![Jinbum Park](/assets/img/avatar_default.png)
idmap_pgd, arch_phys_to_idmap_offset are setup once while init stage, and never changed after that. so, it is good candidate for __ro_after_init. Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Jinbum Park <jinb.park7@gmail.com> Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
139 lines
3.4 KiB
C
139 lines
3.4 KiB
C
// 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/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)
|
|
{
|
|
pud_t *pud = pud_offset(pgd, 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 */
|
|
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
|
|
}
|