[Bug ld/29851] New: -Wl,-z,ibtplt emits MPX jumps

[mliska at suse dot cz]

https://sourceware.org/bugzilla/show_bug.cgi?id=29851

            Bug ID: 29851
           Summary: -Wl,-z,ibtplt emits MPX jumps
           Product: binutils
           Version: 2.40 (HEAD)
            Status: NEW
          Severity: normal
          Priority: P2
         Component: ld
          Assignee: unassigned at sourceware dot org
          Reporter: mliska at suse dot cz
                CC: hjl.tools at gmail dot com
  Target Milestone: ---

I would like to remove the support for -Wl,-z,bndplt as MPX extension is
outdated and unused. However, I noticed that -Wl,-z,ibtplt emits 'bnd jmp' and
I'm curious if it's correct or not?

$ cat a.c
#include <string.h>

int main(int argc, char **argv)
{
  return strcmp (argv[0], "pes") == 0;
}
$ gcc-12 -shared a.c -fPIC -o libfoo.so -Wl,-z,ibtplt && objdump -d libfoo.so |
less
...
0000000000001050 <strcmp@plt>:
    1050:       f3 0f 1e fa             endbr64
    1054:       f2 ff 25 7d 2f 00 00    bnd jmp *0x2f7d(%rip)        # 3fd8
<strcmp@GLIBC_2.2.5>
    105b:       0f 1f 44 00 00          nopl   0x0(%rax,%rax,1)

Is it correct instruction that is used?

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