// SPDX-License-Identifier: GPL-2.0
/*
* x86_64 specific EFI support functions
* Based on Extensible Firmware Interface Specification version 1.0
*
* Copyright (C) 2005-2008 Intel Co.
* Fenghua Yu <fenghua.yu@intel.com>
* Bibo Mao <bibo.mao@intel.com>
* Chandramouli Narayanan <mouli@linux.intel.com>
* Huang Ying <ying.huang@intel.com>
*
* Code to convert EFI to E820 map has been implemented in elilo bootloader
* based on a EFI patch by Edgar Hucek. Based on the E820 map, the page table
* is setup appropriately for EFI runtime code.
* - mouli 06/14/2007.
*
*/
#define pr_fmt(fmt) "efi: " fmt
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/types.h>
#include <linux/spinlock.h>
#include <linux/memblock.h>
#include <linux/ioport.h>
#include <linux/mc146818rtc.h>
#include <linux/efi.h>
#include <linux/export.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/reboot.h>
#include <linux/slab.h>
#include <linux/ucs2_string.h>
#include <linux/mem_encrypt.h>
#include <linux/sched/task.h>
#include <asm/setup.h>
#include <asm/page.h>
#include <asm/e820/api.h>
#include <asm/pgtable.h>
#include <asm/tlbflush.h>
#include <asm/proto.h>
#include <asm/efi.h>
#include <asm/cacheflush.h>
#include <asm/fixmap.h>
#include <asm/realmode.h>
#include <asm/time.h>
#include <asm/pgalloc.h>
/*
* We allocate runtime services regions top-down, starting from -4G, i.e.
* 0xffff_ffff_0000_0000 and limit EFI VA mapping space to 64G.
*/
static u64 efi_va = EFI_VA_START;
struct efi_scratch efi_scratch;
static void __init early_code_mapping_set_exec(int executable)
{
efi_memory_desc_t *md;
if (!(__supported_pte_mask & _PAGE_NX))
return;
/* Make EFI service code area executable */
for_each_efi_memory_desc(md) {
if (md->type == EFI_RUNTIME_SERVICES_CODE ||
md->type == EFI_BOOT_SERVICES_CODE)
efi_set_executable(md, executable);
}
}
pgd_t * __init efi_call_phys_prolog(void)
{
unsigned long vaddr, addr_pgd, addr_p4d, addr_pud;
pgd_t *save_pgd, *pgd_k, *pgd_efi;
p4d_t *p4d, *p4d_k, *p4d_efi;
pud_t *pud;
int pgd;
int n_pgds, i, j;
if (!efi_enabled(EFI_OLD_MEMMAP)) {
efi_switch_mm(&efi_mm);
return NULL;
}
early_code_mapping_set_exec(1);
n_pgds = DIV_ROUND_UP((max_pfn << PAGE_SHIFT), PGDIR_SIZE);
save_pgd = kmalloc_array(n_pgds, sizeof(*save_pgd), GFP_KERNEL);
/*
* Build 1:1 identity mapping for efi=old_map usage. Note that
* PAGE_OFFSET is PGDIR_SIZE aligned when KASLR is disabled, while
* it is PUD_SIZE ALIGNED with KASLR enabled. So for a given physical
* address X, the pud_index(X) != pud_index(__va(X)), we can only copy
* PUD entry of __va(X) to fill in pud entry of X to build 1:1 mapping.
* This means here we can only reuse the PMD tables of the direct mapping.
*/
for (pgd = 0; pgd < n_pgds; pgd++) {
addr_pgd = (unsigned long)(pgd * PGDIR_SIZE);
vaddr = (unsigned long)__va(pgd * PGDIR_SIZE);
pgd_efi = pgd_offset_k(addr_pgd);
save_pgd[pgd] = *pgd_efi;
p4d = p4d_alloc(&init_mm, pgd_efi, addr_pgd);
if (!p4d) {
pr_err("Failed to allocate p4d table!\n");
goto out;
}
for (i = 0; i < PTRS_PER_P4D; i++) {
addr_p4d = addr_pgd + i * P4D_SIZE;
p4d_efi = p4d + p4d_index(addr_p4d);
pud = pud_alloc(&init_mm, p4d_efi, addr_p4d);
if (!pud) {
pr_err("Failed to allocate pud table!\n");
goto out;
}
for (j = 0; j < PTRS_PER_PUD; j++) {
addr_pud = addr_p4d + j * PUD_SIZE;
if (addr_pud > (max_pfn << PAGE_SHIFT))
break;
vaddr = (unsigned long)__va(addr_pud);
pgd_k = pgd_offset_k(vaddr);
p4d_k = p4d_offset(pgd_k, vaddr);
pud[j] = *pud_offset(p4d_k, vaddr);
}
}
pgd_offset_k(pgd * PGDIR_SIZE)->pgd &= ~_PAGE_NX;
}
out:
__flush_tlb_all();
return save_pgd;
}
void __init efi_call_phys_epilog(pgd_t *save_pgd)
{
/*
* After the lock is released, the original page table is restored.
*/
int pgd_idx, i;
int nr_pgds;
pgd_t *pgd;
p4d_t *p4d;
pud_t *pud;
if (!efi_enabled(EFI_OLD_MEMMAP)) {
efi_switch_mm(efi_scratch.prev_mm);
return;
}
nr_pgds = DIV_ROUND_UP((max_pfn <<