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Violators will be prosecuted for from ; Tue, 7 Mar 2017 03:50:14 +1000 Received: from d23relay08.au.ibm.com (d23relay08.au.ibm.com [9.185.71.33]) by d23dlp02.au.ibm.com (Postfix) with ESMTP id 39F4D2BB0045 for ; Tue, 7 Mar 2017 04:50:11 +1100 (EST) Received: from d23av03.au.ibm.com (d23av03.au.ibm.com [9.190.234.97]) by d23relay08.au.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v26Ho38F43843608 for ; Tue, 7 Mar 2017 04:50:11 +1100 Received: from d23av03.au.ibm.com (localhost [127.0.0.1]) by d23av03.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id v26Hnb1R008141 for ; Tue, 7 Mar 2017 04:49:37 +1100 From: "Naveen N. Rao" To: Masami Hiramatsu Cc: Arnaldo Carvalho de Melo , Steven Rostedt , Ingo Molnar , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Ananth N Mavinakayanahalli , Michael Ellerman Subject: Re: [PATCH v4 2/3] perf: kretprobes: offset from reloc_sym if kernel supports it Date: Mon, 6 Mar 2017 23:19:09 +0530 In-Reply-To: <20170304133405.176da43d40cec7cb00e757e1@kernel.org> References: <20170304133405.176da43d40cec7cb00e757e1@kernel.org> Message-Id: <20170306174909.12395-1-naveen.n.rao@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Masami, Your patch works, thanks! However, I felt we could refactor and reuse some of the code across kprobes.c for this purpose. Can you please see if the below patch is fine? Thanks, Naveen -- 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 --- include/linux/kprobes.h | 1 + kernel/kprobes.c | 40 ++++++++++++++++++++++++++-------------- kernel/trace/trace_kprobe.c | 2 +- 3 files changed, 28 insertions(+), 15 deletions(-) diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h index 862f87adcbb4..6888c9f29cb6 100644 --- a/include/linux/kprobes.h +++ b/include/linux/kprobes.h @@ -267,6 +267,7 @@ 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); diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 524766563896..49f870ea4070 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -1391,21 +1391,19 @@ bool within_kprobe_blacklist(unsigned long addr) * This returns encoded errors if it fails to look up symbol or invalid * combination of parameters. */ -static kprobe_opcode_t *kprobe_addr(struct kprobe *p) +static kprobe_opcode_t *_kprobe_addr(kprobe_opcode_t *addr, + const char *symbol_name, unsigned int offset) { - kprobe_opcode_t *addr = p->addr; - - if ((p->symbol_name && p->addr) || - (!p->symbol_name && !p->addr)) + if ((symbol_name && addr) || (!symbol_name && !addr)) goto invalid; - if (p->symbol_name) { - kprobe_lookup_name(p->symbol_name, addr); + if (symbol_name) { + kprobe_lookup_name(symbol_name, addr); if (!addr) return ERR_PTR(-ENOENT); } - addr = (kprobe_opcode_t *)(((char *)addr) + p->offset); + addr = (kprobe_opcode_t *)(((char *)addr) + offset); if (addr) return addr; @@ -1413,6 +1411,11 @@ static kprobe_opcode_t *kprobe_addr(struct kprobe *p) return ERR_PTR(-EINVAL); } +static kprobe_opcode_t *kprobe_addr(struct kprobe *p) +{ + return _kprobe_addr(p->addr, p->symbol_name, p->offset); +} + /* Check passed kprobe is valid and return kprobe in kprobe_table. */ static struct kprobe *__get_valid_kprobe(struct kprobe *p) { @@ -1874,19 +1877,28 @@ bool __weak arch_function_offset_within_entry(unsigned long offset) return !offset; } +bool function_offset_within_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset) +{ + kprobe_opcode_t *kp_addr = _kprobe_addr(addr, sym, offset); + + if (IS_ERR(kp_addr)) + return false; + + if (!kallsyms_lookup_size_offset((unsigned long)kp_addr, NULL, &offset) || + !arch_function_offset_within_entry(offset)) + return false; + + return true; +} + int register_kretprobe(struct kretprobe *rp) { int ret = 0; struct kretprobe_instance *inst; int i; void *addr; - unsigned long offset; - - addr = kprobe_addr(&rp->kp); - if (!kallsyms_lookup_size_offset((unsigned long)addr, NULL, &offset)) - return -EINVAL; - if (!arch_function_offset_within_entry(offset)) + if (!function_offset_within_entry(rp->kp.addr, rp->kp.symbol_name, rp->kp.offset)) return -EINVAL; if (kretprobe_blacklist_size) { diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index c60f9dc4610e..828ef31a1c27 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -695,7 +695,7 @@ static int create_trace_kprobe(int argc, char **argv) return ret; } if (offset && is_return && - !arch_function_offset_within_entry(offset)) { + !function_offset_within_entry(NULL, symbol, offset)) { pr_info("Given offset is not valid for return probe.\n"); return -EINVAL; } -- 2.11.1