Messages in this thread Patch in this message | | | From | He Kuang <> | Subject | [RFC PATCH v2 12/15] perf bpf: Generate bpf prologue without debuginfo | Date | Sun, 24 May 2015 08:28:08 +0000 |
| |
When probing at function entry, fallback to generate bpf prologue by calling args if '$param' is the only args and no debuginfo is provided.
Signed-off-by: He Kuang <hekuang@huawei.com> --- tools/perf/util/probe-event.c | 54 ++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 53 insertions(+), 1 deletion(-)
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c index ccbf4d9..0de5879 100644 --- a/tools/perf/util/probe-event.c +++ b/tools/perf/util/probe-event.c @@ -46,6 +46,7 @@ #include "probe-event.h" #include "probe-finder.h" #include "session.h" +#include <bpf/libbpf.h> #include <dwarf-regs.h> #define MAX_CMDLEN 256 @@ -287,6 +288,45 @@ static void clear_probe_trace_events(struct probe_trace_event *tevs, int ntevs) clear_probe_trace_event(tevs + i); } +static int convert_parameters_to_bpf_prologue(char *new_prog, int *new_len) +{ + char *new_insn = new_prog; + int i; + int offset; + + /* Find each argument */ + for (i = 0; i < BPF_PROLOGUE_NRARGS_MAX; i++) { + offset = get_arch_calling_reg_offset(i); + if (offset < 0) + break; + + new_insn += bpf_prologue_formal_parameters( + new_prog ? new_insn : NULL, + offset, i); + } + *new_len = new_insn - new_prog; + + return 0; +} + +static int get_bpf_prologue_default(char **result, int *count) +{ + char *new_prog; + + convert_parameters_to_bpf_prologue(NULL, count); + if (*count == 0) + return 0; + + new_prog = malloc(*count); + if (!new_prog) + return -ENOMEM; + + convert_parameters_to_bpf_prologue(new_prog, count); + *result = (char *)new_prog; + + return 0; +} + static bool perf_probe_is_function_entry(struct perf_probe_event *pev) { if (pev->point.file || pev->point.line || pev->point.lazy_line) @@ -931,7 +971,13 @@ int get_bpf_prologue(struct perf_probe_event *pev, char **result, int *count) if (!dinfo) { if (need_dwarf) return -ENOENT; - pr_debug("Could not open debuginfo. Try to use symbols.\n"); + pr_debug("Could not open debuginfo. Generate default prologue.\n"); + + if (perf_probe_is_function_entry(pev) && + pev->nargs == 1 && + !strcmp(pev->args[0].var, "$params")) + return get_bpf_prologue_default(result, count); + return 0; } @@ -943,6 +989,12 @@ int get_bpf_prologue(struct perf_probe_event *pev, char **result, int *count) } #else /* !HAVE_DWARF_SUPPORT */ +int get_bpf_prologue(struct perf_probe_event *pev __maybe_unused, + char **result, int *count) +{ + return -ENOTSUP; +} + static int find_perf_probe_point_from_dwarf(struct probe_trace_point *tp __maybe_unused, struct perf_probe_point *pp __maybe_unused, -- 1.8.5.2
| |