diff options
Diffstat (limited to 'gdb/common/linux-btrace.c')
| -rw-r--r-- | gdb/common/linux-btrace.c | 187 |
1 files changed, 186 insertions, 1 deletions
diff --git a/gdb/common/linux-btrace.c b/gdb/common/linux-btrace.c index 2f8c1cf..ed0cb24 100644 --- a/gdb/common/linux-btrace.c +++ b/gdb/common/linux-btrace.c @@ -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. */ |