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Date:   Fri, 22 Mar 2019 12:16:31 +0100
From:   Greg Kroah-Hartman <>
Cc:     Greg Kroah-Hartman <>,, Mark Rutland <>,
        Will Deacon <>,
        Catalin Marinas <>
Subject: [PATCH 5.0 172/238] arm64: debug: Dont propagate UNKNOWN FAR into si_code for debug signals

5.0-stable review patch.  If anyone has any objections, please let me know.


From: Will Deacon <>

commit b9a4b9d084d978f80eb9210727c81804588b42ff upstream.

FAR_EL1 is UNKNOWN for all debug exceptions other than those caused by
taking a hardware watchpoint. Unfortunately, if a debug handler returns
a non-zero value, then we will propagate the UNKNOWN FAR value to
userspace via the si_addr field of the SIGTRAP siginfo_t.

Instead, let's set si_addr to take on the PC of the faulting instruction,
which we have available in the current pt_regs.

Cc: <>
Reviewed-by: Mark Rutland <>
Signed-off-by: Will Deacon <>
Signed-off-by: Catalin Marinas <>
Signed-off-by: Greg Kroah-Hartman <>

 arch/arm64/mm/fault.c |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -824,11 +824,12 @@ void __init hook_debug_fault_code(int nr
 	debug_fault_info[nr].name	= name;
-asmlinkage int __exception do_debug_exception(unsigned long addr,
+asmlinkage int __exception do_debug_exception(unsigned long addr_if_watchpoint,
 					      unsigned int esr,
 					      struct pt_regs *regs)
 	const struct fault_info *inf = esr_to_debug_fault_info(esr);
+	unsigned long pc = instruction_pointer(regs);
 	int rv;
@@ -838,14 +839,14 @@ asmlinkage int __exception do_debug_exce
 	if (interrupts_enabled(regs))
-	if (user_mode(regs) && !is_ttbr0_addr(instruction_pointer(regs)))
+	if (user_mode(regs) && !is_ttbr0_addr(pc))
-	if (!inf->fn(addr, esr, regs)) {
+	if (!inf->fn(addr_if_watchpoint, esr, regs)) {
 		rv = 1;
 	} else {
 		arm64_notify_die(inf->name, regs,
-				 inf->sig, inf->code, (void __user *)addr, esr);
+				 inf->sig, inf->code, (void __user *)pc, esr);
 		rv = 0;

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