Re: Regression for watchpoint-fork.exp [Re: [PATCH v3 2/5] PR breakpoints/7143 - Watchpoint does not trigger when first set]

[Jan Kratochvil <jan.kratochvil@redhat.com>]

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On Tue, 17 Jun 2014 21:18:50 +0200, Jan Kratochvil wrote:
> On Thu, 20 Mar 2014 14:57:36 +0100, Pedro Alves wrote:
> > Here's what I pushed (nothing else changed).
> 
> 31e77af205cf6564c2bf4c18400b4ca16bdf92cd is the first bad commit
> commit 31e77af205cf6564c2bf4c18400b4ca16bdf92cd
> Author: Pedro Alves <palves@redhat.com>
> Date:   Thu Mar 20 13:26:32 2014 +0000
>     PR breakpoints/7143 - Watchpoint does not trigger when first set
> 
> PASS kernel-3.14.6-200.fc20.x86_64
> FAIL kernel-3.13.10-200.dentrybuflen.fc20.x86_64

That was a red herring, in fact it was due to different GCC.

(gdb) disas marker
Dump of assembler code for function marker:
   0x0000000000400826 <+0>:	push   %rbp
   0x0000000000400827 <+1>:	mov    %rsp,%rbp
=> 0x000000000040082a <+4>:	pop    %rbp
   0x000000000040082b <+5>:	retq   
End of assembler dump.

ptrace(PTRACE_POKEUSER, 24574, offsetof(struct user, u_debugreg), 0x40082a) = -1 EINVAL (Invalid argument)

New GDB in the 'hbreak' case does not align the breakpoint address.
Attaching gzipped gdb.threads/watchpoint-fork-parent-st
from gcc-4.9.0-9.fc21.x86_64.


Jan


../gdb gdb.threads/watchpoint-fork-parent-st -ex 'set pagination off' -ex start -ex 'hbreak marker' -ex 'watch var' -ex c -ex c -ex c
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Reading symbols from gdb.threads/watchpoint-fork-parent-st...done.
Temporary breakpoint 1 at 0x400836: file ./gdb.threads/watchpoint-fork-st.c, line 43.
Starting program: /home/jkratoch/redhat/gdb-test-f20-noasan/gdb/testsuite/gdb.threads/watchpoint-fork-parent-st 

Temporary breakpoint 1, main () at ./gdb.threads/watchpoint-fork-st.c:43
43	  setbuf (stdout, NULL);
Hardware assisted breakpoint 2 at 0x40082a: file ./gdb.threads/watchpoint-fork-st.c, line 33.
Hardware watchpoint 3: var
Continuing.
main: 26352

Breakpoint 2, marker () at ./gdb.threads/watchpoint-fork-st.c:33
33	}
Continuing.
Hardware watchpoint 3: var

Old value = 0
New value = 1
main () at ./gdb.threads/watchpoint-fork-st.c:50
50	  forkoff (1);
Continuing.
main () at ./gdb.threads/watchpoint-fork-st.c:50
50	  forkoff (1);
Couldn't write debug register: Invalid argument.
(gdb) _

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