diff options
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/powerpc/include/asm/mmu.h | 9 | ||||
| -rw-r--r-- | arch/powerpc/mm/book3s64/hash_utils.c | 24 | ||||
| -rw-r--r-- | arch/powerpc/mm/fault.c | 83 |
3 files changed, 60 insertions, 56 deletions
diff --git a/arch/powerpc/include/asm/mmu.h b/arch/powerpc/include/asm/mmu.h index 0699cfeeb8c9..cf2a08bfd5cd 100644 --- a/arch/powerpc/include/asm/mmu.h +++ b/arch/powerpc/include/asm/mmu.h @@ -291,15 +291,6 @@ static inline bool early_radix_enabled(void) } #endif -#ifdef CONFIG_PPC_MEM_KEYS -extern u16 get_mm_addr_key(struct mm_struct *mm, unsigned long address); -#else -static inline u16 get_mm_addr_key(struct mm_struct *mm, unsigned long address) -{ - return 0; -} -#endif /* CONFIG_PPC_MEM_KEYS */ - #ifdef CONFIG_STRICT_KERNEL_RWX static inline bool strict_kernel_rwx_enabled(void) { diff --git a/arch/powerpc/mm/book3s64/hash_utils.c b/arch/powerpc/mm/book3s64/hash_utils.c index 8ed2411c3f39..e951e87a974d 100644 --- a/arch/powerpc/mm/book3s64/hash_utils.c +++ b/arch/powerpc/mm/book3s64/hash_utils.c @@ -1671,30 +1671,6 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned long address, hash_preload(vma->vm_mm, address, is_exec, trap); } -#ifdef CONFIG_PPC_MEM_KEYS -/* - * Return the protection key associated with the given address and the - * mm_struct. - */ -u16 get_mm_addr_key(struct mm_struct *mm, unsigned long address) -{ - pte_t *ptep; - u16 pkey = 0; - unsigned long flags; - - if (!mm || !mm->pgd) - return 0; - - local_irq_save(flags); - ptep = find_linux_pte(mm->pgd, address, NULL, NULL); - if (ptep) - pkey = pte_to_pkey_bits(pte_val(READ_ONCE(*ptep))); - local_irq_restore(flags); - - return pkey; -} -#endif /* CONFIG_PPC_MEM_KEYS */ - #ifdef CONFIG_PPC_TRANSACTIONAL_MEM static inline void tm_flush_hash_page(int local) { diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c index 84af6c8eecf7..8e529e4708e1 100644 --- a/arch/powerpc/mm/fault.c +++ b/arch/powerpc/mm/fault.c @@ -118,9 +118,34 @@ static noinline int bad_area(struct pt_regs *regs, unsigned long address) return __bad_area(regs, address, SEGV_MAPERR); } -static int bad_key_fault_exception(struct pt_regs *regs, unsigned long address, - int pkey) +#ifdef CONFIG_PPC_MEM_KEYS +static noinline int bad_access_pkey(struct pt_regs *regs, unsigned long address, + struct vm_area_struct *vma) { + struct mm_struct *mm = current->mm; + int pkey; + + /* + * We don't try to fetch the pkey from page table because reading + * page table without locking doesn't guarantee stable pte value. + * Hence the pkey value that we return to userspace can be different + * from the pkey that actually caused access error. + * + * It does *not* guarantee that the VMA we find here + * was the one that we faulted on. + * + * 1. T1 : mprotect_key(foo, PAGE_SIZE, pkey=4); + * 2. T1 : set AMR to deny access to pkey=4, touches, page + * 3. T1 : faults... + * 4. T2: mprotect_key(foo, PAGE_SIZE, pkey=5); + * 5. T1 : enters fault handler, takes mmap_sem, etc... + * 6. T1 : reaches here, sees vma_pkey(vma)=5, when we really + * faulted on a pte with its pkey=4. + */ + pkey = vma_pkey(vma); + + up_read(&mm->mmap_sem); + /* * If we are in kernel mode, bail out with a SEGV, this will * be caught by the assembly which will restore the non-volatile @@ -133,6 +158,7 @@ static int bad_key_fault_exception(struct pt_regs *regs, unsigned long address, return 0; } +#endif static noinline int bad_access(struct pt_regs *regs, unsigned long address) { @@ -289,8 +315,31 @@ static bool bad_stack_expansion(struct pt_regs *regs, unsigned long address, return false; } -static bool access_error(bool is_write, bool is_exec, - struct vm_area_struct *vma) +#ifdef CONFIG_PPC_MEM_KEYS +static bool access_pkey_error(bool is_write, bool is_exec, bool is_pkey, + struct vm_area_struct *vma) +{ + /* + * Read or write was blocked by protection keys. This is + * always an unconditional error and can never result in + * a follow-up action to resolve the fault, like a COW. + */ + if (is_pkey) + return true; + + /* + * Make sure to check the VMA so that we do not perform + * faults just to hit a pkey fault as soon as we fill in a + * page. Only called for current mm, hence foreign == 0 + */ + if (!arch_vma_access_permitted(vma, is_write, is_exec, 0)) + return true; + + return false; +} +#endif + +static bool access_error(bool is_write, bool is_exec, struct vm_area_struct *vma) { /* * Allow execution from readable areas if the MMU does not @@ -483,10 +532,6 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address, perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); - if (error_code & DSISR_KEYFAULT) - return bad_key_fault_exception(regs, address, - get_mm_addr_key(mm, address)); - /* * We want to do this outside mmap_sem, because reading code around nip * can result in fault, which will cause a deadlock when called with @@ -555,6 +600,13 @@ retry: return bad_area(regs, address); good_area: + +#ifdef CONFIG_PPC_MEM_KEYS + if (unlikely(access_pkey_error(is_write, is_exec, + (error_code & DSISR_KEYFAULT), vma))) + return bad_access_pkey(regs, address, vma); +#endif /* CONFIG_PPC_MEM_KEYS */ + if (unlikely(access_error(is_write, is_exec, vma))) return bad_access(regs, address); @@ -565,21 +617,6 @@ good_area: */ fault = handle_mm_fault(vma, address, flags); -#ifdef CONFIG_PPC_MEM_KEYS - /* - * we skipped checking for access error due to key earlier. - * Check that using handle_mm_fault error return. - */ - if (unlikely(fault & VM_FAULT_SIGSEGV) && - !arch_vma_access_permitted(vma, is_write, is_exec, 0)) { - - int pkey = vma_pkey(vma); - - up_read(&mm->mmap_sem); - return bad_key_fault_exception(regs, address, pkey); - } -#endif /* CONFIG_PPC_MEM_KEYS */ - major |= fault & VM_FAULT_MAJOR; if (fault_signal_pending(fault, regs)) |