// SPDX-License-Identifier: GPL-2.0-only
/*
 * Architecture specific (i386/x86_64) functions for kexec based crash dumps.
 *
 * Created by: Hariprasad Nellitheertha (hari@in.ibm.com)
 *
 * Copyright (C) IBM Corporation, 2004. All rights reserved.
 * Copyright (C) Red Hat Inc., 2014. All rights reserved.
 * Authors:
 *      Vivek Goyal <vgoyal@redhat.com>
 *
 */

#define pr_fmt(fmt)     "kexec: " fmt

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/smp.h>
#include <linux/reboot.h>
#include <linux/kexec.h>
#include <linux/delay.h>
#include <linux/elf.h>
#include <linux/elfcore.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/memblock.h>

#include <asm/bootparam.h>
#include <asm/processor.h>
#include <asm/hardirq.h>
#include <asm/nmi.h>
#include <asm/hw_irq.h>
#include <asm/apic.h>
#include <asm/e820/types.h>
#include <asm/io_apic.h>
#include <asm/hpet.h>
#include <linux/kdebug.h>
#include <asm/cpu.h>
#include <asm/reboot.h>
#include <asm/intel_pt.h>
#include <asm/crash.h>
#include <asm/cmdline.h>
#include <asm/sev.h>

/* Used while preparing memory map entries for second kernel */
struct crash_memmap_data {
        struct boot_params *params;
        /* Type of memory */
        unsigned int type;
};

#if defined(CONFIG_SMP) && defined(CONFIG_X86_LOCAL_APIC)

static void kdump_nmi_callback(int cpu, struct pt_regs *regs)
{
        crash_save_cpu(regs, cpu);

        /*
         * Disable Intel PT to stop its logging
         */
        cpu_emergency_stop_pt();

        kdump_sev_callback();

        disable_local_APIC();
}

void kdump_nmi_shootdown_cpus(void)
{
        nmi_shootdown_cpus(kdump_nmi_callback);

        disable_local_APIC();
}

/* Override the weak function in kernel/panic.c */
void crash_smp_send_stop(void)
{
        static int cpus_stopped;

        if (cpus_stopped)
                return;

        if (smp_ops.crash_stop_other_cpus)
                smp_ops.crash_stop_other_cpus();
        else
                smp_send_stop();

        cpus_stopped = 1;
}

#else
void crash_smp_send_stop(void)
{
        /* There are no cpus to shootdown */
}
#endif

void native_machine_crash_shutdown(struct pt_regs *regs)
{
        /* This function is only called after the system
         * has panicked or is otherwise in a critical state.
         * The minimum amount of code to allow a kexec'd kernel
         * to run successfully needs to happen here.
         *
         * In practice this means shooting down the other cpus in
         * an SMP system.
         */
        /* The kernel is broken so disable interrupts */
        local_irq_disable();

        crash_smp_send_stop();

        cpu_emergency_disable_virtualization();

        /*
         * Disable Intel PT to stop its logging
         */
        cpu_emergency_stop_pt();

#ifdef CONFIG_X86_IO_APIC
        /* Prevent crash_kexec() from deadlocking on ioapic_lock. */
        ioapic_zap_locks();
        clear_IO_APIC();
#endif
        lapic_shutdown();
        restore_boot_irq_mode();
#ifdef CONFIG_HPET_TIMER
        hpet_disable();
#endif

        /*
         * Non-crash kexec calls enc_kexec_begin() while scheduling is still
         * active. This allows the callback to wait until all in-flight
         * shared<->private conversions are complete. In a crash scenario,
         * enc_kexec_begin() gets called after all but one CPU have been shut
         * down and interrupts have been disabled. This allows the callback to
         * detect a race with the conversion and report it.
         */
        x86_platform.guest.enc_kexec_begin();
        x86_platform.guest.enc_kexec_finish();

        crash_save_cpu(regs, smp_processor_id());
}

#if defined(CONFIG_KEXEC_FILE) || defined(CONFIG_CRASH_HOTPLUG)
static int get_nr_ram_ranges_callback(struct resource *res, void *arg)
{
        unsigned int *nr_ranges = arg;

        (*nr_ranges)++;
        return 0;
}

/* Gather all the required information to prepare elf headers for ram regions */
static struct crash_mem *fill_up_crash_elf_data(void)
{
        unsigned int nr_ranges = 0;
        struct crash_mem *cmem;

        walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
        if (!nr_ranges)
                return NULL;

        /*
         * Exclusion of crash region, crashk_low_res and/or crashk_cma_ranges
         * may cause range splits. So add extra slots here.
         *
         * Exclusion of low 1M may not cause another range split, because the
         * range of exclude is [0, 1M] and the condition for splitting a new
         * region is that the start, end parameters are both in a certain
         * existing region in cmem and cannot be equal to existing region's
         * start or end. Obviously, the start of [0, 1M] cannot meet this
         * condition.
         *
         * But in order to lest the low 1M could be changed in the future,
         * (e.g. [start, 1M]), add a extra slot.
         */
        nr_ranges += 3 + crashk_cma_cnt;
        cmem = vzalloc(struct_size(cmem, ranges, nr_ranges));
        if (!cmem)
                return NULL;

        cmem->max_nr_ranges = nr_ranges;

        return cmem;
}

/*
 * Look for any unwanted ranges between mstart, mend and remove them. This
 * might lead to split and split ranges are put in cmem->ranges[] array
 */
static int elf_header_exclude_ranges(struct crash_mem *cmem)
{
        int ret = 0;
        int i;

        /* Exclude the low 1M because it is always reserved */
        ret = crash_exclude_mem_range(cmem, 0, SZ_1M - 1);
        if (ret)
                return ret;

        /* Exclude crashkernel region */
        ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
        if (ret)
                return ret;

        if (crashk_low_res.end)
                ret = crash_exclude_mem_range(cmem, crashk_low_res.start,
                                              crashk_low_res.end);
        if (ret)
                return ret;

        for (i = 0; i < crashk_cma_cnt; ++i) {
                ret = crash_exclude_mem_range(cmem, crashk_cma_ranges[i].start,
                                              crashk_cma_ranges[i].end);
                if (ret)
                        return ret;
        }

        return 0;
}

static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
{
        struct crash_mem *cmem = arg;

        cmem->ranges[cmem->nr_ranges].start = res->start;
        cmem->ranges[cmem->nr_ranges].end = res->end;
        cmem->nr_ranges++;

        return 0;
}

/* Prepare elf headers. Return addr and size */
static int prepare_elf_headers(void **addr, unsigned long *sz,
                               unsigned long *nr_mem_ranges)
{
        struct crash_mem *cmem;
        int ret;

        cmem = fill_up_crash_elf_data();
        if (!cmem)
                return -ENOMEM;

        ret = walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
        if (ret)
                goto out;

        /* Exclude unwanted mem ranges */
        ret = elf_header_exclude_ranges(cmem);
        if (ret)
                goto out;

        /* Return the computed number of memory ranges, for hotplug usage */
        *nr_mem_ranges = cmem->nr_ranges;

        /* By default prepare 64bit headers */
        ret = crash_prepare_elf64_headers(cmem, IS_ENABLED(CONFIG_X86_64), addr, sz);

out:
        vfree(cmem);
        return ret;
}
#endif

#ifdef CONFIG_KEXEC_FILE
static int add_e820_entry(struct boot_params *params, struct e820_entry *entry)
{
        unsigned int nr_e820_entries;

        nr_e820_entries = params->e820_entries;
        if (nr_e820_entries >= E820_MAX_ENTRIES_ZEROPAGE)
                return 1;

        memcpy(&params->e820_table[nr_e820_entries], entry, sizeof(struct e820_entry));
        params->e820_entries++;
        return 0;
}

static int memmap_entry_callback(struct resource *res, void *arg)
{
        struct crash_memmap_data *cmd = arg;
        struct boot_params *params = cmd->params;
        struct e820_entry ei;

        ei.addr = res->start;
        ei.size = resource_size(res);
        ei.type = cmd->type;
        add_e820_entry(params, &ei);

        return 0;
}

static int memmap_exclude_ranges(struct kimage *image, struct crash_mem *cmem,
                                 unsigned long long mstart,
                                 unsigned long long mend)
{
        unsigned long start, end;
        int ret;

        cmem->ranges[0].start = mstart;
        cmem->ranges[0].end = mend;
        cmem->nr_ranges = 1;

        /* Exclude elf header region */
        start = image->elf_load_addr;
        end = start + image->elf_headers_sz - 1;
        ret = crash_exclude_mem_range(cmem, start, end);

        if (ret)
                return ret;

        /* Exclude dm crypt keys region */
        if (image->dm_crypt_keys_addr) {
                start = image->dm_crypt_keys_addr;
                end = start + image->dm_crypt_keys_sz - 1;
                return crash_exclude_mem_range(cmem, start, end);
        }

        return ret;
}

/* Prepare memory map for crash dump kernel */
int crash_setup_memmap_entries(struct kimage *image, struct boot_params *params)
{
        unsigned int nr_ranges = 0;
        int i, ret = 0;
        unsigned long flags;
        struct e820_entry ei;
        struct crash_memmap_data cmd;
        struct crash_mem *cmem;

        /*
         * In the current x86 architecture code, the elfheader is always
         * allocated at crashk_res.start. But it depends on the allocation
         * position of elfheader in crashk_res. To avoid potential out of
         * bounds in future, add an extra slot.
         *
         * And using random kexec_buf for passing dm crypt keys may cause a
         * range split too, add another extra slot here.
         */
        nr_ranges = 3;
        cmem = vzalloc(struct_size(cmem, ranges, nr_ranges));
        if (!cmem)
                return -ENOMEM;

        cmem->max_nr_ranges = nr_ranges;

        memset(&cmd, 0, sizeof(struct crash_memmap_data));
        cmd.params = params;

        /* Add the low 1M */
        cmd.type = E820_TYPE_RAM;
        flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
        walk_iomem_res_desc(IORES_DESC_NONE, flags, 0, (1<<20)-1, &cmd,
                            memmap_entry_callback);

        /* Add ACPI tables */
        cmd.type = E820_TYPE_ACPI;
        flags = IORESOURCE_MEM | IORESOURCE_BUSY;
        walk_iomem_res_desc(IORES_DESC_ACPI_TABLES, flags, 0, -1, &cmd,
                            memmap_entry_callback);

        /* Add ACPI Non-volatile Storage */
        cmd.type = E820_TYPE_NVS;
        walk_iomem_res_desc(IORES_DESC_ACPI_NV_STORAGE, flags, 0, -1, &cmd,
                            memmap_entry_callback);

        /* Add e820 reserved ranges */
        cmd.type = E820_TYPE_RESERVED;
        flags = IORESOURCE_MEM;
        walk_iomem_res_desc(IORES_DESC_RESERVED, flags, 0, -1, &cmd,
                            memmap_entry_callback);

        /* Add crashk_low_res region */
        if (crashk_low_res.end) {
                ei.addr = crashk_low_res.start;
                ei.size = resource_size(&crashk_low_res);
                ei.type = E820_TYPE_RAM;
                add_e820_entry(params, &ei);
        }

        /* Exclude some ranges from crashk_res and add rest to memmap */
        ret = memmap_exclude_ranges(image, cmem, crashk_res.start, crashk_res.end);
        if (ret)
                goto out;

        for (i = 0; i < cmem->nr_ranges; i++) {
                ei.size = cmem->ranges[i].end - cmem->ranges[i].start + 1;

                /* If entry is less than a page, skip it */
                if (ei.size < PAGE_SIZE)
                        continue;
                ei.addr = cmem->ranges[i].start;
                ei.type = E820_TYPE_RAM;
                add_e820_entry(params, &ei);
        }

        for (i = 0; i < crashk_cma_cnt; ++i) {
                ei.addr = crashk_cma_ranges[i].start;
                ei.size = crashk_cma_ranges[i].end -
                          crashk_cma_ranges[i].start + 1;
                ei.type = E820_TYPE_RAM;
                add_e820_entry(params, &ei);
        }

out:
        vfree(cmem);
        return ret;
}

int crash_load_segments(struct kimage *image)
{
        int ret;
        unsigned long pnum = 0;
        struct kexec_buf kbuf = { .image = image, .buf_min = 0,
                                  .buf_max = ULONG_MAX, .top_down = false };

        /* Prepare elf headers and add a segment */
        ret = prepare_elf_headers(&kbuf.buffer, &kbuf.bufsz, &pnum);
        if (ret)
                return ret;

        image->elf_headers      = kbuf.buffer;
        image->elf_headers_sz   = kbuf.bufsz;
        kbuf.memsz              = kbuf.bufsz;

#ifdef CONFIG_CRASH_HOTPLUG
        /*
         * The elfcorehdr segment size accounts for VMCOREINFO, kernel_map,
         * maximum CPUs and maximum memory ranges.
         */
        if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG))
                pnum = 2 + CONFIG_NR_CPUS_DEFAULT + CONFIG_CRASH_MAX_MEMORY_RANGES;
        else
                pnum += 2 + CONFIG_NR_CPUS_DEFAULT;

        if (pnum < (unsigned long)PN_XNUM) {
                kbuf.memsz = pnum * sizeof(Elf64_Phdr);
                kbuf.memsz += sizeof(Elf64_Ehdr);

                image->elfcorehdr_index = image->nr_segments;

                /* Mark as usable to crash kernel, else crash kernel fails on boot */
                image->elf_headers_sz = kbuf.memsz;
        } else {
                pr_err("number of Phdrs %lu exceeds max\n", pnum);
        }
#endif

        kbuf.buf_align = ELF_CORE_HEADER_ALIGN;
        kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
        ret = kexec_add_buffer(&kbuf);
        if (ret)
                return ret;
        image->elf_load_addr = kbuf.mem;
        kexec_dprintk("Loaded ELF headers at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
                      image->elf_load_addr, kbuf.bufsz, kbuf.memsz);

        return ret;
}
#endif /* CONFIG_KEXEC_FILE */

#ifdef CONFIG_CRASH_HOTPLUG

#undef pr_fmt
#define pr_fmt(fmt) "crash hp: " fmt

int arch_crash_hotplug_support(struct kimage *image, unsigned long kexec_flags)
{

#ifdef CONFIG_KEXEC_FILE
        if (image->file_mode)
                return 1;
#endif
        /*
         * Initially, crash hotplug support for kexec_load was added
         * with the KEXEC_UPDATE_ELFCOREHDR flag. Later, this
         * functionality was expanded to accommodate multiple kexec
         * segment updates, leading to the introduction of the
         * KEXEC_CRASH_HOTPLUG_SUPPORT kexec flag bit. Consequently,
         * when the kexec tool sends either of these flags, it indicates
         * that the required kexec segment (elfcorehdr) is excluded from
         * the SHA calculation.
         */
        return (kexec_flags & KEXEC_UPDATE_ELFCOREHDR ||
                kexec_flags & KEXEC_CRASH_HOTPLUG_SUPPORT);
}

unsigned int arch_crash_get_elfcorehdr_size(void)
{
        unsigned int sz;

        /* kernel_map, VMCOREINFO and maximum CPUs */
        sz = 2 + CONFIG_NR_CPUS_DEFAULT;
        if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG))
                sz += CONFIG_CRASH_MAX_MEMORY_RANGES;
        sz *= sizeof(Elf64_Phdr);
        return sz;
}

/**
 * arch_crash_handle_hotplug_event() - Handle hotplug elfcorehdr changes
 * @image: a pointer to kexec_crash_image
 * @arg: struct memory_notify handler for memory hotplug case and
 *       NULL for CPU hotplug case.
 *
 * Prepare the new elfcorehdr and replace the existing elfcorehdr.
 */
void arch_crash_handle_hotplug_event(struct kimage *image, void *arg)
{
        void *elfbuf = NULL, *old_elfcorehdr;
        unsigned long nr_mem_ranges;
        unsigned long mem, memsz;
        unsigned long elfsz = 0;

        /*
         * As crash_prepare_elf64_headers() has already described all
         * possible CPUs, there is no need to update the elfcorehdr
         * for additional CPU changes.
         */
        if ((image->file_mode || image->elfcorehdr_updated) &&
                ((image->hp_action == KEXEC_CRASH_HP_ADD_CPU) ||
                (image->hp_action == KEXEC_CRASH_HP_REMOVE_CPU)))
                return;

        /*
         * Create the new elfcorehdr reflecting the changes to CPU and/or
         * memory resources.
         */
        if (prepare_elf_headers(&elfbuf, &elfsz, &nr_mem_ranges)) {
                pr_err("unable to create new elfcorehdr");
                goto out;
        }

        /*
         * Obtain address and size of the elfcorehdr segment, and
         * check it against the new elfcorehdr buffer.
         */
        mem = image->segment[image->elfcorehdr_index].mem;
        memsz = image->segment[image->elfcorehdr_index].memsz;
        if (elfsz > memsz) {
                pr_err("update elfcorehdr elfsz %lu > memsz %lu",
                        elfsz, memsz);
                goto out;
        }

        /*
         * Copy new elfcorehdr over the old elfcorehdr at destination.
         */
        old_elfcorehdr = kmap_local_page(pfn_to_page(mem >> PAGE_SHIFT));
        if (!old_elfcorehdr) {
                pr_err("mapping elfcorehdr segment failed\n");
                goto out;
        }

        /*
         * Temporarily invalidate the crash image while the
         * elfcorehdr is updated.
         */
        xchg(&kexec_crash_image, NULL);
        memcpy_flushcache(old_elfcorehdr, elfbuf, elfsz);
        xchg(&kexec_crash_image, image);
        kunmap_local(old_elfcorehdr);
        pr_debug("updated elfcorehdr\n");

out:
        vfree(elfbuf);
}
#endif