Add some minor tweaks to backtracing add-ons and mention in NEWS

* NEWS: mention new backtracing add-ons
* runtime/regs.h: fix bug with REG_LINK macro for __aarch64__
* tapset/linux/ucontext-unwind.stp: tweak the register-taking backtraces to be more general and work
  with other archs

diff --git a/NEWS b/NEWS
index 16d35a46acb3e7fd8f45f64c3adcbacee36ae2f3..8c918e5b2d3bfb31ffadda8c15924f3deb3766be 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -1,5 +1,16 @@
 * What's new in version 4.2, PRERELEASE
 
+- New backtracing functions print_[u]backtrace_fileline() have been added
+  to the tapset. These functions behave similarly to print_[u]backtrace(),
+  the only difference being that file names and line numbers are added
+  to the backtrace.
+
+- Now it is possible to issue a backtrace using user specified pc, sp,
+  and fp which can be used to generate backtraces of different contexts.
+  This was introduced to get backtraces of user code from within the go
+  runtime but it can also be used to do things like generating backtraces
+  of user code from within signal handlers.
+
 - The compiler optimizes out probes with empty handlers. Previously,
   warnings were issued but, the probe was not internally removed. For 
   example, this script now outputs a warning and an error as the only

diff --git a/runtime/regs.h b/runtime/regs.h
index 94680af95a558878737a4238365157982faa037f..f65e500f758bb665658ee491b859d4519fa10cc1 100644 (file)
--- a/runtime/regs.h
+++ b/runtime/regs.h
@@ -44,9 +44,9 @@
 
 #elif defined (__aarch64__)
 
-#define REG_IP(regs) regs->pc
-#define REG_SP(regs) regs->sp
-#define REG_LINK(regs) regs->regs[30]
+#define REG_IP(regs_arg) (regs_arg)->pc
+#define REG_SP(regs_arg) (regs_arg)->sp
+#define REG_LINK(regs_arg) (regs_arg)->regs[30]
 
 #elif defined (__arm__)
 

diff --git a/tapset/linux/ucontext-unwind.stp b/tapset/linux/ucontext-unwind.stp
index 25c1d8acbd298cf5c8ebc59fbbc70eb325adeaf2..f83e328b347302438a71a738bf8a12115462c8f4 100644 (file)
--- a/tapset/linux/ucontext-unwind.stp
+++ b/tapset/linux/ucontext-unwind.stp
@@ -26,15 +26,15 @@ function print_ubacktrace () %{ /* pragma:unwind */ /* pragma:symbols */
  * sfunction print_ubacktrace - Print stack back trace for current user-space task.
  *
  * Equivalent to print_ubacktrace(), but it performs the backtrace
- * using the pc and sp provided.
+ * using the pc, sp, and fp provided.
  *
  * Note: To get (full) backtraces for user space applications and shared
  * shared libraries not mentioned in the current script run stap with
  * -d /path/to/exe-or-so and/or add --ldd to load all needed unwind data.
  */
-function print_ubacktrace (pc:long, sp:long) %{ /* pragma:unwind */ /* pragma:symbols */
+function print_ubacktrace (pc:long, sp:long, fp:long) %{ /* pragma:unwind */ /* pragma:symbols */
 /* myproc-unprivileged */ /* pragma:uprobes */ /* pragma:vma */
-    unsigned long saved_pc, saved_sp;
+    unsigned long saved_pc, saved_sp, saved_fp;
 
     if (_stp_get_uregs(CONTEXT) == NULL) {
         _stp_stack_user_print(CONTEXT, _STP_SYM_FULLER); /* expecting a failure message */
@@ -43,15 +43,27 @@ function print_ubacktrace (pc:long, sp:long) %{ /* pragma:unwind */ /* pragma:sy
 
     saved_pc = REG_IP(CONTEXT->uregs);
     saved_sp = REG_SP(CONTEXT->uregs);
-    REG_IP(CONTEXT->uregs) = STAP_ARG_pc;
+    SET_REG_IP(CONTEXT->uregs, STAP_ARG_pc);
     REG_SP(CONTEXT->uregs) = STAP_ARG_sp;
+#if defined REG_FP
+    saved_fp = REG_FP(CONTEXT->uregs);
+    REG_FP(CONTEXT->uregs) = STAP_ARG_fp;
+#elif defined REG_LINK
+    saved_fp = REG_LINK(CONTEXT->uregs);
+    REG_LINK(CONTEXT->uregs) = STAP_ARG_fp;
+#endif
 
     CONTEXT->uwcache_user.state = uwcache_uninitialized;
     _stp_stack_user_print(CONTEXT, _STP_SYM_FULL);
     CONTEXT->uwcache_user.state = uwcache_uninitialized;
 
-    REG_IP(CONTEXT->uregs) = saved_pc;
+    SET_REG_IP(CONTEXT->uregs, saved_pc);
     REG_SP(CONTEXT->uregs) = saved_sp;
+#if defined REG_FP
+    REG_FP(CONTEXT->uregs) = saved_fp;
+#elif defined REG_LINK
+    REG_LINK(CONTEXT->uregs) = saved_fp;
+#endif
 %}
 
 /**
@@ -114,15 +126,15 @@ function print_ubacktrace_fileline () %{ /* pragma:unwind */ /* pragma:symbols *
  * sfunction print_ubacktrace - Print stack back trace for current user-space task.
  *
  * Equivalent to print_ubacktrace_fileline(), but it performs the backtrace
- * using the pc and sp passed in.
+ * using the pc, sp, and fp passed in.
  *
  * Note: To get (full) backtraces for user space applications and shared
  * shared libraries not mentioned in the current script run stap with
  * -d /path/to/exe-or-so and/or add --ldd to load all needed unwind data.
  */
-function print_ubacktrace_fileline (pc:long, sp:long) %{ /* pragma:unwind */ /* pragma:symbols */
+function print_ubacktrace_fileline (pc:long, sp:long, fp:long) %{ /* pragma:unwind */ /* pragma:symbols */
 /* myproc-unprivileged */ /* pragma:uprobes */ /* pragma:vma */ /* pragma:lines */
-    unsigned long saved_pc, saved_sp;
+    unsigned long saved_pc, saved_sp, saved_fp;
 
     if (_stp_get_uregs(CONTEXT) == NULL) {
         _stp_stack_user_print(CONTEXT, _STP_SYM_FULLER); /* expecting a failure message */
@@ -131,15 +143,27 @@ function print_ubacktrace_fileline (pc:long, sp:long) %{ /* pragma:unwind */ /*
 
     saved_pc = REG_IP(CONTEXT->uregs);
     saved_sp = REG_SP(CONTEXT->uregs);
-    REG_IP(CONTEXT->uregs) = STAP_ARG_pc;
+    SET_REG_IP(CONTEXT->uregs, STAP_ARG_pc);
     REG_SP(CONTEXT->uregs) = STAP_ARG_sp;
+#if defined REG_FP
+    saved_fp = REG_FP(CONTEXT->uregs);
+    REG_FP(CONTEXT->uregs) = STAP_ARG_fp;
+#elif defined REG_LINK
+    saved_fp = REG_LINK(CONTEXT->uregs);
+    REG_LINK(CONTEXT->uregs) = STAP_ARG_fp;
+#endif
 
     CONTEXT->uwcache_user.state = uwcache_uninitialized;
     _stp_stack_user_print(CONTEXT, _STP_SYM_FULLER);
     CONTEXT->uwcache_user.state = uwcache_uninitialized;
 
-    REG_IP(CONTEXT->uregs) = saved_pc;
+    SET_REG_IP(CONTEXT->uregs, saved_pc);
     REG_SP(CONTEXT->uregs) = saved_sp;
+#if defined REG_FP
+    REG_FP(CONTEXT->uregs) = saved_fp;
+#elif defined REG_LINK
+    REG_LINK(CONTEXT->uregs) = saved_fp;
+#endif
 %}
 
 /**