arm64: debug: Don't propagate UNKNOWN FAR into si_code for debug signals (b9a4b9d0) · Commits · 戴 / test

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:

Mark Rutland <mark.rutland@arm.com> Signed-off-by:

Will Deacon <will.deacon@arm.com> Signed-off-by:

Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/mm/fault.c

+5 −4

Original line number	Diff line number	Diff line
		@@ -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_exception(unsigned long addr,
		if (interrupts_enabled(regs))
		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();

		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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