4.9-stable review patch. If anyone has any objections, please let me know.
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From: Chintan Pandya cpandya@codeaurora.org
commit 785a19f9d1dd8a4ab2d0633be4656653bd3de1fc upstream.
The following kernel panic was observed on ARM64 platform due to a stale TLB entry.
1. ioremap with 4K size, a valid pte page table is set. 2. iounmap it, its pte entry is set to 0. 3. ioremap the same address with 2M size, update its pmd entry with a new value. 4. CPU may hit an exception because the old pmd entry is still in TLB, which leads to a kernel panic.
Commit b6bdb7517c3d ("mm/vmalloc: add interfaces to free unmapped page table") has addressed this panic by falling to pte mappings in the above case on ARM64.
To support pmd mappings in all cases, TLB purge needs to be performed in this case on ARM64.
Add a new arg, 'addr', to pud_free_pmd_page() and pmd_free_pte_page() so that TLB purge can be added later in seprate patches.
[toshi.kani@hpe.com: merge changes, rewrite patch description] Fixes: 28ee90fe6048 ("x86/mm: implement free pmd/pte page interfaces") Signed-off-by: Chintan Pandya cpandya@codeaurora.org Signed-off-by: Toshi Kani toshi.kani@hpe.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Cc: mhocko@suse.com Cc: akpm@linux-foundation.org Cc: hpa@zytor.com Cc: linux-mm@kvack.org Cc: linux-arm-kernel@lists.infradead.org Cc: Will Deacon will.deacon@arm.com Cc: Joerg Roedel joro@8bytes.org Cc: stable@vger.kernel.org Cc: Andrew Morton akpm@linux-foundation.org Cc: Michal Hocko mhocko@suse.com Cc: "H. Peter Anvin" hpa@zytor.com Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20180627141348.21777-3-toshi.kani@hpe.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/arm64/mm/mmu.c | 4 ++-- arch/x86/mm/pgtable.c | 12 +++++++----- include/asm-generic/pgtable.h | 8 ++++---- lib/ioremap.c | 4 ++-- 4 files changed, 15 insertions(+), 13 deletions(-)
--- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -804,12 +804,12 @@ int pmd_clear_huge(pmd_t *pmd) return 1; }
-int pud_free_pmd_page(pud_t *pud) +int pud_free_pmd_page(pud_t *pud, unsigned long addr) { return pud_none(*pud); }
-int pmd_free_pte_page(pmd_t *pmd) +int pmd_free_pte_page(pmd_t *pmd, unsigned long addr) { return pmd_none(*pmd); } --- a/arch/x86/mm/pgtable.c +++ b/arch/x86/mm/pgtable.c @@ -657,11 +657,12 @@ int pmd_clear_huge(pmd_t *pmd) /** * pud_free_pmd_page - Clear pud entry and free pmd page. * @pud: Pointer to a PUD. + * @addr: Virtual address associated with pud. * * Context: The pud range has been unmaped and TLB purged. * Return: 1 if clearing the entry succeeded. 0 otherwise. */ -int pud_free_pmd_page(pud_t *pud) +int pud_free_pmd_page(pud_t *pud, unsigned long addr) { pmd_t *pmd; int i; @@ -672,7 +673,7 @@ int pud_free_pmd_page(pud_t *pud) pmd = (pmd_t *)pud_page_vaddr(*pud);
for (i = 0; i < PTRS_PER_PMD; i++) - if (!pmd_free_pte_page(&pmd[i])) + if (!pmd_free_pte_page(&pmd[i], addr + (i * PMD_SIZE))) return 0;
pud_clear(pud); @@ -684,11 +685,12 @@ int pud_free_pmd_page(pud_t *pud) /** * pmd_free_pte_page - Clear pmd entry and free pte page. * @pmd: Pointer to a PMD. + * @addr: Virtual address associated with pmd. * * Context: The pmd range has been unmaped and TLB purged. * Return: 1 if clearing the entry succeeded. 0 otherwise. */ -int pmd_free_pte_page(pmd_t *pmd) +int pmd_free_pte_page(pmd_t *pmd, unsigned long addr) { pte_t *pte;
@@ -704,7 +706,7 @@ int pmd_free_pte_page(pmd_t *pmd)
#else /* !CONFIG_X86_64 */
-int pud_free_pmd_page(pud_t *pud) +int pud_free_pmd_page(pud_t *pud, unsigned long addr) { return pud_none(*pud); } @@ -713,7 +715,7 @@ int pud_free_pmd_page(pud_t *pud) * Disable free page handling on x86-PAE. This assures that ioremap() * does not update sync'd pmd entries. See vmalloc_sync_one(). */ -int pmd_free_pte_page(pmd_t *pmd) +int pmd_free_pte_page(pmd_t *pmd, unsigned long addr) { return pmd_none(*pmd); } --- a/include/asm-generic/pgtable.h +++ b/include/asm-generic/pgtable.h @@ -779,8 +779,8 @@ int pud_set_huge(pud_t *pud, phys_addr_t int pmd_set_huge(pmd_t *pmd, phys_addr_t addr, pgprot_t prot); int pud_clear_huge(pud_t *pud); int pmd_clear_huge(pmd_t *pmd); -int pud_free_pmd_page(pud_t *pud); -int pmd_free_pte_page(pmd_t *pmd); +int pud_free_pmd_page(pud_t *pud, unsigned long addr); +int pmd_free_pte_page(pmd_t *pmd, unsigned long addr); #else /* !CONFIG_HAVE_ARCH_HUGE_VMAP */ static inline int pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot) { @@ -798,11 +798,11 @@ static inline int pmd_clear_huge(pmd_t * { return 0; } -static inline int pud_free_pmd_page(pud_t *pud) +static inline int pud_free_pmd_page(pud_t *pud, unsigned long addr) { return 0; } -static inline int pmd_free_pte_page(pmd_t *pmd) +static inline int pmd_free_pte_page(pmd_t *pmd, unsigned long addr) { return 0; } --- a/lib/ioremap.c +++ b/lib/ioremap.c @@ -84,7 +84,7 @@ static inline int ioremap_pmd_range(pud_ if (ioremap_pmd_enabled() && ((next - addr) == PMD_SIZE) && IS_ALIGNED(phys_addr + addr, PMD_SIZE) && - pmd_free_pte_page(pmd)) { + pmd_free_pte_page(pmd, addr)) { if (pmd_set_huge(pmd, phys_addr + addr, prot)) continue; } @@ -111,7 +111,7 @@ static inline int ioremap_pud_range(pgd_ if (ioremap_pud_enabled() && ((next - addr) == PUD_SIZE) && IS_ALIGNED(phys_addr + addr, PUD_SIZE) && - pud_free_pmd_page(pud)) { + pud_free_pmd_page(pud, addr)) { if (pud_set_huge(pud, phys_addr + addr, prot)) continue; }