[v3,6/8] Windows gdb: Get available XState features
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Commit Message
Also prepares the thread context for the additional registers.
---
v2:
- Remove PKRU from the implemented features mask
v3:
- use throw_winerror_with_name instead of error
- fix formatting and value of xstate_features
---
gdb/nat/windows-nat.c | 57 ++++++++++++++++++++++++++++++++++++++++++-
gdb/nat/windows-nat.h | 5 ++++
2 files changed, 61 insertions(+), 1 deletion(-)
Comments
>>>>> "Hannes" == Hannes Domani <ssbssa@yahoo.de> writes:
Hannes> Also prepares the thread context for the additional registers.
Hannes> ---
Hannes> v2:
Hannes> - Remove PKRU from the implemented features mask
Hannes> v3:
Hannes> - use throw_winerror_with_name instead of error
Hannes> - fix formatting and value of xstate_features
Thanks.
Hannes> + /* Available XState features masked with implemented features. */
Hannes> + xstate_features = (GetEnabledXStateFeatures ()
Hannes> + & X86_XSTATE_SSE_MASK);
Hannes> + /* The extended XState functions are only needed if the available
Hannes> + features exceed SSE. */
Hannes> + if ((xstate_features & ~X86_XSTATE_SSE_MASK) == 0)
Hannes> + xstate_features = 0;
Won't this condition always be true?
Resulting in xstate_features==0 always?
Tom
Am Dienstag, 1. September 2026 um 19:38:06 MESZ hat Tom Tromey <tom@tromey.com> Folgendes geschrieben:
> >>>>> "Hannes" == Hannes Domani <ssbssa@yahoo.de> writes:
>
> Hannes> Also prepares the thread context for the additional registers.
> Hannes> ---
> Hannes> v2:
> Hannes> - Remove PKRU from the implemented features mask
> Hannes> v3:
> Hannes> - use throw_winerror_with_name instead of error
> Hannes> - fix formatting and value of xstate_features
>
> Thanks.
>
> Hannes> + /* Available XState features masked with implemented features. */
> Hannes> + xstate_features = (GetEnabledXStateFeatures ()
> Hannes> + & X86_XSTATE_SSE_MASK);
> Hannes> + /* The extended XState functions are only needed if the available
> Hannes> + features exceed SSE. */
> Hannes> + if ((xstate_features & ~X86_XSTATE_SSE_MASK) == 0)
> Hannes> + xstate_features = 0;
>
> Won't this condition always be true?
> Resulting in xstate_features==0 always?
Yes, with this patch xstate_features is still 0.
The next patch then changes the 'and' of the first xstate_features to use
X86_XSTATE_AVX_MASK instead, so it will be possible to have other values.
Hannes
>>>>> "Hannes" == Hannes Domani <ssbssa@yahoo.de> writes:
Hannes> Yes, with this patch xstate_features is still 0.
Hannes> The next patch then changes the 'and' of the first xstate_features to use
Hannes> X86_XSTATE_AVX_MASK instead, so it will be possible to have other values.
Thanks. Eventually I figured it out... normally I read the patches in
order; sometimes I look ahead but I didn't really think of it this time.
Anyway I think this patch is ok.
Approved-By: Tom Tromey <tom@tromey.com>
Tom
@@ -20,6 +20,7 @@
#include "gdbsupport/common-debug.h"
#include "gdbsupport/gdb_signals.h"
#include "gdbsupport/gdb_wait.h"
+#include "gdbsupport/x86-xstate.h"
#include "target/target.h"
#undef GetModuleFileNameEx
@@ -84,6 +85,8 @@ RtlGetExtendedFeaturesMask_ftype *RtlGetExtendedFeaturesMask;
RtlSetExtendedFeaturesMask_ftype *RtlSetExtendedFeaturesMask;
RtlLocateExtendedFeature_ftype *RtlLocateExtendedFeature;
#endif
+
+DWORD64 xstate_features;
#endif
/* Note that 'debug_events' must be locally defined in the relevant
@@ -99,12 +102,41 @@ windows_thread_info::windows_thread_info (windows_process_info *proc_,
h (h_),
thread_local_base (tlb)
{
+#if defined __i386__ || defined __x86_64__
+ if (xstate_features != 0)
+ {
+ DWORD context_flags = proc->with_context (nullptr, [] (auto *context)
+ {
+ return WindowsContext<decltype(context)>::all;
+ });
+ context_flags |= CONTEXT_XSTATE_FLAG;
+ DWORD xstate_size = 0;
+ InitializeContext (NULL, context_flags, NULL, &xstate_size);
+ context_buffer.reset (xmalloc (xstate_size));
+ CONTEXT *c = nullptr;
+ if (!InitializeContext (context_buffer.get (),
+ context_flags, &c, &xstate_size))
+ {
+ unsigned err = (unsigned) GetLastError ();
+ throw_winerror_with_name (_("InitializeContext failed"), err);
+ }
#ifdef __x86_64__
- if (proc->wow64_process)
+ /* InitializeContext actually initializes a WOW64_CONTEXT when
+ context_flags contains a WOW64_CONTEXT_* value, so a cast is needed.
+ */
+ if (proc->wow64_process)
+ wow64_context = (WOW64_CONTEXT *) c;
+ else
+#endif
+ context = c;
+ }
+#ifdef __x86_64__
+ else if (proc->wow64_process)
{
context_buffer.reset (xmalloc (sizeof (WOW64_CONTEXT)));
wow64_context = (WOW64_CONTEXT *) context_buffer.get ();
}
+#endif
else
#endif
{
@@ -1292,6 +1324,29 @@ initialize_loadable ()
#undef GPA
+#if defined __i386__ || defined __x86_64__
+ if (GetEnabledXStateFeatures != nullptr
+ && InitializeContext != nullptr
+ && GetXStateFeaturesMask != nullptr
+ && SetXStateFeaturesMask != nullptr
+ && LocateXStateFeature != nullptr
+#ifdef __x86_64__
+ && RtlGetExtendedFeaturesMask != nullptr
+ && RtlSetExtendedFeaturesMask != nullptr
+ && RtlLocateExtendedFeature != nullptr
+#endif
+ )
+ {
+ /* Available XState features masked with implemented features. */
+ xstate_features = (GetEnabledXStateFeatures ()
+ & X86_XSTATE_SSE_MASK);
+ /* The extended XState functions are only needed if the available
+ features exceed SSE. */
+ if ((xstate_features & ~X86_XSTATE_SSE_MASK) == 0)
+ xstate_features = 0;
+ }
+#endif
+
return result;
}
@@ -750,6 +750,11 @@ locate_xstate_feature (WOW64_CONTEXT *context, DWORD feature, DWORD *length)
}
#endif
+#if defined __i386__ || defined __x86_64__
+/* Available XState features. */
+extern DWORD64 xstate_features;
+#endif
+
/* This is available starting with Windows 10. */
#ifndef DBG_REPLY_LATER
# define DBG_REPLY_LATER 0x40010001L