perf probe: Use libdw callback routines

Use libdw callback functions aggressively, and remove
local tree-search API. This change simplifies the code.

Changes in v3:
 - Cast Dwarf_Addr to uintmax_t for printf-formats.

Changes in v2:
 - Cast Dwarf_Addr to unsigned long long for printf-formats.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: systemtap <systemtap@sources.redhat.com>
Cc: DLE <dle-develop@lists.sourceforge.net>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Ulrich Drepper <drepper@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
LKML-Reference: <20100225133549.6725.81499.stgit@localhost6.localdomain6>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 86 insertions, 177 deletions

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index c422472fe4d1..6305f344f382 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -38,13 +38,6 @@
 #include "probe-finder.h"
 
 
-/* Dwarf_Die Linkage to parent Die */
-struct die_link {
-        struct die_link *parent;        /* Parent die */
-        Dwarf_Die die;                  /* Current die */
-};
-
-
 /*
  * Generic dwarf analysis helpers
  */
@@ -177,26 +170,6 @@ static bool die_compare_name(Dwarf_Die *dw_die, const char *tname)
         return strcmp(tname, name);
 }
 
-/* Check the address is in the subprogram(function). */
-static bool die_within_subprogram(Dwarf_Die *sp_die, Dwarf_Addr addr,
-                                 size_t *offs)
-{
-        Dwarf_Addr epc;
-        int ret;
-
-        ret = dwarf_haspc(sp_die, addr);
-        if (ret <= 0)
-                return false;
-
-        if (offs) {
-                ret = dwarf_entrypc(sp_die, &epc);
-                DIE_IF(ret == -1);
-                *offs = addr - epc;
-        }
-
-        return true;
-}
-
 /* Get entry pc(or low pc, 1st entry of ranges)  of the die */
 static Dwarf_Addr die_get_entrypc(Dwarf_Die *dw_die)
 {
@@ -208,70 +181,34 @@ static Dwarf_Addr die_get_entrypc(Dwarf_Die *dw_die)
         return epc;
 }
 
-/* Check if the abstract origin's address or not */
-static bool die_compare_abstract_origin(Dwarf_Die *in_die, void *origin_addr)
-{
-        Dwarf_Attribute attr;
-        Dwarf_Die origin;
-
-        if (!dwarf_attr(in_die, DW_AT_abstract_origin, &attr))
-                return false;
-        if (!dwarf_formref_die(&attr, &origin))
-                return false;
-
-        return origin.addr == origin_addr;
-}
-
-/*
- * Search a Die from Die tree.
- * Note: cur_link->die should be deallocated in this function.
- */
-static int __search_die_tree(struct die_link *cur_link,
-                             int (*die_cb)(struct die_link *, void *),
-                             void *data)
+/* Get a variable die */
+static Dwarf_Die *die_find_variable(Dwarf_Die *sp_die, const char *name,
+                                    Dwarf_Die *die_mem)
 {
-        struct die_link new_link;
+        Dwarf_Die child_die;
+        int tag;
         int ret;
 
-        if (!die_cb)
-                return 0;
-
-        /* Check current die */
-        while (!(ret = die_cb(cur_link, data))) {
-                /* Check child die */
-                ret = dwarf_child(&cur_link->die, &new_link.die);
-                if (ret == 0) {
-                        new_link.parent = cur_link;
-                        ret = __search_die_tree(&new_link, die_cb, data);
-                        if (ret)
-                                break;
-                }
+        ret = dwarf_child(sp_die, die_mem);
+        if (ret != 0)
+                return NULL;
 
-                /* Move to next sibling */
-                ret = dwarf_siblingof(&cur_link->die, &cur_link->die);
-                if (ret != 0)
-                        return 0;
-        }
-        return ret;
-}
+        do {
+                tag = dwarf_tag(die_mem);
+                if ((tag == DW_TAG_formal_parameter ||
+                     tag == DW_TAG_variable) &&
+                    (die_compare_name(die_mem, name) == 0))
+                        return die_mem;
 
-/* Search a die in its children's die tree */
-static int search_die_from_children(Dwarf_Die *parent_die,
-                                    int (*die_cb)(struct die_link *, void *),
-                                    void *data)
-{
-        struct die_link new_link;
-        int ret;
+                if (die_find_variable(die_mem, name, &child_die)) {
+                        memcpy(die_mem, &child_die, sizeof(Dwarf_Die));
+                        return die_mem;
+                }
+        } while (dwarf_siblingof(die_mem, die_mem) == 0);
 
-        new_link.parent = NULL;
-        ret = dwarf_child(parent_die, &new_link.die);
-        if (ret == 0)
-                return __search_die_tree(&new_link, die_cb, data);
-        else
-                return 0;
+        return NULL;
 }
 
-
 /*
  * Probe finder related functions
  */
@@ -347,28 +284,13 @@ error:
             " Perhaps, it has been optimized out.", pf->var);
 }
 
-static int variable_search_cb(struct die_link *dlink, void *data)
-{
-        struct probe_finder *pf = (struct probe_finder *)data;
-        int tag;
-
-        tag = dwarf_tag(&dlink->die);
-        DIE_IF(tag < 0);
-        if ((tag == DW_TAG_formal_parameter ||
-             tag == DW_TAG_variable) &&
-            (die_compare_name(&dlink->die, pf->var) == 0)) {
-                show_variable(&dlink->die, pf);
-                return 1;
-        }
-        /* TODO: Support struct members and arrays */
-        return 0;
-}
-
 /* Find a variable in a subprogram die */
 static void find_variable(Dwarf_Die *sp_die, struct probe_finder *pf)
 {
         int ret;
+        Dwarf_Die vr_die;
 
+        /* TODO: Support struct members and arrays */
         if (!is_c_varname(pf->var)) {
                 /* Output raw parameters */
                 ret = snprintf(pf->buf, pf->len, " %s", pf->var);
@@ -379,31 +301,42 @@ static void find_variable(Dwarf_Die *sp_die, struct probe_finder *pf)
 
         pr_debug("Searching '%s' variable in context.\n", pf->var);
         /* Search child die for local variables and parameters. */
-        ret = search_die_from_children(sp_die, variable_search_cb, pf);
-        if (!ret)
+        if (!die_find_variable(sp_die, pf->var, &vr_die))
                 die("Failed to find '%s' in this function.", pf->var);
+
+        show_variable(&vr_die, pf);
 }
 
 /* Show a probe point to output buffer */
-static void show_probe_point(Dwarf_Die *sp_die, size_t offs,
-                             struct probe_finder *pf)
+static void show_probe_point(Dwarf_Die *sp_die, struct probe_finder *pf)
 {
         struct probe_point *pp = pf->pp;
+        Dwarf_Addr eaddr;
+        Dwarf_Die die_mem;
         const char *name;
         char tmp[MAX_PROBE_BUFFER];
         int ret, i, len;
         Dwarf_Attribute fb_attr;
         size_t nops;
 
+        /* If no real subprogram, find a real one */
+        if (!sp_die || dwarf_tag(sp_die) != DW_TAG_subprogram) {
+                sp_die = die_get_real_subprogram(&pf->cu_die,
+                                                 pf->addr, &die_mem);
+                if (!sp_die)
+                        die("Probe point is not found in subprograms.");
+        }
+
         /* Output name of probe point */
         name = dwarf_diename(sp_die);
         if (name) {
-                ret = snprintf(tmp, MAX_PROBE_BUFFER, "%s+%u", name,
-                                (unsigned int)offs);
+                dwarf_entrypc(sp_die, &eaddr);
+                ret = snprintf(tmp, MAX_PROBE_BUFFER, "%s+%lu", name,
+                                (unsigned long)(pf->addr - eaddr));
                 /* Copy the function name if possible */
                 if (!pp->function) {
                         pp->function = strdup(name);
-                        pp->offset = offs;
+                        pp->offset = (size_t)(pf->addr - eaddr);
                 }
         } else {
                 /* This function has no name. */
@@ -450,10 +383,9 @@ static void find_probe_point_by_line(struct probe_finder *pf)
         Dwarf_Lines *lines;
         Dwarf_Line *line;
         size_t nlines, i;
-        Dwarf_Addr addr, epc;
+        Dwarf_Addr addr;
         int lineno;
         int ret;
-        Dwarf_Die *sp_die, die_mem;
 
         ret = dwarf_getsrclines(&pf->cu_die, &lines, &nlines);
         DIE_IF(ret != 0);
@@ -474,77 +406,57 @@ static void find_probe_point_by_line(struct probe_finder *pf)
                          (int)i, lineno, (uintmax_t)addr);
                 pf->addr = addr;
 
-                sp_die = die_get_real_subprogram(&pf->cu_die, addr, &die_mem);
-                if (!sp_die)
-                        die("Probe point is not found in subprograms.");
-                dwarf_entrypc(sp_die, &epc);
-                show_probe_point(sp_die, (size_t)(addr - epc), pf);
+                show_probe_point(NULL, pf);
                 /* Continuing, because target line might be inlined. */
         }
 }
 
+static int probe_point_inline_cb(Dwarf_Die *in_die, void *data)
+{
+        struct probe_finder *pf = (struct probe_finder *)data;
+        struct probe_point *pp = pf->pp;
+
+        /* Get probe address */
+        pf->addr = die_get_entrypc(in_die);
+        pf->addr += pp->offset;
+        pr_debug("found inline addr: 0x%jx\n", (uintmax_t)pf->addr);
+
+        show_probe_point(in_die, pf);
+        return DWARF_CB_OK;
+}
 
 /* Search function from function name */
-static int probe_point_search_cb(struct die_link *dlink, void *data)
+static int probe_point_search_cb(Dwarf_Die *sp_die, void *data)
 {
         struct probe_finder *pf = (struct probe_finder *)data;
         struct probe_point *pp = pf->pp;
-        struct die_link *lk;
-        size_t offs;
-        int tag;
-        int ret;
 
-        tag = dwarf_tag(&dlink->die);
-        if (tag == DW_TAG_subprogram) {
-                if (die_compare_name(&dlink->die, pp->function) == 0) {
-                        if (pp->line) { /* Function relative line */
-                                pf->fname = dwarf_decl_file(&dlink->die);
-                                dwarf_decl_line(&dlink->die, &pf->lno);
-                                pf->lno += pp->line;
-                                find_probe_point_by_line(pf);
-                                return 1;
-                        }
-                        if (dwarf_func_inline(&dlink->die)) {
-                                /* Inlined function, save it. */
-                                pf->origin = dlink->die.addr;
-                                return 0;       /* Continue to search */
-                        }
-                        /* Get probe address */
-                        pf->addr = die_get_entrypc(&dlink->die);
-                        pf->addr += pp->offset;
-                        /* TODO: Check the address in this function */
-                        show_probe_point(&dlink->die, pp->offset, pf);
-                        return 1; /* Exit; no same symbol in this CU. */
-                }
-        } else if (tag == DW_TAG_inlined_subroutine && pf->origin) {
-                if (die_compare_abstract_origin(&dlink->die, pf->origin)) {
-                        /* Get probe address */
-                        pf->addr = die_get_entrypc(&dlink->die);
-                        pf->addr += pp->offset;
-                        pr_debug("found inline addr: 0x%jx\n",
-                                 (uintmax_t)pf->addr);
-                        /* Inlined function. Get a real subprogram */
-                        for (lk = dlink->parent; lk != NULL; lk = lk->parent) {
-                                tag = dwarf_tag(&lk->die);
-                                if (tag == DW_TAG_subprogram &&
-                                    !dwarf_func_inline(&lk->die))
-                                        goto found;
-                        }
-                        die("Failed to find real subprogram.");
-found:
-                        /* Get offset from subprogram */
-                        ret = die_within_subprogram(&lk->die, pf->addr, &offs);
-                        DIE_IF(!ret);
-                        show_probe_point(&lk->die, offs, pf);
-                        /* Continue to search */
-                }
-        }
-        return 0;
+        /* Check tag and diename */
+        if (dwarf_tag(sp_die) != DW_TAG_subprogram ||
+            die_compare_name(sp_die, pp->function) != 0)
+                return 0;
+
+        if (pp->line) { /* Function relative line */
+                pf->fname = dwarf_decl_file(sp_die);
+                dwarf_decl_line(sp_die, &pf->lno);
+                pf->lno += pp->line;
+                find_probe_point_by_line(pf);
+        } else if (!dwarf_func_inline(sp_die)) {
+                /* Real function */
+                pf->addr = die_get_entrypc(sp_die);
+                pf->addr += pp->offset;
+                /* TODO: Check the address in this function */
+                show_probe_point(sp_die, pf);
+        } else
+                /* Inlined function: search instances */
+                dwarf_func_inline_instances(sp_die, probe_point_inline_cb, pf);
+
+        return 1; /* Exit; no same symbol in this CU. */
 }
 
 static void find_probe_point_by_func(struct probe_finder *pf)
 {
-        search_die_from_children(&pf->cu_die, probe_point_search_cb, pf);
+        dwarf_getfuncs(&pf->cu_die, probe_point_search_cb, pf, 0);
 }
 
 /* Find a probe point */
@@ -669,27 +581,25 @@ static void find_line_range_by_line(struct line_finder *lf)
 }
 
 /* Search function from function name */
-static int line_range_search_cb(struct die_link *dlink, void *data)
+static int line_range_search_cb(Dwarf_Die *sp_die, void *data)
 {
         struct line_finder *lf = (struct line_finder *)data;
         struct line_range *lr = lf->lr;
-        int tag;
         int ret;
 
-        tag = dwarf_tag(&dlink->die);
-        if (tag == DW_TAG_subprogram &&
-            die_compare_name(&dlink->die, lr->function) == 0) {
+        if (dwarf_tag(sp_die) == DW_TAG_subprogram &&
+            die_compare_name(sp_die, lr->function) == 0) {
                 /* Get the address range of this function */
-                ret = dwarf_highpc(&dlink->die, &lf->addr_e);
+                ret = dwarf_highpc(sp_die, &lf->addr_e);
                 if (ret == 0)
-                        ret = dwarf_lowpc(&dlink->die, &lf->addr_s);
+                        ret = dwarf_lowpc(sp_die, &lf->addr_s);
                 if (ret != 0) {
                         lf->addr_s = 0;
                         lf->addr_e = 0;
                 }
 
-                lf->fname = dwarf_decl_file(&dlink->die);
-                dwarf_decl_line(&dlink->die, &lr->offset);
+                lf->fname = dwarf_decl_file(sp_die);
+                dwarf_decl_line(sp_die, &lr->offset);
                 pr_debug("fname: %s, lineno:%d\n", lf->fname, lr->offset);
                 lf->lno_s = lr->offset + lr->start;
                 if (!lr->end)
@@ -706,7 +616,7 @@ static int line_range_search_cb(struct die_link *dlink, void *data)
 
 static void find_line_range_by_func(struct line_finder *lf)
 {
-        search_die_from_children(&lf->cu_die, line_range_search_cb, lf);
+        dwarf_getfuncs(&lf->cu_die, line_range_search_cb, lf, 0);
 }
 
 int find_line_range(int fd, struct line_range *lr)
diff --git a/tools/perf/util/probe-finder.h b/tools/perf/util/probe-finder.h
index 9dd4a884d0e6..74525aeb30fe 100644
--- a/tools/perf/util/probe-finder.h
+++ b/tools/perf/util/probe-finder.h
@@ -66,7 +66,6 @@ struct probe_finder {
         Dwarf_Addr              addr;           /* Address */
         const char              *fname;         /* File name */
         int                     lno;            /* Line number */
-        void                    *origin;        /* Inline origin addr */
         Dwarf_Die               cu_die;         /* Current CU */
 
         /* For variable searching */