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[213.175.37.12]) by smtp.gmail.com with ESMTPSA id b14sm1459488wri.112.2022.01.06.00.30.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 06 Jan 2022 00:30:47 -0800 (PST) Date: Thu, 6 Jan 2022 09:30:45 +0100 From: Jiri Olsa To: Masami Hiramatsu Cc: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , netdev@vger.kernel.org, bpf@vger.kernel.org, lkml , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Steven Rostedt , "Naveen N. Rao" , Anil S Keshavamurthy , "David S. Miller" Subject: Re: [PATCH 02/13] kprobe: Keep traced function address Message-ID: References: <20220104080943.113249-1-jolsa@kernel.org> <20220104080943.113249-3-jolsa@kernel.org> <20220105233252.2bc92d14c42827328109d9d0@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220105233252.2bc92d14c42827328109d9d0@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 05, 2022 at 11:32:52PM +0900, Masami Hiramatsu wrote: > On Tue, 4 Jan 2022 09:09:32 +0100 > Jiri Olsa wrote: > > > The bpf_get_func_ip_kprobe helper should return traced function > > address, but it's doing so only for kprobes that are placed on > > the function entry. > > > > If kprobe is placed within the function, bpf_get_func_ip_kprobe > > returns that address instead of function entry. > > > > Storing the function entry directly in kprobe object, so it could > > be used in bpf_get_func_ip_kprobe helper. > > Hmm, please do this in bpf side, which should have some data structure > around the kprobe itself. Do not add this "specialized" field to > the kprobe data structure. ok, will check thanks, jirka > > Thank you, > > > > > Signed-off-by: Jiri Olsa > > --- > > include/linux/kprobes.h | 3 +++ > > kernel/kprobes.c | 12 ++++++++++++ > > kernel/trace/bpf_trace.c | 2 +- > > tools/testing/selftests/bpf/progs/get_func_ip_test.c | 4 ++-- > > 4 files changed, 18 insertions(+), 3 deletions(-) > > > > diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h > > index 8c8f7a4d93af..a204df4fef96 100644 > > --- a/include/linux/kprobes.h > > +++ b/include/linux/kprobes.h > > @@ -74,6 +74,9 @@ struct kprobe { > > /* Offset into the symbol */ > > unsigned int offset; > > > > + /* traced function address */ > > + unsigned long func_addr; > > + > > /* Called before addr is executed. */ > > kprobe_pre_handler_t pre_handler; > > > > diff --git a/kernel/kprobes.c b/kernel/kprobes.c > > index d20ae8232835..c4060a8da050 100644 > > --- a/kernel/kprobes.c > > +++ b/kernel/kprobes.c > > @@ -1310,6 +1310,7 @@ static void init_aggr_kprobe(struct kprobe *ap, struct kprobe *p) > > copy_kprobe(p, ap); > > flush_insn_slot(ap); > > ap->addr = p->addr; > > + ap->func_addr = p->func_addr; > > ap->flags = p->flags & ~KPROBE_FLAG_OPTIMIZED; > > ap->pre_handler = aggr_pre_handler; > > /* We don't care the kprobe which has gone. */ > > @@ -1588,6 +1589,16 @@ static int check_kprobe_address_safe(struct kprobe *p, > > return ret; > > } > > > > +static unsigned long resolve_func_addr(kprobe_opcode_t *addr) > > +{ > > + char str[KSYM_SYMBOL_LEN]; > > + unsigned long offset; > > + > > + if (kallsyms_lookup((unsigned long) addr, NULL, &offset, NULL, str)) > > + return (unsigned long) addr - offset; > > + return 0; > > +} > > + > > int register_kprobe(struct kprobe *p) > > { > > int ret; > > @@ -1600,6 +1611,7 @@ int register_kprobe(struct kprobe *p) > > if (IS_ERR(addr)) > > return PTR_ERR(addr); > > p->addr = addr; > > + p->func_addr = resolve_func_addr(addr); > > > > ret = warn_kprobe_rereg(p); > > if (ret) > > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c > > index 21aa30644219..25631253084a 100644 > > --- a/kernel/trace/bpf_trace.c > > +++ b/kernel/trace/bpf_trace.c > > @@ -1026,7 +1026,7 @@ BPF_CALL_1(bpf_get_func_ip_kprobe, struct pt_regs *, regs) > > { > > struct kprobe *kp = kprobe_running(); > > > > - return kp ? (uintptr_t)kp->addr : 0; > > + return kp ? (uintptr_t)kp->func_addr : 0; > > } > > > > static const struct bpf_func_proto bpf_get_func_ip_proto_kprobe = { > > diff --git a/tools/testing/selftests/bpf/progs/get_func_ip_test.c b/tools/testing/selftests/bpf/progs/get_func_ip_test.c > > index a587aeca5ae0..e988aefa567e 100644 > > --- a/tools/testing/selftests/bpf/progs/get_func_ip_test.c > > +++ b/tools/testing/selftests/bpf/progs/get_func_ip_test.c > > @@ -69,7 +69,7 @@ int test6(struct pt_regs *ctx) > > { > > __u64 addr = bpf_get_func_ip(ctx); > > > > - test6_result = (const void *) addr == &bpf_fentry_test6 + 5; > > + test6_result = (const void *) addr == &bpf_fentry_test6; > > return 0; > > } > > > > @@ -79,6 +79,6 @@ int test7(struct pt_regs *ctx) > > { > > __u64 addr = bpf_get_func_ip(ctx); > > > > - test7_result = (const void *) addr == &bpf_fentry_test7 + 5; > > + test7_result = (const void *) addr == &bpf_fentry_test7; > > return 0; > > } > > -- > > 2.33.1 > > > > > -- > Masami Hiramatsu >