From 308c51561720547a90767a2f367f5390052c51da Mon Sep 17 00:00:00 2001 From: Mark Rutland Date: Fri, 4 Oct 2019 14:58:47 +0100 Subject: [PATCH] arm64: mm: fix spurious fault detection When detecting a spurious EL1 translation fault, we attempt to compare ESR_EL1.DFSC with PAR_EL1.FST. We erroneously use FIELD_PREP() to extract PAR_EL1.FST, when we should be using FIELD_GET(). In the wise words of Robin Murphy: | FIELD_GET() is a UBFX, FIELD_PREP() is a BFI Using FIELD_PREP() means that that dfsc & ESR_ELx_FSC_TYPE is always zero, and hence not equal to ESR_ELx_FSC_FAULT. Thus we detect any unhandled translation fault as spurious. ... so let's use FIELD_GET() to ensure we don't decide all translation faults are spurious. ESR_EL1.DFSC occupies bits [5:0], and requires no shifting. Fixes: 42f91093b043332a ("arm64: mm: Ignore spurious translation faults taken from the kernel") Signed-off-by: Mark Rutland Reported-by: Robin Murphy Cc: Catalin Marinas Cc: James Morse Cc: Will Deacon Signed-off-by: Will Deacon --- arch/arm64/mm/fault.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index 6acd866f31fd..855f2a7954e6 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -275,7 +275,7 @@ static bool __kprobes is_spurious_el1_translation_fault(unsigned long addr, * If we got a different type of fault from the AT instruction, * treat the translation fault as spurious. */ - dfsc = FIELD_PREP(SYS_PAR_EL1_FST, par); + dfsc = FIELD_GET(SYS_PAR_EL1_FST, par); return (dfsc & ESR_ELx_FSC_TYPE) != ESR_ELx_FSC_FAULT; }