From: Mark Rutland <mark.rutland@arm.com>
To: linux-arm-kernel@lists.infradead.org
Cc: Mark Rutland <mark.rutland@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Robin Murphy <robin.murphy@arm.com>,
James Morse <james.morse@arm.com>,
Will Deacon <will.deacon@kernel.org>
Subject: [PATCH] arm64: mm: fix spurious fault detection
Date: Fri, 4 Oct 2019 14:58:47 +0100 [thread overview]
Message-ID: <20191004135847.39326-1-mark.rutland@arm.com> (raw)
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 <mark.rutland@arm.com>
Reported-by: Robin Murphy <robin.murphy@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will.deacon@kernel.org>
---
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 115d7a0e4b08..b0074b91913b 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -266,7 +266,7 @@ 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;
}
--
2.11.0
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next reply other threads:[~2019-10-04 13:58 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-04 13:58 Mark Rutland [this message]
2019-10-04 14:00 ` [PATCH] arm64: mm: fix spurious fault detection Mark Rutland
2019-10-05 9:06 ` Anshuman Khandual
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