[Bug tdep/29790] New: [gdb] FAIL: gdb.arch/i386-pkru.exp: read value after setting value

[Bug tdep/29790] New: [gdb] FAIL: gdb.arch/i386-pkru.exp: read value after setting value

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29790

            Bug ID: 29790
           Summary: [gdb] FAIL: gdb.arch/i386-pkru.exp: read value after
                    setting value
           Product: gdb
           Version: 12.1
            Status: NEW
          Severity: normal
          Priority: P2
         Component: tdep
          Assignee: unassigned at sourceware dot org
          Reporter: vries at gcc dot gnu.org
  Target Milestone: ---

Once in a blue moon, our OBS runs on a machine with pkru support, and I got
(with a gdb 12.1-based package):
...
Running
/home/abuild/rpmbuild/BUILD/gdb-12.1/gdb/testsuite/gdb.arch/i386-pkru.exp ...
PASS: gdb.arch/i386-pkru.exp: probe PKRU support
PASS: gdb.arch/i386-pkru.exp: pkru register
PASS: gdb.arch/i386-pkru.exp: continue to breakpoint: break here 1
PASS: gdb.arch/i386-pkru.exp: read pkru register
PASS: gdb.arch/i386-pkru.exp: set pkru value
FAIL: gdb.arch/i386-pkru.exp: read value after setting value
PASS: gdb.arch/i386-pkru.exp: continue to breakpoint: break here 2
FAIL: gdb.arch/i386-pkru.exp: variable after reading pkru
...

In more detail:
...
(gdb) PASS: gdb.arch/i386-pkru.exp: read pkru register
print /x $pkru = 0x44444444^M
$3 = 0x44444444^M
(gdb) PASS: gdb.arch/i386-pkru.exp: set pkru value
info register pkru^M
pkru           0x12345678          305419896^M
(gdb) FAIL: gdb.arch/i386-pkru.exp: read value after setting value
...

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[Bug tdep/29790] [gdb] FAIL: gdb.arch/i386-pkru.exp: read value after setting value

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29790

--- Comment #1 from Tom de Vries <vries at gcc dot gnu.org> ---
Note: it happened both in gdb-i586-suse-linux-m32.sum and
gdb-i586-suse-linux-m32.-fno-PIE.-no-pie.sum, so it's not a fluke.

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[Bug tdep/29790] [gdb] FAIL: gdb.arch/i386-pkru.exp: read value after setting value

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29790

--- Comment #2 from Tom de Vries <vries at gcc dot gnu.org> ---
OK, that seems to be a kernel bug, fixed by commit 4a804c4f8356 (x86/fpu: Allow
PKRU to be (once again) written by ptrace.)

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[Bug tdep/29790] [gdb] FAIL: gdb.arch/i386-pkru.exp: read value after setting value

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29790

--- Comment #3 from Tom de Vries <vries at gcc dot gnu.org> ---
Created attachment 14544
  --> https://sourceware.org/bugzilla/attachment.cgi?id=14544&action=edit
Tentative patch

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[Bug testsuite/29790] [gdb] FAIL: gdb.arch/i386-pkru.exp: read value after setting value

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29790

Tom de Vries <vries at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|tdep                        |testsuite

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[Bug testsuite/29790] [gdb/testsuite] FAIL: gdb.arch/i386-pkru.exp: read value after setting value

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29790

Tom de Vries <vries at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[gdb] FAIL:                 |[gdb/testsuite] FAIL:
                   |gdb.arch/i386-pkru.exp:     |gdb.arch/i386-pkru.exp:
                   |read value after setting    |read value after setting
                   |value                       |value

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[Bug testsuite/29790] [gdb/testsuite] FAIL: gdb.arch/i386-pkru.exp: read value after setting value

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29790

--- Comment #4 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Tom de Vries <vries@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=b46632ca16021962c33c2ea32b8104fd258ef0af

commit b46632ca16021962c33c2ea32b8104fd258ef0af
Author: Tom de Vries <tdevries@suse.de>
Date:   Tue Jan 3 16:41:05 2023 +0100

    [gdb/testsuite] Add xfail in gdb.arch/i386-pkru.exp

    On a x86_64-linux machine with pkru register, I run into:
    ...
    (gdb) PASS: gdb.arch/i386-pkru.exp: set pkru value
    info register pkru^M
    pkru           0x12345678          305419896^M
    (gdb) FAIL: gdb.arch/i386-pkru.exp: read value after setting value
    ...

    This is a regression due to kernel commit e84ba47e313d ("x86/fpu: Hook up
PKRU
    onto ptrace()").  This is fixed by recent kernel commit 4a804c4f8356
    ("x86/fpu: Allow PKRU to be (once again) written by ptrace.").

    The regression occurs for kernel versions v5.14-rc1 (the first tag
containing
    the regression) up to but excluding v6.2-rc1 (the first tag containing the
fix).

    Fix this by adding an xfail for the appropriate kernel versions.

    Tested on x86_64-linux.

    PR testsuite/29790
    Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29790

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[Bug testsuite/29790] [gdb/testsuite] FAIL: gdb.arch/i386-pkru.exp: read value after setting value

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29790

Tom de Vries <vries at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|NEW                         |RESOLVED
   Target Milestone|---                         |14.1

--- Comment #5 from Tom de Vries <vries at gcc dot gnu.org> ---
Fixed by commit.

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