i] = 0;

        do_enter_rtas(args);
}

/**
 * rtas_call_unlocked() - Invoke an RTAS firmware function without synchronization.
 * @args: RTAS parameter block to be used for the call, must obey RTAS addressing
 *        constraints.
 * @token: Identifies the function being invoked.
 * @nargs: Number of input parameters. Does not include token.
 * @nret: Number of output parameters, including the call status.
 * @....: List of @nargs input parameters.
 *
 * Invokes the RTAS function indicated by @token, which the caller
 * should obtain via rtas_function_token().
 *
 * This function is similar to rtas_call(), but must be used with a
 * limited set of RTAS calls specifically exempted from the general
 * requirement that only one RTAS call may be in progress at any
 * time. Examples include stop-self and ibm,nmi-interlock.
 */
void rtas_call_unlocked(struct rtas_args *args, int token, int nargs, int nret, ...)
{
        va_list list;

        va_start(list, nret);
        va_rtas_call_unlocked(args, token, nargs, nret, list);
        va_end(list);
}

static bool token_is_restricted_errinjct(s32 token)
{
        return token == rtas_function_token(RTAS_FN_IBM_OPEN_ERRINJCT) ||
               token == rtas_function_token(RTAS_FN_IBM_ERRINJCT);
}

/**
 * rtas_call() - Invoke an RTAS firmware function.
 * @token: Identifies the function being invoked.
 * @nargs: Number of input parameters. Does not include token.
 * @nret: Number of output parameters, including the call status.
 * @outputs: Array of @nret output words.
 * @....: List of @nargs input parameters.
 *
 * Invokes the RTAS function indicated by @token, which the caller
 * should obtain via rtas_function_token().
 *
 * The @nargs and @nret arguments must match the number of input and
 * output parameters specified for the RTAS function.
 *
 * rtas_call() returns RTAS status codes, not conventional Linux errno
 * values. Callers must translate any failure to an appropriate errno
 * in syscall context. Most callers of RTAS functions that can return
 * -2 or 990x should use rtas_busy_delay() to correctly handle those
 * statuses before calling again.
 *
 * The return value descriptions are adapted from 7.2.8 [RTAS] Return
 * Codes of the PAPR and CHRP specifications.
 *
 * Context: Process context preferably, interrupt context if
 *          necessary.  Acquires an internal spinlock and may perform
 *          GFP_ATOMIC slab allocation in error path. Unsafe for NMI
 *          context.
 * Return:
 * *                          0 - RTAS function call succeeded.
 * *                         -1 - RTAS function encountered a hardware or
 *                                platform error, or the token is invalid,
 *                                or the function is restricted by kernel policy.
 * *                         -2 - Specs say "A necessary hardware device was busy,
 *                                and the requested function could not be
 *                                performed. The operation should be retried at
 *                                a later time." This is misleading, at least with
 *                                respect to current RTAS implementations. What it
 *                                usually means in practice is that the function
 *                                could not be completed while meeting RTAS's
 *                                deadline for returning control to the OS (250us
 *                                for PAPR/PowerVM, typically), but the call may be
 *                                immediately reattempted to resume work on it.
 * *                         -3 - Parameter error.
 * *                         -7 - Unexpected state change.
 * *                9000...9899 - Vendor-specific success codes.
 * *                9900...9905 - Advisory extended delay. Caller should try
 *                                again after ~10^x ms has elapsed, where x is
 *                                the last digit of the status [0-5]. Again going
 *                                beyond the PAPR text, 990x on PowerVM indicates
 *                                contention for RTAS-internal resources. Other
 *                                RTAS call sequences in progress should be
 *                                allowed to complete before reattempting the
 *                                call.
 * *                      -9000 - Multi-level isolation error.
 * *              -9999...-9004 - Vendor-specific error codes.
 * * Additional negative values - Function-specific error.
 * * Additional positive values - Function-specific success.
 */
int rtas_call(int token, int nargs, int nret, int *outputs, ...)
{
        struct pin_cookie cookie;
        va_list list;
        int i;
        unsigned long flags;
        struct rtas_args *args;
        char *buff_copy = NULL;
        int ret;

        if (!rtas.entry || token == RTAS_UNKNOWN_SERVICE)
                return -1;

        if (token_is_restricted_errinjct(token)) {
                /*
                 * It would be nicer to not discard the error value
                 * from security_locked_down(), but callers expect an
                 * RTAS status, not an errno.
                 */
                if (security_locked_down(LOCKDOWN_RTAS_ERROR_INJECTION))
                        return -1;
        }

        if ((mfmsr() & (MSR_IR|MSR_DR)) != (MSR_IR|MSR_DR)) {
                WARN_ON_ONCE(1);
                return -1;
        }

        raw_spin_lock_irqsave(&rtas_lock, flags);
        cookie = lockdep_pin_lock(&rtas_lock);

        /* We use the global rtas args buffer */
        args = &rtas_args;

        va_start(list, outputs);
        va_rtas_call_unlocked(args, token, nargs, nret, list);
        va_end(list);

        /* A -1 return code indicates that the last command couldn't
           be completed due to a hardware error. */
        if (be32_to_cpu(args->rets[0]) == -1)
                buff_copy = __fetch_rtas_last_error(NULL);

        if (nret > 1 && outputs != NULL)
                for (i = 0; i < nret-1; ++i)
                        outputs[i] = be32_to_cpu(args->rets[i + 1]);
        ret = (nret > 0) ? be32_to_cpu(args->rets[0]) : 0;

        lockdep_unpin_lock(&rtas_lock, cookie);
        raw_spin_unlock_irqrestore(&rtas_lock, flags);

        if (buff_copy) {
                log_error(buff_copy, ERR_TYPE_RTAS_LOG, 0);
                if (slab_is_available())
                        kfree(buff_copy);
        }
        return ret;
}
EXPORT_SYMBOL_GPL(rtas_call);

/**
 * rtas_busy_delay_time() - From an RTAS status value, calculate the
 *                          suggested delay time in milliseconds.
 *
 * @status: a value returned from rtas_call() or similar APIs which return
 *          the status of a RTAS function call.
 *
 * Context: Any context.
 *
 * Return:
 * * 100000 - If @status is 9905.
 * * 10000  - If @status is 9904.
 * * 1000   - If @status is 9903.
 * * 100    - If @status is 9902.
 * * 10     - If @status is 9901.
 * * 1      - If @status is either 9900 or -2. This is "wrong" for -2, but
 *            some callers depend on this behavior, and the worst outcome
 *            is that they will delay for longer than necessary.
 * * 0      - If @status is not a busy or extended delay value.
 */
unsigned int rtas_busy_delay_time(int status)
{
        int order;
        unsigned int ms = 0;

        if (status == RTAS_BUSY) {
                ms = 1;
        } else if (status >= RTAS_EXTENDED_DELAY_MIN &&
                   status <= RTAS_EXTENDED_DELAY_MAX) {
                order = status - RTAS_EXTENDED_DELAY_MIN;
                for (ms = 1; order > 0; order--)
                        ms *= 10;
        }

        return ms;
}

/*
 * Early boot fallback for rtas_busy_delay().
 */
static bool __init rtas_busy_delay_early(int status)
{
        static size_t successive_ext_delays __initdata;
        bool retry;

        switch (status) {
        case RTAS_EXTENDED_DELAY_MIN...RTAS_EXTENDED_DELAY_MAX:
                /*
                 * In the unlikely case that we receive an extended
                 * delay status in early boot, the OS is probably not
                 * the cause, and there's nothing we can do to clear
                 * the condition. Best we can do is delay for a bit
                 * and hope it's transient. Lie to the caller if it
                 * seems like we're stuck in a retry loop.
                 */
                mdelay(1);
                retry = true;
                successive_ext_delays += 1;
                if (successive_ext_delays > 1000) {
                        pr_err("too many extended delays, giving up\n");
                        dump_stack();
                        retry = false;
                        successive_ext_delays = 0;
                }
                break;
        case RTAS_BUSY:
                retry = true;
                successive_ext_delays = 0;
                break;
        default:
                retry = false;
                successive_ext_delays = 0;
                break;
        }

        return retry;
}

/**
 * rtas_busy_delay() - helper for RTAS busy and extended delay statuses
 *
 * @status: a value returned from rtas_call() or similar APIs which return
 *          the status of a RTAS function call.
 *
 * Context: Process context. May sleep or schedule.
 *
 * Return:
 * * true  - @status is RTAS_BUSY or an extended delay hint. The
 *           caller may assume that the CPU has been yielded if necessary,
 *           and that an appropriate delay for @status has elapsed.
 *           Generally the caller should reattempt the RTAS call which
 *           yielded @status.
 *
 * * false - @status is not @RTAS_BUSY nor an extended delay hint. The
 *           caller is responsible for handling @status.
 */
bool __ref rtas_busy_delay(int status)
{
        unsigned int ms;
        bool ret;

        /*
         * Can't do timed sleeps before timekeeping is up.
         */
        if (system_state < SYSTEM_SCHEDULING)
                return rtas_busy_delay_early(status);

        switch (status) {
        case RTAS_EXTENDED_DELAY_MIN...RTAS_EXTENDED_DELAY_MAX:
                ret = true;
                ms = rtas_busy_delay_time(status);
                /*
                 * The extended delay hint can be as high as 100 seconds.
                 * Surely any function returning such a status is either
                 * buggy or isn't going to be significantly slowed by us
                 * polling at 1HZ. Clamp the sleep time to one second.
                 */
                ms = clamp(ms, 1U, 1000U);
                /*
                 * The delay hint is an order-of-magnitude suggestion, not a
                 * minimum. It is fine, possibly even advantageous, for us to
                 * pause for less time than hinted. To make sure pause time will
                 * not be way longer than requested independent of HZ
                 * configuration, use fsleep(). See fsleep() for details of
                 * used sleeping functions.
                 */
                fsleep(ms * 1000);
                break;
        case RTAS_BUSY:
                ret = true;
                /*
                 * We should call again immediately if there's no other
                 * work to do.
                 */
                cond_resched();
                break;
        default:
                ret = false;
                /*
                 * Not a busy or extended delay status; the caller should
                 * handle @status itself. Ensure we warn on misuses in
                 * atomic context regardless.
                 */
                might_sleep();
                break;
        }

        return ret;
}
EXPORT_SYMBOL_GPL(rtas_busy_delay);

int rtas_error_rc(int rtas_rc)
{
        int rc;

        switch (rtas_rc) {
        case RTAS_HARDWARE_ERROR:       /* Hardware Error */
                rc = -EIO;
                break;
        case RTAS_INVALID_PARAMETER:    /* Bad indicator/domain/etc */
                rc = -EINVAL;
                break;
        case -9000:                     /* Isolation error */
                rc = -EFAULT;
                break;
        case -9001:                     /* Outstanding TCE/PTE */
                rc = -EEXIST;
                break;
        case -9002:                     /* No usable slot */
                rc = -ENODEV;
                break;
        default:
                pr_err("%s: unexpected error %d\n", __func__, rtas_rc);
                rc = -ERANGE;
                break;
        }
        return rc;
}
EXPORT_SYMBOL_GPL(rtas_error_rc);

int rtas_get_power_level(int powerdomain, int *level)
{
        int token = rtas_function_token(RTAS_FN_GET_POWER_LEVEL);
        int rc;

        if (token == RTAS_UNKNOWN_SERVICE)
                return -ENOENT;

        while ((rc = rtas_call(token, 1, 2, level, powerdomain)) == RTAS_BUSY)
                udelay(1);

        if (rc < 0)
                return rtas_error_rc(rc);
        return rc;
}
EXPORT_SYMBOL_GPL(rtas_get_power_level);

int rtas_set_power_level(int powerdomain, int level, int *setlevel)
{
        int token = rtas_function_token(RTAS_FN_SET_POWER_LEVEL);
        int rc;

        if (token == RTAS_UNKNOWN_SERVICE)
                return -ENOENT;

        do {
                rc = rtas_call(token, 2, 2, setlevel, powerdomain, level);
        } while (rtas_busy_delay(rc));

        if (rc < 0)
                return rtas_error_rc(rc);
        return rc;
}
EXPORT_SYMBOL_GPL(rtas_set_power_level);

int rtas_get_sensor(int sensor, int index, int *state)
{
        int token = rtas_function_token(RTAS_FN_GET_SENSOR_STATE);
        int rc;

        if (token == RTAS_UNKNOWN_SERVICE)
                return -ENOENT;

        do {
                rc = rtas_call(token, 2, 2, state, sensor, index);
        } while (rtas_busy_delay(rc));

        if (rc < 0)
                return rtas_error_rc(rc);
        return rc;
}
EXPORT_SYMBOL_GPL(rtas_get_sensor);

int rtas_get_sensor_fast(int sensor, int index, int *state)
{
        int token = rtas_function_token(RTAS_FN_GET_SENSOR_STATE);
        int rc;

        if (token == RTAS_UNKNOWN_SERVICE)
                return -ENOENT;

        rc = rtas_call(token, 2, 2, state, sensor, index);
        WARN_ON(rc == RTAS_BUSY || (rc >= RTAS_EXTENDED_DELAY_MIN &&
                                    rc <= RTAS_EXTENDED_DELAY_MAX));

        if (rc < 0)
                return rtas_error_rc(rc);
        return rc;
}

bool rtas_indicator_present(int token, int *maxindex)
{
        int proplen, count, i;
        const struct indicator_elem {
                __be32 token;
                __be32 maxindex;
        } *indicators;

        indicators = of_get_property(rtas.dev, "rtas-indicators", &proplen);
        if (!indicators)
                return false;

        count = proplen / sizeof(struct indicator_elem);

        for (i = 0; i < count; i++) {
                if (__be32_to_cpu(indicators[i].token) != token)
                        continue;
                if (maxindex)
                        *maxindex = __be32_to_cpu(indicators[i].maxindex);
                return true;
        }

        return false;
}

int rtas_set_indicator(int indicator, int index, int new_value)
{
        int token = rtas_function_token(RTAS_FN_SET_INDICATOR);
        int rc;

        if (token == RTAS_UNKNOWN_SERVICE)
                return -ENOENT;

        do {
                rc = rtas_call(token, 3, 1, NULL, indicator, index, new_value);
        } while (rtas_busy_delay(rc));

        if (rc < 0)
                return rtas_error_rc(rc);
        return rc;
}
EXPORT_SYMBOL_GPL(rtas_set_indicator);

/*
 * Ignoring RTAS extended delay
 */
int rtas_set_indicator_fast(int indicator, int index, int new_value)
{
        int token = rtas_function_token(RTAS_FN_SET_INDICATOR);
        int rc;

        if (token == RTAS_UNKNOWN_SERVICE)
                return -ENOENT;

        rc = rtas_call(token, 3, 1, NULL, indicator, index, new_value);

        WARN_ON(rc == RTAS_BUSY || (rc >= RTAS_EXTENDED_DELAY_MIN &&
                                    rc <= RTAS_EXTENDED_DELAY_MAX));

        if (rc < 0)
                return rtas_error_rc(rc);

        return rc;
}

/**
 * rtas_ibm_suspend_me() - Call ibm,suspend-me to suspend the LPAR.
 *
 * @fw_status: RTAS call status will be placed here if not NULL.
 *
 * rtas_ibm_suspend_me() should be called only on a CPU which has
 * received H_CONTINUE from the H_JOIN hcall. All other active CPUs
 * should be waiting to return from H_JOIN.
 *
 * rtas_ibm_suspend_me() may suspend execution of the OS
 * indefinitely. Callers should take appropriate measures upon return, such as
 * resetting watchdog facilities.
 *
 * Callers may choose to retry this call if @fw_status is
 * %RTAS_THREADS_ACTIVE.
 *
 * Return:
 * 0          - The partition has resumed from suspend, possibly after
 *              migration to a different host.
 * -ECANCELED - The operation was aborted.
 * -EAGAIN    - There were other CPUs not in H_JOIN at the time of the call.
 * -EBUSY     - Some other condition prevented the suspend from succeeding.
 * -EIO       - Hardware/platform error.
 */
int rtas_ibm_suspend_me(int *fw_status)
{
        int token = rtas_function_token(RTAS_FN_IBM_SUSPEND_ME);
        int fwrc;
        int ret;

        fwrc = rtas_call(token, 0, 1, NULL);

        switch (fwrc) {
        case 0:
                ret = 0;
                break;
        case RTAS_SUSPEND_ABORTED:
                ret = -ECANCELED;
                break;
        case RTAS_THREADS_ACTIVE:
                ret = -EAGAIN;
                break;
        case RTAS_NOT_SUSPENDABLE:
        case RTAS_OUTSTANDING_COPROC:
                ret = -EBUSY;
                break;
        case -1:
        default:
                ret = -EIO;
                break;
        }

        if (fw_status)
                *fw_status = fwrc;

        return ret;
}

void __noreturn rtas_restart(char *cmd)
{
        if (rtas_flash_term_hook)
                rtas_flash_term_hook(SYS_RESTART);
        pr_emerg("system-reboot returned %d\n",
                 rtas_call(rtas_function_token(RTAS_FN_SYSTEM_REBOOT), 0, 1, NULL));
        for (;;);
}

void rtas_power_off(void)
{
        if (rtas_flash_term_hook)
                rtas_flash_term_hook(SYS_POWER_OFF);
        /* allow power on only with power button press */
        pr_emerg("power-off returned %d\n",
                 rtas_call(rtas_function_token(RTAS_FN_POWER_OFF), 2, 1, NULL, -1, -1));
        for (;;);
}

void __noreturn rtas_halt(void)
{
        if (rtas_flash_term_hook)
                rtas_flash_term_hook(SYS_HALT);
        /* allow power on only with power button press */
        pr_emerg("power-off returned %d\n",
                 rtas_call(rtas_function_token(RTAS_FN_POWER_OFF), 2, 1, NULL, -1, -1));
        for (;;);
}

/* Must be in the RMO region, so we place it here */
static char rtas_os_term_buf[2048];
static bool ibm_extended_os_term;

void rtas_os_term(char *str)
{
        s32 token = rtas_function_token(RTAS_FN_IBM_OS_TERM);
        static struct rtas_args args;
        int status;

        /*
         * Firmware with the ibm,extended-os-term property is guaranteed
         * to always return from an ibm,os-term call. Earlier versions without
         * this property may terminate the partition which we want to avoid
         * since it interferes with panic_timeout.
         */

        if (token == RTAS_UNKNOWN_SERVICE || !ibm_extended_os_term)
                return;

        snprintf(rtas_os_term_buf, 2048, "OS panic: %s", str);

        /*
         * Keep calling as long as RTAS returns a "try again" status,
         * but don't use rtas_busy_delay(), which potentially
         * schedules.
         */
        do {
                rtas_call_unlocked(&args, token, 1, 1, NULL, __pa(rtas_os_term_buf));
                status = be32_to_cpu(args.rets[0]);
        } while (rtas_busy_delay_time(status));

        if (status != 0)
                pr_emerg("ibm,os-term call failed %d\n", status);
}

/**
 * rtas_activate_firmware() - Activate a new version of firmware.
 *
 * Context: This function may sleep.
 *
 * Activate a new version of partition firmware. The OS must call this
 * after resuming from a partition hibernation or migration in order
 * to maintain the ability to perform live firmware updates. It's not
 * catastrophic for this method to be absent or to fail; just log the
 * condition in that case.
 */
void rtas_activate_firmware(void)
{
        int token = rtas_function_token(RTAS_FN_IBM_ACTIVATE_FIRMWARE);
        int fwrc;

        if (token == RTAS_UNKNOWN_SERVICE) {
                pr_notice("ibm,activate-firmware method unavailable\n");
                return;
        }

        mutex_lock(&rtas_ibm_activate_firmware_lock);

        do {
                fwrc = rtas_call(token, 0, 1, NULL);
        } while (rtas_busy_delay(fwrc));

        mutex_unlock(&rtas_ibm_activate_firmware_lock);

        if (fwrc)
                pr_err("ibm,activate-firmware failed (%i)\n", fwrc);
}

/**
 * get_pseries_errorlog() - Find a specific pseries error log in an RTAS
 *                          extended event log.
 * @log: RTAS error/event log
 * @section_id: two character section identifier
 *
 * Return: A pointer to the specified errorlog or NULL if not found.
 */
noinstr struct pseries_errorlog *get_pseries_errorlog(struct rtas_error_log *log,
                                                      uint16_t section_id)
{
        struct rtas_ext_event_log_v6 *ext_log =
                (struct rtas_ext_event_log_v6 *)log->buffer;
        struct pseries_errorlog *sect;
        unsigned char *p, *log_end;
        uint32_t ext_log_length = rtas_error_extended_log_length(log);
        uint8_t log_format = rtas_ext_event_log_format(ext_log);
        uint32_t company_id = rtas_ext_event_company_id(ext_log);

        /* Check that we understand the format */
        if (ext_log_length < sizeof(struct rtas_ext_event_log_v6) ||
            log_format != RTAS_V6EXT_LOG_FORMAT_EVENT_LOG ||
            company_id != RTAS_V6EXT_COMPANY_ID_IBM)
                return NULL;

        log_end = log->buffer + ext_log_length;
        p = ext_log->vendor_log;

        while (p < log_end) {
                sect = (struct pseries_errorlog *)p;
                if (pseries_errorlog_id(sect) == section_id)
                        return sect;
                p += pseries_errorlog_length(sect);
        }

        return NULL;
}

/*
 * The sys_rtas syscall, as originally designed, allows root to pass
 * arbitrary physical addresses to RTAS calls. A number of RTAS calls
 * can be abused to write to arbitrary memory and do other things that
 * are potentially harmful to system integrity, and thus should only
 * be used inside the kernel and not exposed to userspace.
 *
 * All known legitimate users of the sys_rtas syscall will only ever
 * pass addresses that fall within the RMO buffer, and use a known
 * subset of RTAS calls.
 *
 * Accordingly, we filter RTAS requests to check that the call is
 * permitted, and that provided pointers fall within the RMO buffer.
 * If a function is allowed to be invoked via the syscall, then its
 * entry in the rtas_functions table points to a rtas_filter that
 * describes its constraints, with the indexes of the parameters which
 * are expected to contain addresses and sizes of buffers allocated
 * inside the RMO buffer.
 */

static bool in_rmo_buf(u32 base, u32 end)
{
        return base >= rtas_rmo_buf &&
                base < (rtas_rmo_buf + RTAS_USER_REGION_SIZE) &&
                base <= end &&
                end >= rtas_rmo_buf &&
                end < (rtas_rmo_buf + RTAS_USER_REGION_SIZE);
}

static bool block_rtas_call(const struct rtas_function *func, int nargs,
                            struct rtas_args *args)
{
        const struct rtas_filter *f;
        const bool is_platform_dump =
                func == &rtas_function_table[RTAS_FNIDX__IBM_PLATFORM_DUMP];
        const bool is_config_conn =
                func == &rtas_function_table[RTAS_FNIDX__IBM_CONFIGURE_CONNECTOR];
        u32 base, size, end;

        /*
         * Only functions with filters attached are allowed.
         */
        f = func->filter;
        if (!f)
                goto err;
        /*
         * And some functions aren't allowed on LE.
         */
        if (IS_ENABLED(CONFIG_CPU_LITTLE_ENDIAN) && func->banned_for_syscall_on_le)
                goto err;

        if (f->buf_idx1 != -1) {
                base = be32_to_cpu(args->args[f->buf_idx1]);
                if (f->size_idx1 != -1)
                        size = be32_to_cpu(args->args[f->size_idx1]);
                else if (f->fixed_size)
                        size = f->fixed_size;
                else
                        size = 1;

                end = base + size - 1;

                /*
                 * Special case for ibm,platform-dump - NULL buffer
                 * address is used to indicate end of dump processing
                 */
                if (is_platform_dump && base == 0)
                        return false;

                if (!in_rmo_buf(base, end))
                        goto err;
        }

        if (f->buf_idx2 != -1) {
                base = be32_to_cpu(args->args[f->buf_idx2]);
                if (f->size_idx2 != -1)
                        size = be32_to_cpu(args->args[f->size_idx2]);
                else if (f->fixed_size)
                        size = f->fixed_size;
                else
                        size = 1;
                end = base + size - 1;

                /*
                 * Special case for ibm,configure-connector where the
                 * address can be 0
                 */
                if (is_config_conn && base == 0)
                        return false;

                if (!in_rmo_buf(base, end))
                        goto err;
        }

        return false;
err:
        pr_err_ratelimited("sys_rtas: RTAS call blocked - exploit attempt?\n");
        pr_err_ratelimited("sys_rtas: %s nargs=%d (called by %s)\n",
                           func->name, nargs, current->comm);
        return true;
}

/* We assume to be passed big endian arguments */
SYSCALL_DEFINE1(rtas, struct rtas_args __user *, uargs)
{
        const struct rtas_function *func;
        struct pin_cookie cookie;
        struct rtas_args args;
        unsigned long flags;
        char *buff_copy, *errbuf = NULL;
        int nargs, nret, token;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        if (!rtas.entry)
                return -EINVAL;

        if (copy_from_user(&args, uargs, 3 * sizeof(u32)) != 0)
                return -EFAULT;

        nargs = be32_to_cpu(args.nargs);
        nret  = be32_to_cpu(args.nret);
        token = be32_to_cpu(args.token);

        if (nargs >= ARRAY_SIZE(args.args)
            || nret > ARRAY_SIZE(args.args)
            || nargs + nret > ARRAY_SIZE(args.args))
                return -EINVAL;

        nargs = array_index_nospec(nargs, ARRAY_SIZE(args.args));
        nret = array_index_nospec(nret, ARRAY_SIZE(args.args) - nargs);

        /* Copy in args. */
        if (copy_from_user(args.args, uargs->args,
                           nargs * sizeof(rtas_arg_t)) != 0)
                return -EFAULT;

        /*
         * If this token doesn't correspond to a function the kernel
         * understands, you're not allowed to call it.
         */
        func = rtas_token_to_function_untrusted(token);
        if (!func)
                return -EINVAL;

        args.rets = &args.args[nargs];
        memset(args.rets, 0, nret * sizeof(rtas_arg_t));

        if (block_rtas_call(func, nargs, &args))
                return -EINVAL;

        if (token_is_restricted_errinjct(token)) {
                int err;

                err = security_locked_down(LOCKDOWN_RTAS_ERROR_INJECTION);
                if (err)
                        return err;
        }

        /* Need to handle ibm,suspend_me call specially */
        if (token == rtas_function_token(RTAS_FN_IBM_SUSPEND_ME)) {

                /*
                 * rtas_ibm_suspend_me assumes the streamid handle is in cpu
                 * endian, or at least the hcall within it requires it.
                 */
                int rc = 0;
                u64 handle = ((u64)be32_to_cpu(args.args[0]) << 32)
                              | be32_to_cpu(args.args[1]);
                rc = rtas_syscall_dispatch_ibm_suspend_me(handle);
                if (rc == -EAGAIN)
                        args.rets[0] = cpu_to_be32(RTAS_NOT_SUSPENDABLE);
                else if (rc == -EIO)
                        args.rets[0] = cpu_to_be32(-1);
                else if (rc)
                        return rc;
                goto copy_return;
        }

        buff_copy = get_errorlog_buffer();

        /*
         * If this function has a mutex assigned to it, we must
         * acquire it to avoid interleaving with any kernel-based uses
         * of the same function. Kernel-based sequences acquire the
         * appropriate mutex explicitly.
         */
        if (func->lock)
                mutex_lock(func->lock);

        raw_spin_lock_irqsave(&rtas_lock, flags);
        cookie = lockdep_pin_lock(&rtas_lock);

        rtas_args = args;
        do_enter_rtas(&rtas_args);
        args = rtas_args;

        /* A -1 return code indicates that the last command couldn't
           be completed due to a hardware error. */
        if (be32_to_cpu(args.rets[0]) == -1)
                errbuf = __fetch_rtas_last_error(buff_copy);

        lockdep_unpin_lock(&rtas_lock, cookie);
        raw_spin_unlock_irqrestore(&rtas_lock, flags);

        if (func->lock)
                mutex_unlock(func->lock);

        if (buff_copy) {
                if (errbuf)
                        log_error(errbuf, ERR_TYPE_RTAS_LOG, 0);
                kfree(buff_copy);
        }

 copy_return:
        /* Copy out args. */
        if (copy_to_user(uargs->args + nargs,
                         args.args + nargs,
                         nret * sizeof(rtas_arg_t)) != 0)
                return -EFAULT;

        return 0;
}

static void __init rtas_function_table_init(void)
{
        struct property *prop;

        for (size_t i = 0; i < ARRAY_SIZE(rtas_function_table); ++i) {
                struct rtas_function *curr = &rtas_function_table[i];
                struct rtas_function *prior;
                int cmp;

                curr->token = RTAS_UNKNOWN_SERVICE;

                if (i == 0)
                        continue;
                /*
                 * Ensure table is sorted correctly for binary search
                 * on function names.
                 */
                prior = &rtas_function_table[i - 1];

                cmp = strcmp(prior->name, curr->name);
                if (cmp < 0)
                        continue;

                if (cmp == 0) {
                        pr_err("'%s' has duplicate function table entries\n",
                               curr->name);
                } else {
                        pr_err("function table unsorted: '%s' wrongly precedes '%s'\n",
                               prior->name, curr->name);
                }
        }

        for_each_property_of_node(rtas.dev, prop) {
                struct rtas_function *func;

                if (prop->length != sizeof(u32))
                        continue;

                func = __rtas_name_to_function(prop->name);
                if (!func)
                        continue;

                func->token = be32_to_cpup((__be32 *)prop->value);

                pr_debug("function %s has token %u\n", func->name, func->token);
        }
}

/*
 * Call early during boot, before mem init, to retrieve the RTAS
 * information from the device-tree and allocate the RMO buffer for userland
 * accesses.
 */
void __init rtas_initialize(void)
{
        unsigned long rtas_region = RTAS_INSTANTIATE_MAX;
        u32 base, size, entry;
        int no_base, no_size, no_entry;

        /* Get RTAS dev node and fill up our "rtas" structure with infos
         * about it.
         */
        rtas.dev = of_find_node_by_name(NULL, "rtas");
        if (!rtas.dev)
                return;

        no_base = of_property_read_u32(rtas.dev, "linux,rtas-base", &base);
        no_size = of_property_read_u32(rtas.dev, "rtas-size", &size);
        if (no_base || no_size) {
                of_node_put(rtas.dev);
                rtas.dev = NULL;
                return;
        }

        rtas.base = base;
        rtas.size = size;
        no_entry = of_property_read_u32(rtas.dev, "linux,rtas-entry", &entry);
        rtas.entry = no_entry ? rtas.base : entry;

        init_error_log_max();

        /* Must be called before any function token lookups */
        rtas_function_table_init();

        /*
         * Discover this now to avoid a device tree lookup in the
         * panic path.
         */
        ibm_extended_os_term = of_property_read_bool(rtas.dev, "ibm,extended-os-term");

        /* If RTAS was found, allocate the RMO buffer for it and look for
         * the stop-self token if any
         */
#ifdef CONFIG_PPC64
        if (firmware_has_feature(FW_FEATURE_LPAR))
                rtas_region = min(ppc64_rma_size, RTAS_INSTANTIATE_MAX);
#endif
        rtas_rmo_buf = memblock_phys_alloc_range(RTAS_USER_REGION_SIZE, PAGE_SIZE,
                                                 0, rtas_region);
        if (!rtas_rmo_buf)
                panic("ERROR: RTAS: Failed to allocate %lx bytes below %pa\n",
                      PAGE_SIZE, &rtas_region);

        rtas_work_area_reserve_arena(rtas_region);
}

int __init early_init_dt_scan_rtas(unsigned long node,
                const char *uname, int depth, void *data)
{
        const u32 *basep, *entryp, *sizep;

        if (depth != 1 || strcmp(uname, "rtas") != 0)
                return 0;

        basep  = of_get_flat_dt_prop(node, "linux,rtas-base", NULL);
        entryp = of_get_flat_dt_prop(node, "linux,rtas-entry", NULL);
        sizep  = of_get_flat_dt_prop(node, "rtas-size", NULL);

#ifdef CONFIG_PPC64
        /* need this feature to decide the crashkernel offset */
        if (of_get_flat_dt_prop(node, "ibm,hypertas-functions", NULL))
                powerpc_firmware_features |= FW_FEATURE_LPAR;
#endif

        if (basep && entryp && sizep) {
                rtas.base = *basep;
                rtas.entry = *entryp;
                rtas.size = *sizep;
        }

        /* break now */
        return 1;
}

static DEFINE_RAW_SPINLOCK(timebase_lock);
static u64 timebase = 0;

void rtas_give_timebase(void)
{
        unsigned long flags;

        raw_spin_lock_irqsave(&timebase_lock, flags);
        hard_irq_disable();
        rtas_call(rtas_function_token(RTAS_FN_FREEZE_TIME_BASE), 0, 1, NULL);
        timebase = get_tb();
        raw_spin_unlock(&timebase_lock);

        while (timebase)
                barrier();
        rtas_call(rtas_function_token(RTAS_FN_THAW_TIME_BASE), 0, 1, NULL);
        local_irq_restore(flags);
}

void rtas_take_timebase(void)
{
        while (!timebase)
                barrier();
        raw_spin_lock(&timebase_lock);
        set_tb(timebase >> 32, timebase & 0xffffffff);
        timebase = 0;
        raw_spin_unlock(&timebase_lock);
}