From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-181.mta1.migadu.com (out-181.mta1.migadu.com [95.215.58.181]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B74662750E6 for ; Tue, 26 Aug 2025 16:51:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.181 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756227101; cv=none; b=paLzGlmIKWkNnqDwOB891coTkFUpIpixt/2/Cso1xQncGYKdVeBeP+bwumY6Ov2gzyZcITjoCOJBELtXu3TIAORyk5RrYsjRIoVZfEBlDddMK4OLjioY/pewQF71i2j9nQBOs8rHonfZm6jHzhJ9v9YzRy/xyzNzqMqOtj+uCxk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756227101; c=relaxed/simple; bh=er1lq/dzsrmFZwsv2XyfdQy2+0Y7HeZOJLs86tFN+BE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=JfeszKfV/Ps7Ci0PkHbcEWzUkT8ItqKYiPtPrHqMnVXmjF89hxEsXNi87kuoJW/lm3i3Dw62KFE+tpj4KtwwsydDZ2xy00ROe4eeZF3QBZ8jeDXTo2GTRI913dKjgssWhj/m+qiu+1jei1cPY9HK77uER8RwXdfAIjbfYMuY5ko= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=GZ5oM5Jn; arc=none smtp.client-ip=95.215.58.181 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="GZ5oM5Jn" Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1756227096; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=qnzpS995oSOSAmi/9OR2XBD5gzrE04xt0mbKyF2sQXU=; b=GZ5oM5JnBURFXQr6PfYeyqv3JcusbV4mlcSjz/z3d+E2E2iRcqUy3EcwG7jLGSkJylG4t1 GlqPh0K3FekjPeIlrW44T8vStlPQhGUNYV+6OcLpa5SP0UwSPDGfXOLc46Nr6k6TIeJzNQ tYEz1DfuwUbulkj+hrRAUy16k3ooCa0= Date: Tue, 26 Aug 2025 09:51:08 -0700 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH bpf-next v15 2/2] selftests/bpf: Enrich subtest_basic_usdt case in selftests to cover SIB handling logic Content-Language: en-GB To: Jiawei Zhao , ast@kernel.org Cc: daniel@iogearbox.net, andrii@kernel.org, bpf@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org References: <20250823071839.1191350-1-phoenix500526@163.com> <20250823071839.1191350-3-phoenix500526@163.com> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Yonghong Song In-Reply-To: <20250823071839.1191350-3-phoenix500526@163.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT On 8/23/25 12:18 AM, Jiawei Zhao wrote: > When using GCC on x86-64 to compile an usdt prog with -O1 or higher > optimization, the compiler will generate SIB addressing mode for global > array and PC-relative addressing mode for global variable, > e.g. "1@-96(%rbp,%rax,8)" and "-1@4+t1(%rip)". You can remove "-1@t+t1(%rip)" which is not relavent to this patch. Also, please also mention usage of STAP_PROBE_ASM so the test works for both gcc and clang. I tested the patch with gcc/clang for x86_64 and it works fine. I didn't test 32-bit x86 arch. > > In this patch: > - enrich subtest_basic_usdt test case to cover SIB addressing usdt argument spec > handling logic > > Signed-off-by: Jiawei Zhao > --- > tools/testing/selftests/bpf/prog_tests/usdt.c | 62 ++++++++++++++++++- > tools/testing/selftests/bpf/progs/test_usdt.c | 32 ++++++++++ > 2 files changed, 92 insertions(+), 2 deletions(-) > > diff --git a/tools/testing/selftests/bpf/prog_tests/usdt.c b/tools/testing/selftests/bpf/prog_tests/usdt.c > index 9057e983cc54..4b264f7d3324 100644 > --- a/tools/testing/selftests/bpf/prog_tests/usdt.c > +++ b/tools/testing/selftests/bpf/prog_tests/usdt.c > @@ -10,6 +10,26 @@ > > int lets_test_this(int); > > +#if defined(__x86_64__) || defined(__i386__) > +/* > + * SIB (Scale-Index-Base) addressing format: > + * "size@(base_reg, index_reg, scale)" > + * - 'size' is the size in bytes of the array element, and its sign indicates > + * whether the type is signed (negative) or unsigned (positive). > + * - 'base_reg' is the register holding the base address, normally rdx or edx > + * - 'index_reg' is the register holding the index, normally rax or eax > + * - 'scale' is the scaling factor (typically 1, 2, 4, or 8), which matches the > + * size of the element type. > + * > + * For example, for an array of 'short' (signed 2-byte elements), the SIB spec would be: > + * - size: -2 (negative because 'short' is signed) > + * - scale: 2 (since sizeof(short) == 2) > + * The resulting SIB format: "-2@(%%rdx,%%rax,2)" > + */ > +static volatile short array[] = {-1, -2, -3, -4}; > +#define USDT_SIB_ARG_SPEC -2@(%%rdx,%%rax,2) > +#endif > + > static volatile int idx = 2; > static volatile __u64 bla = 0xFEDCBA9876543210ULL; > static volatile short nums[] = {-1, -2, -3, -4}; > @@ -25,6 +45,10 @@ unsigned short test_usdt0_semaphore SEC(".probes"); > unsigned short test_usdt3_semaphore SEC(".probes"); > unsigned short test_usdt12_semaphore SEC(".probes"); > > +#if defined(__x86_64__) || defined(__i386__) > +unsigned short test_usdt_sib_semaphore SEC(".probes"); > +#endif > + > static void __always_inline trigger_func(int x) { > long y = 42; > > @@ -40,12 +64,27 @@ static void __always_inline trigger_func(int x) { > } > } > > +#if defined(__x86_64__) || defined(__i386__) > +static void trigger_sib_spec(void) > +{ > + /* Base address + offset + (index * scale) */ > + /* Force SIB addressing with inline assembly */ > + asm volatile( > + STAP_PROBE_ASM(test, usdt_sib, USDT_SIB_ARG_SPEC) > + : > + : "d"(array), "a"(0) > + : "memory" > + ); > +} > +#endif > + > static void subtest_basic_usdt(void) > { > LIBBPF_OPTS(bpf_usdt_opts, opts); > struct test_usdt *skel; > struct test_usdt__bss *bss; > int err, i; > + const __u64 expected_cookie = 0xcafedeadbeeffeed; > > skel = test_usdt__open_and_load(); > if (!ASSERT_OK_PTR(skel, "skel_open")) > @@ -59,20 +98,29 @@ static void subtest_basic_usdt(void) > goto cleanup; > > /* usdt0 won't be auto-attached */ > - opts.usdt_cookie = 0xcafedeadbeeffeed; > + opts.usdt_cookie = expected_cookie; > skel->links.usdt0 = bpf_program__attach_usdt(skel->progs.usdt0, > 0 /*self*/, "/proc/self/exe", > "test", "usdt0", &opts); > if (!ASSERT_OK_PTR(skel->links.usdt0, "usdt0_link")) > goto cleanup; > > +#if defined(__x86_64__) || defined(__i386__) > + opts.usdt_cookie = expected_cookie; > + skel->links.usdt_sib = bpf_program__attach_usdt(skel->progs.usdt_sib, > + 0 /*self*/, "/proc/self/exe", > + "test", "usdt_sib", &opts); formate issue in the above? > + if (!ASSERT_OK_PTR(skel->links.usdt_sib, "usdt_sib_link")) > + goto cleanup; > +#endif > + > trigger_func(1); > > ASSERT_EQ(bss->usdt0_called, 1, "usdt0_called"); > ASSERT_EQ(bss->usdt3_called, 1, "usdt3_called"); > ASSERT_EQ(bss->usdt12_called, 1, "usdt12_called"); > > - ASSERT_EQ(bss->usdt0_cookie, 0xcafedeadbeeffeed, "usdt0_cookie"); > + ASSERT_EQ(bss->usdt0_cookie, expected_cookie, "usdt0_cookie"); > ASSERT_EQ(bss->usdt0_arg_cnt, 0, "usdt0_arg_cnt"); > ASSERT_EQ(bss->usdt0_arg_ret, -ENOENT, "usdt0_arg_ret"); > ASSERT_EQ(bss->usdt0_arg_size, -ENOENT, "usdt0_arg_size"); > @@ -156,6 +204,16 @@ static void subtest_basic_usdt(void) > ASSERT_EQ(bss->usdt3_args[1], 42, "usdt3_arg2"); > ASSERT_EQ(bss->usdt3_args[2], (uintptr_t)&bla, "usdt3_arg3"); > > +#if defined(__x86_64__) || defined(__i386__) > + trigger_sib_spec(); > + ASSERT_EQ(bss->usdt_sib_called, 1, "usdt_sib_called"); > + ASSERT_EQ(bss->usdt_sib_cookie, expected_cookie, "usdt_sib_cookie"); > + ASSERT_EQ(bss->usdt_sib_arg_cnt, 1, "usdt_sib_arg_cnt"); > + ASSERT_EQ(bss->usdt_sib_arg, nums[0], "usdt_sib_arg"); > + ASSERT_EQ(bss->usdt_sib_arg_ret, 0, "usdt_sib_arg_ret"); > + ASSERT_EQ(bss->usdt_sib_arg_size, sizeof(nums[0]), "usdt_sib_arg_size"); > +#endif > + > cleanup: > test_usdt__destroy(skel); > } > diff --git a/tools/testing/selftests/bpf/progs/test_usdt.c b/tools/testing/selftests/bpf/progs/test_usdt.c > index 096488f47fbc..63db72253316 100644 > --- a/tools/testing/selftests/bpf/progs/test_usdt.c > +++ b/tools/testing/selftests/bpf/progs/test_usdt.c > @@ -107,4 +107,36 @@ int BPF_USDT(usdt12, int a1, int a2, long a3, long a4, unsigned a5, > return 0; > } > > + > +int usdt_sib_called; > +u64 usdt_sib_cookie; > +int usdt_sib_arg_cnt; > +int usdt_sib_arg_ret; > +u64 usdt_sib_arg; > +int usdt_sib_arg_size; > + > +/* > + * usdt_sib is only tested on x86-related architectures, so it requires > + * manual attach since auto-attach will panic tests under other architectures > + */ > +SEC("usdt") > +int usdt_sib(struct pt_regs *ctx) > +{ > + long tmp; > + > + if (my_pid != (bpf_get_current_pid_tgid() >> 32)) > + return 0; > + > + __sync_fetch_and_add(&usdt_sib_called, 1); > + > + usdt_sib_cookie = bpf_usdt_cookie(ctx); > + usdt_sib_arg_cnt = bpf_usdt_arg_cnt(ctx); > + > + usdt_sib_arg_ret = bpf_usdt_arg(ctx, 0, &tmp); > + usdt_sib_arg = (short)tmp; Maybe change usdt_sib_arg type as short? > + usdt_sib_arg_size = bpf_usdt_arg_size(ctx, 0); > + > + return 0; > +} > + > char _license[] SEC("license") = "GPL";