Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit bd62f1fe authored by Will Deacon's avatar Will Deacon Committed by Greg Kroah-Hartman
Browse files

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



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: <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>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 4b3a3ab0

arch/arm64/mm/fault.c

+5 −4
Original line number Diff line number Diff line
@@ -827,11 +827,12 @@ 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 = debug_fault_info + DBG_ESR_EVT(esr);

	unsigned long pc = instruction_pointer(regs);

	int rv;



	/*
@@ -841,10 +842,10 @@ asmlinkage int __exception do_debug_exception(unsigned long addr, 
	if (interrupts_enabled(regs))

		trace_hardirqs_off();



	if (user_mode(regs) && instruction_pointer(regs) > TASK_SIZE)

	if (user_mode(regs) && pc > TASK_SIZE)

		arm64_apply_bp_hardening();



	if (!inf->fn(addr, esr, regs)) {

	if (!inf->fn(addr_if_watchpoint, esr, regs)) {

		rv = 1;

	} else {

		struct siginfo info;
@@ -853,7 +854,7 @@ asmlinkage int __exception do_debug_exception(unsigned long addr, 
		info.si_signo = inf->sig;

		info.si_errno = 0;

		info.si_code  = inf->code;

		info.si_addr  = (void __user *)addr;

		info.si_addr  = (void __user *)pc;

		arm64_notify_die(inf->name, regs, &info, esr);

		rv = 0;

	}