| Message ID | 20190301132809.24653-2-will.deacon@arm.com |
|---|---|
| State | Accepted |
| Commit | b9a4b9d084d978f80eb9210727c81804588b42ff |
| Headers | show |
| Series | [01/10] arm64: debug: Don't propagate UNKNOWN FAR into si_code for debug signals | expand |
On Fri, Mar 01, 2019 at 01:28:00PM +0000, Will Deacon wrote: > 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> > Signed-off-by: Will Deacon <will.deacon@arm.com> Reviewed-by: Mark Rutland <mark.rutland@arm.com> Mark. > --- > arch/arm64/mm/fault.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c > index efb7b2cbead5..ef46925096f0 100644 > --- 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_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; > } > > -- > 2.11.0 >
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index efb7b2cbead5..ef46925096f0 100644 --- 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_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; }
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> Signed-off-by: Will Deacon <will.deacon@arm.com> --- arch/arm64/mm/fault.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) -- 2.11.0