From 41770089162edd23ea7ae33b7952585316accde5 Mon Sep 17 00:00:00 2001 From: Simon Marchi Date: Fri, 1 Sep 2023 14:12:07 -0400 Subject: [PATCH] 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 Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30818 --- gdbserver/i387-fp.cc | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/gdbserver/i387-fp.cc b/gdbserver/i387-fp.cc index 4229d60327e..27f8e2dbb73 100644 --- a/gdbserver/i387-fp.cc +++ b/gdbserver/i387-fp.cc @@ -469,7 +469,7 @@ i387_cache_to_xsave (struct regcache *regcache, void *buf) if (memcmp (raw, p + 32, 32) != 0) { xstate_bv |= X86_XSTATE_ZMM; - memcpy (p, raw, 32); + memcpy (p + 32, raw, 32); } /* YMMH sub-register. */ @@ -477,7 +477,7 @@ i387_cache_to_xsave (struct regcache *regcache, void *buf) if (memcmp (raw, p + 16, 16) != 0) { xstate_bv |= X86_XSTATE_ZMM; - memcpy (p, raw, 16); + memcpy (p + 16, raw, 16); } /* XMM sub-register. */ -- 2.30.2