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arm64: Improve detection of user/non-user mappings in set_pte(_at)

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Commit cab15ce604 ("arm64: Introduce execute-only page access
permissions") allowed a valid user PTE to have the PTE_USER bit clear.
As a consequence, the pte_valid_not_user() macro in set_pte() was
replaced with pte_valid_global() under the assumption that only user
pages have the nG bit set. EFI mappings, however, also have the nG bit
set and set_pte() wrongly ignores issuing the DSB+ISB.

This patch reinstates the pte_valid_not_user() macro and adds the
PTE_UXN bit check since all kernel mappings have this bit set. For
clarity, pte_exec() is renamed to pte_user_exec() as it only checks for
the absence of PTE_UXN. Consequently, the user executable check in
set_pte_at() drops the pte_ng() test since pte_user_exec() is
sufficient.

Fixes: cab15ce604 ("arm64: Introduce execute-only page access permissions")
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Catalin Marinas 2017-01-27 10:54:12 +00:00 committed by Will Deacon
parent 49f6cba617
commit ec663d967b
1 changed files with 9 additions and 6 deletions
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15
arch/arm64/include/asm/pgtable.h
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@ -71,9 +71,8 @@ extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)];
#define pte_young(pte) (!!(pte_val(pte) & PTE_AF))
#define pte_special(pte) (!!(pte_val(pte) & PTE_SPECIAL))
#define pte_write(pte) (!!(pte_val(pte) & PTE_WRITE))
#define pte_exec(pte) (!(pte_val(pte) & PTE_UXN))
#define pte_user_exec(pte) (!(pte_val(pte) & PTE_UXN))
#define pte_cont(pte) (!!(pte_val(pte) & PTE_CONT))
#define pte_ng(pte) (!!(pte_val(pte) & PTE_NG))
#ifdef CONFIG_ARM64_HW_AFDBM
#define pte_hw_dirty(pte) (pte_write(pte) && !(pte_val(pte) & PTE_RDONLY))
@ -84,8 +83,12 @@ extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)];
#define pte_dirty(pte) (pte_sw_dirty(pte) || pte_hw_dirty(pte))
#define pte_valid(pte) (!!(pte_val(pte) & PTE_VALID))
#define pte_valid_global(pte) \
((pte_val(pte) & (PTE_VALID | PTE_NG)) == PTE_VALID)
/*
* Execute-only user mappings do not have the PTE_USER bit set. All valid
* kernel mappings have the PTE_UXN bit set.
*/
#define pte_valid_not_user(pte) \
((pte_val(pte) & (PTE_VALID | PTE_USER | PTE_UXN)) == (PTE_VALID | PTE_UXN))
#define pte_valid_young(pte) \
((pte_val(pte) & (PTE_VALID | PTE_AF)) == (PTE_VALID | PTE_AF))
@ -178,7 +181,7 @@ static inline void set_pte(pte_t *ptep, pte_t pte)
* Only if the new pte is valid and kernel, otherwise TLB maintenance
* or update_mmu_cache() have the necessary barriers.
*/
if (pte_valid_global(pte)) {
if (pte_valid_not_user(pte)) {
dsb(ishst);
isb();
}
@ -212,7 +215,7 @@ static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
pte_val(pte) &= ~PTE_RDONLY;
else
pte_val(pte) |= PTE_RDONLY;
if (pte_ng(pte) && pte_exec(pte) && !pte_special(pte))
if (pte_user_exec(pte) && !pte_special(pte))
__sync_icache_dcache(pte, addr);
}