Messages in this thread Patch in this message | | | From | He Kuang <> | Subject | [RFC PATCH v2 11/15] perf bpf: Synthesize vars to generate bpf prologue | Date | Sun, 24 May 2015 08:28:07 +0000 |
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After gethered all vars represented in trace_probe_arg, we can now use functions in libbpf to generate the args prologue.
Signed-off-by: He Kuang <hekuang@huawei.com> --- tools/perf/util/probe-finder.c | 83 +++++++++++++++++++++++++++++++++++++++++- 1 file changed, 81 insertions(+), 2 deletions(-)
diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c index 6785eab..455ff0f 100644 --- a/tools/perf/util/probe-finder.c +++ b/tools/perf/util/probe-finder.c @@ -1242,6 +1242,67 @@ end: return ret; } +/* + * Convert args to bpf prologue + * 1) First pass for calculating the new program length: + * synthesize_probe_bpf(arg, nargs, NULL, &new_len); + * + * 2) 2nd pass do the actually convert + * new_prog = malloc(sizeof(struct bpf_insn) * new_len); + * synthesize_probe_bpf(arg, nargs, new_prog, &new_len); + */ +static int synthesize_probe_bpf(struct probe_trace_arg *arg, + int nargs, + char *new_prog, + int *new_len) +{ + int i; + char *new_insn = new_prog; + + if (nargs == 0) { + *new_len = 0; + return 0; + } + + new_insn += bpf_prologue_begin(new_prog); + /* Find each argument */ + for (i = 0; i < nargs; i++) { + struct probe_trace_arg_ref *ref = arg[i].ref; + unsigned int regn = arg[i].regn; + + /* Print argument value */ + if (arg[i].value[0] == '@' && ref) { + /* TODO parse other arguments */ + pr_debug("%d%+ld", regn, ref->offset); + } else { + int depth = 0; + + new_insn += bpf_prologue_arg_deref( + get_arch_reg_offset(regn), + i + 1, + depth++, + new_prog ? new_insn : NULL, + !ref); + + while (ref) { + new_insn += bpf_prologue_arg_deref( + ref->offset, + i + 1, + depth++, + new_prog ? new_insn : NULL, + !ref->next); + ref = ref->next; + } + } + } + + new_insn += bpf_prologue_end(new_prog ? new_insn : NULL, + nargs); + *new_len = new_insn - new_prog; + + return 0; +} + /* Add a found probe point into trace event list */ static int add_probe_trace_event(Dwarf_Die *sc_die, struct probe_finder *pf) { @@ -1335,6 +1396,8 @@ int debuginfo__find_bpf_prologue(struct debuginfo *dbg, .pf = {.pev = pev, .callback = generate_bpf_prologue}, .mod = dbg->mod, .max_tevs = BPF_MAX_TEVS}; struct probe_trace_event *tevs; + struct probe_trace_event *tev; + char *new_prog; int ret; /* Allocate result tevs array */ @@ -1347,9 +1410,25 @@ int debuginfo__find_bpf_prologue(struct debuginfo *dbg, ret = debuginfo__find_probes(dbg, &tf.pf); - *result = NULL; - *count = 0; + tev = &tevs[0]; + + synthesize_probe_bpf(tev->args, tev->nargs, NULL, count); + if (*count == 0) + goto end; + + new_prog = malloc(*count); + if (!new_prog) { + ret = -ENOMEM; + goto end; + } + synthesize_probe_bpf(tev->args, tev->nargs, new_prog, count); + + /* assign result to tvar */ + *result = (char *)new_prog; + +end: + /* release tevs */ free(tevs); return ret; } -- 1.8.5.2
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