tracing/kprobes: Make special variable names more self-explainable

Rename special variables to more self-explainable names as below:
- $rv to $retval
- $sa to $stack
- $aN to $argN
- $sN to $stackN

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Frank Ch. Eigler <fche@redhat.com>
LKML-Reference: <20091007222759.1684.3319.stgit@dhcp-100-2-132.bos.redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

diff --git a/Documentation/trace/kprobetrace.txt b/Documentation/trace/kprobetrace.txt
index 4208253..1541524 100644 (file)
--- a/Documentation/trace/kprobetrace.txt
+++ b/Documentation/trace/kprobetrace.txt
@@ -35,13 +35,13 @@ Synopsis of kprobe_events
  MEMADDR       : Address where the probe is inserted.
 
  FETCHARGS     : Arguments. Each probe can have up to 128 args.
-  %REG : Fetch register REG
-  @ADDR        : Fetch memory at ADDR (ADDR should be in kernel)
+  %REG         : Fetch register REG
+  @ADDR                : Fetch memory at ADDR (ADDR should be in kernel)
   @SYM[+|-offs]        : Fetch memory at SYM +|- offs (SYM should be a data symbol)
-  $sN  : Fetch Nth entry of stack (N >= 0)
-  $sa  : Fetch stack address.
-  $aN  : Fetch function argument. (N >= 0)(*)
-  $rv  : Fetch return value.(**)
+  $stackN      : Fetch Nth entry of stack (N >= 0)
+  $stack       : Fetch stack address.
+  $argN                : Fetch function argument. (N >= 0)(*)
+  $retval      : Fetch return value.(**)
   +|-offs(FETCHARG) : Fetch memory at FETCHARG +|- offs address.(***)
   NAME=FETCHARG: Set NAME as the argument name of FETCHARG.
 
@@ -84,13 +84,13 @@ Usage examples
 To add a probe as a new event, write a new definition to kprobe_events
 as below.
 
-  echo p:myprobe do_sys_open dfd=$a0 filename=$a1 flags=$a2 mode=$a3 > /sys/kernel/debug/tracing/kprobe_events
+  echo p:myprobe do_sys_open dfd=$arg0 filename=$arg1 flags=$arg2 mode=$arg3 > /sys/kernel/debug/tracing/kprobe_events
 
  This sets a kprobe on the top of do_sys_open() function with recording
 1st to 4th arguments as "myprobe" event. As this example shows, users can
 choose more familiar names for each arguments.
 
-  echo r:myretprobe do_sys_open $rv >> /sys/kernel/debug/tracing/kprobe_events
+  echo r:myretprobe do_sys_open $retval >> /sys/kernel/debug/tracing/kprobe_events
 
  This sets a kretprobe on the return point of do_sys_open() function with
 recording return value as "myretprobe" event.
@@ -137,11 +137,11 @@ events, you need to enable it.
 #           TASK-PID    CPU#    TIMESTAMP  FUNCTION
 #              | |       |          |         |
            <...>-1447  [001] 1038282.286875: myprobe: (do_sys_open+0x0/0xd6) dfd=3 filename=7fffd1ec4440 flags=8000 mode=0
-           <...>-1447  [001] 1038282.286878: myretprobe: (sys_openat+0xc/0xe <- do_sys_open) $rv=fffffffffffffffe
+           <...>-1447  [001] 1038282.286878: myretprobe: (sys_openat+0xc/0xe <- do_sys_open) $retval=fffffffffffffffe
            <...>-1447  [001] 1038282.286885: myprobe: (do_sys_open+0x0/0xd6) dfd=ffffff9c filename=40413c flags=8000 mode=1b6
-           <...>-1447  [001] 1038282.286915: myretprobe: (sys_open+0x1b/0x1d <- do_sys_open) $rv=3
+           <...>-1447  [001] 1038282.286915: myretprobe: (sys_open+0x1b/0x1d <- do_sys_open) $retval=3
            <...>-1447  [001] 1038282.286969: myprobe: (do_sys_open+0x0/0xd6) dfd=ffffff9c filename=4041c6 flags=98800 mode=10
-           <...>-1447  [001] 1038282.286976: myretprobe: (sys_open+0x1b/0x1d <- do_sys_open) $rv=3
+           <...>-1447  [001] 1038282.286976: myretprobe: (sys_open+0x1b/0x1d <- do_sys_open) $retval=3
 
 
  Each line shows when the kernel hits an event, and <- SYMBOL means kernel

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index ba6d3bd..3313fa7 100644 (file)
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -215,22 +215,22 @@ static int probe_arg_string(char *buf, size_t n, struct fetch_func *ff)
        int ret = -EINVAL;
 
        if (ff->func == fetch_argument)
-               ret = snprintf(buf, n, "$a%lu", (unsigned long)ff->data);
+               ret = snprintf(buf, n, "$arg%lu", (unsigned long)ff->data);
        else if (ff->func == fetch_register) {
                const char *name;
                name = regs_query_register_name((unsigned int)((long)ff->data));
                ret = snprintf(buf, n, "%%%s", name);
        } else if (ff->func == fetch_stack)
-               ret = snprintf(buf, n, "$s%lu", (unsigned long)ff->data);
+               ret = snprintf(buf, n, "$stack%lu", (unsigned long)ff->data);
        else if (ff->func == fetch_memory)
                ret = snprintf(buf, n, "@0x%p", ff->data);
        else if (ff->func == fetch_symbol) {
                struct symbol_cache *sc = ff->data;
                ret = snprintf(buf, n, "@%s%+ld", sc->symbol, sc->offset);
        } else if (ff->func == fetch_retvalue)
-               ret = snprintf(buf, n, "$rv");
+               ret = snprintf(buf, n, "$retval");
        else if (ff->func == fetch_stack_address)
-               ret = snprintf(buf, n, "$sa");
+               ret = snprintf(buf, n, "$stack");
        else if (ff->func == fetch_indirect) {
                struct indirect_fetch_data *id = ff->data;
                size_t l = 0;
@@ -427,40 +427,36 @@ static int parse_probe_vars(char *arg, struct fetch_func *ff, int is_return)
        int ret = 0;
        unsigned long param;
 
-       switch (arg[0]) {
-       case 'a':       /* argument */
-               ret = strict_strtoul(arg + 1, 10, &param);
-               if (ret || param > PARAM_MAX_ARGS)
-                       ret = -EINVAL;
-               else {
-                       ff->func = fetch_argument;
-                       ff->data = (void *)param;
-               }
-               break;
-       case 'r':       /* retval or retaddr */
-               if (is_return && arg[1] == 'v') {
+       if (strcmp(arg, "retval") == 0) {
+               if (is_return) {
                        ff->func = fetch_retvalue;
                        ff->data = NULL;
                } else
                        ret = -EINVAL;
-               break;
-       case 's':       /* stack */
-               if (arg[1] == 'a') {
+       } else if (strncmp(arg, "stack", 5) == 0) {
+               if (arg[5] == '\0') {
                        ff->func = fetch_stack_address;
                        ff->data = NULL;
-               } else {
-                       ret = strict_strtoul(arg + 1, 10, &param);
+               } else if (isdigit(arg[5])) {
+                       ret = strict_strtoul(arg + 5, 10, &param);
                        if (ret || param > PARAM_MAX_STACK)
                                ret = -EINVAL;
                        else {
                                ff->func = fetch_stack;
                                ff->data = (void *)param;
                        }
+               } else
+                       ret = -EINVAL;
+       } else if (strncmp(arg, "arg", 3) == 0 && isdigit(arg[3])) {
+               ret = strict_strtoul(arg + 3, 10, &param);
+               if (ret || param > PARAM_MAX_ARGS)
+                       ret = -EINVAL;
+               else {
+                       ff->func = fetch_argument;
+                       ff->data = (void *)param;
                }
-               break;
-       default:
+       } else
                ret = -EINVAL;
-       }
        return ret;
 }
 
@@ -548,10 +544,10 @@ static int create_trace_probe(int argc, char **argv)
         *  - Add kprobe: p[:[GRP/]EVENT] KSYM[+OFFS]|KADDR [FETCHARGS]
         *  - Add kretprobe: r[:[GRP/]EVENT] KSYM[+0] [FETCHARGS]
         * Fetch args:
-        *  $aN : fetch Nth of function argument. (N:0-)
-        *  $rv : fetch return value
-        *  $sa : fetch stack address
-        *  $sN : fetch Nth of stack (N:0-)
+        *  $argN       : fetch Nth of function argument. (N:0-)
+        *  $retval     : fetch return value
+        *  $stack      : fetch stack address
+        *  $stackN     : fetch Nth of stack (N:0-)
         *  @ADDR       : fetch memory at ADDR (ADDR should be in kernel)
         *  @SYM[+|-offs] : fetch memory at SYM +|- offs (SYM is a data symbol)
         *  %REG        : fetch register REG