// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright IBM Corp. 2005, 2011
 *
 * Author(s): Rolf Adelsberger,
 *            Michael Holzheu <holzheu@linux.vnet.ibm.com>
 */

#include <linux/device.h>
#include <linux/mm.h>
#include <linux/kexec.h>
#include <linux/delay.h>
#include <linux/reboot.h>
#include <linux/ftrace.h>
#include <linux/debug_locks.h>
#include <linux/cpufeature.h>
#include <asm/guarded_storage.h>
#include <asm/machine.h>
#include <asm/pfault.h>
#include <asm/cio.h>
#include <asm/fpu.h>
#include <asm/setup.h>
#include <asm/smp.h>
#include <asm/ipl.h>
#include <asm/diag.h>
#include <asm/elf.h>
#include <asm/asm-offsets.h>
#include <asm/cacheflush.h>
#include <asm/abs_lowcore.h>
#include <asm/os_info.h>
#include <asm/set_memory.h>
#include <asm/stacktrace.h>
#include <asm/nmi.h>
#include <asm/sclp.h>

typedef void (*relocate_kernel_t)(unsigned long, unsigned long, unsigned long);
typedef int (*purgatory_t)(int);

extern const unsigned char relocate_kernel[];
extern const unsigned long long relocate_kernel_len;

#ifdef CONFIG_CRASH_DUMP

/*
 * Reset the system, copy boot CPU registers to absolute zero,
 * and jump to the kdump image
 */
static void __do_machine_kdump(void *data)
{
        struct kimage *image = data;
        purgatory_t purgatory;
        unsigned long prefix;

        purgatory = (purgatory_t)image->start;

        /* store_status() saved the prefix register to lowcore */
        prefix = (unsigned long)get_lowcore()->prefixreg_save_area;

        /* Now do the reset  */
        s390_reset_system();

        /*
         * Copy dump CPU store status info to absolute zero.
         * This need to be done *after* s390_reset_system set the
         * prefix register of this CPU to zero
         */
        memcpy(absolute_pointer(get_lowcore()->floating_pt_save_area),
               phys_to_virt(prefix + __LC_FPREGS_SAVE_AREA), 512);

        call_nodat(1, int, purgatory, int, 1);

        /* Die if kdump returns */
        disabled_wait();
}

/*
 * Start kdump: create a LGR log entry, store status of all CPUs and
 * branch to __do_machine_kdump.
 */
static noinline void __machine_kdump(void *image)
{
        struct mcesa *mcesa;
        union ctlreg2 cr2_old, cr2_new;
        int this_cpu, cpu;

        lgr_info_log();
        /* Get status of the other CPUs */
        this_cpu = smp_find_processor_id(stap());
        for_each_online_cpu(cpu) {
                if (cpu == this_cpu)
                        continue;
                if (smp_store_status(cpu))
                        continue;
        }
        /* Store status of the boot CPU */
        mcesa = __va(get_lowcore()->mcesad & MCESA_ORIGIN_MASK);
        if (cpu_has_vx())
                save_vx_regs((__vector128 *) mcesa->vector_save_area);
        if (cpu_has_gs()) {
                local_ctl_store(2, &cr2_old.reg);
                cr2_new = cr2_old;
                cr2_new.gse = 1;
                local_ctl_load(2, &cr2_new.reg);
                save_gs_cb((struct gs_cb *) mcesa->guarded_storage_save_area);
                local_ctl_load(2, &cr2_old.reg);
        }
        /*
         * To create a good backchain for this CPU in the dump store_status
         * is passed the address of a function. The address is saved into
         * the PSW save area of the boot CPU and the function is invoked as
         * a tail call of store_status. The backchain in the dump will look
         * like this:
         *   restart_int_handler ->  __machine_kexec -> __do_machine_kdump
         * The call to store_status() will not return.
         */
        store_status(__do_machine_kdump, image);
}

#endif /* CONFIG_CRASH_DUMP */

/*
 * Check if kdump checksums are valid: We call purgatory with parameter "0"
 */
static bool kdump_csum_valid(struct kimage *image)
{
#ifdef CONFIG_CRASH_DUMP
        purgatory_t purgatory = (purgatory_t)image->start;
        int rc;

        rc = call_nodat(1, int, purgatory, int, 0);
        return rc == 0;
#else
        return false;
#endif
}

#ifdef CONFIG_CRASH_DUMP

void crash_free_reserved_phys_range(unsigned long begin, unsigned long end)
{
        unsigned long addr, size;

        for (addr = begin; addr < end; addr += PAGE_SIZE)
                free_reserved_page(pfn_to_page(addr >> PAGE_SHIFT));
        size = begin - crashk_res.start;
        if (size)
                os_info_crashkernel_add(crashk_res.start, size);
        else
                os_info_crashkernel_add(0, 0);
}

static void crash_protect_pages(int protect)
{
        unsigned long size;

        if (!crashk_res.end)
                return;
        size = resource_size(&crashk_res);
        if (protect)
                set_memory_ro(crashk_res.start, size >> PAGE_SHIFT);
        else
                set_memory_rw(crashk_res.start, size >> PAGE_SHIFT);
}

void arch_kexec_protect_crashkres(void)
{
        crash_protect_pages(1);
}

void arch_kexec_unprotect_crashkres(void)
{
        crash_protect_pages(0);
}

#endif

/*
 * Give back memory to hypervisor before new kdump is loaded
 */
static int machine_kexec_prepare_kdump(void)
{
#ifdef CONFIG_CRASH_DUMP
        if (machine_is_vm())
                diag10_range(PFN_DOWN(crashk_res.start),
                             PFN_DOWN(crashk_res.end - crashk_res.start + 1));
        return 0;
#else
        return -EINVAL;
#endif
}

int machine_kexec_prepare(struct kimage *image)
{
        void *reboot_code_buffer;

        if (image->type == KEXEC_TYPE_CRASH)
                return machine_kexec_prepare_kdump();

        /* We don't support anything but the default image type for now. */
        if (image->type != KEXEC_TYPE_DEFAULT)
                return -EINVAL;

        /* Get the destination where the assembler code should be copied to.*/
        reboot_code_buffer = page_to_virt(image->control_code_page);

        /* Then copy it */
        memcpy(reboot_code_buffer, relocate_kernel, relocate_kernel_len);
        return 0;
}

void machine_kexec_cleanup(struct kimage *image)
{
}

void machine_shutdown(void)
{
}

void machine_crash_shutdown(struct pt_regs *regs)
{
        set_os_info_reipl_block();
}

/*
 * Do normal kexec
 */
static void __do_machine_kexec(void *data)
{
        unsigned long data_mover, entry, diag308_subcode;
        struct kimage *image = data;

        data_mover = page_to_phys(image->control_code_page);
        entry = virt_to_phys(&image->head);
        diag308_subcode = DIAG308_CLEAR_RESET;
        if (sclp.has_iplcc)
                diag308_subcode |= DIAG308_FLAG_EI;
        s390_reset_system();

        call_nodat(3, void, (relocate_kernel_t)data_mover,
                   unsigned long, entry,
                   unsigned long, image->start,
                   unsigned long, diag308_subcode);

        /* Die if kexec returns */
        disabled_wait();
}

/*
 * Reset system and call either kdump or normal kexec
 */
static void __machine_kexec(void *data)
{
        pfault_fini();
        tracing_off();
        debug_locks_off();
#ifdef CONFIG_CRASH_DUMP
        if (((struct kimage *) data)->type == KEXEC_TYPE_CRASH)
                __machine_kdump(data);
#endif
        __do_machine_kexec(data);
}

/*
 * Do either kdump or normal kexec. In case of kdump we first ask
 * purgatory, if kdump checksums are valid.
 */
void machine_kexec(struct kimage *image)
{
        if (image->type == KEXEC_TYPE_CRASH && !kdump_csum_valid(image))
                return;
        tracer_disable();
        smp_send_stop();
        smp_call_ipl_cpu(__machine_kexec, image);
}