[patch v4 13/13] btrace, x86: restrict to Atom

[markus.t.metzger@intel.com]

From: Markus Metzger <markus.t.metzger@intel.com>

Restrict branch tracing support to Atom processors.

2012-11-27 Markus Metzger <markus.t.metzger@intel.com>

	* amd64-linux-nat.c (amd64_linux_supports_btrace): New.
	(_initialize_amd64_linux_nat): Change supports_btrace method.
	* i386-linux-nat.c (i386_linux_supports_btrace): New.
	(_initialize_i386_linux_nat): Change supports_btrace method.

gdbserver/
	* linux-low.h (linux_target_ops): Add supports_btrace method.
	* linux-low.c (linux_low_supports_btrace): New.
	(linux_target_ops): Change supports_btrace method.
	* linux-x86-low.c (x86_supports_btrace): New.
	(the_low_target): Add supports_btrace method.


---
 gdb/amd64-linux-nat.c         |   36 +++++++++++++++++++++++++++++++++++-
 gdb/gdbserver/linux-low.c     |   15 ++++++++++++++-
 gdb/gdbserver/linux-low.h     |    2 ++
 gdb/gdbserver/linux-x86-low.c |   31 +++++++++++++++++++++++++++++++
 gdb/i386-linux-nat.c          |   36 +++++++++++++++++++++++++++++++++++-
 5 files changed, 117 insertions(+), 3 deletions(-)

diff --git a/gdb/amd64-linux-nat.c b/gdb/amd64-linux-nat.c
index 0e38a57..a65285b 100644
--- a/gdb/amd64-linux-nat.c
+++ b/gdb/amd64-linux-nat.c
@@ -1081,6 +1081,40 @@ amd64_linux_read_description (struct target_ops *ops)
     }
 }
 
+/* Check if the target supports branch tracing.  */
+static int
+amd64_linux_supports_btrace (void)
+{
+  unsigned int cpuid, model, family;
+
+  if (!linux_supports_btrace ())
+    return 0;
+
+  __asm__ __volatile__ ("movl   $1, %%eax;"
+			"cpuid;"
+			: "=a" (cpuid)
+			:: "%ebx", "%ecx", "%edx");
+
+  family = (cpuid >> 8) & 0xf;
+  model = (cpuid >> 4) & 0xf;
+
+  switch (family)
+    {
+    case 6:
+      model += (cpuid >> 12) & 0xf0;
+
+      switch (model)
+        {
+	case 28: /* Atom.  */
+	case 38:
+	case 39:
+	  return 1;
+	}
+    }
+
+  return 0;
+}
+
 /* Enable branch tracing for @ptid.  */
 static struct btrace_target_info *
 amd64_linux_enable_btrace (ptid_t ptid)
@@ -1162,7 +1196,7 @@ _initialize_amd64_linux_nat (void)
   t->to_read_description = amd64_linux_read_description;
 
   /* Add btrace methods.  */
-  t->to_supports_btrace = linux_supports_btrace;
+  t->to_supports_btrace = amd64_linux_supports_btrace;
   t->to_enable_btrace = amd64_linux_enable_btrace;
   t->to_disable_btrace = amd64_linux_disable_btrace;
   t->to_btrace_has_changed = linux_btrace_has_changed;
diff --git a/gdb/gdbserver/linux-low.c b/gdb/gdbserver/linux-low.c
index ffaa96f..99f347c 100644
--- a/gdb/gdbserver/linux-low.c
+++ b/gdb/gdbserver/linux-low.c
@@ -5795,6 +5795,19 @@ linux_qxfer_libraries_svr4 (const char *annex, unsigned char *readbuf,
   return len;
 }
 
+/* See linux-low.h.  */
+static int
+linux_low_supports_btrace (void)
+{
+  if (!linux_supports_btrace ())
+    return 0;
+
+  if (*the_low_target.supports_btrace == NULL)
+    return 0;
+
+  return (*the_low_target.supports_btrace) ();
+}
+
 /* Read branch trace data for @tinfo as btrace xml document into @buffer.  */
 static void
 linux_low_read_btrace (struct btrace_target_info *tinfo, struct buffer *buffer)
@@ -5884,7 +5897,7 @@ static struct target_ops linux_target_ops = {
   linux_get_min_fast_tracepoint_insn_len,
   linux_qxfer_libraries_svr4,
   linux_supports_agent,
-  linux_supports_btrace,
+  linux_low_supports_btrace,
   linux_enable_btrace,
   linux_disable_btrace,
   linux_btrace_has_changed,
diff --git a/gdb/gdbserver/linux-low.h b/gdb/gdbserver/linux-low.h
index 99d882a..5768a77 100644
--- a/gdb/gdbserver/linux-low.h
+++ b/gdb/gdbserver/linux-low.h
@@ -169,6 +169,8 @@ struct linux_target_ops
      for use as a fast tracepoint.  */
   int (*get_min_fast_tracepoint_insn_len) (void);
 
+  /* Returns true if the low target supports btrace.  */
+  int (*supports_btrace) (void);
 };
 
 extern struct linux_target_ops the_low_target;
diff --git a/gdb/gdbserver/linux-x86-low.c b/gdb/gdbserver/linux-x86-low.c
index 1215bae..e12fccb 100644
--- a/gdb/gdbserver/linux-x86-low.c
+++ b/gdb/gdbserver/linux-x86-low.c
@@ -1859,6 +1859,36 @@ x86_get_min_fast_tracepoint_insn_len (void)
     }
 }
 
+/* See linux-low.h.  */
+static int
+x86_supports_btrace (void)
+{
+  unsigned int cpuid, model, family;
+
+  __asm__ __volatile__ ("movl   $1, %%eax;"
+			"cpuid;"
+			: "=a" (cpuid)
+			:: "%ebx", "%ecx", "%edx");
+
+  family = (cpuid >> 8) & 0xf;
+  model = (cpuid >> 4) & 0xf;
+
+  switch (family)
+    {
+    case 6:
+      model += (cpuid >> 12) & 0xf0;
+
+      switch (model)
+        {
+	case 28: /* Atom.  */
+	case 38:
+	  return 1;
+	}
+    }
+
+  return 0;
+}
+
 static void
 add_insns (unsigned char *start, int len)
 {
@@ -3214,4 +3244,5 @@ struct linux_target_ops the_low_target =
   x86_install_fast_tracepoint_jump_pad,
   x86_emit_ops,
   x86_get_min_fast_tracepoint_insn_len,
+  x86_supports_btrace,
 };
diff --git a/gdb/i386-linux-nat.c b/gdb/i386-linux-nat.c
index c12d94a..3f1e524 100644
--- a/gdb/i386-linux-nat.c
+++ b/gdb/i386-linux-nat.c
@@ -1010,6 +1010,40 @@ i386_linux_read_description (struct target_ops *ops)
     return tdesc_i386_linux;
 }
 
+/* Check if the target supports branch tracing.  */
+static int
+i386_linux_supports_btrace (void)
+{
+  unsigned int cpuid, model, family;
+
+  if (!linux_supports_btrace ())
+    return 0;
+
+  __asm__ __volatile__ ("movl   $1, %%eax;"
+			"cpuid;"
+			: "=a" (cpuid)
+			:: "%ebx", "%ecx", "%edx");
+
+  family = (cpuid >> 8) & 0xf;
+  model = (cpuid >> 4) & 0xf;
+
+  switch (family)
+    {
+    case 6:
+      model += (cpuid >> 12) & 0xf0;
+
+      switch (model)
+        {
+	case 28: /* Atom.  */
+	case 38:
+	case 39:
+	  return 1;
+	}
+    }
+
+  return 0;
+}
+
 /* Enable branch tracing for @ptid.  */
 static struct btrace_target_info *
 i386_linux_enable_btrace (ptid_t ptid)
@@ -1086,7 +1120,7 @@ _initialize_i386_linux_nat (void)
   t->to_read_description = i386_linux_read_description;
 
   /* Add btrace methods.  */
-  t->to_supports_btrace = linux_supports_btrace;
+  t->to_supports_btrace = i386_linux_supports_btrace;
   t->to_enable_btrace = i386_linux_enable_btrace;
   t->to_disable_btrace = i386_linux_disable_btrace;
   t->to_btrace_has_changed = linux_btrace_has_changed;
-- 
1.7.1