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arm64: expose FAR_EL1 tag bits in siginfo

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The kernel currently clears the tag bits (i.e. bits 56-63) in the fault
address exposed via siginfo.si_addr and sigcontext.fault_address. However,
the tag bits may be needed by tools in order to accurately diagnose
memory errors, such as HWASan [1] or future tools based on the Memory
Tagging Extension (MTE).

Expose these bits via the arch_untagged_si_addr mechanism, so that
they are only exposed to signal handlers with the SA_EXPOSE_TAGBITS
flag set.

[1] http://clang.llvm.org/docs/HardwareAssistedAddressSanitizerDesign.html

Signed-off-by: Peter Collingbourne <pcc@google.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://linux-review.googlesource.com/id/Ia8876bad8c798e0a32df7c2ce1256c4771c81446
Link: https://lore.kernel.org/r/0010296597784267472fa13b39f8238d87a72cf8.1605904350.git.pcc@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Peter Collingbourne
2020-11-20 12:33:46 -08:00
committed by Catalin Marinas
parent 6ac05e832a
commit dceec3ff78
11 changed files with 121 additions and 72 deletions
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5
arch/arm64/kernel/debug-monitors.c
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@@ -234,9 +234,8 @@ static void send_user_sigtrap(int si_code)
if (interrupts_enabled(regs))
local_irq_enable();
arm64_force_sig_fault(SIGTRAP, si_code,
(void __user *)instruction_pointer(regs),
"User debug trap");
arm64_force_sig_fault(SIGTRAP, si_code, instruction_pointer(regs),
"User debug trap");
}
static int single_step_handler(unsigned long unused, unsigned int esr,