arm64: Expose ESR_EL1 information to user when SIGSEGV/SIGBUS

This information is useful for instruction emulators to detect
read/write and access size without having to decode the faulting
instruction. The current patch exports it via sigcontext (struct
esr_context) and is only valid for SIGSEGV and SIGBUS.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
diff --git a/arch/arm64/include/uapi/asm/sigcontext.h b/arch/arm64/include/uapi/asm/sigcontext.h
index 690ad51..b72cf40 100644
--- a/arch/arm64/include/uapi/asm/sigcontext.h
+++ b/arch/arm64/include/uapi/asm/sigcontext.h
@@ -53,5 +53,12 @@
 	__uint128_t vregs[32];
 };
 
+/* ESR_EL1 context */
+#define ESR_MAGIC	0x45535201
+
+struct esr_context {
+	struct _aarch64_ctx head;
+	u64 esr;
+};
 
 #endif /* _UAPI__ASM_SIGCONTEXT_H */