x86, ptrace: new ptrace BTS API
Here's the new ptrace BTS API that supports two different overflow handling mechanisms (wrap-around and buffer-full-signal) to support two different use cases (debugging and profiling).
It further combines buffer allocation and configuration.
Opens:
- memory rlimit
- overflow signal
What would be the right signal to use?
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 3e78c12..18972a3 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -33,12 +33,6 @@
/*
- * The maximal size of a BTS buffer per traced task in number of BTS
- * records.
- */
-#define PTRACE_BTS_BUFFER_MAX 4000
-
-/*
* does not yet catch signals sent when the child dies.
* in exit.c or in signal.c.
*/
@@ -466,17 +460,12 @@
return 0;
}
-static int ptrace_bts_max_buffer_size(void)
-{
- return PTRACE_BTS_BUFFER_MAX;
-}
-
-static int ptrace_bts_get_buffer_size(struct task_struct *child)
+static int ptrace_bts_get_size(struct task_struct *child)
{
if (!child->thread.ds_area_msr)
return -ENXIO;
- return ds_get_bts_size((void *)child->thread.ds_area_msr);
+ return ds_get_bts_index((void *)child->thread.ds_area_msr);
}
static int ptrace_bts_read_record(struct task_struct *child,
@@ -485,7 +474,7 @@
{
struct bts_struct ret;
int retval;
- int bts_size;
+ int bts_end;
int bts_index;
if (!child->thread.ds_area_msr)
@@ -494,15 +483,15 @@
if (index < 0)
return -EINVAL;
- bts_size = ds_get_bts_size((void *)child->thread.ds_area_msr);
- if (bts_size <= index)
+ bts_end = ds_get_bts_end((void *)child->thread.ds_area_msr);
+ if (bts_end <= index)
return -EINVAL;
/* translate the ptrace bts index into the ds bts index */
bts_index = ds_get_bts_index((void *)child->thread.ds_area_msr);
bts_index -= (index + 1);
if (bts_index < 0)
- bts_index += bts_size;
+ bts_index += bts_end;
retval = ds_read_bts((void *)child->thread.ds_area_msr,
bts_index, &ret);
@@ -530,19 +519,97 @@
return sizeof(*in);
}
-static int ptrace_bts_config(struct task_struct *child,
- unsigned long options)
+static int ptrace_bts_clear(struct task_struct *child)
{
- unsigned long debugctl_mask = ds_debugctl_mask();
- int retval;
-
- retval = ptrace_bts_get_buffer_size(child);
- if (retval < 0)
- return retval;
- if (retval == 0)
+ if (!child->thread.ds_area_msr)
return -ENXIO;
- if (options & PTRACE_BTS_O_TRACE_TASK) {
+ return ds_clear((void *)child->thread.ds_area_msr);
+}
+
+static int ptrace_bts_drain(struct task_struct *child,
+ struct bts_struct __user *out)
+{
+ int end, i;
+ void *ds = (void *)child->thread.ds_area_msr;
+
+ if (!ds)
+ return -ENXIO;
+
+ end = ds_get_bts_index(ds);
+ if (end <= 0)
+ return end;
+
+ for (i = 0; i < end; i++, out++) {
+ struct bts_struct ret;
+ int retval;
+
+ retval = ds_read_bts(ds, i, &ret);
+ if (retval < 0)
+ return retval;
+
+ if (copy_to_user(out, &ret, sizeof(ret)))
+ return -EFAULT;
+ }
+
+ ds_clear(ds);
+
+ return i;
+}
+
+static int ptrace_bts_config(struct task_struct *child,
+ const struct ptrace_bts_config __user *ucfg)
+{
+ struct ptrace_bts_config cfg;
+ unsigned long debugctl_mask;
+ int bts_size, ret;
+ void *ds;
+
+ if (copy_from_user(&cfg, ucfg, sizeof(cfg)))
+ return -EFAULT;
+
+ bts_size = 0;
+ ds = (void *)child->thread.ds_area_msr;
+ if (ds) {
+ bts_size = ds_get_bts_size(ds);
+ if (bts_size < 0)
+ return bts_size;
+ }
+
+ if (bts_size != cfg.size) {
+ ret = ds_free((void **)&child->thread.ds_area_msr);
+ if (ret < 0)
+ return ret;
+
+ if (cfg.size > 0)
+ ret = ds_allocate((void **)&child->thread.ds_area_msr,
+ cfg.size);
+ ds = (void *)child->thread.ds_area_msr;
+ if (ds)
+ set_tsk_thread_flag(child, TIF_DS_AREA_MSR);
+ else
+ clear_tsk_thread_flag(child, TIF_DS_AREA_MSR);
+
+ if (ret < 0)
+ return ret;
+
+ bts_size = ds_get_bts_size(ds);
+ if (bts_size <= 0)
+ return bts_size;
+ }
+
+ if (ds) {
+ if (cfg.flags & PTRACE_BTS_O_SIGNAL) {
+ ret = ds_set_overflow(ds, DS_O_SIGNAL);
+ } else {
+ ret = ds_set_overflow(ds, DS_O_WRAP);
+ }
+ if (ret < 0)
+ return ret;
+ }
+
+ debugctl_mask = ds_debugctl_mask();
+ if (ds && (cfg.flags & PTRACE_BTS_O_TRACE)) {
child->thread.debugctlmsr |= debugctl_mask;
set_tsk_thread_flag(child, TIF_DEBUGCTLMSR);
} else {
@@ -555,7 +622,7 @@
clear_tsk_thread_flag(child, TIF_DEBUGCTLMSR);
}
- if (options & PTRACE_BTS_O_TIMESTAMPS)
+ if (ds && (cfg.flags & PTRACE_BTS_O_SCHED))
set_tsk_thread_flag(child, TIF_BTS_TRACE_TS);
else
clear_tsk_thread_flag(child, TIF_BTS_TRACE_TS);
@@ -563,59 +630,32 @@
return 0;
}
-static int ptrace_bts_status(struct task_struct *child)
+static int ptrace_bts_status(struct task_struct *child,
+ struct ptrace_bts_config __user *ucfg)
{
- unsigned long debugctl_mask = ds_debugctl_mask();
- int retval, status = 0;
+ void *ds = (void *)child->thread.ds_area_msr;
+ struct ptrace_bts_config cfg;
- retval = ptrace_bts_get_buffer_size(child);
- if (retval < 0)
- return retval;
- if (retval == 0)
- return -ENXIO;
+ memset(&cfg, 0, sizeof(cfg));
- if (ptrace_bts_get_buffer_size(child) <= 0)
- return -ENXIO;
+ if (ds) {
+ cfg.size = ds_get_bts_size(ds);
- if (test_tsk_thread_flag(child, TIF_DEBUGCTLMSR) &&
- child->thread.debugctlmsr & debugctl_mask)
- status |= PTRACE_BTS_O_TRACE_TASK;
- if (test_tsk_thread_flag(child, TIF_BTS_TRACE_TS))
- status |= PTRACE_BTS_O_TIMESTAMPS;
+ if (ds_get_overflow(ds) == DS_O_SIGNAL)
+ cfg.flags |= PTRACE_BTS_O_SIGNAL;
- return status;
-}
+ if (test_tsk_thread_flag(child, TIF_DEBUGCTLMSR) &&
+ child->thread.debugctlmsr & ds_debugctl_mask())
+ cfg.flags |= PTRACE_BTS_O_TRACE;
-static int ptrace_bts_allocate_bts(struct task_struct *child,
- int size_in_records)
-{
- int retval = 0;
- void *ds;
-
- if (size_in_records < 0)
- return -EINVAL;
-
- if (size_in_records > ptrace_bts_max_buffer_size())
- return -EINVAL;
-
- if (size_in_records == 0) {
- ptrace_bts_config(child, /* options = */ 0);
- } else {
- retval = ds_allocate(&ds, size_in_records);
- if (retval)
- return retval;
+ if (test_tsk_thread_flag(child, TIF_BTS_TRACE_TS))
+ cfg.flags |= PTRACE_BTS_O_SCHED;
}
- if (child->thread.ds_area_msr)
- ds_free((void **)&child->thread.ds_area_msr);
+ if (copy_to_user(ucfg, &cfg, sizeof(cfg)))
+ return -EFAULT;
- child->thread.ds_area_msr = (unsigned long)ds;
- if (child->thread.ds_area_msr)
- set_tsk_thread_flag(child, TIF_DS_AREA_MSR);
- else
- clear_tsk_thread_flag(child, TIF_DS_AREA_MSR);
-
- return retval;
+ return sizeof(cfg);
}
void ptrace_bts_take_timestamp(struct task_struct *tsk,
@@ -626,9 +666,6 @@
.variant.jiffies = jiffies
};
- if (ptrace_bts_get_buffer_size(tsk) <= 0)
- return;
-
ptrace_bts_write_record(tsk, &rec);
}
@@ -808,30 +845,32 @@
break;
#endif
- case PTRACE_BTS_MAX_BUFFER_SIZE:
- ret = ptrace_bts_max_buffer_size();
- break;
-
- case PTRACE_BTS_ALLOCATE_BUFFER:
- ret = ptrace_bts_allocate_bts(child, data);
- break;
-
- case PTRACE_BTS_GET_BUFFER_SIZE:
- ret = ptrace_bts_get_buffer_size(child);
- break;
-
- case PTRACE_BTS_READ_RECORD:
- ret = ptrace_bts_read_record
- (child, data,
- (struct bts_struct __user *) addr);
- break;
-
case PTRACE_BTS_CONFIG:
- ret = ptrace_bts_config(child, data);
+ ret = ptrace_bts_config
+ (child, (struct ptrace_bts_config __user *)addr);
break;
case PTRACE_BTS_STATUS:
- ret = ptrace_bts_status(child);
+ ret = ptrace_bts_status
+ (child, (struct ptrace_bts_config __user *)addr);
+ break;
+
+ case PTRACE_BTS_SIZE:
+ ret = ptrace_bts_get_size(child);
+ break;
+
+ case PTRACE_BTS_GET:
+ ret = ptrace_bts_read_record
+ (child, data, (struct bts_struct __user *) addr);
+ break;
+
+ case PTRACE_BTS_CLEAR:
+ ret = ptrace_bts_clear(child);
+ break;
+
+ case PTRACE_BTS_DRAIN:
+ ret = ptrace_bts_drain
+ (child, (struct bts_struct __user *) addr);
break;
default:
@@ -1017,12 +1056,12 @@
case PTRACE_SETOPTIONS:
case PTRACE_SET_THREAD_AREA:
case PTRACE_GET_THREAD_AREA:
- case PTRACE_BTS_MAX_BUFFER_SIZE:
- case PTRACE_BTS_ALLOCATE_BUFFER:
- case PTRACE_BTS_GET_BUFFER_SIZE:
- case PTRACE_BTS_READ_RECORD:
case PTRACE_BTS_CONFIG:
case PTRACE_BTS_STATUS:
+ case PTRACE_BTS_SIZE:
+ case PTRACE_BTS_GET:
+ case PTRACE_BTS_CLEAR:
+ case PTRACE_BTS_DRAIN:
return sys_ptrace(request, pid, addr, data);
default: