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[PATCHv6,6/9] gdb: move xcr0 == 0 check into i386_linux_core_read_description

Message ID caae19571535b44e3bf18f6401bf5e37f9243d96.1715185683.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
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Commit Message

Andrew Burgess May 8, 2024, 4:46 p.m. UTC 
  Currently, in i386_linux_core_read_description, if GDB fails to
extract an xcr0 value from the core file, then we will have a default
zero value for the xcr0 variable, we still call the
i386_linux_read_description function, which checks for this zero value
and returns nullptr.

Back in i386_linux_core_read_description we spot the nullptr return
value from i386_linux_read_description and call
i386_linux_read_description again, but this time passing a default
value for xcr0.

In the next commit I plan to rework i386_linux_read_description, and
in so doing I will remove the check for xcr0 == 0, this is inline with
how the amd64 code is written.

However, this means that the 'xcr0 == 0' check needs to move up the
stack to i386_linux_core_read_description, again, this brings the i386
code into line with the amd64 code.

This is just a refactor in preparation for the next commit, there
should be no user visible changes after this commit.

Approved-By: Felix Willgerodt <felix.willgerodt@intel.com>
---
 gdb/i386-linux-tdep.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

Comments

John Baldwin May 8, 2024, 10:54 p.m. UTC | #1 
On 5/8/24 9:46 AM, Andrew Burgess wrote:
> Currently, in i386_linux_core_read_description, if GDB fails to
> extract an xcr0 value from the core file, then we will have a default
> zero value for the xcr0 variable, we still call the
> i386_linux_read_description function, which checks for this zero value
> and returns nullptr.
> 
> Back in i386_linux_core_read_description we spot the nullptr return
> value from i386_linux_read_description and call
> i386_linux_read_description again, but this time passing a default
> value for xcr0.
> 
> In the next commit I plan to rework i386_linux_read_description, and
> in so doing I will remove the check for xcr0 == 0, this is inline with
> how the amd64 code is written.
> 
> However, this means that the 'xcr0 == 0' check needs to move up the
> stack to i386_linux_core_read_description, again, this brings the i386
> code into line with the amd64 code.
> 
> This is just a refactor in preparation for the next commit, there
> should be no user visible changes after this commit.
> 
> Approved-By: Felix Willgerodt <felix.willgerodt@intel.com>

Approved-By: John Baldwin <jhb@FreeBSD.org>
diff mbox series

Patch

diff --git a/gdb/i386-linux-tdep.c b/gdb/i386-linux-tdep.c
index a78f03fac8d..511e43f3b6f 100644
--- a/gdb/i386-linux-tdep.c
+++ b/gdb/i386-linux-tdep.c
@@ -714,15 +714,16 @@  i386_linux_core_read_description (struct gdbarch *gdbarch,
   /* Linux/i386.  */
   x86_xsave_layout layout;
   uint64_t xcr0 = i386_linux_core_read_xsave_info (abfd, layout);
-  const struct target_desc *tdesc = i386_linux_read_description (xcr0);
 
-  if (tdesc != NULL)
-    return tdesc;
+  if (xcr0 == 0)
+    {
+      if (bfd_get_section_by_name (abfd, ".reg-xfp") != nullptr)
+	xcr0 = X86_XSTATE_SSE_MASK;
+      else
+	xcr0 = X86_XSTATE_X87_MASK;
+    }
 
-  if (bfd_get_section_by_name (abfd, ".reg-xfp") != NULL)
-    return i386_linux_read_description (X86_XSTATE_SSE_MASK);
-  else
-    return i386_linux_read_description (X86_XSTATE_X87_MASK);
+  return i386_linux_read_description (xcr0);
 }
 
 /* Similar to i386_supply_fpregset, but use XSAVE extended state.  */