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mmu: arm64: fix ability to write to protected memory

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Use the mem_text_address_writeable function if
CONFIG_KERNEL_TEXT_RDONLY is specified. Modify the
page table entry rather than the pmd, depending
on pmd type.

Change-Id: I04390a9b7376b299161842e87150802da2d4d728
Signed-off-by: Neil Leeder <nleeder@codeaurora.org>
This commit is contained in:
Laura Abbott 2014-11-26 11:53:02 -05:00 committed by Neil Leeder
parent de4cd7bbca
commit 4fad4d37bd
1 changed files with 15 additions and 6 deletions
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21
arch/arm64/mm/mmu.c
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@ -75,7 +75,9 @@ static struct cachepolicy cache_policies[] __initdata = {
#ifdef CONFIG_STRICT_MEMORY_RWX
static struct {
pmd_t *pmd;
pte_t *pte;
pmd_t saved_pmd;
pte_t saved_pte;
bool made_writeable;
} mem_unprotect;
@ -126,11 +128,15 @@ void mem_text_address_writeable(u64 addr)
mem_unprotect.pmd = pmd_offset(pud, addr);
addr_aligned = addr & PAGE_MASK;
mem_unprotect.saved_pmd = *mem_unprotect.pmd;
if ((mem_unprotect.saved_pmd & PMD_TYPE_MASK) != PMD_TYPE_SECT)
return;
set_pmd(mem_unprotect.pmd,
__pmd(__pa(addr_aligned) | prot_sect_kernel));
if ((mem_unprotect.saved_pmd & PMD_TYPE_MASK) == PMD_TYPE_SECT) {
set_pmd(mem_unprotect.pmd,
__pmd(__pa(addr_aligned) | prot_sect_kernel));
} else {
mem_unprotect.pte = pte_offset_kernel(mem_unprotect.pmd, addr);
mem_unprotect.saved_pte = *mem_unprotect.pte;
set_pte(mem_unprotect.pte, pfn_pte(__pa(addr) >> PAGE_SHIFT,
PAGE_KERNEL_EXEC));
}
flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
mem_unprotect.made_writeable = 1;
@ -140,7 +146,10 @@ void mem_text_address_writeable(u64 addr)
void mem_text_address_restore(u64 addr)
{
if (mem_unprotect.made_writeable) {
*mem_unprotect.pmd = mem_unprotect.saved_pmd;
if ((mem_unprotect.saved_pmd & PMD_TYPE_MASK) == PMD_TYPE_SECT)
*mem_unprotect.pmd = mem_unprotect.saved_pmd;
else
*mem_unprotect.pte = mem_unprotect.saved_pte;
flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
}
}