[PATCH v4 06/13] gdb: Support XSAVE layouts for the current host in the FreeBSD x86 targets.

[John Baldwin <jhb@FreeBSD.org>]

Use the CPUID instruction to fetch the offsets of supported state
components.
---
 gdb/amd64-fbsd-nat.c | 40 +++++++++-------------------------
 gdb/configure.nat    |  5 +++--
 gdb/i386-fbsd-nat.c  | 39 ++++++++-------------------------
 gdb/x86-fbsd-nat.c   | 51 ++++++++++++++++++++++++++++++++++++++++++++
 gdb/x86-fbsd-nat.h   | 29 ++++++++++++++++++++++++-
 5 files changed, 101 insertions(+), 63 deletions(-)

diff --git a/gdb/amd64-fbsd-nat.c b/gdb/amd64-fbsd-nat.c
index bae267f230f..f17a30f3483 100644
--- a/gdb/amd64-fbsd-nat.c
+++ b/gdb/amd64-fbsd-nat.c
@@ -31,9 +31,9 @@
 
 #include "amd64-tdep.h"
 #include "amd64-fbsd-tdep.h"
+#include "i387-tdep.h"
 #include "amd64-nat.h"
 #include "x86-nat.h"
-#include "gdbsupport/x86-xstate.h"
 #include "x86-fbsd-nat.h"
 
 class amd64_fbsd_nat_target final : public x86_fbsd_nat_target
@@ -47,10 +47,6 @@ class amd64_fbsd_nat_target final : public x86_fbsd_nat_target
 
 static amd64_fbsd_nat_target the_amd64_fbsd_nat_target;
 
-#ifdef PT_GETXSTATE_INFO
-static size_t xsave_len;
-#endif
-
 /* This is a layout of the amd64 'struct reg' but with i386
    registers.  */
 
@@ -146,9 +142,9 @@ amd64_fbsd_nat_target::fetch_registers (struct regcache *regcache, int regnum)
      fetching the FPU/XSAVE state unnecessarily.  */
 
 #ifdef PT_GETXSTATE_INFO
-  if (xsave_len != 0)
+  if (xsave_info.xsave_len != 0)
     {
-      void *xstateregs = alloca (xsave_len);
+      void *xstateregs = alloca (xsave_info.xsave_len);
 
       if (ptrace (PT_GETXSTATE, pid, (PTRACE_TYPE_ARG3) xstateregs, 0) == -1)
 	perror_with_name (_("Couldn't get extended state status"));
@@ -223,9 +219,9 @@ amd64_fbsd_nat_target::store_registers (struct regcache *regcache, int regnum)
      fetching the FPU/XSAVE state unnecessarily.  */
 
 #ifdef PT_GETXSTATE_INFO
-  if (xsave_len != 0)
+  if (xsave_info.xsave_len != 0)
     {
-      void *xstateregs = alloca (xsave_len);
+      void *xstateregs = alloca (xsave_info.xsave_len);
 
       if (ptrace (PT_GETXSTATE, pid, (PTRACE_TYPE_ARG3) xstateregs, 0) == -1)
 	perror_with_name (_("Couldn't get extended state status"));
@@ -233,7 +229,7 @@ amd64_fbsd_nat_target::store_registers (struct regcache *regcache, int regnum)
       amd64_collect_xsave (regcache, regnum, xstateregs, 0);
 
       if (ptrace (PT_SETXSTATE, pid, (PTRACE_TYPE_ARG3) xstateregs,
-		  xsave_len) == -1)
+		  xsave_info.xsave_len) == -1)
 	perror_with_name (_("Couldn't write extended state status"));
       return;
     }
@@ -303,10 +299,6 @@ amd64fbsd_supply_pcb (struct regcache *regcache, struct pcb *pcb)
 const struct target_desc *
 amd64_fbsd_nat_target::read_description ()
 {
-#ifdef PT_GETXSTATE_INFO
-  static int xsave_probed;
-  static uint64_t xcr0;
-#endif
   struct reg regs;
   int is64;
 
@@ -315,25 +307,13 @@ amd64_fbsd_nat_target::read_description ()
     perror_with_name (_("Couldn't get registers"));
   is64 = (regs.r_cs == GSEL (GUCODE_SEL, SEL_UPL));
 #ifdef PT_GETXSTATE_INFO
-  if (!xsave_probed)
-    {
-      struct ptrace_xstate_info info;
-
-      if (ptrace (PT_GETXSTATE_INFO, inferior_ptid.pid (),
-		  (PTRACE_TYPE_ARG3) &info, sizeof (info)) == 0)
-	{
-	  xsave_len = info.xsave_len;
-	  xcr0 = info.xsave_mask;
-	}
-      xsave_probed = 1;
-    }
-
-  if (xsave_len != 0)
+  probe_xsave_layout (inferior_ptid.pid ());
+  if (xsave_info.xsave_len != 0)
     {
       if (is64)
-	return amd64_target_description (xcr0, true);
+	return amd64_target_description (xsave_info.xsave_mask, true);
       else
-	return i386_target_description (xcr0, true);
+	return i386_target_description (xsave_info.xsave_mask, true);
     }
 #endif
   if (is64)
diff --git a/gdb/configure.nat b/gdb/configure.nat
index aabcdeff989..b371ad89afe 100644
--- a/gdb/configure.nat
+++ b/gdb/configure.nat
@@ -166,7 +166,8 @@ case ${gdb_host} in
 	    i386)
 		# Host: FreeBSD/i386
 		NATDEPFILES="${NATDEPFILES} x86-nat.o nat/x86-dregs.o \
-		x86-bsd-nat.o x86-fbsd-nat.o i386-fbsd-nat.o bsd-kvm.o"
+		nat/x86-xstate.o x86-bsd-nat.o x86-fbsd-nat.o i386-fbsd-nat.o \
+		bsd-kvm.o"
 		;;
 	    mips)
 		# Host: FreeBSD/mips
@@ -195,7 +196,7 @@ case ${gdb_host} in
 		# Host: FreeBSD/amd64
 		NATDEPFILES="${NATDEPFILES} amd64-nat.o \
 		amd64-fbsd-nat.o bsd-kvm.o x86-nat.o nat/x86-dregs.o \
-		x86-bsd-nat.o x86-fbsd-nat.o"
+		nat/x86-xstate.o x86-bsd-nat.o x86-fbsd-nat.o"
 		;;
 	esac
 	;;
diff --git a/gdb/i386-fbsd-nat.c b/gdb/i386-fbsd-nat.c
index 927771e8b20..0a6328cdae1 100644
--- a/gdb/i386-fbsd-nat.c
+++ b/gdb/i386-fbsd-nat.c
@@ -31,7 +31,6 @@
 #include "i386-fbsd-tdep.h"
 #include "i387-tdep.h"
 #include "x86-nat.h"
-#include "gdbsupport/x86-xstate.h"
 #include "x86-fbsd-nat.h"
 
 class i386_fbsd_nat_target final : public x86_fbsd_nat_target
@@ -47,10 +46,6 @@ class i386_fbsd_nat_target final : public x86_fbsd_nat_target
 
 static i386_fbsd_nat_target the_i386_fbsd_nat_target;
 
-#ifdef PT_GETXSTATE_INFO
-static size_t xsave_len;
-#endif
-
 static int have_ptrace_xmmregs;
 
 /* Fetch register REGNUM from the inferior.  If REGNUM is -1, do this
@@ -102,9 +97,9 @@ i386_fbsd_nat_target::fetch_registers (struct regcache *regcache, int regnum)
      fetching the FPU/XSAVE state unnecessarily.  */
 
 #ifdef PT_GETXSTATE_INFO
-  if (xsave_len != 0)
+  if (xsave_info.xsave_len != 0)
     {
-      void *xstateregs = alloca (xsave_len);
+      void *xstateregs = alloca (xsave_info.xsave_len);
 
       if (ptrace (PT_GETXSTATE, pid, (PTRACE_TYPE_ARG3) xstateregs, 0) == -1)
 	perror_with_name (_("Couldn't get extended state status"));
@@ -181,17 +176,17 @@ i386_fbsd_nat_target::store_registers (struct regcache *regcache, int regnum)
      fetching the FPU/XSAVE state unnecessarily.  */
 
 #ifdef PT_GETXSTATE_INFO
-  if (xsave_len != 0)
+  if (xsave_info.xsave_len != 0)
     {
-      void *xstateregs = alloca (xsave_len);
+      void *xstateregs = alloca (xsave_info.xsave_len);
 
       if (ptrace (PT_GETXSTATE, pid, (PTRACE_TYPE_ARG3) xstateregs, 0) == -1)
 	perror_with_name (_("Couldn't get extended state status"));
 
       i387_collect_xsave (regcache, regnum, xstateregs, 0);
 
-      if (ptrace (PT_SETXSTATE, pid, (PTRACE_TYPE_ARG3) xstateregs, xsave_len)
-	  == -1)
+      if (ptrace (PT_SETXSTATE, pid, (PTRACE_TYPE_ARG3) xstateregs,
+		  xsave_info.xsave_len) == -1)
 	perror_with_name (_("Couldn't write extended state status"));
       return;
     }
@@ -309,28 +304,12 @@ i386fbsd_supply_pcb (struct regcache *regcache, struct pcb *pcb)
 const struct target_desc *
 i386_fbsd_nat_target::read_description ()
 {
-#ifdef PT_GETXSTATE_INFO
-  static int xsave_probed;
-  static uint64_t xcr0;
-#endif
   static int xmm_probed;
 
 #ifdef PT_GETXSTATE_INFO
-  if (!xsave_probed)
-    {
-      struct ptrace_xstate_info info;
-
-      if (ptrace (PT_GETXSTATE_INFO, inferior_ptid.pid (),
-		  (PTRACE_TYPE_ARG3) &info, sizeof (info)) == 0)
-	{
-	  xsave_len = info.xsave_len;
-	  xcr0 = info.xsave_mask;
-	}
-      xsave_probed = 1;
-    }
-
-  if (xsave_len != 0)
-    return i386_target_description (xcr0, true);
+  probe_xsave_layout (inferior_ptid.pid ());
+  if (xsave_info.xsave_len != 0)
+    return i386_target_description (xsave_info.xsave_mask, true);
 #endif
 
   if (!xmm_probed)
diff --git a/gdb/x86-fbsd-nat.c b/gdb/x86-fbsd-nat.c
index 5d1c9fc7665..5907fda5d3a 100644
--- a/gdb/x86-fbsd-nat.c
+++ b/gdb/x86-fbsd-nat.c
@@ -19,6 +19,9 @@
 
 #include "defs.h"
 #include "x86-fbsd-nat.h"
+#ifdef PT_GETXSTATE_INFO
+#include "nat/x86-xstate.h"
+#endif
 
 /* Implement the virtual fbsd_nat_target::low_new_fork method.  */
 
@@ -43,3 +46,51 @@ x86_fbsd_nat_target::low_new_fork (ptid_t parent, pid_t child)
   child_state = x86_debug_reg_state (child);
   *child_state = *parent_state;
 }
+
+#ifdef PT_GETXSTATE_INFO
+/* Implement the "xfer_partial" target_ops method.  */
+
+enum target_xfer_status
+x86_fbsd_nat_target::xfer_partial (enum target_object object,
+				   const char *annex, gdb_byte *readbuf,
+				   const gdb_byte *writebuf,
+				   ULONGEST offset, ULONGEST len,
+				   ULONGEST *xfered_len)
+{
+  switch (object)
+    {
+    case TARGET_OBJECT_X86_XSAVE_LAYOUT:
+      if (xsave_layout.sizeof_xsave == 0)
+	return TARGET_XFER_E_IO;
+
+      if (offset > sizeof (xsave_layout))
+	return TARGET_XFER_E_IO;
+
+      if (offset + len > sizeof (xsave_layout))
+	len = sizeof (xsave_layout) - offset;
+
+      memcpy (readbuf, ((gdb_byte *) &xsave_layout) + offset, len);
+      *xfered_len = len;
+      return len == 0 ? TARGET_XFER_EOF : TARGET_XFER_OK;
+    default:
+      return fbsd_nat_target::xfer_partial (object, annex, readbuf, writebuf,
+					    offset, len, xfered_len);
+    }
+}
+
+void
+x86_fbsd_nat_target::probe_xsave_layout (pid_t pid)
+{
+  if (xsave_probed)
+    return;
+
+  xsave_probed = true;
+
+  if (ptrace (PT_GETXSTATE_INFO, pid, (PTRACE_TYPE_ARG3) &xsave_info,
+	      sizeof (xsave_info)) != 0)
+    return;
+  if (xsave_info.xsave_len != 0)
+    x86_fetch_xsave_layout (xsave_info.xsave_mask, xsave_info.xsave_len,
+			    xsave_layout);
+}
+#endif
diff --git a/gdb/x86-fbsd-nat.h b/gdb/x86-fbsd-nat.h
index 0a1308f3584..1b5cdfc1a9b 100644
--- a/gdb/x86-fbsd-nat.h
+++ b/gdb/x86-fbsd-nat.h
@@ -20,6 +20,11 @@
 #ifndef X86_FBSD_NAT_H
 #define X86_FBSD_NAT_H
 
+#include <sys/ptrace.h>
+
+#ifdef PT_GETXSTATE_INFO
+#include "gdbsupport/x86-xstate.h"
+#endif
 #include "fbsd-nat.h"
 #include "x86-bsd-nat.h"
 
@@ -27,10 +32,32 @@
 
 class x86_fbsd_nat_target : public x86bsd_nat_target<fbsd_nat_target>
 {
+  void low_new_fork (ptid_t parent, pid_t child) override;
+
+public:
   bool supports_stopped_by_hw_breakpoint () override
   { return true; }
 
-  void low_new_fork (ptid_t parent, pid_t child) override;
+#ifdef PT_GETXSTATE_INFO
+  enum target_xfer_status xfer_partial (enum target_object object,
+					const char *annex,
+					gdb_byte *readbuf,
+					const gdb_byte *writebuf,
+					ULONGEST offset, ULONGEST len,
+					ULONGEST *xfered_len) override;
+
+protected:
+  void probe_xsave_layout (pid_t pid);
+
+  struct ptrace_xstate_info xsave_info;
+  x86_xsave_layout xsave_layout;
+
+private:
+  bool xsave_probed;
+#endif
 };
 
+#ifdef PT_GETXSTATE_INFO
+#endif
+
 #endif /* x86-bsd-nat.h */
-- 
2.39.1