BACKPORT: arm64: expose FAR_EL1 tag bits in siginfo
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>
(cherry picked from commit dceec3ff78076757311d92a388d50d0251fb7dbb)
[pcc: resolved minor conflicts in arch/arm64/include/asm/exception.h and arch/arm64/mm/fault.c]
Bug: 135772972
Change-Id: Ia8876bad8c798e0a32df7c2ce1256c4771c81446
diff --git a/arch/arm64/include/asm/exception.h b/arch/arm64/include/asm/exception.h
index 0756191..7853739 100644
--- a/arch/arm64/include/asm/exception.h
+++ b/arch/arm64/include/asm/exception.h
@@ -37,7 +37,7 @@ asmlinkage void enter_from_user_mode(void);
asmlinkage void exit_to_user_mode(void);
void arm64_enter_nmi(struct pt_regs *regs);
void arm64_exit_nmi(struct pt_regs *regs);
-void do_mem_abort(unsigned long addr, unsigned int esr, struct pt_regs *regs);
+void do_mem_abort(unsigned long far, unsigned int esr, struct pt_regs *regs);
void do_undefinstr(struct pt_regs *regs);
void do_bti(struct pt_regs *regs);
asmlinkage void bad_mode(struct pt_regs *regs, int reason, unsigned int esr);