Improve support for XSAVE with debuggers.

- Dump an NT_X86_XSTATE note if XSAVE is in use. This note is designed
  to match what Linux does in that 1) it dumps the entire XSAVE area
  including the fxsave state, and 2) it stashes a copy of the current
  xsave mask in the unused padding between the fxsave state and the
  xstate header at the same location used by Linux.
- Teach readelf() to recognize NT_X86_XSTATE notes.
- Change PT_GET/SETXSTATE to take the entire XSAVE state instead of
  only the extra portion. This avoids having to always make two
  ptrace() calls to get or set the full XSAVE state.
- Add a PT_GET_XSTATE_INFO which returns the length of the current
  XSTATE save area (so the size of the buffer needed for PT_GETXSTATE)
  and the current XSAVE mask (%xcr0).

Differential Revision:	https://reviews.freebsd.org/D1193
Reviewed by:	kib
MFC after:	2 weeks

1 files changed, 14 insertions, 3 deletions

diff --git a/sys/x86/include/ptrace.h b/sys/x86/include/ptrace.h
index 16a04d1..16f9c62 100644
--- a/sys/x86/include/ptrace.h
+++ b/sys/x86/include/ptrace.h
@@ -37,14 +37,25 @@
 
 /*
  * On amd64 (PT_FIRSTMACH + 0) and (PT_FIRSTMACH + 1) are old values for
- * PT_GETXSTATE and PT_SETXSTATE.  They should not be (re)used.
+ * PT_GETXSTATE_OLD and PT_SETXSTATE_OLD.  They should not be (re)used.
  */
 
 #ifdef __i386__
 #define	PT_GETXMMREGS	(PT_FIRSTMACH + 0)
 #define	PT_SETXMMREGS	(PT_FIRSTMACH + 1)
 #endif
-#define	PT_GETXSTATE	(PT_FIRSTMACH + 2)
-#define	PT_SETXSTATE	(PT_FIRSTMACH + 3)
+#ifdef _KERNEL
+#define	PT_GETXSTATE_OLD (PT_FIRSTMACH + 2)
+#define	PT_SETXSTATE_OLD (PT_FIRSTMACH + 3)
+#endif
+#define	PT_GETXSTATE_INFO (PT_FIRSTMACH + 4)
+#define	PT_GETXSTATE	(PT_FIRSTMACH + 5)
+#define	PT_SETXSTATE	(PT_FIRSTMACH + 6)
+
+/* Argument structure for PT_GETXSTATE_INFO. */
+struct ptrace_xstate_info {
+	uint64_t	xsave_mask;
+	uint32_t	xsave_len;
+};
 
 #endif