ARM: 7487/1: mm: avoid setting nG bit for user mappings that aren't present
Swap entries are encoding in ptes such that !pte_present(pte) and pte_file(pte). The remaining bits of the descriptor are used to identify the swapfile and offset within it to the swap entry. When writing such a pte for a user virtual address, set_pte_at unconditionally sets the nG bit, which (in the case of LPAE) will corrupt the swapfile offset and lead to a BUG: [ 140.494067] swap_free: Unused swap offset entry 000763b4 [ 140.509989] BUG: Bad page map in process rs:main Q:Reg pte:0ec76800 pmd:8f92e003 This patch fixes the problem by only setting the nG bit for user mappings that are actually present. Cc: <stable@vger.kernel.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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@ -195,25 +195,6 @@ static inline pte_t *pmd_page_vaddr(pmd_t pmd)
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#define pte_clear(mm,addr,ptep) set_pte_ext(ptep, __pte(0), 0)
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#if __LINUX_ARM_ARCH__ < 6
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static inline void __sync_icache_dcache(pte_t pteval)
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{
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}
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#else
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extern void __sync_icache_dcache(pte_t pteval);
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#endif
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static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
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pte_t *ptep, pte_t pteval)
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{
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if (addr >= TASK_SIZE)
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set_pte_ext(ptep, pteval, 0);
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else {
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__sync_icache_dcache(pteval);
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set_pte_ext(ptep, pteval, PTE_EXT_NG);
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}
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}
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#define pte_none(pte) (!pte_val(pte))
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#define pte_present(pte) (pte_val(pte) & L_PTE_PRESENT)
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#define pte_write(pte) (!(pte_val(pte) & L_PTE_RDONLY))
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@ -226,6 +207,27 @@ static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
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((pte_val(pte) & (L_PTE_PRESENT | L_PTE_USER)) == \
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(L_PTE_PRESENT | L_PTE_USER))
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#if __LINUX_ARM_ARCH__ < 6
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static inline void __sync_icache_dcache(pte_t pteval)
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{
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}
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#else
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extern void __sync_icache_dcache(pte_t pteval);
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#endif
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static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
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pte_t *ptep, pte_t pteval)
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{
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unsigned long ext = 0;
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if (addr < TASK_SIZE && pte_present_user(pteval)) {
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__sync_icache_dcache(pteval);
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ext |= PTE_EXT_NG;
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}
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set_pte_ext(ptep, pteval, ext);
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}
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#define PTE_BIT_FUNC(fn,op) \
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static inline pte_t pte_##fn(pte_t pte) { pte_val(pte) op; return pte; }
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@ -231,8 +231,6 @@ void __sync_icache_dcache(pte_t pteval)
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struct page *page;
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struct address_space *mapping;
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if (!pte_present_user(pteval))
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return;
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if (cache_is_vipt_nonaliasing() && !pte_exec(pteval))
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/* only flush non-aliasing VIPT caches for exec mappings */
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return;
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