// 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/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/virtext.h>
#include <asm/intel_pt.h>
#include <asm/crash.h>
#include <asm/cmdline.h>

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

/*
 * This is used to VMCLEAR all VMCSs loaded on the
 * processor. And when loading kvm_intel module, the
 * callback function pointer will be assigned.
 *
 * protected by rcu.
 */
crash_vmclear_fn __rcu *crash_vmclear_loaded_vmcss = NULL;
EXPORT_SYMBOL_GPL(crash_vmclear_loaded_vmcss);

static inline void cpu_crash_vmclear_loaded_vmcss(void)
{
        crash_vmclear_fn *do_vmclear_operation = NULL;

        rcu_read_lock();
        do_vmclear_operation = rcu_dereference(crash_vmclear_loaded_vmcss);
        if (do_vmclear_operation)
                do_vmclear_operation();
        rcu_read_unlock();
}

#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);

        /*
         * VMCLEAR VMCSs loaded on all cpus if needed.
         */
        cpu_crash_vmclear_loaded_vmcss();

        /* Disable VMX or SVM if needed.
         *
         * We need to disable virtualization on all CPUs.
         * Having VMX or SVM enabled on any CPU may break rebooting
         * after the kdump kernel has finished its task.
         */
        cpu_emergency_vmxoff();
        cpu_emergency_svm_disable();

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

        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();

        /*
         * VMCLEAR VMCSs loaded on this cpu if needed.
         */
        cpu_crash_vmclear_loaded_vmcss();

        /* Booting kdump kernel with VMX or SVM enabled won't work,
         * because (among other limitations) we can't disable paging
         * with the virt flags.
         */
        cpu_emergency_vmxoff();
        cpu_emergency_svm_disable();

        /*
         * 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
        crash_save_cpu(regs, safe_smp_processor_id());
}

#ifdef CONFIG_KEXEC_FILE

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 and/or crashk_low_res may cause
         * another range split. So add extra two slots here.
         */
        nr_ranges += 2;
        cmem = vzalloc(struct_size(cmem, ranges, nr_ranges));
        if (!cmem)
                return NULL;

        cmem->max_nr_ranges = nr_ranges;
        cmem->nr_ranges = 0;

        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;

        /* Exclude the low 1M because it is always reserved */
        ret = crash_exclude_mem_range(cmem, 0, (1<<20)-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);

        return ret;
}

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(struct kimage *image, void **addr,
                                        unsigned long *sz)
{
        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;

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

out:
        vfree(cmem);
        return ret;
}

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;

        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;
        return crash_exclude_mem_range(cmem, start, end);
}

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

        cmem = vzalloc(struct_size(cmem, ranges, 1));
        if (!cmem)
                return -ENOMEM;

        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);
        }

out:
        vfree(cmem);
        return ret;
}

int crash_load_segments(struct kimage *image)
{
        int ret;
        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(image, &kbuf.buffer, &kbuf.bufsz);
        if (ret)
                return ret;

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

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

        return ret;
}
#endif /* CONFIG_KEXEC_FILE */