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LBR, BTM, or BTS records may have incorrect branch "from" information afer an 

EIST transition, T-states, C1E, or Adaptive Thermal Throttling (AAJ122).

This results in sporadic test fails. Disable btrace on those processors.

gdb/
	* common/linux-btrace.c: Include sys/ptrace, sys/types, sys/wait.h,
	and signal.h.
	(linux_supports_btrace): Add kernel and
	cpuid check.
	(kernel_supports_btrace): New function.
	(cpu_supports_btrace): New function.
	(intel_supports_btrace): New function.
This commit is contained in:
Markus Metzger 2013-03-11 08:38:27 +00:00
parent 2ae8c8e7ce
commit a950d57c9f
2 changed files with 196 additions and 1 deletions
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10
gdb/ChangeLog
View File

@ -1,3 +1,13 @@
2013-03-11 Markus Metzger <markus.t.metzger@intel.com>
* common/linux-btrace.c: Include sys/ptrace, sys/types, sys/wait.h,
and signal.h.
(linux_supports_btrace): Add kernel and
cpuid check.
(kernel_supports_btrace): New function.
(cpu_supports_btrace): New function.
(intel_supports_btrace): New function.
2013-03-11 Markus Metzger <markus.t.metzger@intel.com>
* target.h (enum target_object): Add TARGET_OBJECT_BTRACE.

187
gdb/common/linux-btrace.c
View File

@ -40,6 +40,10 @@
#include <sys/syscall.h>
#include <sys/mman.h>
#include <sys/user.h>
#include <sys/ptrace.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <signal.h>
/* A branch trace record in perf_event. */
struct perf_event_bts
@ -247,12 +251,193 @@ perf_event_read_bts (struct btrace_target_info* tinfo, const uint8_t *begin,
return btrace;
}
/* Check whether the kernel supports branch tracing. */
static int
kernel_supports_btrace (void)
{
struct perf_event_attr attr;
pid_t child, pid;
int status, file;
errno = 0;
child = fork ();
switch (child)
{
case -1:
warning (_("test branch tracing: cannot fork: %s."), strerror (errno));
return 0;
case 0:
status = ptrace (PTRACE_TRACEME, 0, NULL, NULL);
if (status != 0)
{
warning (_("test branch tracing: cannot PTRACE_TRACEME: %s."),
strerror (errno));
_exit (1);
}
status = raise (SIGTRAP);
if (status != 0)
{
warning (_("test branch tracing: cannot raise SIGTRAP: %s."),
strerror (errno));
_exit (1);
}
_exit (1);
default:
pid = waitpid (child, &status, 0);
if (pid != child)
{
warning (_("test branch tracing: bad pid %ld, error: %s."),
(long) pid, strerror (errno));
return 0;
}
if (!WIFSTOPPED (status))
{
warning (_("test branch tracing: expected stop. status: %d."),
status);
return 0;
}
memset (&attr, 0, sizeof (attr));
attr.type = PERF_TYPE_HARDWARE;
attr.config = PERF_COUNT_HW_BRANCH_INSTRUCTIONS;
attr.sample_period = 1;
attr.sample_type = PERF_SAMPLE_IP | PERF_SAMPLE_ADDR;
attr.exclude_kernel = 1;
attr.exclude_hv = 1;
attr.exclude_idle = 1;
file = syscall (SYS_perf_event_open, &attr, child, -1, -1, 0);
if (file >= 0)
close (file);
kill (child, SIGKILL);
ptrace (PTRACE_KILL, child, NULL, NULL);
pid = waitpid (child, &status, 0);
if (pid != child)
{
warning (_("test branch tracing: bad pid %ld, error: %s."),
(long) pid, strerror (errno));
if (!WIFSIGNALED (status))
warning (_("test branch tracing: expected killed. status: %d."),
status);
}
return (file >= 0);
}
}
/* Check whether an Intel cpu supports branch tracing. */
static int
intel_supports_btrace (void)
{
#if defined __i386__ || defined __x86_64__
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 0x6:
model += (cpuid >> 12) & 0xf0;
switch (model)
{
case 0x1a: /* Nehalem */
case 0x1f:
case 0x1e:
case 0x2e:
case 0x25: /* Westmere */
case 0x2c:
case 0x2f:
case 0x2a: /* Sandy Bridge */
case 0x2d:
case 0x3a: /* Ivy Bridge */
/* AAJ122: LBR, BTM, or BTS records may have incorrect branch
"from" information afer an EIST transition, T-states, C1E, or
Adaptive Thermal Throttling. */
return 0;
}
}
return 1;
#else /* !defined __i386__ && !defined __x86_64__ */
return 0;
#endif /* !defined __i386__ && !defined __x86_64__ */
}
/* Check whether the cpu supports branch tracing. */
static int
cpu_supports_btrace (void)
{
#if defined __i386__ || defined __x86_64__
char vendor[13];
__asm__ __volatile__ ("xorl %%ebx, %%ebx;"
"xorl %%ecx, %%ecx;"
"xorl %%edx, %%edx;"
"movl $0, %%eax;"
"cpuid;"
"movl %%ebx, %0;"
"movl %%edx, %1;"
"movl %%ecx, %2;"
: "=m" (vendor[0]),
"=m" (vendor[4]),
"=m" (vendor[8])
:
: "%eax", "%ebx", "%ecx", "%edx");
vendor[12] = '\0';
if (strcmp (vendor, "GenuineIntel") == 0)
return intel_supports_btrace ();
/* Don't know about others. Let's assume they do. */
return 1;
#else /* !defined __i386__ && !defined __x86_64__ */
return 0;
#endif /* !defined __i386__ && !defined __x86_64__ */
}
/* See linux-btrace.h. */
int
linux_supports_btrace (void)
{
return 1;
static int cached;
if (cached == 0)
{
if (!kernel_supports_btrace ())
cached = -1;
else if (!cpu_supports_btrace ())
cached = -1;
else
cached = 1;
}
return cached > 0;
}
/* See linux-btrace.h. */