// SPDX-License-Identifier: GPL-2.0-only
/*
 * handle transition of Linux booting another kernel
 * Copyright (C) 2002-2005 Eric Biederman  <ebiederm@xmission.com>
 */

#define pr_fmt(fmt)     "kexec: " fmt

#include <linux/mm.h>
#include <linux/kexec.h>
#include <linux/string.h>
#include <linux/gfp.h>
#include <linux/reboot.h>
#include <linux/numa.h>
#include <linux/ftrace.h>
#include <linux/io.h>
#include <linux/suspend.h>
#include <linux/vmalloc.h>
#include <linux/efi.h>
#include <linux/cc_platform.h>

#include <asm/init.h>
#include <asm/tlbflush.h>
#include <asm/mmu_context.h>
#include <asm/io_apic.h>
#include <asm/debugreg.h>
#include <asm/kexec-bzimage64.h>
#include <asm/setup.h>
#include <asm/set_memory.h>
#include <asm/cpu.h>

#ifdef CONFIG_ACPI
/*
 * Used while adding mapping for ACPI tables.
 * Can be reused when other iomem regions need be mapped
 */
struct init_pgtable_data {
        struct x86_mapping_info *info;
        pgd_t *level4p;
};

static int mem_region_callback(struct resource *res, void *arg)
{
        struct init_pgtable_data *data = arg;
        unsigned long mstart, mend;

        mstart = res->start;
        mend = mstart + resource_size(res) - 1;

        return kernel_ident_mapping_init(data->info, data->level4p, mstart, mend);
}

static int
map_acpi_tables(struct x86_mapping_info *info, pgd_t *level4p)
{
        struct init_pgtable_data data;
        unsigned long flags;
        int ret;

        data.info = info;
        data.level4p = level4p;
        flags = IORESOURCE_MEM | IORESOURCE_BUSY;

        ret = walk_iomem_res_desc(IORES_DESC_ACPI_TABLES, flags, 0, -1,
                                  &data, mem_region_callback);
        if (ret && ret != -EINVAL)
                return ret;

        /* ACPI tables could be located in ACPI Non-volatile Storage region */
        ret = walk_iomem_res_desc(IORES_DESC_ACPI_NV_STORAGE, flags, 0, -1,
                                  &data, mem_region_callback);
        if (ret && ret != -EINVAL)
                return ret;

        return 0;
}
#else
static int map_acpi_tables(struct x86_mapping_info *info, pgd_t *level4p) { return 0; }
#endif

#ifdef CONFIG_KEXEC_FILE
const struct kexec_file_ops * const kexec_file_loaders[] = {
                &kexec_bzImage64_ops,
                NULL
};
#endif

static int
map_efi_systab(struct x86_mapping_info *info, pgd_t *level4p)
{
#ifdef CONFIG_EFI
        unsigned long mstart, mend;

        if (!efi_enabled(EFI_BOOT))
                return 0;

        mstart = (boot_params.efi_info.efi_systab |
                        ((u64)boot_params.efi_info.efi_systab_hi<<32));

        if (efi_enabled(EFI_64BIT))
                mend = mstart + sizeof(efi_system_table_64_t);
        else
                mend = mstart + sizeof(efi_system_table_32_t);

        if (!mstart)
                return 0;

        return kernel_ident_mapping_init(info, level4p, mstart, mend);
#endif
        return 0;
}

static void free_transition_pgtable(struct kimage *image)
{
        free_page((unsigned long)image->arch.p4d);
        image->arch.p4d = NULL;
        free_page((unsigned long)image->arch.pud);
        image->arch.pud = NULL;
        free_page((unsigned long)image->arch.pmd);
        image->arch.pmd = NULL;
        free_page((unsigned long)image->arch.pte);
        image->arch.pte = NULL;
}

static int init_transition_pgtable(struct kimage *image, pgd_t *pgd)
{
        pgprot_t prot = PAGE_KERNEL_EXEC_NOENC;
        unsigned long vaddr, paddr;
        int result = -ENOMEM;
        p4d_t *p4d;
        pud_t *pud;
        pmd_t *pmd;
        pte_t *pte;

        vaddr = (unsigned long)relocate_kernel;
        paddr = __pa(page_address(image->control_code_page)+PAGE_SIZE);
        pgd += pgd_index(vaddr);
        if (!pgd_present(*pgd)) {
                p4d = (p4d_t *)get_zeroed_page(GFP_KERNEL);
                if (!p4d)
                        goto err;
                image->arch.p4d = p4d;
                set_pgd(pgd, __pgd(__pa(p4d) | _KERNPG_TABLE));
        }
        p4d = p4d_offset(pgd, vaddr);
        if (!p4d_present(*p4d)) {
                pud = (pud_t *)get_zeroed_page(GFP_KERNEL);
                if (!pud)
                        goto err;
                image->arch.pud = pud;
                set_p4d(p4d, __p4d(__pa(pud) | _KERNPG_TABLE));
        }
        pud = pud_offset(p4d, vaddr);
        if (!pud_present(*pud)) {
                pmd = (pmd_t *)get_zeroed_page(GFP_KERNEL);
                if (!pmd)
                        goto err;
                image->arch.pmd = pmd;
                set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE));
        }
        pmd = pmd_offset(pud, vaddr);
        if (!pmd_present(*pmd)) {
                pte = (pte_t *)get_zeroed_page(GFP_KERNEL);
                if (!pte)
                        goto err;
                image->arch.pte = pte;
                set_pmd(pmd, __pmd(__pa(pte) | _KERNPG_TABLE));
        }
        pte = pte_offset_kernel(pmd, vaddr);

        if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
                prot = PAGE_KERNEL_EXEC;

        set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, prot));
        return 0;
err:
        return result;
}

static void *alloc_pgt_page(void *data)
{
        struct kimage *image = (struct kimage *)data;
        struct page *page;
        void *p = NULL;

        page = kimage_alloc_control_pages(image, 0);
        if (page) {
                p = page_address(page);
                clear_page(p);
        }

        return p;
}

static int init_pgtable(struct kimage *image, unsigned long start_pgtable)
{
        struct x86_mapping_info info = {
                .alloc_pgt_page = alloc_pgt_page,
                .context        = image,
                .page_flag      = __PAGE_KERNEL_LARGE_EXEC,
                .kernpg_flag    = _KERNPG_TABLE_NOENC,
        };
        unsigned long mstart, mend;
        pgd_t *level4p;
        int result;
        int i;

        level4p = (pgd_t *)__va(start_pgtable);
        clear_page(level4p);

        if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT)) {
                info.page_flag   |= _PAGE_ENC;
                info.kernpg_flag |= _PAGE_ENC;
        }

        if (direct_gbpages)
                info.direct_gbpages = true;

        for (i = 0; i < nr_pfn_mapped; i++) {
                mstart = pfn_mapped[i].start << PAGE_SHIFT;
                mend   = pfn_mapped[i].end << PAGE_SHIFT;

                result = kernel_ident_mapping_init(&info,
                                                 level4p, mstart, mend);
                if (result)
                        return result;
        }

        /*
         * segments's mem ranges could be outside 0 ~ max_pfn,
         * for example when jump back to original kernel from kexeced kernel.
         * or first kernel is booted with user mem map, and second kernel
         * could be loaded out of that range.
         */
        for (i = 0; i < image->nr_segments; i++) {
                mstart = image->segment[i].mem;
                mend   = mstart + image->segment[i].memsz;

                result = kernel_ident_mapping_init(&info,
                                                 level4p, mstart, mend);

                if (result)
                        return result;
        }

        /*
         * Prepare EFI systab and ACPI tables for kexec kernel since they are
         * not covered by pfn_mapped.
         */
        result = map_efi_systab(&info, level4p);
        if (result)
                return result;

        result = map_acpi_tables(&info, level4p);
        if (result)
                return result;

        return init_transition_pgtable(image, level4p);
}

static void load_segments(void)
{
        __asm__ __volatile__ (
                "\tmovl %0,%%ds\n"
                "\tmovl %0,%%es\n"
                "\tmovl %0,%%ss\n"
                "\tmovl %0,%%fs\n"
                "\tmovl %0,%%gs\n"
                : : "a" (__KERNEL_DS) : "memory"
                );
}

int machine_kexec_prepare(struct kimage *image)
{
        unsigned long start_pgtable;
        int result;

        /* Calculate the offsets */
        start_pgtable = page_to_pfn(image->control_code_page) << PAGE_SHIFT;

        /* Setup the identity mapped 64bit page table */
        result = init_pgtable(image, start_pgtable);
        if (result)
                return result;

        return 0;
}

void machine_kexec_cleanup(struct kimage *image)
{
        free_transition_pgtable(image);
}

/*
 * Do not allocate memory (or fail in any way) in machine_kexec().
 * We are past the point of no return, committed to rebooting now.
 */
void machine_kexec(struct kimage *image)
{
        unsigned long page_list[PAGES_NR];
        void *control_page;
        int save_ftrace_enabled;

#ifdef CONFIG_KEXEC_JUMP
        if (image->preserve_context)
                save_processor_state();
#endif

        save_ftrace_enabled = __ftrace_enabled_save();

        /* Interrupts aren't acceptable while we reboot */
        local_irq_disable();
        hw_breakpoint_disable();
        cet_disable();

        if (image->preserve_context) {
#ifdef CONFIG_X86_IO_APIC
                /*
                 * We need to put APICs in legacy mode so that we can
                 * get timer interrupts in second kernel. kexec/kdump
                 * paths already have calls to restore_boot_irq_mode()
                 * in one form or other. kexec jump path also need one.
                 */
                clear_IO_APIC();
                restore_boot_irq_mode();
#endif
        }

        control_page = page_address(image->control_code_page) + PAGE_SIZE;
        __memcpy(control_page, relocate_kernel, KEXEC_CONTROL_CODE_MAX_SIZE);

        page_list[PA_CONTROL_PAGE] = virt_to_phys(control_page);
        page_list[VA_CONTROL_PAGE] = (unsigned long)control_page;
        page_list[PA_TABLE_PAGE] =
          (unsigned long)__pa(page_address(image->control_code_page));

        if (image->type == KEXEC_TYPE_DEFAULT)
                page_list[PA_SWAP_PAGE] = (page_to_pfn(image->swap_page)
                                                << PAGE_SHIFT);

        /*
         * The segment registers are funny things, they have both a
         * visible and an invisible part.  Whenever the visible part is
         * set to a specific selector, the invisible part is loaded
         * with from a table in memory.  At no other time is the
         * descriptor table in memory accessed.
         *
         * I take advantage of this here by force loading the
         * segments, before I zap the gdt with an invalid value.
         */
        load_segments();
        /*
         * The gdt & idt are now invalid.
         * If you want to load them you must set up your own idt & gdt.
         */
        native_idt_invalidate();
        native_gdt_invalidate();

        /* now call it */
        image->start = relocate_kernel((unsigned long)image->head,
                                       (unsigned long)page_list,
                                       image->start,
                                       image->preserve_context,
                                       cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT));

#ifdef CONFIG_KEXEC_JUMP
        if (image->preserve_context)
                restore_processor_state();
#endif

        __ftrace_enabled_restore(save_ftrace_enabled);
}

/* arch-dependent functionality related to kexec file-based syscall */

#ifdef CONFIG_KEXEC_FILE
void *arch_kexec_kernel_image_load(struct kimage *image)
{
        vfree(image->elf_headers);
        image->elf_headers = NULL;

        if (!image->fops || !image->fops->load)
                return ERR_PTR(-ENOEXEC);

        return image->fops->load(image, image->kernel_buf,
                                 image->kernel_buf_len, image->initrd_buf,
                                 image->initrd_buf_len, image->cmdline_buf,
                                 image->cmdline_buf_len);
}

/*
 * Apply purgatory relocations.
 *
 * @pi:         Purgatory to be relocated.
 * @section:    Section relocations applying to.
 * @relsec:     Section containing RELAs.
 * @symtabsec:  Corresponding symtab.
 *
 * TODO: Some of the code belongs to generic code. Move that in kexec.c.
 */
int arch_kexec_apply_relocations_add(struct purgatory_info *pi,
                                     Elf_Shdr *section, const Elf_Shdr *relsec,
                                     const Elf_Shdr *symtabsec)
{
        unsigned int i;
        Elf64_Rela *rel;
        Elf64_Sym *sym;
        void *location;
        unsigned long address, sec_base, value;
        const char *strtab, *name, *shstrtab;
        const Elf_Shdr *sechdrs;

        /* String & section header string table */
        sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;
        strtab = (char *)pi->ehdr + sechdrs[symtabsec->sh_link].sh_offset;
        shstrtab = (char *)pi->ehdr + sechdrs[pi->ehdr->e_shstrndx].sh_offset;

        rel = (void *)pi->ehdr + relsec->sh_offset;

        pr_debug("Applying relocate section %s to %u\n",
                 shstrtab + relsec->sh_name, relsec->sh_info);

        for (i = 0; i < relsec->sh_size / sizeof(*rel); i++) {

                /*
                 * rel[i].r_offset contains byte offset from beginning
                 * of section to the storage unit affected.
                 *
                 * This is location to update. This is temporary buffer
                 * where section is currently loaded. This will finally be
                 * loaded to a different address later, pointed to by
                 * ->sh_addr. kexec takes care of moving it
                 *  (kexec_load_segment()).
                 */
                location = pi->purgatory_buf;
                location += section->sh_offset;
                location += rel[i].r_offset;

                /* Final address of the location */
                address = section->sh_addr + rel[i].r_offset;

                /*
                 * rel[i].r_info contains information about symbol table index
                 * w.r.t which relocation must be made and type of relocation
                 * to apply. ELF64_R_SYM() and ELF64_R_TYPE() macros get
                 * these respectively.
                 */
                sym = (void *)pi->ehdr + symtabsec->sh_offset;
                sym += ELF64_R_SYM(rel[i].r_info);

                if (sym->st_name)
                        name = strtab + sym->st_name;
                else
                        name = shstrtab + sechdrs[sym->st_shndx].sh_name;

                pr_debug("Symbol: %s info: %02x shndx: %02x value=%llx size: %llx\n",
                         name, sym->st_info, sym->st_shndx, sym->st_value,
                         sym->st_size);

                if (sym->st_shndx == SHN_UNDEF) {
                        pr_err("Undefined symbol: %s\n", name);
                        return -ENOEXEC;
                }

                if (sym->st_shndx == SHN_COMMON) {
                        pr_err("symbol '%s' in common section\n", name);
                        return -ENOEXEC;
                }

                if (sym->st_shndx == SHN_ABS)
                        sec_base = 0;
                else if (sym->st_shndx >= pi->ehdr->e_shnum) {
                        pr_err("Invalid section %d for symbol %s\n",
                               sym->st_shndx, name);
                        return -ENOEXEC;
                } else
                        sec_base = pi->sechdrs[sym->st_shndx].sh_addr;

                value = sym->st_value;
                value += sec_base;
                value += rel[i].r_addend;

                switch (ELF64_R_TYPE(rel[i].r_info)) {
                case R_X86_64_NONE:
                        break;
                case R_X86_64_64:
                        *(u64 *)location = value;
                        break;
                case R_X86_64_32:
                        *(u32 *)location = value;
                        if (value != *(u32 *)location)
                                goto overflow;
                        break;
                case R_X86_64_32S:
                        *(s32 *)location = value;
                        if ((s64)value != *(s32 *)location)
                                goto overflow;
                        break;
                case R_X86_64_PC32:
                case R_X86_64_PLT32:
                        value -= (u64)address;
                        *(u32 *)location = value;
                        break;
                default:
                        pr_err("Unknown rela relocation: %llu\n",
                               ELF64_R_TYPE(rel[i].r_info));
                        return -ENOEXEC;
                }
        }
        return 0;

overflow:
        pr_err("Overflow in relocation type %d value 0x%lx\n",
               (int)ELF64_R_TYPE(rel[i].r_info), value);
        return -ENOEXEC;
}
#endif /* CONFIG_KEXEC_FILE */

static int
kexec_mark_range(unsigned long start, unsigned long end, bool protect)
{
        struct page *page;
        unsigned int nr_pages;

        /*
         * For physical range: [start, end]. We must skip the unassigned
         * crashk resource with zero-valued "end" member.
         */
        if (!end || start > end)
                return 0;

        page = pfn_to_page(start >> PAGE_SHIFT);
        nr_pages = (end >> PAGE_SHIFT) - (start >> PAGE_SHIFT) + 1;
        if (protect)
                return set_pages_ro(page, nr_pages);
        else
                return set_pages_rw(page, nr_pages);
}

static void kexec_mark_crashkres(bool protect)
{
        unsigned long control;

        kexec_mark_range(crashk_low_res.start, crashk_low_res.end, protect);

        /* Don't touch the control code page used in crash_kexec().*/
        control = PFN_PHYS(page_to_pfn(kexec_crash_image->control_code_page));
        /* Control code page is located in the 2nd page. */
        kexec_mark_range(crashk_res.start, control + PAGE_SIZE - 1, protect);
        control += KEXEC_CONTROL_PAGE_SIZE;
        kexec_mark_range(control, crashk_res.end, protect);
}

void arch_kexec_protect_crashkres(void)
{
        kexec_mark_crashkres(true);
}

void arch_kexec_unprotect_crashkres(void)
{
        kexec_mark_crashkres(false);
}

/*
 * During a traditional boot under SME, SME will encrypt the kernel,
 * so the SME kexec kernel also needs to be un-encrypted in order to
 * replicate a normal SME boot.
 *
 * During a traditional boot under SEV, the kernel has already been
 * loaded encrypted, so the SEV kexec kernel needs to be encrypted in
 * order to replicate a normal SEV boot.
 */
int arch_kexec_post_alloc_pages(void *vaddr, unsigned int pages, gfp_t gfp)
{
        if (!cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT))
                return 0;

        /*
         * If host memory encryption is active we need to be sure that kexec
         * pages are not encrypted because when we boot to the new kernel the
         * pages won't be accessed encrypted (initially).
         */
        return set_memory_decrypted((unsigned long)vaddr, pages);
}

void arch_kexec_pre_free_pages(void *vaddr, unsigned int pages)
{
        if (!cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT))
                return;

        /*
         * If host memory encryption is active we need to reset the pages back
         * to being an encrypted mapping before freeing them.
         */
        set_memory_encrypted((unsigned long)vaddr, pages);
}