perf/probes: Support function entry relative line number

Add function-entry relative line number specifying support to
perf-probe. This allows users to define probes by line number
from entry of the function.

 e.g.

  perf probe schedule:16

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Frank Ch. Eigler <fche@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
LKML-Reference: <20091027204319.30545.30678.stgit@harusame>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 61 insertions, 18 deletions

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 6d3bac9f947..db96186e02a 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -114,7 +114,7 @@ static int strtailcmp(const char *s1, const char *s2)
 }
 
 /* Find the fileno of the target file. */
-static Dwarf_Unsigned die_get_fileno(Dwarf_Die cu_die, const char *fname)
+static Dwarf_Unsigned cu_find_fileno(Dwarf_Die cu_die, const char *fname)
 {
         Dwarf_Signed cnt, i;
         Dwarf_Unsigned found = 0;
@@ -335,6 +335,36 @@ static int attr_get_locdesc(Dwarf_Attribute attr, Dwarf_Locdesc *desc,
         return ret;
 }
 
+/* Get decl_file attribute value (file number) */
+static Dwarf_Unsigned die_get_decl_file(Dwarf_Die sp_die)
+{
+        Dwarf_Attribute attr;
+        Dwarf_Unsigned fno;
+        int ret;
+
+        ret = dwarf_attr(sp_die, DW_AT_decl_file, &attr, &__dw_error);
+        DIE_IF(ret != DW_DLV_OK);
+        dwarf_formudata(attr, &fno, &__dw_error);
+        DIE_IF(ret != DW_DLV_OK);
+        dwarf_dealloc(__dw_debug, attr, DW_DLA_ATTR);
+        return fno;
+}
+
+/* Get decl_line attribute value (line number) */
+static Dwarf_Unsigned die_get_decl_line(Dwarf_Die sp_die)
+{
+        Dwarf_Attribute attr;
+        Dwarf_Unsigned lno;
+        int ret;
+
+        ret = dwarf_attr(sp_die, DW_AT_decl_line, &attr, &__dw_error);
+        DIE_IF(ret != DW_DLV_OK);
+        dwarf_formudata(attr, &lno, &__dw_error);
+        DIE_IF(ret != DW_DLV_OK);
+        dwarf_dealloc(__dw_debug, attr, DW_DLA_ATTR);
+        return lno;
+}
+
 /*
  * Probe finder related functions
  */
@@ -501,6 +531,7 @@ static void show_probepoint(Dwarf_Die sp_die, Dwarf_Signed offs,
         DIE_IF(ret < 0);
         DIE_IF(ret >= MAX_PROBE_BUFFER);
         len = ret;
+        pr_debug("Probe point found: %s\n", tmp);
 
         /* Find each argument */
         get_current_frame_base(sp_die, pf);
@@ -536,17 +567,16 @@ static int probeaddr_callback(struct die_link *dlink, void *data)
 }
 
 /* Find probe point from its line number */
-static void find_by_line(Dwarf_Die cu_die, struct probe_finder *pf)
+static void find_by_line(struct probe_finder *pf)
 {
-        struct probe_point *pp = pf->pp;
-        Dwarf_Signed cnt, i;
+        Dwarf_Signed cnt, i, clm;
         Dwarf_Line *lines;
         Dwarf_Unsigned lineno = 0;
         Dwarf_Addr addr;
         Dwarf_Unsigned fno;
         int ret;
 
-        ret = dwarf_srclines(cu_die, &lines, &cnt, &__dw_error);
+        ret = dwarf_srclines(pf->cu_die, &lines, &cnt, &__dw_error);
         DIE_IF(ret != DW_DLV_OK);
 
         for (i = 0; i < cnt; i++) {
@@ -557,15 +587,20 @@ static void find_by_line(Dwarf_Die cu_die, struct probe_finder *pf)
 
                 ret = dwarf_lineno(lines[i], &lineno, &__dw_error);
                 DIE_IF(ret != DW_DLV_OK);
-                if (lineno != (Dwarf_Unsigned)pp->line)
+                if (lineno != pf->lno)
                         continue;
 
+                ret = dwarf_lineoff(lines[i], &clm, &__dw_error);
+                DIE_IF(ret != DW_DLV_OK);
+
                 ret = dwarf_lineaddr(lines[i], &addr, &__dw_error);
                 DIE_IF(ret != DW_DLV_OK);
-                pr_debug("Probe point found: 0x%llx\n", addr);
+                pr_debug("Probe line found: line[%d]:%u,%d addr:0x%llx\n",
+                         (int)i, (unsigned)lineno, (int)clm, addr);
                 pf->addr = addr;
                 /* Search a real subprogram including this line, */
-                ret = search_die_from_children(cu_die, probeaddr_callback, pf);
+                ret = search_die_from_children(pf->cu_die,
+                                               probeaddr_callback, pf);
                 if (ret == 0)
                         die("Probe point is not found in subprograms.\n");
                 /* Continuing, because target line might be inlined. */
@@ -587,6 +622,13 @@ static int probefunc_callback(struct die_link *dlink, void *data)
         DIE_IF(ret == DW_DLV_ERROR);
         if (tag == DW_TAG_subprogram) {
                 if (die_compare_name(dlink->die, pp->function) == 0) {
+                        if (pp->line) { /* Function relative line */
+                                pf->fno = die_get_decl_file(dlink->die);
+                                pf->lno = die_get_decl_line(dlink->die)
+                                         + pp->line;
+                                find_by_line(pf);
+                                return 1;
+                        }
                         if (die_inlined_subprogram(dlink->die)) {
                                 /* Inlined function, save it. */
                                 ret = dwarf_die_CU_offset(dlink->die,
@@ -631,9 +673,9 @@ found:
         return 0;
 }
 
-static void find_by_func(Dwarf_Die cu_die, struct probe_finder *pf)
+static void find_by_func(struct probe_finder *pf)
 {
-        search_die_from_children(cu_die, probefunc_callback, pf);
+        search_die_from_children(pf->cu_die, probefunc_callback, pf);
 }
 
 /* Find a probe point */
@@ -641,7 +683,6 @@ int find_probepoint(int fd, struct probe_point *pp)
 {
         Dwarf_Half addr_size = 0;
         Dwarf_Unsigned next_cuh = 0;
-        Dwarf_Die cu_die = 0;
         int cu_number = 0, ret;
         struct probe_finder pf = {.pp = pp};
 
@@ -659,25 +700,27 @@ int find_probepoint(int fd, struct probe_point *pp)
                         break;
 
                 /* Get the DIE(Debugging Information Entry) of this CU */
-                ret = dwarf_siblingof(__dw_debug, 0, &cu_die, &__dw_error);
+                ret = dwarf_siblingof(__dw_debug, 0, &pf.cu_die, &__dw_error);
                 DIE_IF(ret != DW_DLV_OK);
 
                 /* Check if target file is included. */
                 if (pp->file)
-                        pf.fno = die_get_fileno(cu_die, pp->file);
+                        pf.fno = cu_find_fileno(pf.cu_die, pp->file);
 
                 if (!pp->file || pf.fno) {
                         /* Save CU base address (for frame_base) */
-                        ret = dwarf_lowpc(cu_die, &pf.cu_base, &__dw_error);
+                        ret = dwarf_lowpc(pf.cu_die, &pf.cu_base, &__dw_error);
                         DIE_IF(ret == DW_DLV_ERROR);
                         if (ret == DW_DLV_NO_ENTRY)
                                 pf.cu_base = 0;
-                        if (pp->line)
-                                find_by_line(cu_die, &pf);
                         if (pp->function)
-                                find_by_func(cu_die, &pf);
+                                find_by_func(&pf);
+                        else {
+                                pf.lno = pp->line;
+                                find_by_line(&pf);
+                        }
                 }
-                dwarf_dealloc(__dw_debug, cu_die, DW_DLA_DIE);
+                dwarf_dealloc(__dw_debug, pf.cu_die, DW_DLA_DIE);
         }
         ret = dwarf_finish(__dw_debug, &__dw_error);
         DIE_IF(ret != DW_DLV_OK);