gdb/arch: assert that X86_XSTATE_MPX is not set for x32
While trying to merge this commit:
commit 4bb20a6244b7091a9a7a2ae35dfbd7e8db27550a
Date: Wed Mar 20 04:13:18 2024 -0700
gdbserver: Clear X86_XSTATE_MPX bits in xcr0 on x32
With this patch series of mine:
https://inbox.sourceware.org/gdb-patches/cover.1706801009.git.aburgess@redhat.com
I worried that there could be other paths that could result in an xcr0
value that has X86_XSTATE_MPX set in x32 mode. As everyone eventually
calls amd64_create_target_description to build their target
description, I figured we could assert in here that if X86_XSTATE_MPX
is set then we should not be an x32 target, this should uncover any
other bugs in this area.
I'm not currently able to build/run any x32 binaries, so I have no way
to test this.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31511
diff --git a/gdb/arch/amd64.c b/gdb/arch/amd64.c
index b8ff427..f182e68 100644
--- a/gdb/arch/amd64.c
+++ b/gdb/arch/amd64.c
@@ -66,8 +66,12 @@
if (xcr0 & X86_XSTATE_AVX)
regnum = create_feature_i386_64bit_avx (tdesc.get (), regnum);
- if ((xcr0 & X86_XSTATE_MPX) && !is_x32)
- regnum = create_feature_i386_64bit_mpx (tdesc.get (), regnum);
+ if (xcr0 & X86_XSTATE_MPX)
+ {
+ /* MPX is not available on x32. */
+ gdb_assert (!is_x32);
+ regnum = create_feature_i386_64bit_mpx (tdesc.get (), regnum);
+ }
if (xcr0 & X86_XSTATE_AVX512)
regnum = create_feature_i386_64bit_avx512 (tdesc.get (), regnum);
