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* [Bug gdb/30818] New: GDB + GDBserver doesn't set AVX512 registers properly
@ 2023-09-01 14:39 simon.marchi at polymtl dot ca
2023-09-02 2:14 ` [Bug gdb/30818] " cvs-commit at gcc dot gnu.org
2023-09-02 2:15 ` simark at simark dot ca
0 siblings, 2 replies; 3+ messages in thread
From: simon.marchi at polymtl dot ca @ 2023-09-01 14:39 UTC (permalink / raw)
To: gdb-prs
https://sourceware.org/bugzilla/show_bug.cgi?id=30818
Bug ID: 30818
Summary: GDB + GDBserver doesn't set AVX512 registers properly
Product: gdb
Version: HEAD
Status: NEW
Severity: normal
Priority: P2
Component: gdb
Assignee: unassigned at sourceware dot org
Reporter: simon.marchi at polymtl dot ca
Target Milestone: ---
On a machine with AVX512 support (AMD EPYC 9634), I see:
$ make check TESTS="gdb.arch/i386-avx512.exp"
RUNTESTFLAGS="--target_board=native-gdbserver"
...
FAIL: gdb.arch/i386-avx512.exp: check contents of zmm_data[16] after writing
ZMM regs
...
I can reproduce more simply with (after connecting to gdbserver):
(gdb) print $zmm16.v8_int64
$1 = {0, 0, 0, 0, 0, 0, 0, 0}
(gdb) print $zmm16.v8_int64 = {11,22,33,44,55,66,77,88}
$2 = {11, 22, 33, 44, 55, 66, 77, 88}
(gdb) print $zmm16.v8_int64
$3 = {11, 22, 33, 44, 55, 66, 77, 88}
(gdb) step
5 ++x;
(gdb) print $zmm16.v8_int64
$4 = {11, 22, 77, 88, 0, 0, 0, 0}
It looks like writing to the local regcache in GDB worked fine, but the
writeback to gdbserver didn't work fine.
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* [Bug gdb/30818] GDB + GDBserver doesn't set AVX512 registers properly
2023-09-01 14:39 [Bug gdb/30818] New: GDB + GDBserver doesn't set AVX512 registers properly simon.marchi at polymtl dot ca
@ 2023-09-02 2:14 ` cvs-commit at gcc dot gnu.org
2023-09-02 2:15 ` simark at simark dot ca
1 sibling, 0 replies; 3+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2023-09-02 2:14 UTC (permalink / raw)
To: gdb-prs
https://sourceware.org/bugzilla/show_bug.cgi?id=30818
--- Comment #1 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Simon Marchi <simark@sourceware.org>:
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=41770089162edd23ea7ae33b7952585316accde5
commit 41770089162edd23ea7ae33b7952585316accde5
Author: Simon Marchi <simon.marchi@efficios.com>
Date: Fri Sep 1 14:12:07 2023 -0400
gdbserver: i387_cache_to_xsave: fix copy dest of zmm registers
On a machine with AVX512 support (AMD EPYC 9634), I see these failures:
$ make check TESTS="gdb.arch/i386-avx512.exp"
RUNTESTFLAGS="--target_board=native-gdbserver"
...
FAIL: gdb.arch/i386-avx512.exp: check contents of zmm_data[16] after
writing ZMM regs
FAIL: gdb.arch/i386-avx512.exp: check contents of zmm_data[17] after
writing ZMM regs
FAIL: gdb.arch/i386-avx512.exp: check contents of zmm_data[18] after
writing ZMM regs
...
The problem can be reduced to:
(gdb) print $zmm16.v8_int64
$1 = {0, 0, 0, 0, 0, 0, 0, 0}
(gdb) print $zmm16.v8_int64 = {11,22,33,44,55,66,77,88}
$2 = {11, 22, 33, 44, 55, 66, 77, 88}
(gdb) print $zmm16.v8_int64
$3 = {11, 22, 33, 44, 55, 66, 77, 88}
(gdb) step
5 ++x;
(gdb) print $zmm16.v8_int64
$4 = {11, 22, 77, 88, 0, 0, 0, 0}
Writing to the local regcache in GDB works fine, but the writeback to
gdbserver (which happens when resuming / stepping) doesn't work (the
code being stepped doesn't touch AVX registers, so we don't expect the
value of zmm16 to change when stepping).
The problem is on the gdbserver side, the zmmh and ymmh portions of the
zmm register are not memcpied at the right place in the xsave buffer. Fix
that. Note now how the two modified memcpy calls match the memcmp calls
just above them.
With this patch, gdb.arch/i386-avx512.exp passes completely for me.
Change-Id: I22c417e0f5e88d4bc635a0f08f8817a031c76433
Reviewed-by: John Baldwin <jhb@FreeBSD.org>
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30818
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* [Bug gdb/30818] GDB + GDBserver doesn't set AVX512 registers properly
2023-09-01 14:39 [Bug gdb/30818] New: GDB + GDBserver doesn't set AVX512 registers properly simon.marchi at polymtl dot ca
2023-09-02 2:14 ` [Bug gdb/30818] " cvs-commit at gcc dot gnu.org
@ 2023-09-02 2:15 ` simark at simark dot ca
1 sibling, 0 replies; 3+ messages in thread
From: simark at simark dot ca @ 2023-09-02 2:15 UTC (permalink / raw)
To: gdb-prs
https://sourceware.org/bugzilla/show_bug.cgi?id=30818
Simon Marchi <simark at simark dot ca> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution|--- |FIXED
CC| |simark at simark dot ca
--- Comment #2 from Simon Marchi <simark at simark dot ca> ---
Fixed.
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2023-09-01 14:39 [Bug gdb/30818] New: GDB + GDBserver doesn't set AVX512 registers properly simon.marchi at polymtl dot ca
2023-09-02 2:14 ` [Bug gdb/30818] " cvs-commit at gcc dot gnu.org
2023-09-02 2:15 ` simark at simark dot ca
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