From: Mark Rutland <mark.rutland@arm.com> To: Will Deacon <will.deacon@arm.com> Cc: linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com, stable@vger.kernel.org Subject: Re: [PATCH 01/10] arm64: debug: Don't propagate UNKNOWN FAR into si_code for debug signals Date: Fri, 1 Mar 2019 13:45:04 +0000 [thread overview] Message-ID: <20190301134503.GB15517@lakrids.cambridge.arm.com> (raw) In-Reply-To: <20190301132809.24653-2-will.deacon@arm.com> 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 >
WARNING: multiple messages have this Message-ID (diff)
From: Mark Rutland <mark.rutland@arm.com> To: Will Deacon <will.deacon@arm.com> Cc: catalin.marinas@arm.com, stable@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH 01/10] arm64: debug: Don't propagate UNKNOWN FAR into si_code for debug signals Date: Fri, 1 Mar 2019 13:45:04 +0000 [thread overview] Message-ID: <20190301134503.GB15517@lakrids.cambridge.arm.com> (raw) In-Reply-To: <20190301132809.24653-2-will.deacon@arm.com> 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 > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2019-03-01 13:45 UTC|newest] Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-03-01 13:27 [PATCH 00/10] Rework debug exception handling code Will Deacon 2019-03-01 13:28 ` [PATCH 01/10] arm64: debug: Don't propagate UNKNOWN FAR into si_code for debug signals Will Deacon 2019-03-01 13:28 ` Will Deacon 2019-03-01 13:45 ` Mark Rutland [this message] 2019-03-01 13:45 ` Mark Rutland 2019-03-05 13:35 ` Sasha Levin 2019-03-01 13:28 ` [PATCH 02/10] arm64: debug: Ensure debug handlers check triggering exception level Will Deacon 2019-03-01 13:28 ` Will Deacon 2019-03-01 13:46 ` Mark Rutland 2019-03-01 13:46 ` Mark Rutland 2019-03-05 13:35 ` Sasha Levin 2019-03-01 13:28 ` [PATCH 03/10] arm64: debug: Remove unused return value from do_debug_exception() Will Deacon 2019-03-01 13:48 ` Mark Rutland 2019-03-01 13:28 ` [PATCH 04/10] arm64: debug: Rename addr parameter for non-watchpoint exception hooks Will Deacon 2019-03-01 13:49 ` Mark Rutland 2019-03-01 13:28 ` [PATCH 05/10] arm64: debug: Remove meaningless comment Will Deacon 2019-03-01 14:08 ` Mark Rutland 2019-03-01 13:28 ` [PATCH 06/10] arm64: debug: Separate debug hooks based on target exception level Will Deacon 2019-03-01 14:07 ` Mark Rutland 2019-03-01 13:28 ` [PATCH 07/10] arm64: kprobes: Avoid calling kprobes debug handlers explicitly Will Deacon 2019-03-01 14:12 ` Mark Rutland 2019-03-01 13:28 ` [PATCH 08/10] arm64: debug: Remove redundant user_mode(regs) checks from debug handlers Will Deacon 2019-03-01 14:13 ` Mark Rutland 2019-03-01 13:28 ` [PATCH 09/10] arm64: probes: Move magic BRK values into brk-imm.h Will Deacon 2019-03-01 14:16 ` Mark Rutland 2019-03-01 13:28 ` [PATCH 10/10] arm64: debug: Clean up brk_handler() Will Deacon 2019-03-01 14:17 ` Mark Rutland 2019-03-01 16:24 ` [PATCH 00/10] Rework debug exception handling code Catalin Marinas
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