Re: [PATCH] Fix the multithread program core thread message error

[Hui Zhu <teawater@gmail.com>]

Thanks for your help, Amerigo.

Hui

Fix the multithread program core thread message error.
This issue just affect arch with neither has CORE_DUMP_USE_REGSET
nor ELF_CORE_COPY_TASK_REGS, ARM is one of them.
The thread message of core file is generated in
elf_dump_thread_status.  The register values is set by
elf_core_copy_task_regs in this function.
If a arch doesn't define ELF_CORE_COPY_TASK_REGS, The function
elf_core_copy_task_regs will do nothing.  Then the core file will
not have the register message of thread.
So add elf_core_copy_regs to set regiser values if
ELF_CORE_COPY_TASK_REGS doesn't define.
The following is how to reproduce this issue:
cat 1.c
#include <stdio.h>
#include <pthread.h>
#include <assert.h>

void td1(void * i)
{
       while (1)
       {
               printf ("1\n");
               sleep (1);
       }

       return;
}

void td2(void * i)
{
       while (1)
       {
               printf ("2\n");
               sleep (1);
       }

       return;
}

int
main(int argc,char *argv[],char *envp[])
{
       pthread_t       t1,t2;

       pthread_create(&t1, NULL, (void*)td1, NULL);
       pthread_create(&t2, NULL, (void*)td2, NULL);

       sleep (10);

       assert(0);

       return (0);
}
arm-xxx-gcc -g -lpthread 1.c -o 1
copy 1.c and 1 to a arm board.
Goto this board.
ulimit -c 1800000
./1
# ./1
1
2
1
...
...
1
1: 1.c:37: main: Assertion `0' failed.
Aborted (core dumped)
Then you can get a core file.
gdb 1 core.xxx
Without the patch:
(gdb) info threads
 3 process 909  0x00000000 in ?? ()
 2 process 908  0x00000000 in ?? ()
* 1 process 907  0x4a6e2238 in raise () from /lib/libc.so.6
You can found that the pc of 909 and 908 is 0x00000000.
With the patch:
(gdb) info threads
 3 process 885  0x4a749974 in nanosleep () from /lib/libc.so.6
 2 process 884  0x4a749974 in nanosleep () from /lib/libc.so.6
* 1 process 883  0x4a6e2238 in raise () from /lib/libc.so.6
The pc of 885 and 884 is right.

Signed-off-by: Hui Zhu <teawater@gmail.com>
---
 elfcore.h |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/linux/elfcore.h b/include/linux/elfcore.h
index 7605c5e..03ec167 100644
--- a/include/linux/elfcore.h
+++ b/include/linux/elfcore.h
@@ -125,6 +125,8 @@ static inline int elf_core_copy_task_regs(struct
task_struct *t, elf_gregset_t*
 #ifdef ELF_CORE_COPY_TASK_REGS

       return ELF_CORE_COPY_TASK_REGS(t, elfregs);
+#else
+       elf_core_copy_regs(elfregs, task_pt_regs(t));
 #endif
       return 0;
 }