RE: [PATCH 5/8] Windows gdb: Prepare XState functions

> -----Original Message-----
> From: Hannes Domani <[email protected]>
> Sent: Sonntag, 12. Juli 2026 13:32
> To: [email protected]
> Subject: [PATCH 5/8] Windows gdb: Prepare XState functions
> 
> These functions will then be used to access the XState registers.
> ---
>  gdb/nat/windows-nat.c |  31 +++++++++++  gdb/nat/windows-nat.h | 116
> ++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 147 insertions(+)
> 
> diff --git a/gdb/nat/windows-nat.c b/gdb/nat/windows-nat.c index
> 689601f3a82..cd1f9e7bc64 100644
> --- a/gdb/nat/windows-nat.c
> +++ b/gdb/nat/windows-nat.c
> @@ -73,6 +73,19 @@ InitializeProcThreadAttributeList_ftype
> *InitializeProcThreadAttributeList;
>  UpdateProcThreadAttribute_ftype *UpdateProcThreadAttribute;
> DeleteProcThreadAttributeList_ftype *DeleteProcThreadAttributeList;
> 
> +#if defined __i386__ || defined __x86_64__
> +GetEnabledXStateFeatures_ftype *GetEnabledXStateFeatures;
> +InitializeContext_ftype *InitializeContext; GetXStateFeaturesMask_ftype
> +*GetXStateFeaturesMask; SetXStateFeaturesMask_ftype
> +*SetXStateFeaturesMask; LocateXStateFeature_ftype *LocateXStateFeature;
> +#ifdef __x86_64__ RtlGetExtendedFeaturesMask_ftype
> +*RtlGetExtendedFeaturesMask; RtlSetExtendedFeaturesMask_ftype
> +*RtlSetExtendedFeaturesMask; RtlLocateExtendedFeature_ftype
> +*RtlLocateExtendedFeature; #endif #endif
> +
>  /* Note that 'debug_events' must be locally defined in the relevant
>     functions.  */
>  #define DEBUG_EVENTS(fmt, ...) \
> @@ -1191,6 +1204,14 @@ initialize_loadable ()
>        GPA (hm, InitializeProcThreadAttributeList);
>        GPA (hm, UpdateProcThreadAttribute);
>        GPA (hm, DeleteProcThreadAttributeList);
> +
> +#if defined __i386__ || defined __x86_64__
> +      GPA (hm, GetEnabledXStateFeatures);
> +      GPA (hm, InitializeContext);
> +      GPA (hm, GetXStateFeaturesMask);
> +      GPA (hm, SetXStateFeaturesMask);
> +      GPA (hm, LocateXStateFeature);
> +#endif
>      }
> 
>    /* Set variables to dummy versions of these processes if the function @@ -
> 1256,6 +1277,16 @@ initialize_loadable ()
>  	GPA (hm, GetThreadDescription);
>      }
> 
> +#ifdef __x86_64__
> +  hm = LoadLibrary (TEXT ("ntdll.dll"));
> +  if (hm)
> +    {
> +      GPA (hm, RtlGetExtendedFeaturesMask);
> +      GPA (hm, RtlSetExtendedFeaturesMask);
> +      GPA (hm, RtlLocateExtendedFeature);
> +    }
> +#endif
> +
>  #undef GPA
> 
>    return result;
> diff --git a/gdb/nat/windows-nat.h b/gdb/nat/windows-nat.h index
> 76688fa90da..a344b0a966f 100644
> --- a/gdb/nat/windows-nat.h
> +++ b/gdb/nat/windows-nat.h
> @@ -35,6 +35,9 @@
>  #define CONTEXT_EXTENDED_REGISTERS 0
>  #endif
> 
> +#define CONTEXT_EXTENDED_REGISTERS_FLAG	0x20
> +#define CONTEXT_XSTATE_FLAG		0x40
> +
>  namespace windows_nat
>  {
> 
> @@ -456,6 +459,14 @@ extern BOOL create_process (const wchar_t
> *image, wchar_t *command_line,  #define InitializeProcThreadAttributeList
> dyn_InitializeProcThreadAttributeList
>  #define UpdateProcThreadAttribute dyn_UpdateProcThreadAttribute
> #define DeleteProcThreadAttributeList dyn_DeleteProcThreadAttributeList
> +#define GetEnabledXStateFeatures	dyn_GetEnabledXStateFeatures
> +#define InitializeContext		dyn_InitializeContext
> +#define GetXStateFeaturesMask		dyn_GetXStateFeaturesMask
> +#define SetXStateFeaturesMask		dyn_SetXStateFeaturesMask
> +#define LocateXStateFeature		dyn_LocateXStateFeature
> +#define RtlGetExtendedFeaturesMask	dyn_RtlGetExtendedFeaturesMask
> +#define RtlSetExtendedFeaturesMask	dyn_RtlSetExtendedFeaturesMask
> +#define RtlLocateExtendedFeature	dyn_RtlLocateExtendedFeature
> 
>  typedef BOOL WINAPI (AdjustTokenPrivileges_ftype) (HANDLE, BOOL,
>  						   PTOKEN_PRIVILEGES,
> @@ -550,6 +561,35 @@ extern DeleteProcThreadAttributeList_ftype
> *DeleteProcThreadAttributeList;
> 
>  extern bool disable_randomization_available ();
> 
> +#if defined __i386__ || defined __x86_64__ typedef DWORD64 (WINAPI
> +GetEnabledXStateFeatures_ftype) (); extern
> +GetEnabledXStateFeatures_ftype *GetEnabledXStateFeatures;
> +
> +typedef BOOL (WINAPI InitializeContext_ftype) (PVOID, DWORD,
> +					       PCONTEXT*, PDWORD);
> +extern InitializeContext_ftype *InitializeContext;
> +
> +typedef BOOL (WINAPI GetXStateFeaturesMask_ftype) (PCONTEXT,
> PDWORD64);
> +extern GetXStateFeaturesMask_ftype *GetXStateFeaturesMask;
> +
> +typedef BOOL (WINAPI SetXStateFeaturesMask_ftype) (PCONTEXT,
> DWORD64);
> +extern SetXStateFeaturesMask_ftype *SetXStateFeaturesMask;
> +
> +typedef PVOID (WINAPI LocateXStateFeature_ftype) (PCONTEXT, DWORD,
> +PDWORD); extern LocateXStateFeature_ftype *LocateXStateFeature;
> +
> +#ifdef __x86_64__
> +typedef DWORD64 (WINAPI RtlGetExtendedFeaturesMask_ftype) (PVOID);
> +extern RtlGetExtendedFeaturesMask_ftype *RtlGetExtendedFeaturesMask;
> +
> +typedef VOID (WINAPI RtlSetExtendedFeaturesMask_ftype) (PVOID,
> +DWORD64); extern RtlSetExtendedFeaturesMask_ftype
> +*RtlSetExtendedFeaturesMask;
> +
> +typedef PVOID (WINAPI RtlLocateExtendedFeature_ftype) (PVOID, DWORD,
> +PDWORD); extern RtlLocateExtendedFeature_ftype
> +*RtlLocateExtendedFeature; #endif #endif
> +
>  /* Helper classes to get the correct ContextFlags values based on the
>     used type (CONTEXT or WOW64_CONTEXT).  */
> 
> @@ -615,16 +655,69 @@ enum_process_modules (CONTEXT *, HANDLE
> process,
>    return EnumProcessModules (process, modules, size, needed);  }
> 
> +#if defined __i386__ || defined __x86_64__ static inline BOOL
> +get_xstate_features_mask (CONTEXT *context, DWORD64 *mask) {
> +  return GetXStateFeaturesMask (context, mask); }
> +
> +static inline BOOL
> +set_xstate_features_mask (CONTEXT *context, DWORD64 mask) {
> +  return SetXStateFeaturesMask (context, mask); }
> +
> +static inline PVOID
> +locate_xstate_feature (CONTEXT *context, DWORD feature, DWORD
> *length)
> +{
> +  return LocateXStateFeature (context, feature, length); } #endif
> +
>  #ifdef __x86_64__
>  static inline BOOL
>  get_thread_context (HANDLE h, WOW64_CONTEXT *context)  {
> +  if ((context->ContextFlags & CONTEXT_XSTATE_FLAG) != 0)
> +    {
> +      /* Wow64GetThreadContext doesn't handle
> CONTEXT_EXTENDED_REGISTERS and
> +	 CONTEXT_XSTATE combined correctly, but separate they work fine.
> */
> +      DWORD flags = context->ContextFlags;
> +      context->ContextFlags &= ~CONTEXT_EXTENDED_REGISTERS_FLAG;
> +      BOOL ret = Wow64GetThreadContext (h, context);
> +      context->ContextFlags = flags;
> +      if (!ret)
> +	return FALSE;
> +
> +      context->ContextFlags &= ~CONTEXT_XSTATE_FLAG;
> +      ret = Wow64GetThreadContext (h, context);
> +      context->ContextFlags = flags;
> +      return ret;
> +    }
> +
>    return Wow64GetThreadContext (h, context);  }
> 
>  static inline BOOL
>  set_thread_context (HANDLE h, WOW64_CONTEXT *context)  {
> +  if ((context->ContextFlags & CONTEXT_XSTATE_FLAG) != 0)
> +    {
> +      /* Same limitation as Wow64GetThreadContext above.  */
> +      DWORD flags = context->ContextFlags;
> +      context->ContextFlags &= ~CONTEXT_EXTENDED_REGISTERS_FLAG;
> +      BOOL ret = Wow64SetThreadContext (h, context);
> +      context->ContextFlags = flags;
> +      if (!ret)
> +	return FALSE;
> +
> +      context->ContextFlags &= ~CONTEXT_XSTATE_FLAG;
> +      ret = Wow64SetThreadContext (h, context);
> +      context->ContextFlags = flags;
> +      return ret;
> +    }
> +
>    return Wow64SetThreadContext (h, context);  }
> 
> @@ -642,6 +735,29 @@ enum_process_modules (WOW64_CONTEXT *,
> HANDLE process,
>    return EnumProcessModulesEx (process, modules, size, needed,
>  			       LIST_MODULES_32BIT);
>  }
> +
> +static inline BOOL
> +get_xstate_features_mask (WOW64_CONTEXT *context, DWORD64 *mask)
> {
> +  /* Use lower level function, since there is no
> +Wow64GetXStateFeaturesMask.  */
> +  *mask = RtlGetExtendedFeaturesMask (context + 1);
> +  return TRUE;
> +}
> +
> +static inline BOOL
> +set_xstate_features_mask (WOW64_CONTEXT *context, DWORD64 mask) {
> +  /* Use lower level function, since there is no
> +Wow64SetXStateFeaturesMask.  */
> +  RtlSetExtendedFeaturesMask (context + 1, mask);
> +  return TRUE;
> +}
> +
> +static inline PVOID
> +locate_xstate_feature (WOW64_CONTEXT *context, DWORD feature,
> DWORD
> +*length) {
> +  /* Use lower level function, since there is no
> +Wow64LocateXStateFeature.  */
> +  return RtlLocateExtendedFeature (context + 1, feature, length); }
>  #endif
> 
>  /* This is available starting with Windows 10.  */
> --
> 2.54.0
> 

For this and the following patch:  I can see that you introduced x86 specific code,
but used the generic windows-nat.c/.h files for it. In gdb linux code we try to keep
arch specific details in separate files. 

In an earlier patch you tried to keep it separate for windows, too:
"Move x86 register code into x86-windows-nat.c ". 

I am not familiar with windows specific code, but do you think moving this to an arch
specific file (for instance gdb/x86-windows-nat.c) is an option?

Thanks,
Christina