return -ENOTSUP;
}
#endif
+
+/*
+ * die_has_loclist - Check if DW_AT_location of @vr_die is a location list
+ * @vr_die: a variable DIE
+ */
+static bool die_has_loclist(Dwarf_Die *vr_die)
+{
+ Dwarf_Attribute loc;
+ int tag = dwarf_tag(vr_die);
+
+ if (tag != DW_TAG_formal_parameter &&
+ tag != DW_TAG_variable)
+ return false;
+
+ return (dwarf_attr_integrate(vr_die, DW_AT_location, &loc) &&
+ dwarf_whatform(&loc) == DW_FORM_sec_offset);
+}
+
+/*
+ * die_is_optimized_target - Check if target program is compiled with
+ * optimization
+ * @cu_die: a CU DIE
+ *
+ * For any object in given CU whose DW_AT_location is a location list,
+ * target program is compiled with optimization. This is applicable to
+ * clang as well.
+ */
+bool die_is_optimized_target(Dwarf_Die *cu_die)
+{
+ Dwarf_Die tmp_die;
+
+ if (die_has_loclist(cu_die))
+ return true;
+
+ if (!dwarf_child(cu_die, &tmp_die) &&
+ die_is_optimized_target(&tmp_die))
+ return true;
+
+ if (!dwarf_siblingof(cu_die, &tmp_die) &&
+ die_is_optimized_target(&tmp_die))
+ return true;
+
+ return false;
+}
+
+/*
+ * die_search_idx - Search index of given line address
+ * @lines: Line records of single CU
+ * @nr_lines: Number of @lines
+ * @addr: address we are looking for
+ * @idx: index to be set by this function (return value)
+ *
+ * Search for @addr by looping over every lines of CU. If address
+ * matches, set index of that line in @idx. Note that single source
+ * line can have multiple line records. i.e. single source line can
+ * have multiple index.
+ */
+static bool die_search_idx(Dwarf_Lines *lines, unsigned long nr_lines,
+ Dwarf_Addr addr, unsigned long *idx)
+{
+ unsigned long i;
+ Dwarf_Addr tmp;
+
+ for (i = 0; i < nr_lines; i++) {
+ if (dwarf_lineaddr(dwarf_onesrcline(lines, i), &tmp))
+ return false;
+
+ if (tmp == addr) {
+ *idx = i;
+ return true;
+ }
+ }
+ return false;
+}
+
+/*
+ * die_get_postprologue_addr - Search next address after function prologue
+ * @entrypc_idx: entrypc index
+ * @lines: Line records of single CU
+ * @nr_lines: Number of @lines
+ * @hignpc: high PC address of function
+ * @postprologue_addr: Next address after function prologue (return value)
+ *
+ * Look for prologue-end marker. If there is no explicit marker, return
+ * address of next line record or next source line.
+ */
+static bool die_get_postprologue_addr(unsigned long entrypc_idx,
+ Dwarf_Lines *lines,
+ unsigned long nr_lines,
+ Dwarf_Addr highpc,
+ Dwarf_Addr *postprologue_addr)
+{
+ unsigned long i;
+ int entrypc_lno, lno;
+ Dwarf_Line *line;
+ Dwarf_Addr addr;
+ bool p_end;
+
+ /* entrypc_lno is actual source line number */
+ line = dwarf_onesrcline(lines, entrypc_idx);
+ if (dwarf_lineno(line, &entrypc_lno))
+ return false;
+
+ for (i = entrypc_idx; i < nr_lines; i++) {
+ line = dwarf_onesrcline(lines, i);
+
+ if (dwarf_lineaddr(line, &addr) ||
+ dwarf_lineno(line, &lno) ||
+ dwarf_lineprologueend(line, &p_end))
+ return false;
+
+ /* highpc is exclusive. [entrypc,highpc) */
+ if (addr >= highpc)
+ break;
+
+ /* clang supports prologue-end marker */
+ if (p_end)
+ break;
+
+ /* Actual next line in source */
+ if (lno != entrypc_lno)
+ break;
+
+ /*
+ * Single source line can have multiple line records.
+ * For Example,
+ * void foo() { printf("hello\n"); }
+ * contains two line records. One points to declaration and
+ * other points to printf() line. Variable 'lno' won't get
+ * incremented in this case but 'i' will.
+ */
+ if (i != entrypc_idx)
+ break;
+ }
+
+ dwarf_lineaddr(line, postprologue_addr);
+ if (*postprologue_addr >= highpc)
+ dwarf_lineaddr(dwarf_onesrcline(lines, i - 1),
+ postprologue_addr);
+
+ return true;
+}
+
+/*
+ * die_skip_prologue - Use next address after prologue as probe location
+ * @sp_die: a subprogram DIE
+ * @cu_die: a CU DIE
+ * @entrypc: entrypc of the function
+ *
+ * Function prologue prepares stack and registers before executing function
+ * logic. When target program is compiled without optimization, function
+ * parameter information is only valid after prologue. When we probe entrypc
+ * of the function, and try to record function parameter, it contains
+ * garbage value.
+ */
+void die_skip_prologue(Dwarf_Die *sp_die, Dwarf_Die *cu_die,
+ Dwarf_Addr *entrypc)
+{
+ size_t nr_lines = 0;
+ unsigned long entrypc_idx = 0;
+ Dwarf_Lines *lines = NULL;
+ Dwarf_Addr postprologue_addr;
+ Dwarf_Addr highpc;
+
+ if (dwarf_highpc(sp_die, &highpc))
+ return;
+
+ if (dwarf_getsrclines(cu_die, &lines, &nr_lines))
+ return;
+
+ if (!die_search_idx(lines, nr_lines, *entrypc, &entrypc_idx))
+ return;
+
+ if (!die_get_postprologue_addr(entrypc_idx, lines, nr_lines,
+ highpc, &postprologue_addr))
+ return;
+
+ *entrypc = postprologue_addr;
+}
return die_walk_lines(sp_die, probe_point_lazy_walker, pf);
}
-static bool var_has_loclist(Dwarf_Die *cu_die)
-{
- Dwarf_Attribute loc;
- int tag = dwarf_tag(cu_die);
-
- if (tag != DW_TAG_formal_parameter &&
- tag != DW_TAG_variable)
- return false;
-
- return (dwarf_attr_integrate(cu_die, DW_AT_location, &loc) &&
- dwarf_whatform(&loc) == DW_FORM_sec_offset);
-}
-
-/*
- * For any object in given CU whose DW_AT_location is a location list,
- * target program is compiled with optimization.
- */
-static bool optimized_target(Dwarf_Die *cu_die)
-{
- Dwarf_Die tmp_die;
-
- if (var_has_loclist(cu_die))
- return true;
-
- if (!dwarf_child(cu_die, &tmp_die) && optimized_target(&tmp_die))
- return true;
-
- if (!dwarf_siblingof(cu_die, &tmp_die) && optimized_target(&tmp_die))
- return true;
-
- return false;
-}
-
-static bool get_entrypc_idx(Dwarf_Lines *lines, unsigned long nr_lines,
- Dwarf_Addr pf_addr, unsigned long *entrypc_idx)
-{
- unsigned long i;
- Dwarf_Addr addr;
-
- for (i = 0; i < nr_lines; i++) {
- if (dwarf_lineaddr(dwarf_onesrcline(lines, i), &addr))
- return false;
-
- if (addr == pf_addr) {
- *entrypc_idx = i;
- return true;
- }
- }
- return false;
-}
-
-static bool get_postprologue_addr(unsigned long entrypc_idx,
- Dwarf_Lines *lines,
- unsigned long nr_lines,
- Dwarf_Addr highpc,
- Dwarf_Addr *postprologue_addr)
-{
- unsigned long i;
- int entrypc_lno, lno;
- Dwarf_Line *line;
- Dwarf_Addr addr;
- bool p_end;
-
- /* entrypc_lno is actual source line number */
- line = dwarf_onesrcline(lines, entrypc_idx);
- if (dwarf_lineno(line, &entrypc_lno))
- return false;
-
- for (i = entrypc_idx; i < nr_lines; i++) {
- line = dwarf_onesrcline(lines, i);
-
- if (dwarf_lineaddr(line, &addr) ||
- dwarf_lineno(line, &lno) ||
- dwarf_lineprologueend(line, &p_end))
- return false;
-
- /* highpc is exclusive. [entrypc,highpc) */
- if (addr >= highpc)
- break;
-
- /* clang supports prologue-end marker */
- if (p_end)
- break;
-
- /* Actual next line in source */
- if (lno != entrypc_lno)
- break;
-
- /*
- * Single source line can have multiple line records.
- * For Example,
- * void foo() { printf("hello\n"); }
- * contains two line records. One points to declaration and
- * other points to printf() line. Variable 'lno' won't get
- * incremented in this case but 'i' will.
- */
- if (i != entrypc_idx)
- break;
- }
-
- dwarf_lineaddr(line, postprologue_addr);
- if (*postprologue_addr >= highpc)
- dwarf_lineaddr(dwarf_onesrcline(lines, i - 1),
- postprologue_addr);
-
- return true;
-}
-
-static void __skip_prologue(Dwarf_Die *sp_die, struct probe_finder *pf)
-{
- size_t nr_lines = 0;
- unsigned long entrypc_idx = 0;
- Dwarf_Lines *lines = NULL;
- Dwarf_Addr postprologue_addr;
- Dwarf_Addr highpc;
-
- if (dwarf_highpc(sp_die, &highpc))
- return;
-
- if (dwarf_getsrclines(&pf->cu_die, &lines, &nr_lines))
- return;
-
- if (!get_entrypc_idx(lines, nr_lines, pf->addr, &entrypc_idx))
- return;
-
- if (!get_postprologue_addr(entrypc_idx, lines, nr_lines,
- highpc, &postprologue_addr))
- return;
-
- pf->addr = postprologue_addr;
-}
-
static void skip_prologue(Dwarf_Die *sp_die, struct probe_finder *pf)
{
struct perf_probe_point *pp = &pf->pev->point;
return;
/* Compiled with optimization? */
- if (optimized_target(&pf->cu_die))
+ if (die_is_optimized_target(&pf->cu_die))
return;
/* Don't know entrypc? */
"Probe on address 0x%" PRIx64 " to force probing at the function entry.\n\n",
pf->addr);
- __skip_prologue(sp_die, pf);
+ die_skip_prologue(sp_die, &pf->cu_die, &pf->addr);
}
static int probe_point_inline_cb(Dwarf_Die *in_die, void *data)
projects / cascardo / linux.git / commitdiff