* [PATCH] x86/signal: fix restart_syscall number for x32 tasks
@ 2015-11-30 21:54 Dmitry V. Levin
2015-12-05 17:55 ` [tip:x86/urgent] x86/signal: Fix " tip-bot for Dmitry V. Levin
0 siblings, 1 reply; 5+ messages in thread
From: Dmitry V. Levin @ 2015-11-30 21:54 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, H. Peter Anvin
Cc: Elvira Khabirova, x86, linux-kernel
When restarting a syscall with regs->ax == -ERESTART_RESTARTBLOCK,
regs->ax is assigned to a restart_syscall number. For x32 tasks,
this syscall number must have __X32_SYSCALL_BIT set, otherwise it
will be an x86_64 syscall number instead of a valid x32 syscall number.
Reported-by: strace/tests/restart_syscall.test
Reported-and-tested-by: Elvira Khabirova <lineprinter0@gmail.com>
Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
Cc: stable@vger.kernel.org
---
arch/x86/kernel/signal.c | 17 ++++++++++-------
1 file changed, 10 insertions(+), 7 deletions(-)
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index b7ffb7c..cb6282c 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -690,12 +690,15 @@ handle_signal(struct ksignal *ksig, struct pt_regs *regs)
signal_setup_done(failed, ksig, stepping);
}
-#ifdef CONFIG_X86_32
-#define NR_restart_syscall __NR_restart_syscall
-#else /* !CONFIG_X86_32 */
-#define NR_restart_syscall \
- test_thread_flag(TIF_IA32) ? __NR_ia32_restart_syscall : __NR_restart_syscall
-#endif /* CONFIG_X86_32 */
+static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs)
+{
+#if defined(CONFIG_X86_32) || !defined(CONFIG_X86_64)
+ return __NR_restart_syscall;
+#else /* !CONFIG_X86_32 && CONFIG_X86_64 */
+ return test_thread_flag(TIF_IA32) ? __NR_ia32_restart_syscall :
+ __NR_restart_syscall | (regs->orig_ax & __X32_SYSCALL_BIT);
+#endif /* CONFIG_X86_32 || !CONFIG_X86_64 */
+}
/*
* Note that 'init' is a special process: it doesn't get signals it doesn't
@@ -724,7 +727,7 @@ void do_signal(struct pt_regs *regs)
break;
case -ERESTART_RESTARTBLOCK:
- regs->ax = NR_restart_syscall;
+ regs->ax = get_nr_restart_syscall(regs);
regs->ip -= 2;
break;
}
--
ldv
^ permalink raw reply related [flat|nested] 5+ messages in thread
* [tip:x86/urgent] x86/signal: Fix restart_syscall number for x32 tasks
2015-11-30 21:54 [PATCH] x86/signal: fix restart_syscall number for x32 tasks Dmitry V. Levin
@ 2015-12-05 17:55 ` tip-bot for Dmitry V. Levin
0 siblings, 0 replies; 5+ messages in thread
From: tip-bot for Dmitry V. Levin @ 2015-12-05 17:55 UTC (permalink / raw)
To: linux-tip-commits; +Cc: mingo, ldv, hpa, tglx, linux-kernel, lineprinter0
Commit-ID: 22eab1108781eff09961ae7001704f7bd8fb1dce
Gitweb: http://git.kernel.org/tip/22eab1108781eff09961ae7001704f7bd8fb1dce
Author: Dmitry V. Levin <ldv@altlinux.org>
AuthorDate: Tue, 1 Dec 2015 00:54:36 +0300
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Sat, 5 Dec 2015 18:52:14 +0100
x86/signal: Fix restart_syscall number for x32 tasks
When restarting a syscall with regs->ax == -ERESTART_RESTARTBLOCK,
regs->ax is assigned to a restart_syscall number. For x32 tasks, this
syscall number must have __X32_SYSCALL_BIT set, otherwise it will be
an x86_64 syscall number instead of a valid x32 syscall number. This
issue has been there since the introduction of x32.
Reported-by: strace/tests/restart_syscall.test
Reported-and-tested-by: Elvira Khabirova <lineprinter0@gmail.com>
Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
Cc: Elvira Khabirova <lineprinter0@gmail.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20151130215436.GA25996@altlinux.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
arch/x86/kernel/signal.c | 17 ++++++++++-------
1 file changed, 10 insertions(+), 7 deletions(-)
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index b7ffb7c..cb6282c 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -690,12 +690,15 @@ handle_signal(struct ksignal *ksig, struct pt_regs *regs)
signal_setup_done(failed, ksig, stepping);
}
-#ifdef CONFIG_X86_32
-#define NR_restart_syscall __NR_restart_syscall
-#else /* !CONFIG_X86_32 */
-#define NR_restart_syscall \
- test_thread_flag(TIF_IA32) ? __NR_ia32_restart_syscall : __NR_restart_syscall
-#endif /* CONFIG_X86_32 */
+static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs)
+{
+#if defined(CONFIG_X86_32) || !defined(CONFIG_X86_64)
+ return __NR_restart_syscall;
+#else /* !CONFIG_X86_32 && CONFIG_X86_64 */
+ return test_thread_flag(TIF_IA32) ? __NR_ia32_restart_syscall :
+ __NR_restart_syscall | (regs->orig_ax & __X32_SYSCALL_BIT);
+#endif /* CONFIG_X86_32 || !CONFIG_X86_64 */
+}
/*
* Note that 'init' is a special process: it doesn't get signals it doesn't
@@ -724,7 +727,7 @@ void do_signal(struct pt_regs *regs)
break;
case -ERESTART_RESTARTBLOCK:
- regs->ax = NR_restart_syscall;
+ regs->ax = get_nr_restart_syscall(regs);
regs->ip -= 2;
break;
}
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] x86/signal: fix restart_syscall number for x32 tasks
@ 2015-12-07 23:22 Andy Lutomirski
2015-12-13 3:44 ` Dmitry V. Levin
0 siblings, 1 reply; 5+ messages in thread
From: Andy Lutomirski @ 2015-12-07 23:22 UTC (permalink / raw)
To: X86 ML, linux-kernel, Dmitry V. Levin, lvira Khabirova
[not real reply because I'm using a bad internet connection right now
and I'm not set up with my usual Gmane reply hack right now]
The new code is (whitespace-damaged):
static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs)
{
#if defined(CONFIG_X86_32) || !defined(CONFIG_X86_64)
return __NR_restart_syscall;
#else /* !CONFIG_X86_32 && CONFIG_X86_64 */
return test_thread_flag(TIF_IA32) ? __NR_ia32_restart_syscall :
__NR_restart_syscall | (regs->orig_ax & __X32_SYSCALL_BIT);
#endif /* CONFIG_X86_32 || !CONFIG_X86_64 */
}
This is IMO awful. This use of TIF_IA32 is wrong, and this is
otherwise gross. Can we do it for real:
if (is_ia32_task())
return __NR_ia32_restart_syscall;
else
return __NR_restart_syscall | (regs->orig_ax & __X32_SYSCALL_BIT);
/* preserve x32 bit */
I'd send the patch myself, but you apparently have a good test case
for this, and I don't.
(this isn't a regression, and I'm not suggesting any change for 4.4 or
for stable. But for 4.5, can we do it right, please?)
And yes, I'll send a patch to rename is_ia32_task, but that's orthogonal.
--Andy
P.S. I'm still hoping to kill TIF_IA32 entirely some time soon.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] x86/signal: fix restart_syscall number for x32 tasks
2015-12-07 23:22 [PATCH] x86/signal: fix " Andy Lutomirski
@ 2015-12-13 3:44 ` Dmitry V. Levin
2015-12-17 20:27 ` Andy Lutomirski
0 siblings, 1 reply; 5+ messages in thread
From: Dmitry V. Levin @ 2015-12-13 3:44 UTC (permalink / raw)
To: Andy Lutomirski; +Cc: X86 ML, linux-kernel, Elvira Khabirova
On Mon, Dec 07, 2015 at 03:22:06PM -0800, Andy Lutomirski wrote:
> [not real reply because I'm using a bad internet connection right now
> and I'm not set up with my usual Gmane reply hack right now]
>
> The new code is (whitespace-damaged):
>
> static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs)
> {
> #if defined(CONFIG_X86_32) || !defined(CONFIG_X86_64)
> return __NR_restart_syscall;
> #else /* !CONFIG_X86_32 && CONFIG_X86_64 */
> return test_thread_flag(TIF_IA32) ? __NR_ia32_restart_syscall :
> __NR_restart_syscall | (regs->orig_ax & __X32_SYSCALL_BIT);
> #endif /* CONFIG_X86_32 || !CONFIG_X86_64 */
> }
>
> This is IMO awful. This use of TIF_IA32 is wrong, and this is
> otherwise gross. Can we do it for real:
>
> if (is_ia32_task())
> return __NR_ia32_restart_syscall;
> else
> return __NR_restart_syscall | (regs->orig_ax & __X32_SYSCALL_BIT);
> /* preserve x32 bit */
>
> I'd send the patch myself, but you apparently have a good test case
> for this, and I don't.
Unfortunately, this won't compile on CONFIG_X86_32 because
__NR_ia32_restart_syscall is defined for CONFIG_X86_64 only.
Something like this should work:
static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs)
{
#ifdef CONFIG_X86_64
if (is_ia32_task())
return __NR_ia32_restart_syscall;
# ifdef CONFIG_X86_X32_ABI
if (regs->orig_ax & __X32_SYSCALL_BIT)
return __NR_restart_syscall | __X32_SYSCALL_BIT;
# endif
#endif
return __NR_restart_syscall;
}
I don't see any way to avoid ifdefs here, sorry.
--
ldv
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] x86/signal: fix restart_syscall number for x32 tasks
2015-12-13 3:44 ` Dmitry V. Levin
@ 2015-12-17 20:27 ` Andy Lutomirski
0 siblings, 0 replies; 5+ messages in thread
From: Andy Lutomirski @ 2015-12-17 20:27 UTC (permalink / raw)
To: Dmitry V. Levin; +Cc: X86 ML, linux-kernel, Elvira Khabirova
On Sat, Dec 12, 2015 at 7:44 PM, Dmitry V. Levin <ldv@altlinux.org> wrote:
> On Mon, Dec 07, 2015 at 03:22:06PM -0800, Andy Lutomirski wrote:
>> [not real reply because I'm using a bad internet connection right now
>> and I'm not set up with my usual Gmane reply hack right now]
>>
>> The new code is (whitespace-damaged):
>>
>> static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs)
>> {
>> #if defined(CONFIG_X86_32) || !defined(CONFIG_X86_64)
>> return __NR_restart_syscall;
>> #else /* !CONFIG_X86_32 && CONFIG_X86_64 */
>> return test_thread_flag(TIF_IA32) ? __NR_ia32_restart_syscall :
>> __NR_restart_syscall | (regs->orig_ax & __X32_SYSCALL_BIT);
>> #endif /* CONFIG_X86_32 || !CONFIG_X86_64 */
>> }
>>
>> This is IMO awful. This use of TIF_IA32 is wrong, and this is
>> otherwise gross. Can we do it for real:
>>
>> if (is_ia32_task())
>> return __NR_ia32_restart_syscall;
>> else
>> return __NR_restart_syscall | (regs->orig_ax & __X32_SYSCALL_BIT);
>> /* preserve x32 bit */
>>
>> I'd send the patch myself, but you apparently have a good test case
>> for this, and I don't.
>
> Unfortunately, this won't compile on CONFIG_X86_32 because
> __NR_ia32_restart_syscall is defined for CONFIG_X86_64 only.
>
> Something like this should work:
>
> static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs)
> {
> #ifdef CONFIG_X86_64
> if (is_ia32_task())
> return __NR_ia32_restart_syscall;
> # ifdef CONFIG_X86_X32_ABI
> if (regs->orig_ax & __X32_SYSCALL_BIT)
> return __NR_restart_syscall | __X32_SYSCALL_BIT;
> # endif
> #endif
> return __NR_restart_syscall;
> }
Looks good to me. Want to send a patch?
--Andy
^ permalink raw reply [flat|nested] 5+ messages in thread
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2015-11-30 21:54 [PATCH] x86/signal: fix restart_syscall number for x32 tasks Dmitry V. Levin
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2015-12-07 23:22 [PATCH] x86/signal: fix " Andy Lutomirski
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