[PATCH 20/25] powerpc: Handle exceptions caused by pkey violation
From: Ram Pai <hidden>
Date: 2017-09-08 22:47:19
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Linus Torvalds
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 <redacted> --- arch/powerpc/mm/fault.c | 37 ++++++++++++++++++++++++++++++++----- 1 files changed, 32 insertions(+), 5 deletions(-)
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 4797d08..a16bc43 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c@@ -145,6 +145,23 @@ static noinline int bad_area(struct pt_regs *regs, unsigned long address) return __bad_area(regs, address, SEGV_MAPERR); } +static int bad_page_fault_exception(struct pt_regs *regs, unsigned long address, + int si_code) +{ + int sig = SIGBUS; + int code = BUS_OBJERR; + +#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS + if (si_code & DSISR_KEYFAULT) { + sig = SIGSEGV; + code = SEGV_PKUERR; + } +#endif /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */ + + _exception(sig, regs, code, address); + return 0; +} + static int do_sigbus(struct pt_regs *regs, unsigned long address, unsigned int fault) {
@@ -391,11 +408,9 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address, return 0; if (unlikely(page_fault_is_bad(error_code))) { - if (is_user) { - _exception(SIGBUS, regs, BUS_OBJERR, address); - return 0; - } - return SIGBUS; + if (!is_user) + return SIGBUS; + return bad_page_fault_exception(regs, address, error_code); } /* Additional sanity check(s) */
@@ -492,6 +507,18 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address, if (unlikely(access_error(is_write, is_exec, vma))) return bad_area(regs, address); +#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS + if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE, + is_exec, 0)) + return __bad_area(regs, address, SEGV_PKUERR); +#endif /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */ + + + /* handle_mm_fault() needs to know if its a instruction access + * fault. + */ + if (is_exec) + flags |= FAULT_FLAG_INSTRUCTION; /* * If for any reason at all we couldn't handle the fault, * make sure we exit gracefully rather than endlessly redo
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1.7.1