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>

1 files changed, 51 insertions, 5 deletions

diff --git a/arch/x86/kernel/ds.c b/arch/x86/kernel/ds.c
index e7855def97c3..6eb5d49a36bb 100644
--- a/arch/x86/kernel/ds.c
+++ b/arch/x86/kernel/ds.c
@@ -177,18 +177,20 @@ static inline void set_info_data(char *base, unsigned long value)
 }
 
 
-int ds_allocate(void **dsp, size_t bts_size_in_records)
+int ds_allocate(void **dsp, size_t bts_size_in_bytes)
 {
-        size_t bts_size_in_bytes = 0;
-        void *bts = 0;
-        void *ds = 0;
+        size_t bts_size_in_records;
+        void *bts;
+        void *ds;
 
         if (!ds_cfg.sizeof_ds || !ds_cfg.sizeof_bts)
                 return -EOPNOTSUPP;
 
-        if (bts_size_in_records < 0)
+        if (bts_size_in_bytes < 0)
                 return -EINVAL;
 
+        bts_size_in_records =
+                bts_size_in_bytes / ds_cfg.sizeof_bts;
         bts_size_in_bytes =
                 bts_size_in_records * ds_cfg.sizeof_bts;
 
@@ -233,9 +235,21 @@ int ds_get_bts_size(void *ds)
         if (!ds_cfg.sizeof_ds || !ds_cfg.sizeof_bts)
                 return -EOPNOTSUPP;
 
+        if (!ds)
+                return 0;
+
         size_in_bytes =
                 get_bts_absolute_maximum(ds) -
                 get_bts_buffer_base(ds);
+        return size_in_bytes;
+}
+
+int ds_get_bts_end(void *ds)
+{
+        size_t size_in_bytes = ds_get_bts_size(ds);
+
+        if (size_in_bytes <= 0)
+                return size_in_bytes;
 
         return size_in_bytes / ds_cfg.sizeof_bts;
 }
@@ -254,6 +268,38 @@ int ds_get_bts_index(void *ds)
         return index_offset_in_bytes / ds_cfg.sizeof_bts;
 }
 
+int ds_set_overflow(void *ds, int method)
+{
+        switch (method) {
+        case DS_O_SIGNAL:
+                return -EOPNOTSUPP;
+        case DS_O_WRAP:
+                return 0;
+        default:
+                return -EINVAL;
+        }
+}
+
+int ds_get_overflow(void *ds)
+{
+        return DS_O_WRAP;
+}
+
+int ds_clear(void *ds)
+{
+        int bts_size = ds_get_bts_size(ds);
+        void *bts_base;
+
+        if (bts_size <= 0)
+                return bts_size;
+
+        bts_base = get_bts_buffer_base(ds);
+        memset(bts_base, 0, bts_size);
+
+        set_bts_index(ds, bts_base);
+        return 0;
+}
+
 int ds_read_bts(void *ds, size_t index, struct bts_struct *out)
 {
         void *bts;