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Mon, 10 Jul 2023 03:51:37 -0700 (PDT) Received: from localhost.localdomain ([43.132.98.106]) by smtp.gmail.com with ESMTPSA id 17-20020a17090a191100b00263eb5054ebsm6475036pjg.27.2023.07.10.03.51.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 10 Jul 2023 03:51:37 -0700 (PDT) From: menglong8.dong@gmail.com X-Google-Original-From: imagedong@tencent.com To: yhs@meta.com, daniel@iogearbox.net, alexei.starovoitov@gmail.com Cc: ast@kernel.org, andrii@kernel.org, martin.lau@linux.dev, song@kernel.org, yhs@fb.com, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@google.com, haoluo@google.com, dsahern@kernel.org, jolsa@kernel.org, x86@kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Menglong Dong Subject: [PATCH RESEND bpf-next v8 0/3] bpf, x86: allow function arguments up to 12 for TRACING Date: Mon, 10 Jul 2023 18:48:31 +0800 Message-Id: <20230710104834.947884-1-imagedong@tencent.com> X-Mailer: git-send-email 2.40.1 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230710_035139_855592_38D21235 X-CRM114-Status: GOOD ( 21.63 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: Menglong Dong For now, the BPF program of type BPF_PROG_TYPE_TRACING can only be used on the kernel functions whose arguments count less than or equal to 6, if not considering '> 8 bytes' struct argument. This is not friendly at all, as too many functions have arguments count more than 6. According to the current kernel version, below is a statistics of the function arguments count: argument count | function count 7 | 704 8 | 270 9 | 84 10 | 47 11 | 47 12 | 27 13 | 22 14 | 5 15 | 0 16 | 1 Therefore, let's enhance it by increasing the function arguments count allowed in arch_prepare_bpf_trampoline(), for now, only x86_64. In the 1st patch, we save/restore regs with BPF_DW size to make the code in save_regs()/restore_regs() simpler. In the 2nd patch, we make arch_prepare_bpf_trampoline() support to copy function arguments in stack for x86 arch. Therefore, the maximum arguments can be up to MAX_BPF_FUNC_ARGS for FENTRY, FEXIT and MODIFY_RETURN. Meanwhile, we clean the potential garbage value when we copy the arguments on-stack. And the 3rd patch is for the testcases of the this series. Changes since v7: - split the testcases, and add fentry_many_args/fexit_many_args to DENYLIST.aarch64 in 3rd patch Changes since v6: - somit nits from commit message and comment in the 1st patch - remove the inline in get_nr_regs() in the 1st patch - rename some function and various in the 1st patch Changes since v5: - adjust the commit log of the 1st patch, avoiding confusing people that bugs exist in current code - introduce get_nr_regs() to get the space that used to pass args on stack correct in the 2nd patch - add testcases to tracing_struct.c instead of fentry_test.c and fexit_test.c Changes since v4: - consider the case of the struct in arguments can't be hold by regs - add comment for some code - add testcases for MODIFY_RETURN - rebase to the latest Changes since v3: - try make the stack pointer 16-byte aligned. Not sure if I'm right :) - introduce clean_garbage() to clean the grabage when argument count is 7 - use different data type in bpf_testmod_fentry_test{7,12} - add testcase for grabage values in ctx Changes since v2: - keep MAX_BPF_FUNC_ARGS still - clean garbage value in upper bytes in the 2nd patch - move bpf_fentry_test{7,12} to bpf_testmod.c and rename them to bpf_testmod_fentry_test{7,12} meanwhile in the 3rd patch Changes since v1: - change the maximun function arguments to 14 from 12 - add testcases (Jiri Olsa) - instead EMIT4 with EMIT3_off32 for "lea" to prevent overflow Menglong Dong (3): bpf, x86: save/restore regs with BPF_DW size bpf, x86: allow function arguments up to 12 for TRACING selftests/bpf: add testcase for TRACING with 6+ arguments arch/x86/net/bpf_jit_comp.c | 246 +++++++++++++++--- net/bpf/test_run.c | 23 +- tools/testing/selftests/bpf/DENYLIST.aarch64 | 2 + .../selftests/bpf/bpf_testmod/bpf_testmod.c | 49 +++- .../selftests/bpf/prog_tests/fentry_test.c | 43 ++- .../selftests/bpf/prog_tests/fexit_test.c | 43 ++- .../selftests/bpf/prog_tests/modify_return.c | 20 +- .../selftests/bpf/prog_tests/tracing_struct.c | 19 ++ .../selftests/bpf/progs/fentry_many_args.c | 39 +++ .../selftests/bpf/progs/fexit_many_args.c | 40 +++ .../selftests/bpf/progs/modify_return.c | 40 +++ .../selftests/bpf/progs/tracing_struct.c | 54 ++++ 12 files changed, 561 insertions(+), 57 deletions(-) create mode 100644 tools/testing/selftests/bpf/progs/fentry_many_args.c create mode 100644 tools/testing/selftests/bpf/progs/fexit_many_args.c