From e6c2a4797e101a25eced94aa9e1fc42c30247aec Mon Sep 17 00:00:00 2001 From: Ram Pai Date: Thu, 18 Jan 2018 17:50:40 -0800 Subject: [PATCH] powerpc: Handle exceptions caused by pkey violation Handle Data and Instruction exceptions caused by memory protection-key. The CPU will detect the key fault if the HPTE is already programmed with the key. However if the HPTE is not hashed, a key fault will not be detected by the hardware. The software will detect pkey violation in such a case. Signed-off-by: Ram Pai Signed-off-by: Thiago Jung Bauermann Signed-off-by: Michael Ellerman --- arch/powerpc/include/asm/reg.h | 1 - arch/powerpc/kernel/exceptions-64s.S | 2 +- arch/powerpc/mm/fault.c | 22 ++++++++++++++++++++++ 3 files changed, 23 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h index b779f3ccd412..ffc9990e8040 100644 --- a/arch/powerpc/include/asm/reg.h +++ b/arch/powerpc/include/asm/reg.h @@ -312,7 +312,6 @@ DSISR_BAD_EXT_CTRL) #define DSISR_BAD_FAULT_64S (DSISR_BAD_FAULT_32S | \ DSISR_ATTR_CONFLICT | \ - DSISR_KEYFAULT | \ DSISR_UNSUPP_MMU | \ DSISR_PRTABLE_FAULT | \ DSISR_ICSWX_NO_CT | \ diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S index 1a4f51f35870..42a47d83282c 100644 --- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -1527,7 +1527,7 @@ USE_TEXT_SECTION() .balign IFETCH_ALIGN_BYTES do_hash_page: #ifdef CONFIG_PPC_BOOK3S_64 - lis r0,(DSISR_BAD_FAULT_64S|DSISR_DABRMATCH)@h + lis r0,(DSISR_BAD_FAULT_64S | DSISR_DABRMATCH | DSISR_KEYFAULT)@h ori r0,r0,DSISR_BAD_FAULT_64S@l and. r0,r4,r0 /* weird error? */ bne- handle_page_fault /* if not, try to insert a HPTE */ diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c index c07896c19517..6417a659b02d 100644 --- a/arch/powerpc/mm/fault.c +++ b/arch/powerpc/mm/fault.c @@ -427,6 +427,11 @@ 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) { + _exception(SIGSEGV, regs, SEGV_PKUERR, address); + return 0; + } + /* * 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 @@ -498,6 +503,23 @@ good_area: * the fault. */ fault = handle_mm_fault(vma, address, flags); + +#ifdef CONFIG_PPC_MEM_KEYS + /* + * if the HPTE is not hashed, hardware will not detect + * a key fault. Lets check if we failed because of a + * software detected key fault. + */ + if (unlikely(fault & VM_FAULT_SIGSEGV) && + !arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE, + is_exec, 0)) { + int pkey = vma_pkey(vma); + + if (likely(pkey)) + return __bad_area(regs, address, SEGV_PKUERR); + } +#endif /* CONFIG_PPC_MEM_KEYS */ + major |= fault & VM_FAULT_MAJOR; /*