x86, ptrace: support for branch trace store(BTS)
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Changes to the last version:
- split implementation into two layers: ds/bts and ptrace
- renamed TIF's
- save/restore ds save area msr in __switch_to_xtra()
- make block-stepping only look at BTF bit
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@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 3399c1be..8d0dd8b 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -2,6 +2,9 @@
/*
* Pentium III FXSR, SSE support
* Gareth Hughes <gareth@valinux.com>, May 2000
+ *
+ * BTS tracing
+ * Markus Metzger <markus.t.metzger@intel.com>, Dec 2007
*/
#include <linux/kernel.h>
@@ -26,6 +29,14 @@
#include <asm/desc.h>
#include <asm/prctl.h>
#include <asm/proto.h>
+#include <asm/ds.h>
+
+
+/*
+ * 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.
@@ -455,6 +466,165 @@
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)
+{
+ if (!child->thread.ds_area_msr)
+ return -ENXIO;
+
+ return ds_get_bts_size((void *)child->thread.ds_area_msr);
+}
+
+static int ptrace_bts_get_index(struct task_struct *child)
+{
+ if (!child->thread.ds_area_msr)
+ return -ENXIO;
+
+ return ds_get_bts_index((void *)child->thread.ds_area_msr);
+}
+
+static int ptrace_bts_read_record(struct task_struct *child,
+ long index,
+ struct bts_struct __user *out)
+{
+ struct bts_struct ret;
+ int retval;
+
+ if (!child->thread.ds_area_msr)
+ return -ENXIO;
+
+ retval = ds_read_bts((void *)child->thread.ds_area_msr,
+ index, &ret);
+ if (retval)
+ return retval;
+
+ if (copy_to_user(out, &ret, sizeof(ret)))
+ return -EFAULT;
+
+ return sizeof(ret);
+}
+
+static int ptrace_bts_write_record(struct task_struct *child,
+ const struct bts_struct *in)
+{
+ int retval;
+
+ if (!child->thread.ds_area_msr)
+ return -ENXIO;
+
+ retval = ds_write_bts((void *)child->thread.ds_area_msr, in);
+ if (retval)
+ return retval;
+
+ return sizeof(*in);
+}
+
+static int ptrace_bts_config(struct task_struct *child,
+ unsigned long options)
+{
+ unsigned long debugctl_mask = ds_debugctl_mask();
+ int retval;
+
+ retval = ptrace_bts_get_buffer_size(child);
+ if (retval < 0)
+ return retval;
+ if (retval == 0)
+ return -ENXIO;
+
+ if (options & PTRACE_BTS_O_TRACE_TASK) {
+ child->thread.debugctlmsr |= debugctl_mask;
+ set_tsk_thread_flag(child, TIF_DEBUGCTLMSR);
+ } else {
+ /* there is no way for us to check whether we 'own'
+ * the respective bits in the DEBUGCTL MSR, we're
+ * about to clear */
+ child->thread.debugctlmsr &= ~debugctl_mask;
+
+ if (!child->thread.debugctlmsr)
+ clear_tsk_thread_flag(child, TIF_DEBUGCTLMSR);
+ }
+
+ if (options & PTRACE_BTS_O_TIMESTAMPS)
+ set_tsk_thread_flag(child, TIF_BTS_TRACE_TS);
+ else
+ clear_tsk_thread_flag(child, TIF_BTS_TRACE_TS);
+
+ return 0;
+}
+
+static int ptrace_bts_status(struct task_struct *child)
+{
+ unsigned long debugctl_mask = ds_debugctl_mask();
+ int retval, status = 0;
+
+ retval = ptrace_bts_get_buffer_size(child);
+ if (retval < 0)
+ return retval;
+ if (retval == 0)
+ return -ENXIO;
+
+ if (ptrace_bts_get_buffer_size(child) <= 0)
+ return -ENXIO;
+
+ 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;
+
+ return status;
+}
+
+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 (child->thread.ds_area_msr)
+ ds_free((void **)&child->thread.ds_area_msr);
+
+ 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;
+}
+
+void ptrace_bts_take_timestamp(struct task_struct *tsk,
+ enum bts_qualifier qualifier)
+{
+ struct bts_struct rec = {
+ .qualifier = qualifier,
+ .variant.timestamp = sched_clock()
+ };
+
+ if (ptrace_bts_get_buffer_size(tsk) <= 0)
+ return;
+
+ ptrace_bts_write_record(tsk, &rec);
+}
+
/*
* Called by kernel/ptrace.c when detaching..
*
@@ -466,6 +636,11 @@
#ifdef TIF_SYSCALL_EMU
clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
#endif
+ ptrace_bts_config(child, /* options = */ 0);
+ if (child->thread.ds_area_msr) {
+ ds_free((void **)&child->thread.ds_area_msr);
+ clear_tsk_thread_flag(child, TIF_DS_AREA_MSR);
+ }
}
long arch_ptrace(struct task_struct *child, long request, long addr, long data)
@@ -626,6 +801,36 @@
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_GET_INDEX:
+ ret = ptrace_bts_get_index(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);
+ break;
+
+ case PTRACE_BTS_STATUS:
+ ret = ptrace_bts_status(child);
+ break;
+
default:
ret = ptrace_request(child, request, addr, data);
break;
@@ -809,6 +1014,13 @@
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_GET_INDEX:
+ case PTRACE_BTS_READ_RECORD:
+ case PTRACE_BTS_CONFIG:
+ case PTRACE_BTS_STATUS:
return sys_ptrace(request, pid, addr, data);
default:
