Introduce _stp_get_uregs and _STP_PROBE_STATE_FULL_UREGS flag.

No actual functionality change yet. _STP_PROBE_STATE_FULL_UREGS
is set for context probe_flags if full user register set is available
after calling _stp_get_uregs().

diff --git a/runtime/runtime_defines.h b/runtime/runtime_defines.h
index 6a31d2fcea024a1ced281c5be41a08c137afa61f..0fb29ba0fc7a47cb61aab3faff4d4222e99440db 100644 (file)
--- a/runtime/runtime_defines.h
+++ b/runtime/runtime_defines.h
@@ -99,3 +99,5 @@ typedef char string_t[MAXSTRINGLEN];
 /* Defines for CONTEXT probe_flags. */
 /* Probe occured in user space, also indicate regs fully from user. */
 #define _STP_PROBE_STATE_USER_MODE  1
+/* _stp_get_uregs() was called and full user registers were recovered. */
+#define _STP_PROBE_STATE_FULL_UREGS 2

diff --git a/runtime/stack.c b/runtime/stack.c
index 62836bebd8a52d6e97d58a72cc9d34b69bf8eef7..e52b4f4f467d8b47853cc68f48ccdee08994837c 100644 (file)
--- a/runtime/stack.c
+++ b/runtime/stack.c
@@ -145,6 +145,27 @@ static void _stp_stack_print_fallback(unsigned long s, int v, int l, int k) {
 // used through context-unwind.stp.
 #if defined (CONFIG_KPROBES)
 
+/** Gets user space registers when available, also sets context probe_flags
+ * _STP_PROBE_STATE_FULL_UREGS if appropriate.  Should be used instead of
+ * accessing context uregs field directly when (full) uregs are needed
+ * from kernel context.
+ */
+static struct pt_regs *_stp_get_uregs(struct context *c)
+{
+  /* When the probe occurred in user context uregs are always complete. */
+  if (c->uregs && c->probe_flags & _STP_PROBE_STATE_USER_MODE)
+    c->probe_flags |= _STP_PROBE_STATE_FULL_UREGS;
+  else if (c->uregs == NULL)
+    {
+      /* First try simple recovery through task_pt_regs,
+        on some platforms that already provides complete uregs. */
+      c->uregs = task_pt_regs (current);
+      if (_stp_task_pt_regs_valid(current, c->uregs))
+       c->probe_flags |= _STP_PROBE_STATE_FULL_UREGS;
+    }
+  return c->uregs;
+}
+
 /** Prints the stack backtrace
  * @param regs A pointer to the struct pt_regs.
  * @param verbose _STP_SYM_FULL or _STP_SYM_BRIEF
@@ -200,14 +221,8 @@ static void _stp_stack_print(struct context *c, int sym_flags, int stack_flags)
                                      in __stp_stack_print() below. */
                }
        } else if (stack_flags == _STP_STACK_USER) {
-               /* use task_pt_regs, regs might be kernel regs, or not set. */
-               if (c->uregs && (c->probe_flags & _STP_PROBE_STATE_USER_MODE)) {
-                       regs = c->uregs;
-                       uregs_valid = 1;
-               } else {
-                       regs = task_pt_regs(current);
-                       uregs_valid = _stp_task_pt_regs_valid(current, regs);
-               }
+               regs = _stp_get_uregs(c);
+               uregs_valid = c->probe_flags & _STP_PROBE_STATE_FULL_UREGS;
 
                if (! current->mm || ! regs) {
                        if (sym_flags & _STP_SYM_SYMBOL)