[Bug testsuite/30132] New: [gdb/testsuite] FAIL: gdb.arch/amd64-disp-step-avx.exp: continue until exit at amd64-disp-step-avx

["vries at gcc dot gnu.org" <sourceware-bugzilla@sourceware.org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=30132

            Bug ID: 30132
           Summary: [gdb/testsuite] FAIL:
                    gdb.arch/amd64-disp-step-avx.exp: continue until exit
                    at amd64-disp-step-avx
           Product: gdb
           Version: HEAD
            Status: NEW
          Severity: normal
          Priority: P2
         Component: testsuite
          Assignee: unassigned at sourceware dot org
          Reporter: vries at gcc dot gnu.org
  Target Milestone: ---

On SLE-11, with glibc 2.11.3, I run into:
...
(gdb) PASS: gdb.arch/amd64-disp-step-avx.exp: vex3: var128 has expected value
after
continue^M
Continuing.^M
^M
Program received signal SIGSEGV, Segmentation fault.^M
0x0000000000400283 in _exit (status=0) at
../sysdeps/unix/sysv/linux/_exit.c:33^M
33      ../sysdeps/unix/sysv/linux/_exit.c: No such file or directory.^M
(gdb) FAIL: gdb.arch/amd64-disp-step-avx.exp: continue until exit at
amd64-disp-step-avx
...

This not related to gdb, just by running the exec we get the same result.

The problem is that the test-case:
- calls glibc's _exit
- uses -nostartfiles, putting the burden for any necessary initialization for
  calling glibc's _exit on the test-case itself
- uses static, meaning there's no additional initialization by say
  dynamic linker or libc.so initializer

So, when we get to the second insn here:
...
000000000040acb0 <_exit>:
  40acb0:       48 63 d7                movslq %edi,%rdx
  40acb3:       64 4c 8b 14 25 00 00    mov    %fs:0x0,%r10
...
there's insufficient initialization done, and we run into the segfault.

Adding this in start:
...
         .rept 200
         nop
+        call __pthread_initialize_minimal
         .endr
...
is sufficient to fix it.  But that doesn't compile on my development system
with glibc 2.31.

We could just not run through to exit.

Or do the syscall in the test-case.

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