diff options
| -rw-r--r-- | gdb/ChangeLog | 6 | ||||
| -rw-r--r-- | gdb/nat/linux-btrace.c | 32 |
2 files changed, 36 insertions, 2 deletions
diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 769858b..fd8a624 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,5 +1,11 @@ 2018-02-09 Markus Metzger <markus.t.metzger@intel.com> + * nat/linux-btrace.c (diagnose_perf_event_open_fail): New. + (linux_enable_pt, linux_enable_bts): Call + diagnose_perf_event_open_fail. + +2018-02-09 Markus Metzger <markus.t.metzger@intel.com> + * nat/linux-btrace.c (perf_event_pt_event_type): Improve error message. Remove parameter and change return type. Update callers. Move it. (linux_enable_bts, linux_enable_pt): Improve error message. diff --git a/gdb/nat/linux-btrace.c b/gdb/nat/linux-btrace.c index 301649b..8eadf7a 100644 --- a/gdb/nat/linux-btrace.c +++ b/gdb/nat/linux-btrace.c @@ -409,6 +409,34 @@ cpu_supports_bts (void) } } +/* The perf_event_open syscall failed. Try to print a helpful error + message. */ + +static void +diagnose_perf_event_open_fail () +{ + switch (errno) + { + case EPERM: + case EACCES: + { + static const char filename[] = "/proc/sys/kernel/perf_event_paranoid"; + gdb_file_up file = gdb_fopen_cloexec (filename, "r"); + if (file.get () == nullptr) + break; + + int level, found = fscanf (file.get (), "%d", &level); + if (found == 1 && level > 2) + error (_("You do not have permission to record the process. " + "Try setting %s to 2 or less."), filename); + } + + break; + } + + error (_("Failed to start recording: %s"), safe_strerror (errno)); +} + /* Enable branch tracing in BTS format. */ static struct btrace_target_info * @@ -448,7 +476,7 @@ linux_enable_bts (ptid_t ptid, const struct btrace_config_bts *conf) errno = 0; scoped_fd fd (syscall (SYS_perf_event_open, &bts->attr, pid, -1, -1, 0)); if (fd.get () < 0) - error (_("Failed to start recording: %s"), safe_strerror (errno)); + diagnose_perf_event_open_fail (); /* Convert the requested size in bytes to pages (rounding up). */ pages = ((size_t) conf->size / PAGE_SIZE @@ -578,7 +606,7 @@ linux_enable_pt (ptid_t ptid, const struct btrace_config_pt *conf) errno = 0; scoped_fd fd (syscall (SYS_perf_event_open, &pt->attr, pid, -1, -1, 0)); if (fd.get () < 0) - error (_("Failed to start recording: %s"), safe_strerror (errno)); + diagnose_perf_event_open_fail (); /* Allocate the configuration page. */ scoped_mmap data (nullptr, PAGE_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, |