diff mbox series

[PATCHv4,07/10] gdb/arch: assert that X86_XSTATE_MPX is not set for x32

Message ID 40475ef7aa9325c0802eb86018d642024b26a28e.1712245988.git.aburgess@redhat.com
State New
Headers
Series x86/Linux Target Description Changes |

Checks

Context Check Description
linaro-tcwg-bot/tcwg_gdb_build--master-aarch64 success Testing passed
linaro-tcwg-bot/tcwg_gdb_build--master-arm success Testing passed
linaro-tcwg-bot/tcwg_gdb_check--master-arm success Testing passed
linaro-tcwg-bot/tcwg_gdb_check--master-aarch64 success Testing passed

Commit Message

Andrew Burgess April 5, 2024, 12:33 p.m. UTC 
  While rebasing this series past this commit:

  commit 4bb20a6244b7091a9a7a2ae35dfbd7e8db27550a
  Date:   Wed Mar 20 04:13:18 2024 -0700

      gdbserver: Clear X86_XSTATE_MPX bits in xcr0 on x32

I worried that there could be other paths that might result in an xcr0
value which 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 will 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, but the author of commit 4bb20a6244b7091 did test this
series with that assert in place and didn't see any problems.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31511
---
 gdb/arch/amd64.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/gdb/arch/amd64.c b/gdb/arch/amd64.c
index cb9683c6931..94d55d72a4e 100644
--- a/gdb/arch/amd64.c
+++ b/gdb/arch/amd64.c
@@ -65,8 +65,12 @@  amd64_create_target_description (uint64_t xcr0, bool is_x32, bool is_linux,
   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);