From a34a985499895a46a4dacff727d0fbc63cdc75e8 Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Mon, 12 Apr 2010 13:17:29 -0400 Subject: [PATCH] perf probe: Support DW_OP_call_frame_cfa in debuginfo When building kernel without CONFIG_FRAME_POINTER, gcc uses CFA (canonical frame address) for frame base. With this patch, perf probe just gets CFI (call frame information) from debuginfo and search corresponding CFA from the CFI. IOW, this allows perf probe works correctly on the kernel without CONFIG_FRAME_POINTER. ./perf probe -fn sched_slice:12 lw.weight Fatal: DW_OP 156 is not supported. (^^^ DW_OP_call_frame_cfa) ./perf probe -fn sched_slice:12 lw.weight Add new event: probe:sched_slice (on sched_slice:12 with weight=lw.weight) Cc: Ingo Molnar Cc: Paul Mackerras Cc: Peter Zijlstra Cc: Mike Galbraith Cc: Frederic Weisbecker LKML-Reference: <20100412171728.3790.98217.stgit@localhost6.localdomain6> Signed-off-by: Masami Hiramatsu Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/probe-finder.c | 14 +++++++++++--- tools/perf/util/probe-finder.h | 1 + 2 files changed, 12 insertions(+), 3 deletions(-) diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c index ab476736cbe..1f4528555d4 100644 --- a/tools/perf/util/probe-finder.c +++ b/tools/perf/util/probe-finder.c @@ -398,7 +398,6 @@ static void convert_location(Dwarf_Op *op, struct probe_finder *pf) const char *regs; struct kprobe_trace_arg *tvar = pf->tvar; - /* TODO: support CFA */ /* If this is based on frame buffer, set the offset */ if (op->atom == DW_OP_fbreg) { if (pf->fb_ops == NULL) @@ -629,11 +628,17 @@ static void convert_probe_point(Dwarf_Die *sp_die, struct probe_finder *pf) /* Get the frame base attribute/ops */ dwarf_attr(sp_die, DW_AT_frame_base, &fb_attr); ret = dwarf_getlocation_addr(&fb_attr, pf->addr, &pf->fb_ops, &nops, 1); - if (ret <= 0 || nops == 0) + if (ret <= 0 || nops == 0) { pf->fb_ops = NULL; + } else if (nops == 1 && pf->fb_ops[0].atom == DW_OP_call_frame_cfa && + pf->cfi != NULL) { + Dwarf_Frame *frame; + ret = dwarf_cfi_addrframe(pf->cfi, pf->addr, &frame); + DIE_IF(ret != 0); + dwarf_frame_cfa(frame, &pf->fb_ops, &nops); + } /* Find each argument */ - /* TODO: use dwarf_cfi_addrframe */ tev->nargs = pf->pev->nargs; tev->args = xzalloc(sizeof(struct kprobe_trace_arg) * tev->nargs); for (i = 0; i < pf->pev->nargs; i++) { @@ -842,6 +847,9 @@ int find_kprobe_trace_events(int fd, struct perf_probe_event *pev, if (!dbg) return -ENOENT; + /* Get the call frame information from this dwarf */ + pf.cfi = dwarf_getcfi(dbg); + off = 0; line_list__init(&pf.lcache); /* Loop on CUs (Compilation Unit) */ diff --git a/tools/perf/util/probe-finder.h b/tools/perf/util/probe-finder.h index 2a271321944..310ce897229 100644 --- a/tools/perf/util/probe-finder.h +++ b/tools/perf/util/probe-finder.h @@ -42,6 +42,7 @@ struct probe_finder { struct list_head lcache; /* Line cache for lazy match */ /* For variable searching */ + Dwarf_CFI *cfi; /* Call Frame Information */ Dwarf_Op *fb_ops; /* Frame base attribute */ struct perf_probe_arg *pvar; /* Current target variable */ struct kprobe_trace_arg *tvar; /* Current result variable */