Process debuginfo for bpf prologue, the process function is copied and
modified from debuginfo__find_trace_events(), but use a different
callback function for generating bpf prologue bytecode.

Signed-off-by: He Kuang <heku...@huawei.com>
---
 tools/perf/util/probe-event.c  | 27 +++++++++++++
 tools/perf/util/probe-event.h  |  2 +
 tools/perf/util/probe-finder.c | 90 ++++++++++++++++++++++++++++++++++++++++++
 tools/perf/util/probe-finder.h |  4 ++
 4 files changed, 123 insertions(+)

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index c307cd7..fbdda4d 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -906,6 +906,33 @@ out:
        return ret;
 }
 
+int get_bpf_prologue(struct perf_probe_event *pev, char **result, int *count)
+{
+       int ret;
+       struct debuginfo *dinfo;
+       bool need_dwarf;
+
+       ret = init_symbol_maps(false);
+       if (ret < 0)
+               return ret;
+
+       need_dwarf = perf_probe_event_need_dwarf(pev);
+
+       dinfo = open_debuginfo(NULL, !need_dwarf);
+
+       if (!dinfo) {
+               if (need_dwarf)
+                       return -ENOENT;
+               pr_debug("Could not open debuginfo. Try to use symbols.\n");
+               return 0;
+       }
+
+       pr_debug("Try to generate bpf prologue from debuginfo.\n");
+
+       ret = debuginfo__find_bpf_prologue(dinfo, pev, result, count);
+
+       return ret;
+}
 #else  /* !HAVE_DWARF_SUPPORT */
 
 static int
diff --git a/tools/perf/util/probe-event.h b/tools/perf/util/probe-event.h
index 3b6c284..5a6b86e 100644
--- a/tools/perf/util/probe-event.h
+++ b/tools/perf/util/probe-event.h
@@ -115,6 +115,8 @@ extern int synthesize_probe_trace_arg_bpf(struct 
probe_trace_arg *arg,
 extern int synthesize_probe_trace_arg_bpf_begin(struct strbuf *buf);
 extern int synthesize_probe_trace_arg_bpf_end(struct probe_trace_arg *arg,
                                        struct strbuf *buf, int num);
+extern int get_bpf_prologue(struct perf_probe_event *pev,
+                       char **result, int *count);
 
 /* Check the perf_probe_event needs debuginfo */
 extern bool perf_probe_event_need_dwarf(struct perf_probe_event *pev);
diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 249e6cb..bfb7625 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -1164,6 +1164,71 @@ static int expand_probe_args(Dwarf_Die *sc_die, struct 
probe_finder *pf,
        return n;
 }
 
+#define BPF_PROLOGUE_MAX_LEN (1024)
+static int generate_bpf_prologue(Dwarf_Die *sc_die, struct probe_finder *pf)
+{
+       struct perf_probe_arg *args;
+       int ret = 0, i;
+       Dwarf_Die vr_die;
+       struct strbuf buf;
+       int narg;
+
+       if (pf->tvar)
+               return -ERANGE;
+
+       pf->tvar = (struct probe_trace_arg *)
+               malloc(sizeof(struct probe_trace_arg));
+       if (pf->tvar == NULL)
+               return -ENOMEM;
+
+       /* Expand special probe argument if exist */
+       args = zalloc(sizeof(struct perf_probe_arg) * MAX_PROBE_ARGS);
+       if (args == NULL)
+               return -ENOMEM;
+
+       narg = expand_probe_args(sc_die, pf, args);
+       if (narg <= 0)
+               goto end;
+
+       strbuf_init(&buf, BPF_PROLOGUE_MAX_LEN);
+       synthesize_probe_trace_arg_bpf_begin(&buf);
+
+       /* Find each argument */
+       for (i = 0; i < narg; i++) {
+               pf->pvar = &args[i];
+
+               memset(pf->tvar, 0, sizeof(struct probe_trace_arg));
+               /* Search child die for local variables and parameters. */
+               if (!die_find_variable_at(sc_die, pf->pvar->var,
+                                               pf->addr, &vr_die)) {
+                       /* Search again in global variables */
+                       if (!die_find_variable_at(&pf->cu_die, pf->pvar->var,
+                                                       0, &vr_die)) {
+                               pr_warning("Failed to find '%s' in this 
function.\n",
+                                       pf->pvar->var);
+                               ret = -ENOENT;
+                       }
+               }
+
+               if (ret >= 0)
+                       ret = convert_variable(&vr_die, pf);
+               if (ret != 0)
+                       break;
+
+               ret = synthesize_probe_trace_arg_bpf(pf->tvar, &buf, i);
+               if (ret)
+                       goto end;
+       }
+
+       synthesize_probe_trace_arg_bpf_end(pf->tvar, &buf, narg);
+
+       pr_debug("bpf_prologue: insn num=%d\n", pf->tvar->insns_cnt);
+
+end:
+       free(args);
+       return ret;
+}
+
 /* Add a found probe point into trace event list */
 static int add_probe_trace_event(Dwarf_Die *sc_die, struct probe_finder *pf)
 {
@@ -1248,6 +1313,31 @@ int debuginfo__find_trace_events(struct debuginfo *dbg,
        return (ret < 0) ? ret : tf.ntevs;
 }
 
+int debuginfo__find_bpf_prologue(struct debuginfo *dbg,
+                               struct perf_probe_event *pev,
+                               char **result, int *count)
+{
+       struct probe_finder pf = {.pev = pev,
+                                 .callback = generate_bpf_prologue};
+       int ret;
+
+       pf.tvar = NULL;
+       ret = debuginfo__find_probes(dbg, &pf);
+       if (ret == -ERANGE)
+               ret = 0;
+
+       if (pf.tvar) {
+               *result = pf.tvar->insns;
+               *count = pf.tvar->insns_cnt;
+               free(pf.tvar);
+       } else {
+               *result = NULL;
+               *count = 0;
+       }
+
+       return ret;
+}
+
 #define MAX_VAR_LEN 64
 
 /* Collect available variables in this scope */
diff --git a/tools/perf/util/probe-finder.h b/tools/perf/util/probe-finder.h
index ebf8c8c..28437978 100644
--- a/tools/perf/util/probe-finder.h
+++ b/tools/perf/util/probe-finder.h
@@ -40,6 +40,10 @@ extern int debuginfo__find_trace_events(struct debuginfo 
*dbg,
                                        struct probe_trace_event **tevs,
                                        int max_tevs);
 
+extern int debuginfo__find_bpf_prologue(struct debuginfo *dbg,
+                                       struct perf_probe_event *pev,
+                                       char **result, int *count);
+
 /* Find a perf_probe_point from debuginfo */
 extern int debuginfo__find_probe_point(struct debuginfo *dbg,
                                       unsigned long addr,
-- 
1.8.5.2

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