Am 10.09.2015 um 10:30 schrieb Russell King - ARM Linux <linux@xxxxxxxxxxxxxxxx>:
> On Thu, Sep 10, 2015 at 08:42:57AM +0200, Dr. H. Nikolaus Schaller wrote:
>>
>> Am 08.09.2015 um 23:07 schrieb Tony Lindgren <tony@xxxxxxxxxxx>:
>>
>>> * Grazvydas Ignotas <notasas@xxxxxxxxx> [150908 13:44]:
>>>> On Tue, Sep 8, 2015 at 4:38 PM, Tony Lindgren <tony@xxxxxxxxxxx> wrote:
>>>>> * Grazvydas Ignotas <notasas@xxxxxxxxx> [150908 05:50]:
>>>>>> Hi,
>>>>>>
>>>>>> this is a longstanding problem I'm seeing since the very beginning,
>>>>>> which was around 3.12 or so (when I've first got the hardware) and it
>>>>>> seems 4.2 is affected by it still. Basically what happens is Xorg
>>>>>> randomly segfaults at some "impossible" location. I don't have the
>>>>>> details at the moment (could get them is needed), but from what I
>>>>>> examined with gdb some time ago the situation did not make any sense.
>>>>>>
>>>>>> There are 2 workarounds that I know which make the problem go away
>>>>>> (one is enough):
>>>>>> - recompile Xorg with -marm (I'm using Debian armhf so it's thumb2 by default)
>>>>>> - disable ARCH_MULTI_V6 in the kernel config
>>>>>>
>>>>>> Because of the above workarounds I have forgotten about it several
>>>>>> times, but it regularly comes back and bites again. It would look like
>>>>>> some missing erratum workaround, but I have all of them enabled in the
>>>>>> kernel.
>>>>>>
>>>>>> Does anyone know about this? Perhaps some missing erratum workaround
>>>>>> in the bootloader? u-boot isn't too old here (2015.07).
>>>>>
>>>>> Seems like some incorrect handling with CONFIG_CPU_V6 compiled in..
>>>>> Maybe try to narrow it down by commenting out some CONFIG_CPU_V6 and
>>>>> __LINUX_ARM_ARCH__ = 6 ifdefs in the git grep CONFIG_CPU_V6
>>>>> places ignoring uncompress and davinci code.
>>>>
>>>> ok with that it was quite easy to find. On a kernel with ARCH_MULTI_V6
>>>> disabled, it is enough to just do this:
>>>>
>>>> --- a/arch/arm/kernel/signal.c
>>>> +++ b/arch/arm/kernel/signal.c
>>>> @@ -340,13 +340,13 @@ setup_return(struct pt_regs *regs, struct ksignal *ksig,
>>>> /*
>>>> * The LSB of the handler determines if we're going to
>>>> * be using THUMB or ARM mode for this signal handler.
>>>> */
>>>> thumb = handler & 1;
>>>>
>>>> -#if __LINUX_ARM_ARCH__ >= 7
>>>> +#if 0 //__LINUX_ARM_ARCH__ >= 7
>>>> /*
>>>> * Clear the If-Then Thumb-2 execution state
>>>> * ARM spec requires this to be all 000s in ARM mode
>>>> * Snapdragon S4/Krait misbehaves on a Thumb=>ARM
>>>> * signal transition without this.
>>>> */
>>>>
>>>> ... and the problem appears, so I guess this needs some real
>>>> multiplatform handling,.
>>>
>>> OK nice to hear you found it. Yeah looks like some runtime
>>> capability check is needed.
>>>
>>>>> Do you have some easy way to reproduce this issue?
>>>>
>>>> Just moving a browser window around with mouse usually triggers it
>>>> within a minute.
>>>
>>> OK good to know.
>>
>> It looks as if this is the solution for the same symptom on our OMAP3 board (gta04).
>> There, it suffices to draw on the touch screen for ~10 seconds to make the xserver segfault.
>>
>> [we are using the binary xserver from debian wheezy
>> ii xserver-xorg-core 2:1.12.4-6+deb7u5 armhf Xorg X server - core server]
>>
>> We know about this bug for a while, but so far did think that some touch screen
>> event bit has changed and we have to fix our touch screen driver.
>>
>> Now, disabling CONFIG_ARCH_MULTI_V6 also makes the bug go away and adding the
>>>> #if 0 //__LINUX_ARM_ARCH__ >= 7
>> makes it re-appear.
>>
>> A while ago I tried to debug running the x-server under strace and could find that it also has
>> something to do with SIGALRM.
>>
>> And that is very consistent with “enable/disable” by modifying arch/arm/kernel/signal.c
>
> It would be really nice if someone could diagnose what's going on here.
> What exception is causing the X server to be killed (someone said a
> segfault)? What is the register state at the point that happens? What
> does the code look like Is it happening inside the SIGALRM handler, or
> when the SIGALRM handler has returned?
>
> I'd suggest attaching gdb to the X server, but remember to set gdb to
> ignore SIGPIPEs.
I don’t have a setup to run gdb (with source) on the device and really zero
experience with Xserver sources. But maybe Grazvydas can do that better
than me.
Attached is some strace I had recorded during my earlier experiments.
X-Server appears not only to heavily use SIGALRM but SIGIO.
And it looks as if it a SEGFAULT appears inside the SIGIO handler after
having done 3 syscalls (select, read, clock_gettime) but before the
sigreturn. At least in this example.
Xserver then does a graceful shutdown after SEGFAULT. I.e. it prints the
segfault message by itself.
Hope this is a useful piece to solve the puzzle and helps a little.
BR,
Nikolaus
…
--- SIGALRM (Alarm clock) @ 0 (0) ---
--- SIGIO (I/O possible) @ 0 (0) ---
select(12, [9 10 11], NULL, NULL, {0, 0}) = 1 (in [9], left {0, 0})
read(9, ";\230\353T^\351\n\0\3\0\0\0:\4\0\0;\230\353T^\351\n\0\3\0\1\0=\7\0\0"..., 256) = 64
clock_gettime(CLOCK_MONOTONIC, {7330, 494831541}) = 0
sigreturn() = ? (mask now [ILL ABRT KILL USR1 SEGV PIPE TERM STKFLT CHLD STOP TSTP TTIN XFSZ VTALRM PROF IO PWR RTMIN])
sigreturn() = ? (mask now [])
setitimer(ITIMER_REAL, {it_interval={0, 0}, it_value={0, 0}}, NULL) = 0
select(256, [1 3 4 5 12 13 14 15 16 19], NULL, NULL, {0, 0}) = 1 (in [19], left {0, 0})
clock_gettime(CLOCK_MONOTONIC, {7330, 499042967}) = 0
setitimer(ITIMER_REAL, {it_interval={0, 20000}, it_value={0, 20000}}, NULL) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 500050047}) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 501911619}) = 0
--- SIGIO (I/O possible) @ 0 (0) ---
select(12, [9 10 11], NULL, NULL, {0, 0}) = 1 (in [9], left {0, 0})
read(9, ";\230\353Tw\20\v\0\3\0\0\0h\4\0\0;\230\353Tw\20\v\0\3\0\1\0\256\7\0\0"..., 256) = 64
clock_gettime(CLOCK_MONOTONIC, {7330, 504536131}) = 0
sigreturn() = ? (mask now [HUP QUIT ILL])
clock_gettime(CLOCK_MONOTONIC, {7330, 506275633}) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 506855467}) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 507587889}) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 508442381}) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 508961180}) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 509418943}) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 509998777}) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 511860350}) = 0
--- SIGIO (I/O possible) @ 0 (0) ---
select(12, [9 10 11], NULL, NULL, {0, 0}) = 1 (in [9], left {0, 0})
read(9, ";\230\353TT7\v\0\3\0\0\0\242\4\0\0;\230\353TT7\v\0\3\0\1\0\367\7\0\0"..., 256) = 64
clock_gettime(CLOCK_MONOTONIC, {7330, 514484861}) = 0
sigreturn() = ? (mask now [])
clock_gettime(CLOCK_MONOTONIC, {7330, 516224363}) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 516743162}) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 517200926}) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 517719725}) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 518452147}) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 519367674}) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 519947508}) = 0
--- SIGALRM (Alarm clock) @ 0 (0) ---
sigreturn() = ? (mask now [])
--- SIGIO (I/O possible) @ 0 (0) ---
select(12, [9 10 11], NULL, NULL, {0, 0}) = 1 (in [9], left {0, 0})
read(9, ";\230\353Tn^\v\0\3\0\0\0\370\4\0\0;\230\353Tn^\v\0\3\0\1\0y\10\0\0"..., 256) = 64
clock_gettime(CLOCK_MONOTONIC, {7330, 525074461}) = 0
sigreturn() = ? (mask now [])
setitimer(ITIMER_REAL, {it_interval={0, 0}, it_value={0, 0}}, NULL) = 0
select(256, [1 3 4 5 12 13 14 15 16 19], NULL, NULL, {0, 0}) = 1 (in [19], left {0, 0})
clock_gettime(CLOCK_MONOTONIC, {7330, 528400877}) = 0
setitimer(ITIMER_REAL, {it_interval={0, 20000}, it_value={0, 20000}}, NULL) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 529377440}) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 530018309}) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 531910399}) = 0
--- SIGIO (I/O possible) @ 0 (0) ---
select(12, [9 10 11], NULL, NULL, {0, 0}) = 1 (in [9], left {0, 0})
read(9, ";\230\353T\246\205\v\0\3\0\0\0V\5\0\0;\230\353T\246\205\v\0\3\0\1\0\336\10\0\0"..., 256) = 64
clock_gettime(CLOCK_MONOTONIC, {7330, 534534910}) = 0
sigreturn() = ? (mask now [HUP QUIT ILL])
writev(20, [{"\6\0T\3\256\332o\0\345\0\0\0\3\0\0\1\0\0\0\0h\0\377\0h\0\377\0\0\1\1\0"..., 224}], 1) = 224
clock_gettime(CLOCK_MONOTONIC, {7330, 542164305}) = 0
--- SIGIO (I/O possible) @ 0 (0) ---
select(12, [9 10 11], NULL, NULL, {0, 0}) = 1 (in [9], left {0, 0})
read(9, ";\230\353TX\255\v\0\3\0\0\0\317\5\0\0;\230\353TX\255\v\0\3\0\1\0T\t\0\0"..., 256) = 64
clock_gettime(CLOCK_MONOTONIC, {7330, 546253660}) = 0
sigreturn() = ? (mask now [HUP QUIT ILL])
read(20, "5\20\4\0\236\0\0\1\3\0\0\1\33\1\257\0\224\4\6\0\237\0\0\1\236\0\0\1)\0\0\0"..., 4096) = 1088
clock_gettime(CLOCK_MONOTONIC, {7330, 548756102}) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 549366453}) = 0
--- SIGALRM (Alarm clock) @ 0 (0) ---
sigreturn() = ? (mask now [HUP QUIT ILL])
--- SIGIO (I/O possible) @ 0 (0) ---
select(12, [9 10 11], NULL, NULL, {0, 0}) = 1 (in [9], left {0, 0})
read(9, ";\230\353T\273\323\v\0\3\0\0\0K\6\0\0;\230\353T\273\323\v\0\3\0\1\0\314\t\0\0"..., 256) = 64
clock_gettime(CLOCK_MONOTONIC, {7330, 554707029}) = 0
sigreturn() = ? (mask now [HUP QUIT ILL])
setitimer(ITIMER_REAL, {it_interval={0, 0}, it_value={0, 0}}, NULL) = 0
select(256, [1 3 4 5 12 13 14 15 16 19], NULL, NULL, {0, 0}) = 1 (in [19], left {0, 0})
clock_gettime(CLOCK_MONOTONIC, {7330, 558155516}) = 0
setitimer(ITIMER_REAL, {it_interval={0, 20000}, it_value={0, 20000}}, NULL) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 559132078}) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 560749510}) = 0
--- SIGIO (I/O possible) @ 0 (0) ---
select(12, [9 10 11], NULL, NULL, {0, 0}) = 1 (in [9], left {0, 0})
read(9, ";\230\353T\325\372\v\0\3\0\0\0\326\6\0\0;\230\353T\325\372\v\0\3\0\1\0:\n\0\0"..., 256) = 64
clock_gettime(CLOCK_MONOTONIC, {7330, 564564207}) = 0
--- SIGSEGV (Segmentation fault) @ 0 (0) ---
write(2, "\n", 1
) = 1
clock_gettime(CLOCK_MONOTONIC, {7330, 565968016}) = 0
write(0, "[ 7330.565] ", 13) = 13
write(0, "\n", 1) = 1
write(2, "Backtrace:\n", 11Backtrace:
) = 11
clock_gettime(CLOCK_MONOTONIC, {7330, 568195799}) = 0
write(0, "[ 7330.568] ", 13) = 13
write(0, "Backtrace:\n", 11) = 11
write(2, "\n", 1
) = 1
clock_gettime(CLOCK_MONOTONIC, {7330, 571125486}) = 0
write(0, "[ 7330.571] ", 13) = 13
write(0, "\n", 1) = 1
futex(0xb6c587d0, FUTEX_WAKE_PRIVATE, 2147483647) = 0
write(2, "Segmentation fault at address (n"..., 36Segmentation fault at address (nil)
) = 36
clock_gettime(CLOCK_MONOTONIC, {7330, 575092772}) = 0
write(0, "[ 7330.575] ", 13) = 13
write(0, "Segmentation fault at address (n"..., 36) = 36
write(2, "\nFatal server error:\n", 21
Fatal server error:
) = 21
clock_gettime(CLOCK_MONOTONIC, {7330, 577412108}) = 0
write(0, "[ 7330.577] ", 13) = 13
write(0, "\nFatal server error:\n", 21) = 21
write(2, "Caught signal 11 (Segmentation f"..., 55Caught signal 11 (Segmentation fault). Server aborting
) = 55
--- SIGALRM (Alarm clock) @ 0 (0) ---
sigreturn() = ? (mask now [ABRT BUS FPE USR1 SEGV USR2 ALRM STKFLT CHLD CONT TTIN TTOU URG XCPU VTALRM PROF WINCH IO PWR RTMIN])
clock_gettime(CLOCK_MONOTONIC, {7330, 582752684}) = 0
write(0, "[ 7330.582] ", 13) = 13
write(0, "Caught signal 11 (Segmentation f"..., 55) = 55
write(2, "\n", 1
) = 1
clock_gettime(CLOCK_MONOTONIC, {7330, 585041502}) = 0
write(0, "[ 7330.585] ", 13) = 13
write(0, "\n", 1) = 1
write(2, "\nPlease consult the The X.Org Fo"..., 85
Please consult the The X.Org Foundation support
at http://wiki.x.org
for help.
) = 85
clock_gettime(CLOCK_MONOTONIC, {7330, 587208250}) = 0
write(0, "[ 7330.587] ", 13) = 13
write(0, "\nPlease consult the The X.Org Fo"..., 85) = 85
write(2, "Please also check the log file a"..., 84Please also check the log file at "/var/log/Xorg.0.log" for additional information.
) = 84
clock_gettime(CLOCK_MONOTONIC, {7330, 589466551}) = 0
write(0, "[ 7330.589] ", 13) = 13
write(0, "Please also check the log file a"..., 84) = 84
write(2, "\n", 1
) = 1
clock_gettime(CLOCK_MONOTONIC, {7330, 593525389}) = 0
write(0, "[ 7330.593] ", 13) = 13
write(0, "\n", 1) = 1
close(1) = 0
close(3) = 0
close(4) = 0
close(5) = 0
unlink("/tmp/.X11-unix/X0") = 0
unlink("/tmp/.X0-lock") = 0
rt_sigprocmask(SIG_BLOCK, [ALRM CHLD TSTP TTIN TTOU VTALRM WINCH IO], [SEGV IO], 8) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 599567869}) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 601948240}) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 603168943}) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 604145506}) = 0
fcntl64(9, F_GETFL) = 0x2802 (flags O_RDWR|O_NONBLOCK|O_ASYNC)
fcntl64(9, F_SETFL, O_RDWR|O_NONBLOCK) = 0
fcntl64(9, F_GETFD) = 0
close(9) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 606983641}) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 608509520}) = 0
write(0, "[ 7330.608] ", 13) = 13
write(0, "(II) evdev: Touchscreen: Close\n", 31) = 31
clock_gettime(CLOCK_MONOTONIC, {7330, 610798338}) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 611408690}) = 0
write(0, "[ 7330.611] ", 13) = 13
write(0, "(II) UnloadModule: \"evdev\"\n", 27) = 27
clock_gettime(CLOCK_MONOTONIC, {7330, 613361815}) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 614368895}) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 615009764}) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 615986326}) = 0
fcntl64(10, F_GETFL) = 0x2802 (flags O_RDWR|O_NONBLOCK|O_ASYNC)
fcntl64(10, F_SETFL, O_RDWR|O_NONBLOCK) = 0
fcntl64(10, F_GETFD) = 0
close(10) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 618336180}) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 619007567}) = 0
write(0, "[ 7330.619] ", 13) = 13
write(0, "(II) evdev: Power Button: Close\n", 32) = 32
clock_gettime(CLOCK_MONOTONIC, {7330, 621601561}) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 622181395}) = 0
write(0, "[ 7330.622] ", 13) = 13
write(0, "(II) UnloadModule: \"evdev\"\n", 27) = 27
fcntl64(11, F_GETFL) = 0x2802 (flags O_RDWR|O_NONBLOCK|O_ASYNC)
fcntl64(11, F_SETFL, O_RDWR|O_NONBLOCK) = 0
fcntl64(11, F_GETFD) = 0
rt_sigaction(SIGIO, {SIG_IGN, [IO], 0x4000000 /* SA_??? */}, {0xb6f0d63d, [IO], 0x4000000 /* SA_??? */}, 8) = 0
close(11) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 626606443}) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 627308348}) = 0
write(0, "[ 7330.627] ", 13) = 13
write(0, "(II) evdev: AUX Button: Close\n", 30) = 30
clock_gettime(CLOCK_MONOTONIC, {7330, 629261473}) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 629810789}) = 0
write(0, "[ 7330.629] ", 13) = 13
write(0, "(II) UnloadModule: \"evdev\"\n", 27) = 27
rt_sigprocmask(SIG_SETMASK, [SEGV IO], NULL, 8) = 0
--- SIGALRM (Alarm clock) @ 0 (0) ---
sigreturn() = ? (mask now [])
rt_sigprocmask(SIG_BLOCK, [IO], [SEGV IO], 8) = 0
clock_gettime(CLOCK_MONOTONIC, {7330, 634663084}) = 0
write(0, "[ 7330.634] ", 13) = 13
write(0, "(NI) OMAPFBLeaveVT\n", 19) = 19
ioctl(7, KDSETMODE, 0) = 0
--- SIGALRM (Alarm clock) @ 0 (0) ---
sigreturn() = ? (mask now [])
ioctl(7, KDSKBMODE, 0x3) = 0
ioctl(7, SNDCTL_TMR_TIMEBASE or TCGETS, {B38400 -opost -isig -icanon -echo ...}) = 0
ioctl(7, SNDCTL_TMR_START or TCSETS, {B38400 opost isig icanon echo ...}) = 0
ioctl(7, SNDCTL_TMR_TIMEBASE or TCGETS, {B38400 opost isig icanon echo ...}) = 0
ioctl(7, VIDIOC_RESERVED or VT_GETMODE, 0xbef3b348) = 0
ioctl(7, VIDIOC_ENUM_FMT or VT_SETMODE, 0xbef3b348) = 0
ioctl(7, VT_ACTIVATE, 0x1) = 0
ioctl(7, VT_WAITACTIVE, 0x1) = 0
close(7) = 0
write(2, "Server terminated with error (1)"..., 52Server terminated with error (1). Closing log file.
) = 52
clock_gettime(CLOCK_MONOTONIC, {7330, 655903318}) = 0
write(0, "[ 7330.655] ", 13) = 13
write(0, "Server terminated with error (1)"..., 52) = 52
close(0) = 0
rt_sigprocmask(SIG_BLOCK, [ALRM CHLD TSTP TTIN TTOU VTALRM WINCH IO], [SEGV IO], 8) = 0
rt_sigprocmask(SIG_UNBLOCK, [ABRT], NULL, 8) = 0
tgkill(4586, 4586, SIGABRT) = 0
--- SIGABRT (Aborted) @ 0 (0) ---
root@gta04:~#
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