From 35b6f55aa9ba65141f2def0997e23aab13715d3f Mon Sep 17 00:00:00 2001 From: "Naveen N. Rao" Date: Wed, 22 Feb 2017 19:23:39 +0530 Subject: [PATCH] trace/kprobes: Allow return probes with offsets and absolute addresses Since the kernel includes many non-global functions with same names, we will need to use offsets from other symbols (typically _text/_stext) or absolute addresses to place return probes on specific functions. Also, the core register_kretprobe() API never forbid use of offsets or absolute addresses with kretprobes. Allow its use with the trace infrastructure. To distinguish kernels that support this, update ftrace README to explicitly call this out. Signed-off-by: Naveen N. Rao Acked-by: Masami Hiramatsu Cc: Ananth N Mavinakayanahalli Cc: Michael Ellerman Cc: Steven Rostedt Cc: linuxppc-dev@lists.ozlabs.org Link: http://lkml.kernel.org/r/183e7ce2921a08c9c755ee9a5da3134febc6695b.1487770934.git.naveen.n.rao@linux.vnet.ibm.com Signed-off-by: Arnaldo Carvalho de Melo --- kernel/trace/trace.c | 1 + kernel/trace/trace_kprobe.c | 8 -------- 2 files changed, 1 insertion(+), 8 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index f35109514a01..0ed834d6beb0 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4355,6 +4355,7 @@ static const char readme_msg[] = "\t -:[/]\n" #ifdef CONFIG_KPROBE_EVENTS "\t place: [:][+]|\n" + "place (kretprobe): [:][+]|\n" #endif #ifdef CONFIG_UPROBE_EVENTS "\t place: :\n" diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index eadd96ef772f..18775ef182f8 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -680,10 +680,6 @@ static int create_trace_kprobe(int argc, char **argv) return -EINVAL; } if (isdigit(argv[1][0])) { - if (is_return) { - pr_info("Return probe point must be a symbol.\n"); - return -EINVAL; - } /* an address specified */ ret = kstrtoul(&argv[1][0], 0, (unsigned long *)&addr); if (ret) { @@ -699,10 +695,6 @@ static int create_trace_kprobe(int argc, char **argv) pr_info("Failed to parse symbol.\n"); return ret; } - if (offset && is_return) { - pr_info("Return probe must be used without offset.\n"); - return -EINVAL; - } } argc -= 2; argv += 2; -- 2.20.1