x86, ptrace: change BTS GET ptrace interface

Change the ptrace interface to mimick an array from newst to oldest.

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>

2 files changed, 22 insertions, 25 deletions

diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index ec86abaab530..3e78c124e2d2 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -479,26 +479,33 @@ static int ptrace_bts_get_buffer_size(struct task_struct *child)
         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;
+        int bts_size;
+        int bts_index;
 
         if (!child->thread.ds_area_msr)
                 return -ENXIO;
 
+        if (index < 0)
+                return -EINVAL;
+
+        bts_size = ds_get_bts_size((void *)child->thread.ds_area_msr);
+        if (bts_size <= 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;
+
         retval = ds_read_bts((void *)child->thread.ds_area_msr,
-                             index, &ret);
+                             bts_index, &ret);
         if (retval)
                 return retval;
 
@@ -813,10 +820,6 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data)
                 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,
@@ -1017,7 +1020,6 @@ asmlinkage long sys32_ptrace(long request, u32 pid, u32 addr, u32 data)
         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:
diff --git a/include/asm-x86/ptrace-abi.h b/include/asm-x86/ptrace-abi.h
index 6fadc5214e14..b473ad45e9ca 100644
--- a/include/asm-x86/ptrace-abi.h
+++ b/include/asm-x86/ptrace-abi.h
@@ -99,32 +99,27 @@
    ENXIO........no buffer allocated */
 #define PTRACE_BTS_GET_BUFFER_SIZE 42
 
-/* Return the index of the next bts record to be written,
-   if successful; -1, otherwise.
-   EOPNOTSUPP...processor does not support bts tracing
-   ENXIO........no buffer allocated
-   After the first warp-around, this is the start of the circular bts buffer. */
-#define PTRACE_BTS_GET_INDEX 43
-
-/* Read the DATA'th bts record into a ptrace_bts_record buffer provided in ADDR.
+/* Read the DATA'th bts record into a ptrace_bts_record buffer
+   provided in ADDR.
+   Records are ordered from newest to oldest.
    Return 0, if successful; -1, otherwise
    EOPNOTSUPP...processor does not support bts tracing
    ENXIO........no buffer allocated
    EINVAL.......invalid index */
-#define PTRACE_BTS_READ_RECORD 44
+#define PTRACE_BTS_READ_RECORD 43
 
 /* Configure last branch trace; the configuration is given as a bit-mask of
    PTRACE_BTS_O_* options in DATA; parameter ADDR is ignored.
    Return 0, if successful; -1, otherwise
    EOPNOTSUPP...processor does not support bts tracing
    ENXIO........no buffer allocated */
-#define PTRACE_BTS_CONFIG 45
+#define PTRACE_BTS_CONFIG 44
 
 /* Return the configuration as bit-mask of PTRACE_BTS_O_* options
    if successful; -1, otherwise.
    EOPNOTSUPP...processor does not support bts tracing
    ENXIO........no buffer allocated */
-#define PTRACE_BTS_STATUS 46
+#define PTRACE_BTS_STATUS 45
 
 /* Trace configuration options */
 /* Collect last branch trace */