perf probe: Introduce debuginfo to encapsulate dwarf information

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@hitachi.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Link: http://lkml.kernel.org/r/20110627072739.6528.12438.stgit@fedora15
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

3 files changed, 182 insertions, 136 deletions

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index f0223166e761..920c1957d6d3 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 53d219bddb48..3e44a3e36519 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 0f1ed3d25a20..c478b42a2473 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 */