Hello Linux folk,
while investigating some strange process crashes (SIGSEGV) we noticed
that the core files generated by the Linux kernel (3.10-amd64) do not
include all CPU registers; here namely the SSE2 (FPREGSET?) related
registers:
# eu-readelf --notes core
...
CORE 336 PRSTATUS
info.si_signo: 11, info.si_code: 0, info.si_errno: 0, cursig: 11
sigpend: <>
sighold: <>
pid: 6918, ppid: 18764, pgrp: 6918, sid: 18764
utime: 1.116000, stime: 0.004000, cutime: 0.000000, cstime: 0.000000
orig_rax: -1, fpvalid: 0
r15: 0 r14: 0
r13: 140734211556208 r12: 4195248
rbp: 0x0000000000000000 rbx: 0
r11: 140504440818576 r10: 0
r9: 140504444297440 r8: 140504444220160
rax: 80000 rcx: 0
rdx: 100000 rsi: 140734211556216
rdi: 1 rip: 0x00000000004004e7
rflags: 0x0000000000010246 rsp: 0x00007fff3cb00298
fs.base: 0x00007fc9bd9df700 gs.base: 0x0000000000000000
cs: 0x0033 ss: 0x002b ds: 0x0000 es: 0x0000 fs: 0x0000 gs: 0x0000
...
In contrast to that "gdb generate-core-file" contains an additional note:
# eu-readelf --notes core.7335
...
CORE 512 FPREGSET
xmm0: 0x00000000000000000000000000000000
xmm1: 0x2f2f2f2f2f2f2f2f2f2f2f2f2f2f2f2f
xmm2: 0x00000000000000000000000000000000
xmm3: 0x00000000000000000000ff0000000000
xmm4: 0x00000000000000000000000000000000
xmm5: 0x00000000000000000000000000000000
xmm6: 0x00000000000000000000000000000000
xmm7: 0x00000000000000000000000000000000
xmm8: 0x00000000000000000000000000000000
xmm9: 0x00000000000000000000000000000000
xmm10: 0x00000000000000000000000000000000
xmm11: 0x00000000000000000000000000000000
xmm12: 0x00000000000000000000000000000000
xmm13: 0x00000000000000000000000000000000
xmm14: 0x00000000000000000000000000000000
xmm15: 0x00000000000000000000000000000000
st0: 0x00000000000000000000 st1: 0x00000000000000000000
st2: 0x00000000000000000000 st3: 0x00000000000000000000
st4: 0x00000000000000000000 st5: 0x00000000000000000000
st6: 0x00000000000000000000 st7: 0x00000000000000000000
mxcsr: 0x0000000000001f80
fcw: 0x037f fsw: 0x0000
...
Is there some way to include all CPU registers into the core dump, as
the current information is not enough to diagnose the cause of some
strange crashes, which might be related to the use of SSE2 with Xen.
Currently we're using this:
kernel.core_pattern = /var/tmp/core/core-%e-%p-%t
kernel.core_uses_pid = 1
fs.suid_dumpable = 2
Would a "pipe" core-handler be able to access the still existing process
and create a more complete dump?
On 17.12.2014 10:14, Frediano Ziglio wrote:
> 2014-12-16 16:44 GMT+00:00 Frediano Ziglio <fredd...@gmail.com>:
>> 2014-12-16 16:23 GMT+00:00 Ian Campbell <ian.campb...@citrix.com>:
...
>> First we (I'll try when I reach home) can check if memset in glibc (or
>> the version called from talloc_zero) can use SSE. A possible dmesg
>> output and /proc/cpuinfo content could help too but I think SSE are
>> now quite common.
>
> I have access to some core dumps. glibc memset is using SSE,
> specifically xmm0 register.
>
> Unfortunately is seems that core dumps contains only standard
> registers, so all register appears zeroed. If you try with a newer gdb
> version is shows that registers are not available.
Thank you in advance.
Philipp
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