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| author | John David Anglin <dave.anglin@bell.net> | 2021-11-09 00:48:16 +0300 |
|---|---|---|
| committer | Helge Deller <deller@gmx.de> | 2021-11-14 00:10:56 +0300 |
| commit | 38860b2c8bb1b92f61396eb06a63adff916fc31d (patch) | |
| tree | 121428c7e59fe17646c82b4fcd3196cf83b9ed68 /arch/parisc/include | |
| parent | f0d1cfac45abb1c47792cda19ed680c30cee22bb (diff) | |
| download | linux-38860b2c8bb1b92f61396eb06a63adff916fc31d.tar.xz | |
parisc: Flush kernel data mapping in set_pte_at() when installing pte for user page
For years, there have been random segmentation faults in userspace on
SMP PA-RISC machines. It occurred to me that this might be a problem in
set_pte_at(). MIPS and some other architectures do cache flushes when
installing PTEs with the present bit set.
Here I have adapted the code in update_mmu_cache() to flush the kernel
mapping when the kernel flush is deferred, or when the kernel mapping
may alias with the user mapping. This simplifies calls to
update_mmu_cache().
I also changed the barrier in set_pte() from a compiler barrier to a
full memory barrier. I know this change is not sufficient to fix the
problem. It might not be needed.
I have had a few days of operation with 5.14.16 to 5.15.1 and haven't
seen any random segmentation faults on rp3440 or c8000 so far.
Signed-off-by: John David Anglin <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>
Cc: stable@kernel.org # 5.12+
Diffstat (limited to 'arch/parisc/include')
| -rw-r--r-- | arch/parisc/include/asm/pgtable.h | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/arch/parisc/include/asm/pgtable.h b/arch/parisc/include/asm/pgtable.h index 7badd872f05a..3e7cf882639f 100644 --- a/arch/parisc/include/asm/pgtable.h +++ b/arch/parisc/include/asm/pgtable.h @@ -76,6 +76,8 @@ static inline void purge_tlb_entries(struct mm_struct *mm, unsigned long addr) purge_tlb_end(flags); } +extern void __update_cache(pte_t pte); + /* Certain architectures need to do special things when PTEs * within a page table are directly modified. Thus, the following * hook is made available. @@ -83,11 +85,14 @@ static inline void purge_tlb_entries(struct mm_struct *mm, unsigned long addr) #define set_pte(pteptr, pteval) \ do { \ *(pteptr) = (pteval); \ - barrier(); \ + mb(); \ } while(0) #define set_pte_at(mm, addr, pteptr, pteval) \ do { \ + if (pte_present(pteval) && \ + pte_user(pteval)) \ + __update_cache(pteval); \ *(pteptr) = (pteval); \ purge_tlb_entries(mm, addr); \ } while (0) @@ -303,6 +308,7 @@ extern unsigned long *empty_zero_page; #define pte_none(x) (pte_val(x) == 0) #define pte_present(x) (pte_val(x) & _PAGE_PRESENT) +#define pte_user(x) (pte_val(x) & _PAGE_USER) #define pte_clear(mm, addr, xp) set_pte_at(mm, addr, xp, __pte(0)) #define pmd_flag(x) (pmd_val(x) & PxD_FLAG_MASK) @@ -410,7 +416,7 @@ extern void paging_init (void); #define PG_dcache_dirty PG_arch_1 -extern void update_mmu_cache(struct vm_area_struct *, unsigned long, pte_t *); +#define update_mmu_cache(vms,addr,ptep) __update_cache(*ptep) /* Encode and de-code a swap entry */ |