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

markus.t.metzger
2012-11-27T10:49:53Z

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