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 4.9/4.14 BACKPORT 1/2] arm64: debug: Don't propagate UNKNOWN FAR into si_code for debug signals
Date: Wed, 3 Apr 2019 11:33:25 +0100 [thread overview]
Message-ID: <20190403103326.29161-1-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> # 4.9.y and 4.14.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 | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index ad49ae8f3967..051b32084776 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -673,11 +673,12 @@ 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;
@@ -688,19 +689,19 @@ 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 {
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 10:33 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-03 10:33 Will Deacon [this message]
2019-04-03 10:33 ` [PATCH 4.9 BACKPORT 2/2] arm64: debug: Ensure debug handlers check triggering exception level Will Deacon
[not found] ` <20190405141522.584C621850@mail.kernel.org>
2019-04-05 14:16 ` [PATCH 4.9/4.14 BACKPORT 1/2] arm64: debug: Don't propagate UNKNOWN FAR into si_code for debug signals Will Deacon
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190403103326.29161-1-will.deacon@arm.com \
--to=will.deacon@arm.com \
--cc=catalin.marinas@arm.com \
--cc=gregkh@linuxfoundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=sashal@kernel.org \
--cc=stable@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).