From patchwork Tue Dec 26 19:11:48 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexei Starovoitov X-Patchwork-Id: 13504970 X-Patchwork-Delegate: bpf@iogearbox.net Received: from mail-pl1-f169.google.com (mail-pl1-f169.google.com [209.85.214.169]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5CCEC1852 for ; Tue, 26 Dec 2023 19:12:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="ZK3//YxB" Received: by mail-pl1-f169.google.com with SMTP id d9443c01a7336-1d4414ec9c7so3582825ad.0 for ; Tue, 26 Dec 2023 11:12:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1703617935; x=1704222735; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=rn6iIsum+b6kmR4581Z0EKGq5rMcJt9n3ejwgYBQG0Y=; b=ZK3//YxBpbG7dt65jwTl9PD2ZRs8lB5QgQqae3q8c1biJ0i0WMx5wCR+cy1c/4CDDR 6oG5E8MmJ/AodilvD6hH141yPr8AXEXGtT6v54txQ1qo8lryDkqz0C44oKk0mTtDJupz TRUUKoS5tuMvByiMiiwYIRT0feqmAxfvVPfLcFB3AM64n8+G9V2c5Jy65+wJg8NVciy0 Oq6BB9UjqeD+3zm6dGM4NdOvJDJZ60dSmMot7vIQSlYoGsJWO1J+dat/KzrpjsGxspTh cCkV7voVilJkYeXkT3sORvbEZDRVMGD3aJcu3g+omTm30CQpCj+G7xVDl6azueYoP069 wyCA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1703617935; x=1704222735; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=rn6iIsum+b6kmR4581Z0EKGq5rMcJt9n3ejwgYBQG0Y=; b=p4B+CDZISw7bi6pKdB/yvoNRmKtgE3qAAvUmju2D0Py3vXTYngmOJRDKGWd9v4EqAo yKT6wzZmiqptAOeRKTl7bUFc3EY3YcBfBkgt9Pwxp95wdJ3yNPfrx5Hwmk62iJ6/v8/A hpUUdQTB2Cm/MxIi+QK9r4Q1csbsyq1y1S5KKS3GAB3f/CD4piUxZaCzAimVIuUXntPT OM8LjzpfLA6nvrhhEYyWMsEeX+97KCKan3iiHrl1zw0D4wClUYi0skOxEW3dIW3AY4JR ng2463uwKVxmL0b4SGnIrcTAGWIj44o2eT/zhQU7BfwLnZ/n+38WYdEn1bC7/tXKIQzm Ogjw== X-Gm-Message-State: AOJu0Yy7pHsWdFRNAQKAE/omnMlyuPDnHpTzcYFtisa0G30hRL/wYBtq 46XU7S5QScgidoBwWaC2txcimk/RF7Q= X-Google-Smtp-Source: AGHT+IFrmX43Og+fr5wzIuZrzW2DXtla1SfoXJGPCphv3v4Whi0xHWkuZvq44m7a+lWgWxMNkWJQTg== X-Received: by 2002:a17:902:ea04:b0:1d4:55e0:bd0e with SMTP id s4-20020a170902ea0400b001d455e0bd0emr1820992plg.18.1703617935041; Tue, 26 Dec 2023 11:12:15 -0800 (PST) Received: from localhost.localdomain ([2620:10d:c090:500::4:bc9b]) by smtp.gmail.com with ESMTPSA id 11-20020a170902c20b00b001d3acd7480fsm10306058pll.105.2023.12.26.11.12.13 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Tue, 26 Dec 2023 11:12:14 -0800 (PST) From: Alexei Starovoitov To: bpf@vger.kernel.org Cc: daniel@iogearbox.net, andrii@kernel.org, martin.lau@kernel.org, dxu@dxuuu.xyz, memxor@gmail.com, john.fastabend@gmail.com, jolsa@kernel.org, kernel-team@fb.com Subject: [PATCH v3 bpf-next 6/6] selftests/bpf: Convert profiler.c to bpf_cmp. Date: Tue, 26 Dec 2023 11:11:48 -0800 Message-Id: <20231226191148.48536-7-alexei.starovoitov@gmail.com> X-Mailer: git-send-email 2.39.3 (Apple Git-145) In-Reply-To: <20231226191148.48536-1-alexei.starovoitov@gmail.com> References: <20231226191148.48536-1-alexei.starovoitov@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: bpf@iogearbox.net From: Alexei Starovoitov Convert profiler[123].c to "volatile compare" to compare barrier_var() approach vs bpf_cmp_likely() vs bpf_cmp_unlikely(). bpf_cmp_unlikely() produces correct code, but takes much longer to verify: ./veristat -C -e prog,insns,states before after_with_unlikely Program Insns (A) Insns (B) Insns (DIFF) States (A) States (B) States (DIFF) ------------------------------------ --------- --------- ------------------ ---------- ---------- ----------------- kprobe__proc_sys_write 1603 19606 +18003 (+1123.08%) 123 1678 +1555 (+1264.23%) kprobe__vfs_link 11815 70305 +58490 (+495.05%) 971 4967 +3996 (+411.53%) kprobe__vfs_symlink 5464 42896 +37432 (+685.07%) 434 3126 +2692 (+620.28%) kprobe_ret__do_filp_open 5641 44578 +38937 (+690.25%) 446 3162 +2716 (+608.97%) raw_tracepoint__sched_process_exec 2770 35962 +33192 (+1198.27%) 226 3121 +2895 (+1280.97%) raw_tracepoint__sched_process_exit 1526 2135 +609 (+39.91%) 133 208 +75 (+56.39%) raw_tracepoint__sched_process_fork 265 337 +72 (+27.17%) 19 24 +5 (+26.32%) tracepoint__syscalls__sys_enter_kill 18782 140407 +121625 (+647.56%) 1286 12176 +10890 (+846.81%) bpf_cmp_likely() is equivalent to barrier_var(): ./veristat -C -e prog,insns,states before after_with_likely Program Insns (A) Insns (B) Insns (DIFF) States (A) States (B) States (DIFF) ------------------------------------ --------- --------- -------------- ---------- ---------- ------------- kprobe__proc_sys_write 1603 1663 +60 (+3.74%) 123 127 +4 (+3.25%) kprobe__vfs_link 11815 12090 +275 (+2.33%) 971 971 +0 (+0.00%) kprobe__vfs_symlink 5464 5448 -16 (-0.29%) 434 426 -8 (-1.84%) kprobe_ret__do_filp_open 5641 5739 +98 (+1.74%) 446 446 +0 (+0.00%) raw_tracepoint__sched_process_exec 2770 2608 -162 (-5.85%) 226 216 -10 (-4.42%) raw_tracepoint__sched_process_exit 1526 1526 +0 (+0.00%) 133 133 +0 (+0.00%) raw_tracepoint__sched_process_fork 265 265 +0 (+0.00%) 19 19 +0 (+0.00%) tracepoint__syscalls__sys_enter_kill 18782 18970 +188 (+1.00%) 1286 1286 +0 (+0.00%) kprobe__proc_sys_write 2700 2809 +109 (+4.04%) 107 109 +2 (+1.87%) kprobe__vfs_link 12238 12366 +128 (+1.05%) 267 269 +2 (+0.75%) kprobe__vfs_symlink 7139 7365 +226 (+3.17%) 167 175 +8 (+4.79%) kprobe_ret__do_filp_open 7264 7070 -194 (-2.67%) 180 182 +2 (+1.11%) raw_tracepoint__sched_process_exec 3768 3453 -315 (-8.36%) 211 199 -12 (-5.69%) raw_tracepoint__sched_process_exit 3138 3138 +0 (+0.00%) 83 83 +0 (+0.00%) raw_tracepoint__sched_process_fork 265 265 +0 (+0.00%) 19 19 +0 (+0.00%) tracepoint__syscalls__sys_enter_kill 26679 24327 -2352 (-8.82%) 1067 1037 -30 (-2.81%) kprobe__proc_sys_write 1833 1833 +0 (+0.00%) 157 157 +0 (+0.00%) kprobe__vfs_link 9995 10127 +132 (+1.32%) 803 803 +0 (+0.00%) kprobe__vfs_symlink 5606 5672 +66 (+1.18%) 451 451 +0 (+0.00%) kprobe_ret__do_filp_open 5716 5782 +66 (+1.15%) 462 462 +0 (+0.00%) raw_tracepoint__sched_process_exec 3042 3042 +0 (+0.00%) 278 278 +0 (+0.00%) raw_tracepoint__sched_process_exit 1680 1680 +0 (+0.00%) 146 146 +0 (+0.00%) raw_tracepoint__sched_process_fork 299 299 +0 (+0.00%) 25 25 +0 (+0.00%) tracepoint__syscalls__sys_enter_kill 18372 18372 +0 (+0.00%) 1558 1558 +0 (+0.00%) default (mcpu=v3), no_alu32, cpuv4 have similar differences. Note one place where bpf_nop_mov() is used to workaround the verifier lack of link between the scalar register and its spill to stack. Signed-off-by: Alexei Starovoitov --- .../selftests/bpf/progs/profiler.inc.h | 64 ++++++------------- 1 file changed, 18 insertions(+), 46 deletions(-) diff --git a/tools/testing/selftests/bpf/progs/profiler.inc.h b/tools/testing/selftests/bpf/progs/profiler.inc.h index ba99d17dac54..de3b6e4e4d0a 100644 --- a/tools/testing/selftests/bpf/progs/profiler.inc.h +++ b/tools/testing/selftests/bpf/progs/profiler.inc.h @@ -7,6 +7,7 @@ #include "profiler.h" #include "err.h" +#include "bpf_experimental.h" #ifndef NULL #define NULL 0 @@ -221,8 +222,7 @@ static INLINE void* read_full_cgroup_path(struct kernfs_node* cgroup_node, return payload; if (cgroup_node == cgroup_root_node) *root_pos = payload - payload_start; - if (filepart_length <= MAX_PATH) { - barrier_var(filepart_length); + if (bpf_cmp_likely(filepart_length, <=, MAX_PATH)) { payload += filepart_length; } cgroup_node = BPF_CORE_READ(cgroup_node, parent); @@ -305,9 +305,7 @@ static INLINE void* populate_cgroup_info(struct cgroup_data_t* cgroup_data, size_t cgroup_root_length = bpf_probe_read_kernel_str(payload, MAX_PATH, BPF_CORE_READ(root_kernfs, name)); - barrier_var(cgroup_root_length); - if (cgroup_root_length <= MAX_PATH) { - barrier_var(cgroup_root_length); + if (bpf_cmp_likely(cgroup_root_length, <=, MAX_PATH)) { cgroup_data->cgroup_root_length = cgroup_root_length; payload += cgroup_root_length; } @@ -315,9 +313,7 @@ static INLINE void* populate_cgroup_info(struct cgroup_data_t* cgroup_data, size_t cgroup_proc_length = bpf_probe_read_kernel_str(payload, MAX_PATH, BPF_CORE_READ(proc_kernfs, name)); - barrier_var(cgroup_proc_length); - if (cgroup_proc_length <= MAX_PATH) { - barrier_var(cgroup_proc_length); + if (bpf_cmp_likely(cgroup_proc_length, <=, MAX_PATH)) { cgroup_data->cgroup_proc_length = cgroup_proc_length; payload += cgroup_proc_length; } @@ -347,9 +343,7 @@ static INLINE void* populate_var_metadata(struct var_metadata_t* metadata, metadata->comm_length = 0; size_t comm_length = bpf_core_read_str(payload, TASK_COMM_LEN, &task->comm); - barrier_var(comm_length); - if (comm_length <= TASK_COMM_LEN) { - barrier_var(comm_length); + if (bpf_cmp_likely(comm_length, <=, TASK_COMM_LEN)) { metadata->comm_length = comm_length; payload += comm_length; } @@ -494,10 +488,9 @@ read_absolute_file_path_from_dentry(struct dentry* filp_dentry, void* payload) filepart_length = bpf_probe_read_kernel_str(payload, MAX_PATH, BPF_CORE_READ(filp_dentry, d_name.name)); - barrier_var(filepart_length); - if (filepart_length > MAX_PATH) + bpf_nop_mov(filepart_length); + if (bpf_cmp_unlikely(filepart_length, >, MAX_PATH)) break; - barrier_var(filepart_length); payload += filepart_length; length += filepart_length; @@ -579,9 +572,7 @@ ssize_t BPF_KPROBE(kprobe__proc_sys_write, size_t sysctl_val_length = bpf_probe_read_kernel_str(payload, CTL_MAXNAME, buf); - barrier_var(sysctl_val_length); - if (sysctl_val_length <= CTL_MAXNAME) { - barrier_var(sysctl_val_length); + if (bpf_cmp_likely(sysctl_val_length, <=, CTL_MAXNAME)) { sysctl_data->sysctl_val_length = sysctl_val_length; payload += sysctl_val_length; } @@ -590,9 +581,7 @@ ssize_t BPF_KPROBE(kprobe__proc_sys_write, bpf_probe_read_kernel_str(payload, MAX_PATH, BPF_CORE_READ(filp, f_path.dentry, d_name.name)); - barrier_var(sysctl_path_length); - if (sysctl_path_length <= MAX_PATH) { - barrier_var(sysctl_path_length); + if (bpf_cmp_likely(sysctl_path_length, <=, MAX_PATH)) { sysctl_data->sysctl_path_length = sysctl_path_length; payload += sysctl_path_length; } @@ -658,9 +647,7 @@ int raw_tracepoint__sched_process_exit(void* ctx) kill_data->kill_target_cgroup_proc_length = 0; size_t comm_length = bpf_core_read_str(payload, TASK_COMM_LEN, &task->comm); - barrier_var(comm_length); - if (comm_length <= TASK_COMM_LEN) { - barrier_var(comm_length); + if (bpf_cmp_likely(comm_length, <=, TASK_COMM_LEN)) { kill_data->kill_target_name_length = comm_length; payload += comm_length; } @@ -669,9 +656,7 @@ int raw_tracepoint__sched_process_exit(void* ctx) bpf_probe_read_kernel_str(payload, KILL_TARGET_LEN, BPF_CORE_READ(proc_kernfs, name)); - barrier_var(cgroup_proc_length); - if (cgroup_proc_length <= KILL_TARGET_LEN) { - barrier_var(cgroup_proc_length); + if (bpf_cmp_likely(cgroup_proc_length, <=, KILL_TARGET_LEN)) { kill_data->kill_target_cgroup_proc_length = cgroup_proc_length; payload += cgroup_proc_length; } @@ -731,9 +716,7 @@ int raw_tracepoint__sched_process_exec(struct bpf_raw_tracepoint_args* ctx) const char* filename = BPF_CORE_READ(bprm, filename); size_t bin_path_length = bpf_probe_read_kernel_str(payload, MAX_FILENAME_LEN, filename); - barrier_var(bin_path_length); - if (bin_path_length <= MAX_FILENAME_LEN) { - barrier_var(bin_path_length); + if (bpf_cmp_likely(bin_path_length, <=, MAX_FILENAME_LEN)) { proc_exec_data->bin_path_length = bin_path_length; payload += bin_path_length; } @@ -743,8 +726,7 @@ int raw_tracepoint__sched_process_exec(struct bpf_raw_tracepoint_args* ctx) unsigned int cmdline_length = probe_read_lim(payload, arg_start, arg_end - arg_start, MAX_ARGS_LEN); - if (cmdline_length <= MAX_ARGS_LEN) { - barrier_var(cmdline_length); + if (bpf_cmp_likely(cmdline_length, <=, MAX_ARGS_LEN)) { proc_exec_data->cmdline_length = cmdline_length; payload += cmdline_length; } @@ -821,9 +803,7 @@ int kprobe_ret__do_filp_open(struct pt_regs* ctx) payload = populate_cgroup_info(&filemod_data->cgroup_data, task, payload); size_t len = read_absolute_file_path_from_dentry(filp_dentry, payload); - barrier_var(len); - if (len <= MAX_FILEPATH_LENGTH) { - barrier_var(len); + if (bpf_cmp_likely(len, <=, MAX_FILEPATH_LENGTH)) { payload += len; filemod_data->dst_filepath_length = len; } @@ -876,17 +856,13 @@ int BPF_KPROBE(kprobe__vfs_link, payload = populate_cgroup_info(&filemod_data->cgroup_data, task, payload); size_t len = read_absolute_file_path_from_dentry(old_dentry, payload); - barrier_var(len); - if (len <= MAX_FILEPATH_LENGTH) { - barrier_var(len); + if (bpf_cmp_likely(len, <=, MAX_FILEPATH_LENGTH)) { payload += len; filemod_data->src_filepath_length = len; } len = read_absolute_file_path_from_dentry(new_dentry, payload); - barrier_var(len); - if (len <= MAX_FILEPATH_LENGTH) { - barrier_var(len); + if (bpf_cmp_likely(len, <=, MAX_FILEPATH_LENGTH)) { payload += len; filemod_data->dst_filepath_length = len; } @@ -936,16 +912,12 @@ int BPF_KPROBE(kprobe__vfs_symlink, struct inode* dir, struct dentry* dentry, size_t len = bpf_probe_read_kernel_str(payload, MAX_FILEPATH_LENGTH, oldname); - barrier_var(len); - if (len <= MAX_FILEPATH_LENGTH) { - barrier_var(len); + if (bpf_cmp_likely(len, <=, MAX_FILEPATH_LENGTH)) { payload += len; filemod_data->src_filepath_length = len; } len = read_absolute_file_path_from_dentry(dentry, payload); - barrier_var(len); - if (len <= MAX_FILEPATH_LENGTH) { - barrier_var(len); + if (bpf_cmp_likely(len, <=, MAX_FILEPATH_LENGTH)) { payload += len; filemod_data->dst_filepath_length = len; }