[PATCH 18/20] perf probe: Introduce debuginfo to encapsulate dwarf information

From: Steven Rostedt
Date: Sat Jul 16 2011 - 07:24:00 EST

From: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>

Introduce debuginfo to encapsulate dwarf information.
This new object allows us to reuse and expand debuginfo easily.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/20110627072739.6528.12438.stgit@fedora15
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
---
tools/perf/util/probe-event.c | 78 ++++++++++------
tools/perf/util/probe-finder.c | 201 +++++++++++++++++++++-------------------
tools/perf/util/probe-finder.h | 39 ++++++--
3 files changed, 182 insertions(+), 136 deletions(-)

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index f022316..920c195 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -170,16 +170,17 @@ const char *kernel_get_module_path(const char *module)
}

#ifdef DWARF_SUPPORT
-static int open_vmlinux(const char *module)
+/* Open new debuginfo of given module */
+static struct debuginfo *open_debuginfo(const char *module)
{
const char *path = kernel_get_module_path(module);
+
if (!path) {
pr_err("Failed to find path of %s module.\n",
module ?: "kernel");
- return -ENOENT;
+ return NULL;
}
- pr_debug("Try to open %s\n", path);
- return open(path, O_RDONLY);
+ return debuginfo__new(path);
}

/*
@@ -193,13 +194,24 @@ static int kprobe_convert_to_perf_probe(struct probe_trace_point *tp,
struct map *map;
u64 addr;
int ret = -ENOENT;
+ struct debuginfo *dinfo;

sym = __find_kernel_function_by_name(tp->symbol, &map);
if (sym) {
addr = map->unmap_ip(map, sym->start + tp->offset);
pr_debug("try to find %s+%ld@%" PRIx64 "\n", tp->symbol,
tp->offset, addr);
- ret = find_perf_probe_point((unsigned long)addr, pp);
+
+ dinfo = debuginfo__new_online_kernel(addr);
+ if (dinfo) {
+ ret = debuginfo__find_probe_point(dinfo,
+ (unsigned long)addr, pp);
+ debuginfo__delete(dinfo);
+ } else {
+ pr_debug("Failed to open debuginfo at 0x%" PRIx64 "\n",
+ addr);
+ ret = -ENOENT;
+ }
}
if (ret <= 0) {
pr_debug("Failed to find corresponding probes from "
@@ -220,20 +232,22 @@ static int try_to_find_probe_trace_events(struct perf_probe_event *pev,
int max_tevs, const char *module)
{
bool need_dwarf = perf_probe_event_need_dwarf(pev);
- int fd, ntevs;
+ struct debuginfo *dinfo = open_debuginfo(module);
+ int ntevs;

- fd = open_vmlinux(module);
- if (fd < 0) {
+ if (!dinfo) {
if (need_dwarf) {
pr_warning("Failed to open debuginfo file.\n");
- return fd;
+ return -ENOENT;
}
- pr_debug("Could not open vmlinux. Try to use symbols.\n");
+ pr_debug("Could not open debuginfo. Try to use symbols.\n");
return 0;
}

- /* Searching trace events corresponding to probe event */
- ntevs = find_probe_trace_events(fd, pev, tevs, max_tevs);
+ /* Searching trace events corresponding to a probe event */
+ ntevs = debuginfo__find_trace_events(dinfo, pev, tevs, max_tevs);
+
+ debuginfo__delete(dinfo);

if (ntevs > 0) { /* Succeeded to find trace events */
pr_debug("find %d probe_trace_events.\n", ntevs);
@@ -371,8 +385,9 @@ int show_line_range(struct line_range *lr, const char *module)
{
int l = 1;
struct line_node *ln;
+ struct debuginfo *dinfo;
FILE *fp;
- int fd, ret;
+ int ret;
char *tmp;

/* Search a line range */
@@ -380,13 +395,14 @@ int show_line_range(struct line_range *lr, const char *module)
if (ret < 0)
return ret;

- fd = open_vmlinux(module);
- if (fd < 0) {
+ dinfo = open_debuginfo(module);
+ if (!dinfo) {
pr_warning("Failed to open debuginfo file.\n");
- return fd;
+ return -ENOENT;
}

- ret = find_line_range(fd, lr);
+ ret = debuginfo__find_line_range(dinfo, lr);
+ debuginfo__delete(dinfo);
if (ret == 0) {
pr_warning("Specified source line is not found.\n");
return -ENOENT;
@@ -448,7 +464,8 @@ end:
return ret;
}

-static int show_available_vars_at(int fd, struct perf_probe_event *pev,
+static int show_available_vars_at(struct debuginfo *dinfo,
+ struct perf_probe_event *pev,
int max_vls, struct strfilter *_filter,
bool externs)
{
@@ -463,7 +480,8 @@ static int show_available_vars_at(int fd, struct perf_probe_event *pev,
return -EINVAL;
pr_debug("Searching variables at %s\n", buf);

- ret = find_available_vars_at(fd, pev, &vls, max_vls, externs);
+ ret = debuginfo__find_available_vars_at(dinfo, pev, &vls,
+ max_vls, externs);
if (ret <= 0) {
pr_err("Failed to find variables at %s (%d)\n", buf, ret);
goto end;
@@ -504,24 +522,26 @@ int show_available_vars(struct perf_probe_event *pevs, int npevs,
int max_vls, const char *module,
struct strfilter *_filter, bool externs)
{
- int i, fd, ret = 0;
+ int i, ret = 0;
+ struct debuginfo *dinfo;

ret = init_vmlinux();
if (ret < 0)
return ret;

+ dinfo = open_debuginfo(module);
+ if (!dinfo) {
+ pr_warning("Failed to open debuginfo file.\n");
+ return -ENOENT;
+ }
+
setup_pager();

- for (i = 0; i < npevs && ret >= 0; i++) {
- fd = open_vmlinux(module);
- if (fd < 0) {
- pr_warning("Failed to open debug information file.\n");
- ret = fd;
- break;
- }
- ret = show_available_vars_at(fd, &pevs[i], max_vls, _filter,
+ for (i = 0; i < npevs && ret >= 0; i++)
+ ret = show_available_vars_at(dinfo, &pevs[i], max_vls, _filter,
externs);
- }
+
+ debuginfo__delete(dinfo);
return ret;
}

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 53d219b..3e44a3e 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -116,29 +116,37 @@ static const Dwfl_Callbacks offline_callbacks = {
};

/* Get a Dwarf from offline image */
-static Dwarf *dwfl_init_offline_dwarf(int fd, Dwfl **dwflp, Dwarf_Addr *bias)
+static int debuginfo__init_offline_dwarf(struct debuginfo *self,
+ const char *path)
{
Dwfl_Module *mod;
- Dwarf *dbg = NULL;
+ int fd;

- if (!dwflp)
- return NULL;
+ fd = open(path, O_RDONLY);
+ if (fd < 0)
+ return fd;

- *dwflp = dwfl_begin(&offline_callbacks);
- if (!*dwflp)
- return NULL;
+ self->dwfl = dwfl_begin(&offline_callbacks);
+ if (!self->dwfl)
+ goto error;

- mod = dwfl_report_offline(*dwflp, "", "", fd);
+ mod = dwfl_report_offline(self->dwfl, "", "", fd);
if (!mod)
goto error;

- dbg = dwfl_module_getdwarf(mod, bias);
- if (!dbg) {
+ self->dbg = dwfl_module_getdwarf(mod, &self->bias);
+ if (!self->dbg)
+ goto error;
+
+ return 0;
error:
- dwfl_end(*dwflp);
- *dwflp = NULL;
- }
- return dbg;
+ if (self->dwfl)
+ dwfl_end(self->dwfl);
+ else
+ close(fd);
+ memset(self, 0, sizeof(*self));
+
+ return -ENOENT;
}

#if _ELFUTILS_PREREQ(0, 148)
@@ -174,53 +182,82 @@ static const Dwfl_Callbacks kernel_callbacks = {
};

/* Get a Dwarf from live kernel image */
-static Dwarf *dwfl_init_live_kernel_dwarf(Dwarf_Addr addr, Dwfl **dwflp,
- Dwarf_Addr *bias)
+static int debuginfo__init_online_kernel_dwarf(struct debuginfo *self,
+ Dwarf_Addr addr)
{
- Dwarf *dbg;
-
- if (!dwflp)
- return NULL;
-
- *dwflp = dwfl_begin(&kernel_callbacks);
- if (!*dwflp)
- return NULL;
+ self->dwfl = dwfl_begin(&kernel_callbacks);
+ if (!self->dwfl)
+ return -EINVAL;

/* Load the kernel dwarves: Don't care the result here */
- dwfl_linux_kernel_report_kernel(*dwflp);
- dwfl_linux_kernel_report_modules(*dwflp);
+ dwfl_linux_kernel_report_kernel(self->dwfl);
+ dwfl_linux_kernel_report_modules(self->dwfl);

- dbg = dwfl_addrdwarf(*dwflp, addr, bias);
+ self->dbg = dwfl_addrdwarf(self->dwfl, addr, &self->bias);
/* Here, check whether we could get a real dwarf */
- if (!dbg) {
+ if (!self->dbg) {
pr_debug("Failed to find kernel dwarf at %lx\n",
(unsigned long)addr);
- dwfl_end(*dwflp);
- *dwflp = NULL;
+ dwfl_end(self->dwfl);
+ memset(self, 0, sizeof(*self));
+ return -ENOENT;
}
- return dbg;
+
+ return 0;
}
#else
/* With older elfutils, this just support kernel module... */
-static Dwarf *dwfl_init_live_kernel_dwarf(Dwarf_Addr addr __used, Dwfl **dwflp,
- Dwarf_Addr *bias)
+static int debuginfo__init_online_kernel_dwarf(struct debuginfo *self,
+ Dwarf_Addr addr __used)
{
- int fd;
const char *path = kernel_get_module_path("kernel");

if (!path) {
pr_err("Failed to find vmlinux path\n");
- return NULL;
+ return -ENOENT;
}

pr_debug2("Use file %s for debuginfo\n", path);
- fd = open(path, O_RDONLY);
- if (fd < 0)
+ return debuginfo__init_offline_dwarf(self, path);
+}
+#endif
+
+struct debuginfo *debuginfo__new(const char *path)
+{
+ struct debuginfo *self = zalloc(sizeof(struct debuginfo));
+ if (!self)
return NULL;

- return dwfl_init_offline_dwarf(fd, dwflp, bias);
+ if (debuginfo__init_offline_dwarf(self, path) < 0) {
+ free(self);
+ self = NULL;
+ }
+
+ return self;
+}
+
+struct debuginfo *debuginfo__new_online_kernel(unsigned long addr)
+{
+ struct debuginfo *self = zalloc(sizeof(struct debuginfo));
+ if (!self)
+ return NULL;
+
+ if (debuginfo__init_online_kernel_dwarf(self, (Dwarf_Addr)addr) < 0) {
+ free(self);
+ self = NULL;
+ }
+
+ return self;
+}
+
+void debuginfo__delete(struct debuginfo *self)
+{
+ if (self) {
+ if (self->dwfl)
+ dwfl_end(self->dwfl);
+ free(self);
+ }
}
-#endif

/*
* Probe finder related functions
@@ -949,28 +986,18 @@ static int pubname_search_cb(Dwarf *dbg, Dwarf_Global *gl, void *data)
}

/* Find probe points from debuginfo */
-static int find_probes(int fd, struct probe_finder *pf)
+static int debuginfo__find_probes(struct debuginfo *self,
+ struct probe_finder *pf)
{
struct perf_probe_point *pp = &pf->pev->point;
Dwarf_Off off, noff;
size_t cuhl;
Dwarf_Die *diep;
- Dwarf *dbg = NULL;
- Dwfl *dwfl;
- Dwarf_Addr bias; /* Currently ignored */
int ret = 0;

- dbg = dwfl_init_offline_dwarf(fd, &dwfl, &bias);
- if (!dbg) {
- pr_warning("No debug information found in the vmlinux - "
- "please rebuild with CONFIG_DEBUG_INFO=y.\n");
- close(fd); /* Without dwfl_end(), fd isn't closed. */
- return -EBADF;
- }
-
#if _ELFUTILS_PREREQ(0, 142)
/* Get the call frame information from this dwarf */
- pf->cfi = dwarf_getcfi(dbg);
+ pf->cfi = dwarf_getcfi(self->dbg);
#endif

off = 0;
@@ -989,7 +1016,8 @@ static int find_probes(int fd, struct probe_finder *pf)
.data = pf,
};

- dwarf_getpubnames(dbg, pubname_search_cb, &pubname_param, 0);
+ dwarf_getpubnames(self->dbg, pubname_search_cb,
+ &pubname_param, 0);
if (pubname_param.found) {
ret = probe_point_search_cb(&pf->sp_die, &probe_param);
if (ret)
@@ -998,9 +1026,9 @@ static int find_probes(int fd, struct probe_finder *pf)
}

/* Loop on CUs (Compilation Unit) */
- while (!dwarf_nextcu(dbg, off, &noff, &cuhl, NULL, NULL, NULL)) {
+ while (!dwarf_nextcu(self->dbg, off, &noff, &cuhl, NULL, NULL, NULL)) {
/* Get the DIE(Debugging Information Entry) of this CU */
- diep = dwarf_offdie(dbg, off + cuhl, &pf->cu_die);
+ diep = dwarf_offdie(self->dbg, off + cuhl, &pf->cu_die);
if (!diep)
continue;

@@ -1027,8 +1055,6 @@ static int find_probes(int fd, struct probe_finder *pf)

found:
line_list__free(&pf->lcache);
- if (dwfl)
- dwfl_end(dwfl);

return ret;
}
@@ -1074,8 +1100,9 @@ static int add_probe_trace_event(Dwarf_Die *sp_die, struct probe_finder *pf)
}

/* Find probe_trace_events specified by perf_probe_event from debuginfo */
-int find_probe_trace_events(int fd, struct perf_probe_event *pev,
- struct probe_trace_event **tevs, int max_tevs)
+int debuginfo__find_trace_events(struct debuginfo *self,
+ struct perf_probe_event *pev,
+ struct probe_trace_event **tevs, int max_tevs)
{
struct trace_event_finder tf = {
.pf = {.pev = pev, .callback = add_probe_trace_event},
@@ -1090,7 +1117,7 @@ int find_probe_trace_events(int fd, struct perf_probe_event *pev,
tf.tevs = *tevs;
tf.ntevs = 0;

- ret = find_probes(fd, &tf.pf);
+ ret = debuginfo__find_probes(self, &tf.pf);
if (ret < 0) {
free(*tevs);
*tevs = NULL;
@@ -1184,9 +1211,10 @@ out:
}

/* Find available variables at given probe point */
-int find_available_vars_at(int fd, struct perf_probe_event *pev,
- struct variable_list **vls, int max_vls,
- bool externs)
+int debuginfo__find_available_vars_at(struct debuginfo *self,
+ struct perf_probe_event *pev,
+ struct variable_list **vls,
+ int max_vls, bool externs)
{
struct available_var_finder af = {
.pf = {.pev = pev, .callback = add_available_vars},
@@ -1201,7 +1229,7 @@ int find_available_vars_at(int fd, struct perf_probe_event *pev,
af.vls = *vls;
af.nvls = 0;

- ret = find_probes(fd, &af.pf);
+ ret = debuginfo__find_probes(self, &af.pf);
if (ret < 0) {
/* Free vlist for error */
while (af.nvls--) {
@@ -1219,28 +1247,19 @@ int find_available_vars_at(int fd, struct perf_probe_event *pev,
}

/* Reverse search */
-int find_perf_probe_point(unsigned long addr, struct perf_probe_point *ppt)
+int debuginfo__find_probe_point(struct debuginfo *self, unsigned long addr,
+ struct perf_probe_point *ppt)
{
Dwarf_Die cudie, spdie, indie;
- Dwarf *dbg = NULL;
- Dwfl *dwfl = NULL;
- Dwarf_Addr _addr, baseaddr, bias = 0;
+ Dwarf_Addr _addr, baseaddr;
const char *fname = NULL, *func = NULL, *tmp;
int baseline = 0, lineno = 0, ret = 0;

- /* Open the live linux kernel */
- dbg = dwfl_init_live_kernel_dwarf(addr, &dwfl, &bias);
- if (!dbg) {
- pr_warning("No debug information found in the vmlinux - "
- "please rebuild with CONFIG_DEBUG_INFO=y.\n");
- ret = -EINVAL;
- goto end;
- }
-
/* Adjust address with bias */
- addr += bias;
+ addr += self->bias;
+
/* Find cu die */
- if (!dwarf_addrdie(dbg, (Dwarf_Addr)addr - bias, &cudie)) {
+ if (!dwarf_addrdie(self->dbg, (Dwarf_Addr)addr - self->bias, &cudie)) {
pr_warning("Failed to find debug information for address %lx\n",
addr);
ret = -EINVAL;
@@ -1316,8 +1335,6 @@ post:
}
}
end:
- if (dwfl)
- dwfl_end(dwfl);
if (ret == 0 && (fname || func))
ret = 1; /* Found a point */
return ret;
@@ -1427,26 +1444,15 @@ static int find_line_range_by_func(struct line_finder *lf)
return param.retval;
}

-int find_line_range(int fd, struct line_range *lr)
+int debuginfo__find_line_range(struct debuginfo *self, struct line_range *lr)
{
struct line_finder lf = {.lr = lr, .found = 0};
int ret = 0;
Dwarf_Off off = 0, noff;
size_t cuhl;
Dwarf_Die *diep;
- Dwarf *dbg = NULL;
- Dwfl *dwfl;
- Dwarf_Addr bias; /* Currently ignored */
const char *comp_dir;

- dbg = dwfl_init_offline_dwarf(fd, &dwfl, &bias);
- if (!dbg) {
- pr_warning("No debug information found in the vmlinux - "
- "please rebuild with CONFIG_DEBUG_INFO=y.\n");
- close(fd); /* Without dwfl_end(), fd isn't closed. */
- return -EBADF;
- }
-
/* Fastpath: lookup by function name from .debug_pubnames section */
if (lr->function) {
struct pubname_callback_param pubname_param = {
@@ -1455,7 +1461,8 @@ int find_line_range(int fd, struct line_range *lr)
struct dwarf_callback_param line_range_param = {
.data = (void *)&lf, .retval = 0};

- dwarf_getpubnames(dbg, pubname_search_cb, &pubname_param, 0);
+ dwarf_getpubnames(self->dbg, pubname_search_cb,
+ &pubname_param, 0);
if (pubname_param.found) {
line_range_search_cb(&lf.sp_die, &line_range_param);
if (lf.found)
@@ -1465,11 +1472,12 @@ int find_line_range(int fd, struct line_range *lr)

/* Loop on CUs (Compilation Unit) */
while (!lf.found && ret >= 0) {
- if (dwarf_nextcu(dbg, off, &noff, &cuhl, NULL, NULL, NULL) != 0)
+ if (dwarf_nextcu(self->dbg, off, &noff, &cuhl,
+ NULL, NULL, NULL) != 0)
break;

/* Get the DIE(Debugging Information Entry) of this CU */
- diep = dwarf_offdie(dbg, off + cuhl, &lf.cu_die);
+ diep = dwarf_offdie(self->dbg, off + cuhl, &lf.cu_die);
if (!diep)
continue;

@@ -1503,7 +1511,6 @@ found:
}

pr_debug("path: %s\n", lr->path);
- dwfl_end(dwfl);
return (ret < 0) ? ret : lf.found;
}

diff --git a/tools/perf/util/probe-finder.h b/tools/perf/util/probe-finder.h
index 0f1ed3d..c478b42 100644
--- a/tools/perf/util/probe-finder.h
+++ b/tools/perf/util/probe-finder.h
@@ -16,23 +16,42 @@ static inline int is_c_varname(const char *name)
}

#ifdef DWARF_SUPPORT
+
+#include "dwarf-aux.h"
+
+/* TODO: export debuginfo data structure even if no dwarf support */
+
+/* debug information structure */
+struct debuginfo {
+ Dwarf *dbg;
+ Dwfl *dwfl;
+ Dwarf_Addr bias;
+};
+
+extern struct debuginfo *debuginfo__new(const char *path);
+extern struct debuginfo *debuginfo__new_online_kernel(unsigned long addr);
+extern void debuginfo__delete(struct debuginfo *self);
+
/* Find probe_trace_events specified by perf_probe_event from debuginfo */
-extern int find_probe_trace_events(int fd, struct perf_probe_event *pev,
- struct probe_trace_event **tevs,
- int max_tevs);
+extern int debuginfo__find_trace_events(struct debuginfo *self,
+ struct perf_probe_event *pev,
+ struct probe_trace_event **tevs,
+ int max_tevs);

/* Find a perf_probe_point from debuginfo */
-extern int find_perf_probe_point(unsigned long addr,
- struct perf_probe_point *ppt);
+extern int debuginfo__find_probe_point(struct debuginfo *self,
+ unsigned long addr,
+ struct perf_probe_point *ppt);

/* Find a line range */
-extern int find_line_range(int fd, struct line_range *lr);
+extern int debuginfo__find_line_range(struct debuginfo *self,
+ struct line_range *lr);

/* Find available variables */
-extern int find_available_vars_at(int fd, struct perf_probe_event *pev,
- struct variable_list **vls, int max_points,
- bool externs);
-#include "dwarf-aux.h"
+extern int debuginfo__find_available_vars_at(struct debuginfo *self,
+ struct perf_probe_event *pev,
+ struct variable_list **vls,
+ int max_points, bool externs);

struct probe_finder {
struct perf_probe_event *pev; /* Target probe event */
--
1.7.5.4


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