Commit b9a4b9d0 authored by Will Deacon's avatar Will Deacon Committed by Catalin Marinas

arm64: debug: Don't propagate UNKNOWN FAR into si_code for debug signals

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: <stable@vger.kernel.org>
Reviewed-by: default avatarMark Rutland <mark.rutland@arm.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 3cd0ddb3
...@@ -824,11 +824,12 @@ void __init hook_debug_fault_code(int nr, ...@@ -824,11 +824,12 @@ void __init hook_debug_fault_code(int nr,
debug_fault_info[nr].name = name; 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, unsigned int esr,
struct pt_regs *regs) struct pt_regs *regs)
{ {
const struct fault_info *inf = esr_to_debug_fault_info(esr); const struct fault_info *inf = esr_to_debug_fault_info(esr);
unsigned long pc = instruction_pointer(regs);
int rv; int rv;
/* /*
...@@ -838,14 +839,14 @@ asmlinkage int __exception do_debug_exception(unsigned long addr, ...@@ -838,14 +839,14 @@ asmlinkage int __exception do_debug_exception(unsigned long addr,
if (interrupts_enabled(regs)) if (interrupts_enabled(regs))
trace_hardirqs_off(); trace_hardirqs_off();
if (user_mode(regs) && !is_ttbr0_addr(instruction_pointer(regs))) if (user_mode(regs) && !is_ttbr0_addr(pc))
arm64_apply_bp_hardening(); arm64_apply_bp_hardening();
if (!inf->fn(addr, esr, regs)) { if (!inf->fn(addr_if_watchpoint, esr, regs)) {
rv = 1; rv = 1;
} else { } else {
arm64_notify_die(inf->name, regs, arm64_notify_die(inf->name, regs,
inf->sig, inf->code, (void __user *)addr, esr); inf->sig, inf->code, (void __user *)pc, esr);
rv = 0; rv = 0;
} }
......
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