提交 6a330a3c 编写于 作者: M Masami Hiramatsu 提交者: Arnaldo Carvalho de Melo

perf probe: Support comp_dir to find an absolute source path

Gcc generates DW_AT_comp_dir and stores relative source path if building kernel
without O= option. In that case, perf probe --line sometimes doesn't work
without --source option, because it tries to access relative source path.

This adds DW_AT_comp_dir support to perf probe for finding an absolute source
path when no --source option.

LKML-Reference: <4C36EBE7.3060802@hitachi.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
上级 7cf0b79e
......@@ -201,28 +201,38 @@ static int try_to_find_kprobe_trace_events(struct perf_probe_event *pev,
* a newly allocated path on success.
* Return 0 if file was found and readable, -errno otherwise.
*/
static int get_real_path(const char *raw_path, char **new_path)
static int get_real_path(const char *raw_path, const char *comp_dir,
char **new_path)
{
if (!symbol_conf.source_prefix) {
if (access(raw_path, R_OK) == 0) {
*new_path = strdup(raw_path);
return 0;
} else
return -errno;
const char *prefix = symbol_conf.source_prefix;
if (!prefix) {
if (raw_path[0] != '/' && comp_dir)
/* If not an absolute path, try to use comp_dir */
prefix = comp_dir;
else {
if (access(raw_path, R_OK) == 0) {
*new_path = strdup(raw_path);
return 0;
} else
return -errno;
}
}
*new_path = malloc((strlen(symbol_conf.source_prefix) +
strlen(raw_path) + 2));
*new_path = malloc((strlen(prefix) + strlen(raw_path) + 2));
if (!*new_path)
return -ENOMEM;
for (;;) {
sprintf(*new_path, "%s/%s", symbol_conf.source_prefix,
raw_path);
sprintf(*new_path, "%s/%s", prefix, raw_path);
if (access(*new_path, R_OK) == 0)
return 0;
if (!symbol_conf.source_prefix)
/* In case of searching comp_dir, don't retry */
return -errno;
switch (errno) {
case ENAMETOOLONG:
case ENOENT:
......@@ -318,7 +328,7 @@ int show_line_range(struct line_range *lr)
/* Convert source file path */
tmp = lr->path;
ret = get_real_path(tmp, &lr->path);
ret = get_real_path(tmp, lr->comp_dir, &lr->path);
free(tmp); /* Free old path */
if (ret < 0) {
pr_warning("Failed to find source file. (%d)\n", ret);
......
......@@ -86,6 +86,7 @@ struct line_range {
int end; /* End line number */
int offset; /* Start line offset */
char *path; /* Real path name */
char *comp_dir; /* Compile directory */
struct list_head line_list; /* Visible lines */
};
......
......@@ -144,6 +144,15 @@ static const char *cu_find_realpath(Dwarf_Die *cu_die, const char *fname)
return src;
}
/* Get DW_AT_comp_dir (should be NULL with older gcc) */
static const char *cu_get_comp_dir(Dwarf_Die *cu_die)
{
Dwarf_Attribute attr;
if (dwarf_attr(cu_die, DW_AT_comp_dir, &attr) == NULL)
return NULL;
return dwarf_formstring(&attr);
}
/* Compare diename and tname */
static bool die_compare_name(Dwarf_Die *dw_die, const char *tname)
{
......@@ -1374,6 +1383,7 @@ int find_line_range(int fd, struct line_range *lr)
size_t cuhl;
Dwarf_Die *diep;
Dwarf *dbg;
const char *comp_dir;
dbg = dwarf_begin(fd, DWARF_C_READ);
if (!dbg) {
......@@ -1409,6 +1419,17 @@ int find_line_range(int fd, struct line_range *lr)
}
off = noff;
}
/* Store comp_dir */
if (lf.found) {
comp_dir = cu_get_comp_dir(&lf.cu_die);
if (comp_dir) {
lr->comp_dir = strdup(comp_dir);
if (!lr->comp_dir)
ret = -ENOMEM;
}
}
pr_debug("path: %s\n", lr->path);
dwarf_end(dbg);
......
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