From 1d585e70905e03e8c19c9aaf523ec246ae6b18a1 Mon Sep 17 00:00:00 2001 From: "Naveen N. Rao" Date: Wed, 8 Mar 2017 13:56:06 +0530 Subject: trace/kprobes: Fix check for kretprobe offset within function entry perf specifies an offset from _text and since this offset is fed directly into the arch-specific helper, kprobes tracer rejects installation of kretprobes through perf. Fix this by looking up the actual offset from a function for the specified sym+offset. Refactor and reuse existing routines to limit code duplication -- we repurpose kprobe_addr() for determining final kprobe address and we split out the function entry offset determination into a separate generic helper. Before patch: naveen@ubuntu:~/linux/tools/perf$ sudo ./perf probe -v do_open%return probe-definition(0): do_open%return symbol:do_open file:(null) line:0 offset:0 return:1 lazy:(null) 0 arguments Looking at the vmlinux_path (8 entries long) Using /boot/vmlinux for symbols Open Debuginfo file: /boot/vmlinux Try to find probe point from debuginfo. Matched function: do_open [2d0c7ff] Probe point found: do_open+0 Matched function: do_open [35d76dc] found inline addr: 0xc0000000004ba9c4 Failed to find "do_open%return", because do_open is an inlined function and has no return point. An error occurred in debuginfo analysis (-22). Trying to use symbols. Opening /sys/kernel/debug/tracing//README write=0 Opening /sys/kernel/debug/tracing//kprobe_events write=1 Writing event: r:probe/do_open _text+4469776 Failed to write event: Invalid argument Error: Failed to add events. Reason: Invalid argument (Code: -22) naveen@ubuntu:~/linux/tools/perf$ dmesg | tail [ 33.568656] Given offset is not valid for return probe. After patch: naveen@ubuntu:~/linux/tools/perf$ sudo ./perf probe -v do_open%return probe-definition(0): do_open%return symbol:do_open file:(null) line:0 offset:0 return:1 lazy:(null) 0 arguments Looking at the vmlinux_path (8 entries long) Using /boot/vmlinux for symbols Open Debuginfo file: /boot/vmlinux Try to find probe point from debuginfo. Matched function: do_open [2d0c7d6] Probe point found: do_open+0 Matched function: do_open [35d76b3] found inline addr: 0xc0000000004ba9e4 Failed to find "do_open%return", because do_open is an inlined function and has no return point. An error occurred in debuginfo analysis (-22). Trying to use symbols. Opening /sys/kernel/debug/tracing//README write=0 Opening /sys/kernel/debug/tracing//kprobe_events write=1 Writing event: r:probe/do_open _text+4469808 Writing event: r:probe/do_open_1 _text+4956344 Added new events: probe:do_open (on do_open%return) probe:do_open_1 (on do_open%return) You can now use it in all perf tools, such as: perf record -e probe:do_open_1 -aR sleep 1 naveen@ubuntu:~/linux/tools/perf$ sudo cat /sys/kernel/debug/kprobes/list c000000000041370 k kretprobe_trampoline+0x0 [OPTIMIZED] c0000000004ba0b8 r do_open+0x8 [DISABLED] c000000000443430 r do_open+0x0 [DISABLED] 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/d8cd1ef420ec22e3643ac332fdabcffc77319a42.1488961018.git.naveen.n.rao@linux.vnet.ibm.com Signed-off-by: Arnaldo Carvalho de Melo --- include/linux/kprobes.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/kprobes.h') diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h index 177bdf6c6aeb..47e4da5b4fa2 100644 --- a/include/linux/kprobes.h +++ b/include/linux/kprobes.h @@ -268,6 +268,7 @@ extern void show_registers(struct pt_regs *regs); extern void kprobes_inc_nmissed_count(struct kprobe *p); extern bool arch_within_kprobe_blacklist(unsigned long addr); extern bool arch_function_offset_within_entry(unsigned long offset); +extern bool function_offset_within_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset); extern bool within_kprobe_blacklist(unsigned long addr); -- cgit