From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relay5-d.mail.gandi.net (relay5-d.mail.gandi.net [217.70.183.197]) (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 5E3A92D46CD; Thu, 3 Jul 2025 09:02:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.70.183.197 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751533376; cv=none; b=thSvH96tHGvOzso5W0cACjV6UJhFGWNwA2bcanWtygUfXMFG/6p8Dm5TgpdJheHhvQ1aS0rse8TXbM3pBBuhuBXNsM5vRh8Z7vtwKZO+WEkHZfJ7IhoJYytiHzpTss4HG3X3mq21QwuwjJKO3Abrmf8ts+QfqF9iDSPuro6dk6s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751533376; c=relaxed/simple; bh=Q1POodz7dllwe8vvwG8grYps3LcNyhZgW0DzbG1guYc=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=kMcOgQxdULE13mZhMruQ5Ak10tSr8jx5m26i6kd6oHQCGJA/DhWCkYAYd8F5mTeeXJ5hfn6zbL2uVin4Dx1RXhel/otEtxM6uN0EA8Q0wbpDliRVHK2wzyJVqU8svrI2pHC1qEubgR0m8jFMeuZ1C9hzfZQOqDhe4ADkrie+HRg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com; spf=pass smtp.mailfrom=bootlin.com; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b=SV4Xdrj4; arc=none smtp.client-ip=217.70.183.197 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=bootlin.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b="SV4Xdrj4" Received: by mail.gandi.net (Postfix) with ESMTPSA id 786374330B; Thu, 3 Jul 2025 09:02:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1751533366; 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=5ayPNbL5QX+qOWU/VUJ5uupCiMhgvljlrpugUZ5x/Xs=; b=SV4Xdrj4aFxbWQig/AiujlT0gVjgahKMOOnMD3yeOmvBAULDHqnM2k5tUWokQln9NExKce Yq7sGYKSuZmEIpl2nBbJf7CU3/S0MXWSGhQNXhqJbdDWW+yoQ/nGrPlUOwaGIuIFI48cxM nfSbEiS1kBmHMLkk+3agspgdNOpxRQjukzoqriz9cGrqQFQMnMkSGcPz2H1JsaK0vj7w+H RPWLTXurtnBPaxG6CGElA8BpZc9XEZNlkOgOTMTmQItD8bZIc9gFwRRSAKBo/BtYhH3zUY zCtAJjkIt4lfERKh63zGDHWiObjsr48VeW5Wx+LXKrZfLsHuMKMq1mb4YJS32Q== From: =?utf-8?q?Alexis_Lothor=C3=A9_=28eBPF_Foundation=29?= Date: Thu, 03 Jul 2025 11:02:33 +0200 Subject: [PATCH v2 2/3] tests: add some tests validating skipped functions due to uncertain arg location Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Message-Id: <20250703-btf_skip_structs_on_stack-v2-2-4767e3ba10c9@bootlin.com> References: <20250703-btf_skip_structs_on_stack-v2-0-4767e3ba10c9@bootlin.com> In-Reply-To: <20250703-btf_skip_structs_on_stack-v2-0-4767e3ba10c9@bootlin.com> To: dwarves@vger.kernel.org Cc: bpf@vger.kernel.org, Alan Maguire , Arnaldo Carvalho de Melo , Alexei Starovoitov , Thomas Petazzoni , Bastien Curutchet , ebpf@linuxfoundation.org, =?utf-8?q?Alexis_Lothor=C3=A9_=28eBPF_Foundation=29?= X-Mailer: b4 0.14.2 X-GND-State: clean X-GND-Score: -100 X-GND-Cause: gggruggvucftvghtrhhoucdtuddrgeeffedrtdefgdduleekjecutefuodetggdotefrodftvfcurfhrohhfihhlvgemucfitefpfffkpdcuggftfghnshhusghstghrihgsvgenuceurghilhhouhhtmecufedtudenucesvcftvggtihhpihgvnhhtshculddquddttddmnecujfgurhephfffufggtgfgkfhfjgfvvefosehtkeertdertdejnecuhfhrohhmpeetlhgvgihishcunfhothhhohhrroculdgvuefrhfcuhfhouhhnuggrthhiohhnmdcuoegrlhgvgihishdrlhhothhhohhrvgessghoohhtlhhinhdrtghomheqnecuggftrfgrthhtvghrnhepleejkeetffefveelgeeklefhtefhgfeigeduveffjeehleeifeefjedtudejgeeunecukfhppeeltddrkeelrdduieefrdduvdejnecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehinhgvthepledtrdekledrudeifedruddvjedphhgvlhhopegludelvddrudeikedrtddrvddungdpmhgrihhlfhhrohhmpegrlhgvgihishdrlhhothhhohhrvgessghoohhtlhhinhdrtghomhdpnhgspghrtghpthhtohepledprhgtphhtthhopegvsghpfheslhhinhhugihfohhunhgurghtihhonhdrohhrghdprhgtphhtthhopegsphhfsehvghgvrhdrkhgvrhhnvghlrdhorhhgpdhrtghpthhtohepugifrghrvhgvshesvhhgvghrrdhkvghrnhgvlhdrohhrghdprhgtphhtthhopegrtghmvgeskhgvrhhnvghlrdhorhhgpdhrtghpthhtoheprghsthesf hgsrdgtohhmpdhrtghpthhtohepsggrshhtihgvnhdrtghurhhuthgthhgvthessghoohhtlhhinhdrtghomhdprhgtphhtthhopehthhhomhgrshdrphgvthgriiiiohhnihessghoohhtlhhinhdrtghomhdprhgtphhtthhopegrlhgrnhdrmhgrghhuihhrvgesohhrrggtlhgvrdgtohhm X-GND-Sasl: alexis.lothore@bootlin.com Add a small kernel module representing specific cases likely absent from standard vmlinux files. As a starter, the introduced module exposes a few functions consuming structs passed by value, some passed by register, some passed on the stack: int kmod_test_init(void); int test_kmod_func_ok(int, void *, char, short int); int test_kmod_func_struct_ok(int, void *, char, struct kmod_struct); int test_kmod_func_struct_on_stack_ok(int, void *, char, short int, int, \ void *, char, short int, struct kmod_struct); int test_kmod_func_struct_on_stack_ko(int, void *, char, short int, int, \ void *, char, short int, struct kmod_struct_packed); Then enrich btf_functions.sh to make it perform the following steps: - build the module - generate BTF info and pfunct listing, both with dwarf and the generated BTF - check that any function encoded in BTF is found in DWARF - check that any function announced as skipped is indeed absent from BTF - check that any skipped function has been skipped due to uncertain parameter location Those new tests are executed only if a kernel directory is provided as script's second argument, they are otherwise skipped. Example of the new test execution: Encoding...Matched 4 functions exactly. Ok Validation of skipped function logic... Skipped encoding 1 functions in BTF. Ok Validating skipped functions have uncertain parameter location... Found 1 legitimately skipped function due to uncertain loc Ok Signed-off-by: Alexis Lothoré (eBPF Foundation) --- Changes in v2: - new patch --- tests/btf_functions.sh | 99 ++++++++++++++++++++++++++++++++++++++++++++++++++ tests/kmod/Makefile | 1 + tests/kmod/kmod.c | 69 +++++++++++++++++++++++++++++++++++ 3 files changed, 169 insertions(+) diff --git a/tests/btf_functions.sh b/tests/btf_functions.sh index c92e5ae906f90badfede86eb530108894fbc8c93..64810b7eb51e7f2693929fbf66e0641a9d4e0277 100755 --- a/tests/btf_functions.sh +++ b/tests/btf_functions.sh @@ -193,4 +193,103 @@ if [[ -n "$VERBOSE" ]]; then fi echo "Ok" +# Some specific cases can not be tested directly with a standard kernel. +# We can use the kernel module in kmod/ to test those cases, like packed +# structs passed on the stack. Run this test only if we have the needed +# dependencies (eg: some kernel sources directory passed as argument; those +# must match the used vmlinux file) + +KDIR=${KDIR:-$2} +if [ -z "$KDIR" ] ; then + echo "Skipping kmod tests" + exit 0 +fi + +echo -n "Validation of BTF encoding corner cases with kmod functions; this may take some time: " + +test -n "$VERBOSE" && printf "\nBuilding kmod..." +tests_dir=$(dirname $0) +make -C ${KDIR} M=${tests_dir}/kmod + +test -n "$VERBOSE" && printf "\nEncoding..." +pahole --btf_features=default --lang_exclude=rust --btf_encode_detached=$outdir/kmod.btf \ + --verbose ${tests_dir}/kmod/kmod.ko | grep "skipping BTF encoding of function" \ + > ${outdir}/kmod_skipped_fns + +funcs=$(pfunct --format_path=btf $outdir/kmod.btf 2>/dev/null|sort) +pfunct --all --no_parm_names --format_path=dwarf kmod/kmod.ko | \ + sort|uniq > $outdir/kmod_dwarf.funcs +pfunct --all --no_parm_names --format_path=btf $outdir/kmod.btf 2>/dev/null|\ + awk '{ gsub("^(bpf_kfunc |bpf_fastcall )+",""); print $0}'|sort|uniq > $outdir/kmod_btf.funcs + +exact=0 +while IFS= read -r btf ; do + # Matching process can be kept simpler as the tested binary is + # specifically tailored for tests + dwarf=$(grep -F "$btf" $outdir/kmod_dwarf.funcs) + if [[ "$btf" != "$dwarf" ]]; then + echo "ERROR: mismatch : BTF '$btf' not found; DWARF '$dwarf'" + fail + else + exact=$((exact+1)) + fi +done < $outdir/kmod_btf.funcs + +if [[ -n "$VERBOSE" ]]; then + echo "Matched $exact functions exactly." + echo "Ok" + echo "Validation of skipped function logic..." +fi + +skipped_cnt=$(wc -l ${outdir}/kmod_skipped_fns | awk '{ print $1}') +if [[ "$skipped_cnt" == "0" ]]; then + echo "No skipped functions. Done." + exit 0 +fi + +skipped_fns=$(awk '{print $1}' $outdir/kmod_skipped_fns) +for s in $skipped_fns ; do + # Ensure the skipped function are not in BTF + inbtf=$(grep " $s(" $outdir/kmod_btf.funcs) + if [[ -n "$inbtf" ]]; then + echo "ERROR: '${s}()' was added incorrectly to BTF: '$inbtf'" + fail + fi +done + +if [[ -n "$VERBOSE" ]]; then + echo "Skipped encoding $skipped_cnt functions in BTF." + echo "Ok" + echo "Validating skipped functions have uncertain parameter location..." +fi + +uncertain_loc=$(awk '/due to uncertain parameter location/ { print $1 }' $outdir/kmod_skipped_fns) +legitimate_skip=0 + +for f in $uncertain_loc ; do + # Extract parameters types + raw_params=$(grep ${f} $outdir/kmod_dwarf.funcs|sed -n 's/^[^(]*(\([^)]*\)).*/\1/p') + IFS=',' read -ra params <<< "${raw_params}" + for param in "${params[@]}" + do + # Search any param that could be a struct + struct_type=$(echo ${param}|grep -E '^struct [^*]' | sed -E 's/^struct //') + if [ -n "${struct_type}" ]; then + # Check with pahole if the struct is detected as + # packed + if pahole -C "${struct_type}" kmod/kmod.ko|grep -q __packed__ + then + legitimate_skip=$((legitimate_skip+1)) + continue 2 + fi + fi + done + echo "ERROR: '${f}()' should not have been skipped; it has no parameter with uncertain location" + fail +done + +if [[ -n "$VERBOSE" ]]; then + echo "Found ${legitimate_skip} legitimately skipped function due to uncertain loc" +fi +echo "Ok" exit 0 diff --git a/tests/kmod/Makefile b/tests/kmod/Makefile new file mode 100644 index 0000000000000000000000000000000000000000..e7c2ed929eaf81e91429f744c3778156ed2be2d2 --- /dev/null +++ b/tests/kmod/Makefile @@ -0,0 +1 @@ +obj-m += kmod.o diff --git a/tests/kmod/kmod.c b/tests/kmod/kmod.c new file mode 100644 index 0000000000000000000000000000000000000000..5b93614b6156b05925a6cb48809ad63533ccba3e --- /dev/null +++ b/tests/kmod/kmod.c @@ -0,0 +1,69 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include + +struct kmod_struct { + char a; + short b; + int c; + unsigned long long d; +}; + +struct kmod_struct_packed { + char a; + short b; + int c; + unsigned long long d; +}__packed; + +int test_kmod_func_ok(int a, void *b, char c, short d); +int test_kmod_func_struct_ok(int a, void *b, char c, struct kmod_struct d); +int test_kmod_func_struct_on_stack_ok(int a, void *b, char c, short d, int e, + void *f, char g, short h, + struct kmod_struct i); +int test_kmod_func_struct_on_stack_ko(int a, void *b, char c, short d, int e, + void *f, char g, short h, + struct kmod_struct_packed i); + +noinline int test_kmod_func_ok(int a, void *b, char c, short d) +{ + return a + (long)b + c + d; +} + +noinline int test_kmod_func_struct_ok(int a, void *b, char c, + struct kmod_struct d) +{ + return a + (long)b + c + d.a + d.b + d.c + d.d; +} + +noinline int test_kmod_func_struct_on_stack_ok(int a, void *b, char c, short d, + int e, void *f, char g, short h, + struct kmod_struct i) +{ + return a + (long)b + c + d + e + (long)f + g + h + i.a + i.b + i.c + i.d; +} + +noinline int test_kmod_func_struct_on_stack_ko(int a, void *b, char c, short d, + int e, void *f, char g, short h, + struct kmod_struct_packed i) +{ + return a + (long)b + c + d + e + (long)f + g + h + i.a + i.b + i.c + i.d; +} + +static int kmod_test_init(void) +{ + struct kmod_struct test; + struct kmod_struct_packed test_bis; + + test_kmod_func_ok(0, NULL, 0, 0); + test_kmod_func_struct_ok(0, NULL, 0, test); + test_kmod_func_struct_on_stack_ok(0, NULL, 0, 0, 0, NULL, 0, 0, test); + test_kmod_func_struct_on_stack_ko(0, NULL, 0, 0, 0, NULL, 0, 0, test_bis); + return 0; +} + +module_init(kmod_test_init); + +MODULE_AUTHOR("Alexis Lothoré"); +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("Pahole testing module"); -- 2.50.0