[PATCH] arm64/mm: Identify user instruction aborts

[PATCH] arm64/mm: Identify user instruction aborts

[Anshuman Khandual]

We don't currently set the FAULT_FLAG_INSTRUCTION mm flag for EL0
instruction aborts. This has no functional impact, as we don't override
arch_vma_access_permitted(), and the default implementation always returns
true. However, it would be helpful to provide the flag so that it can be
consumed by tracepoints such as dax_pmd_fault.

This patch sets the FAULT_FLAG_INSTRUCTION flag for EL0 instruction aborts.

Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
---
 arch/arm64/mm/fault.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 1a7e92a..b641449 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -463,6 +463,7 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
 
 	if (is_el0_instruction_abort(esr)) {
 		vm_flags = VM_EXEC;
+		mm_flags |= FAULT_FLAG_INSTRUCTION;
 	} else if ((esr & ESR_ELx_WNR) && !(esr & ESR_ELx_CM)) {
 		vm_flags = VM_WRITE;
 		mm_flags |= FAULT_FLAG_WRITE;
-- 
2.7.4


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Re: [PATCH] arm64/mm: Identify user instruction aborts

[Catalin Marinas]

On Sun, May 05, 2019 at 09:45:12AM +0530, Anshuman Khandual wrote:
> We don't currently set the FAULT_FLAG_INSTRUCTION mm flag for EL0
> instruction aborts. This has no functional impact, as we don't override
> arch_vma_access_permitted(), and the default implementation always returns
> true. However, it would be helpful to provide the flag so that it can be
> consumed by tracepoints such as dax_pmd_fault.
> 
> This patch sets the FAULT_FLAG_INSTRUCTION flag for EL0 instruction aborts.
> 
> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will.deacon@arm.com>
> Cc: Mark Rutland <mark.rutland@arm.com>

Queued for 5.3. Thanks.

-- 
Catalin

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