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[109.67.21.91]) by smtp.googlemail.com with ESMTPSA id y142sm24168521wmd.3.2020.08.15.12.56.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 15 Aug 2020 12:56:35 -0700 (PDT) From: Lior Ribak To: Lior Ribak Cc: bpf@vger.kernel.org Subject: [PATCH] samples/bpf: Support both enter and exit kprobes in helper Date: Sat, 15 Aug 2020 12:56:27 -0700 Message-Id: <20200815195627.305064-1-liorribak@gmail.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Currently, in bpf_load.c, the function write_kprobe_events sets the function name to probe as the probe name. Even though it's valid to set one kprobe on enter and another on exit, bpf_load.c won't handle it, and will return an error 'File exists'. Add a prefix to the event name to indicate if it's on enter or exit, so both an enter and an exit kprobes can be attached. Signed-off-by: Lior Ribak --- samples/bpf/bpf_load.c | 20 +++++++++++++------- 1 file changed, 13 insertions(+), 7 deletions(-) diff --git a/samples/bpf/bpf_load.c b/samples/bpf/bpf_load.c index c5ad528f046e..69102358e91a 100644 --- a/samples/bpf/bpf_load.c +++ b/samples/bpf/bpf_load.c @@ -184,18 +184,24 @@ static int load_and_attach(const char *event, struct bpf_insn *prog, int size) #ifdef __x86_64__ if (strncmp(event, "sys_", 4) == 0) { - snprintf(buf, sizeof(buf), "%c:__x64_%s __x64_%s", - is_kprobe ? 'p' : 'r', event, event); + if (is_kprobe) + event_prefix = "__x64_enter_"; + else + event_prefix = "__x64_exit_"; + snprintf(buf, sizeof(buf), "%c:%s%s __x64_%s", + is_kprobe ? 'p' : 'r', event_prefix, event, event); err = write_kprobe_events(buf); - if (err >= 0) { + if (err >= 0) need_normal_check = false; - event_prefix = "__x64_"; - } } #endif if (need_normal_check) { - snprintf(buf, sizeof(buf), "%c:%s %s", - is_kprobe ? 'p' : 'r', event, event); + if (is_kprobe) + event_prefix = "enter_"; + else + event_prefix = "exit_"; + snprintf(buf, sizeof(buf), "%c:%s%s %s", + is_kprobe ? 'p' : 'r', event_prefix, event, event); err = write_kprobe_events(buf); if (err < 0) { printf("failed to create kprobe '%s' error '%s'\n",