From: Will Deacon <will.deacon@arm.com>
To: gregkh@linuxfoundation.org
Cc: stable@vger.kernel.org, linux-kernel@vger.kernel.org,
sashal@kernel.org, Will Deacon <will.deacon@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>
Subject: [PATCH 4.4 BACKPORT 1/2] arm64: debug: Don't propagate UNKNOWN FAR into si_code for debug signals
Date: Wed, 3 Apr 2019 11:31:13 +0100 [thread overview]
Message-ID: <20190403103114.29050-1-will.deacon@arm.com> (raw)
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> # 4.4.y
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 | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 04c4b88706d8..89abdf9af4e6 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -589,11 +589,12 @@ 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);
struct siginfo info;
int rv;
@@ -604,16 +605,16 @@ asmlinkage int __exception do_debug_exception(unsigned long addr,
if (interrupts_enabled(regs))
trace_hardirqs_off();
- if (!inf->fn(addr, esr, regs)) {
+ if (!inf->fn(addr_if_watchpoint, esr, regs)) {
rv = 1;
} else {
pr_alert("Unhandled debug exception: %s (0x%08x) at 0x%016lx\n",
- inf->name, esr, addr);
+ inf->name, esr, pc);
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("", regs, &info, 0);
rv = 0;
}
--
2.11.0
next reply other threads:[~2019-04-03 10:31 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-03 10:31 Will Deacon [this message]
2019-04-03 10:31 ` [PATCH 4.4 BACKPORT 2/2] arm64: debug: Ensure debug handlers check triggering exception level Will Deacon
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