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// SPDX-License-Identifier: GPL-2.0
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/mm_types.h>
#include <asm/cputype.h>
#include <asm/idmap.h>
#include <asm/hwcap.h>
#include <asm/pgalloc.h>
#include <asm/pgtable.h>
#include <asm/sections.h>
#include <asm/system_info.h>
/*
* Note: accesses outside of the kernel image and the identity map area
* are not supported on any CPU using the idmap tables as its current
* page tables.
*/
pgd_t *idmap_pgd __ro_after_init;
long long arch_phys_to_idmap_offset __ro_after_init;
#ifdef CONFIG_ARM_LPAE
static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end,
unsigned long prot)
{
pmd_t *pmd;
unsigned long next;
if (pud_none_or_clear_bad(pud) || (pud_val(*pud) & L_PGD_SWAPPER)) {
pmd = pmd_alloc_one(&init_mm, addr);
if (!pmd) {
pr_warn("Failed to allocate identity pmd.\n");
return;
}
/*
* Copy the original PMD to ensure that the PMD entries for
* the kernel image are preserved.
*/
if (!pud_none(*pud))
memcpy(pmd, pmd_offset(pud, 0),
PTRS_PER_PMD * sizeof(pmd_t));
pud_populate(&init_mm, pud, pmd);
pmd += pmd_index(addr);
} else
pmd = pmd_offset(pud, addr);
do {
next = pmd_addr_end(addr, end);
*pmd = __pmd((addr & PMD_MASK) | prot);
flush_pmd_entry(pmd);
} while (pmd++, addr = next, addr != end);
}
#else /* !CONFIG_ARM_LPAE */
static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end,
unsigned long prot)
{
pmd_t *pmd = pmd_offset(pud, addr);
addr = (addr & PMD_MASK) | prot;
pmd[0] = __pmd(addr);
addr += SECTION_SIZE;
pmd[1] = __pmd(addr);
flush_pmd_entry(pmd);
}
#endif /* CONFIG_ARM_LPAE */
static void idmap_add_pud(pgd_t *pgd, unsigned long addr, unsigned long end,
unsigned long prot)
{
p4d_t *p4d = p4d_offset(pgd, addr);
pud_t *pud = pud_offset(p4d, addr);
unsigned long next;
do {
next = pud_addr_end(addr, end);
idmap_add_pmd(pud, addr, next, prot);
} while (pud++, addr = next, addr != end);
}
static void identity_mapping_add(pgd_t *pgd, const char *text_start,
const char *text_end, unsigned long prot)
{
unsigned long addr, end;
unsigned long next;
addr = virt_to_idmap(text_start);
end = virt_to_idmap(text_end);
pr_info("Setting up static identity map for 0x%lx - 0x%lx\n", addr, end);
prot |= PMD_TYPE_SECT | PMD_SECT_AP_WRITE | PMD_SECT_AF;
if (cpu_architecture() <= CPU_ARCH_ARMv5TEJ && !cpu_is_xscale_family())
prot |= PMD_BIT4;
pgd += pgd_index(addr);
do {
next = pgd_addr_end(addr, end);
idmap_add_pud(pgd, addr, next, prot);
} while (pgd++, addr = next, addr != end);
}
extern char __idmap_text_start[], __idmap_text_end[];
static int __init init_static_idmap(void)
{
idmap_pgd = pgd_alloc(&init_mm);
if (!idmap_pgd)
return -ENOMEM;
identity_mapping_add(idmap_pgd, __idmap_text_start,
__idmap_text_end, 0);
/* Flush L1 for the hardware to see this page table content */
if (!(elf_hwcap & HWCAP_LPAE))
flush_cache_louis();
return 0;
}
early_initcall(init_static_idmap);
/*
* In order to soft-boot, we need to switch to a 1:1 mapping for the
* cpu_reset functions. This will then ensure that we have predictable
* results when turning off the mmu.
*/
void setup_mm_for_reboot(void)
{
/* Switch to the identity mapping. */
cpu_switch_mm(idmap_pgd, &init_mm);
local_flush_bp_all();
#ifdef CONFIG_CPU_HAS_ASID
/*
* We don't have a clean ASID for the identity mapping, which
* may clash with virtual addresses of the previous page tables
* and therefore potentially in the TLB.
*/
local_flush_tlb_all();
#endif
}
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