From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=95.215.58.32 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793145900; b=PvN5pf42a/6V7SNRvZVwcrW6KjDeMiqxG9e3eOOTSLzz7pzdbXni256vZKB2rjQ3MOiC +gG661/S5nNum3D5EQxPkF6ZWf5DwpEsFFAgVpia9ODsHHE+McypjNMX4wA0qZpJzSfAs UgCek95usAgEZNqf2Cz6AAq9M0ggcM3iKx6sa08poh4O5LtrO9QKzx6Pdpp71nFlYnVsF HQ0huOm+sVcEdg2foS1dhOWEc4xO/A3Yrf3lUHtNq3fEqx1Ocuv29lXYVwB+Ql5rzTBKY X9j66SB9JJ1cIEYSnDhiRHa1SIqjzY46wGT267HjNRtvWXFjeq87R0FAEywwLMptDqg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793145900; h=DMARC-Filter:X-Envelope-To:DKIM-Signature:X-Envelope-To:Received: X-Mizu-Trace-ID:X-Migadu-Flow:From:To:Cc:Subject:Date:Message-ID: X-Mailer:MIME-Version:Content-Type:Content-Transfer-Encoding; bh=nnZL90A72YzliJVsFi6s6eH/Aa1SRWJrwp+wT9rrDms=; b=F3ZB6PvIclwmcHqtasuzILHIcr0Y0ApDMq/yojfkA1T3/L47F2EQqluo49Sc/QKjE9ms nNtwvY3lUbPyn+Sv9XSKTmCYqaKRzMx4bVtG+n8XhTseMTK6MJpNWCVcGNRnx3RhS4cRj s9jbKc7LtKbtUYbFoVb2V8yFtLwt58Kxib9IMXPJXD7FxW7mJGIpwt3MGDZkhL1uhgQe0 39+gwRnJ5yD6nlxG5DiHIgqqF4ObSesNhj+Rl7JySEjnAVFWiOGEAAtoFs3sUjo5um0/H 0Cj/C/M4xjurZMWKJa+eJwWMWiCG4KfUOpk+HVTkCR5Miq2Za0B4bbRmzO3VIAVhmoQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b="Rnw9y2/L"; arc=none smtp.remote-ip=95.215.58.32 Received: from mta1.migadu.com (out-32.mta1.migadu.com [95.215.58.32]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1F1A2606A326 for ; Wed, 28 Oct 2026 00:04:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 1F1A2606A326 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, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=Rnw9y2/L X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=aPEyoyISxDi/yeqexwsXLjl02S+dFCLV05lgg9mFxD8=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1793145898; v=1; x=1793750698; b=Rnw9y2/LSq7Wi6/pF2c8eTGguYcSlZZdHfjTfa+8oJYsu3ZZvltXlaDlyLYJpoLZGa+3y0EQ l9bcTMOPBshatVFmo2guMfU3KQTmYBcefXQt3HyThJ8QvuDRARW2Kn2V7TO82B1/tsSG1are0fv sDsepL7S1UOZip3koOzSCkY4= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id 53d2ab04e0ac4bf2; Wed, 28 Oct 2026 00:04:58 +0000 X-Mizu-Trace-ID: 53d2ab04e0ac4bf2 X-Migadu-Flow: FLOW_OUT From: Vineet Gupta To: bpf@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, eddyz87@gmail.com, memxor@gmail.com, martin.lau@linux.dev, song@kernel.org, yonghong.song@linux.dev, jolsa@kernel.org, emil@etsalapatis.com, ihor.solodrai@linux.dev, john.fastabend@gmail.com, shuah@kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, jose.marchesi@oracle.com, david.faust@oss.qualcomm.com, Vineet Gupta Subject: [PATCH bpf-next v1 5/7] selftests/bpf: don't report arena tests as passing with an empty body Date: Tue, 27 Oct 2026 17:04:09 -0700 Message-ID: <20261028000411.4010967-6-vineet.gupta@linux.dev> X-Mailer: git-send-email 2.56.0 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Some arena tests put the __BPF_FEATURE_ADDR_SPACE_CAST guard inside the function rather than around it, so without arena support the program still exists, its body is empty, and __success __retval(0) is met by doing nothing. A reader sees #584/1 verifier_arena/basic_alloc1_nosleep:OK and concludes arena works. That is worse than the tests which vanish entirely, since nothing hints anything is missing. The guard was never needed to compile those bodies: without the feature __arena is still btf_type_tag("arena"), which every compiler accepts. What it avoided was the load failure that follows from no addr_space_cast being emitted — but only for a body that dereferences an arena pointer. The arena kfuncs take one as a plain scalar: static const struct bpf_reg_types arena_types = { .types = { PTR_TO_ARENA, SCALAR_VALUE } so a test that only passes pointers to bpf_arena_{alloc,free,reserve}_pages() needs no cast and runs fine. test_loader checks skip_reason before it opens anything, so the body no longer has to be empty to stay loadable: drop all 19 in-body guards. They do not all need a tag in their place, which is why 19 guards go and 7 tags arrive: 6 dereference, so they get __skip_without_arena and report SKIP: basic_alloc1{,_nosleep}, basic_alloc2{,_nosleep}, big_alloc1, access_reserved 11 never dereference, so they get no tag and run for real instead of reporting a vacuous OK 2 big_alloc3 and big_alloc4, already inside the file's outer whole-program guard, so the in-body one was redundant The 7th tag goes on check_arena_arg_ret(), which has no guard at all and is the one verifier_arena subtest that really fails under a stock GCC. Measured on bpf-next with a stock bpf-gcc, test_progs before and after: verifier_arena/basic_alloc1 OK -> SKIP verifier_arena/basic_alloc1_nosleep OK -> SKIP verifier_arena/basic_alloc2 OK -> SKIP verifier_arena/basic_alloc2_nosleep OK -> SKIP verifier_arena_large/big_alloc1 OK -> SKIP verifier_arena_large/access_reserved OK -> SKIP verifier_arena/check_arena_arg_ret FAIL -> SKIP the six that dereference stop claiming to pass, and check_arena_arg_ret stops failing. The eleven that do not dereference stay OK, having gone from an empty body to actually running. Removing the guards exposes the arena_base() calls they were hiding. The previous patch made that macro opaque to GCC's -Warray-bounds, so nothing is needed here beyond the guards going away. Signed-off-by: Vineet Gupta --- .../selftests/bpf/progs/verifier_arena.c | 31 +++---------------- .../bpf/progs/verifier_arena_large.c | 16 ++-------- 2 files changed, 7 insertions(+), 40 deletions(-) diff --git a/tools/testing/selftests/bpf/progs/verifier_arena.c b/tools/testing/selftests/bpf/progs/verifier_arena.c index 3b3410802825..21b66d51c61e 100644 --- a/tools/testing/selftests/bpf/progs/verifier_arena.c +++ b/tools/testing/selftests/bpf/progs/verifier_arena.c @@ -27,9 +27,9 @@ struct { SEC("socket") __success __retval(0) +__skip_without_arena int basic_alloc1_nosleep(void *ctx) { -#if defined(__BPF_FEATURE_ADDR_SPACE_CAST) volatile int __arena *page1, *page2, *no_page; page1 = bpf_arena_alloc_pages(&arena, NULL, 1, NUMA_NO_NODE, 0); @@ -52,15 +52,14 @@ int basic_alloc1_nosleep(void *ctx) return 6; if (*page2 != 0 && *page2 != 2) /* use-after-free should return 0 or the stored value */ return 7; -#endif return 0; } SEC("syscall") __success __retval(0) +__skip_without_arena int basic_alloc1(void *ctx) { -#if defined(__BPF_FEATURE_ADDR_SPACE_CAST) volatile int __arena *page1, *page2, *no_page, *page3; page1 = bpf_arena_alloc_pages(&arena, NULL, 1, NUMA_NO_NODE, 0); @@ -91,7 +90,6 @@ int basic_alloc1(void *ctx) return 9; if (*page1 != 1) return 10; -#endif return 0; } @@ -125,9 +123,9 @@ int free_scalar_below_arena(void *ctx) SEC("socket") __success __retval(0) +__skip_without_arena int basic_alloc2_nosleep(void *ctx) { -#if defined(__BPF_FEATURE_ADDR_SPACE_CAST) volatile char __arena *page1, *page2, *page3, *page4; page1 = bpf_arena_alloc_pages(&arena, NULL, 2, NUMA_NO_NODE, 0); @@ -157,15 +155,14 @@ int basic_alloc2_nosleep(void *ctx) return 7; if (*page4 != 0) return 8; -#endif return 0; } SEC("syscall") __success __retval(0) +__skip_without_arena int basic_alloc2(void *ctx) { -#if defined(__BPF_FEATURE_ADDR_SPACE_CAST) volatile char __arena *page1, *page2, *page3, *page4; page1 = bpf_arena_alloc_pages(&arena, NULL, 2, NUMA_NO_NODE, 0); @@ -195,7 +192,6 @@ int basic_alloc2(void *ctx) return 7; if (*page4 != 0) return 8; -#endif return 0; } @@ -233,7 +229,6 @@ SEC("socket") __success __retval(0) int basic_reserve1_nosleep(void *ctx) { -#if defined(__BPF_FEATURE_ADDR_SPACE_CAST) char __arena *page; int ret; @@ -257,7 +252,6 @@ int basic_reserve1_nosleep(void *ctx) page = bpf_arena_alloc_pages(&arena, NULL, 1, NUMA_NO_NODE, 0); if (page) return 4; -#endif return 0; } @@ -265,7 +259,6 @@ SEC("syscall") __success __retval(0) int basic_reserve1(void *ctx) { -#if defined(__BPF_FEATURE_ADDR_SPACE_CAST) char __arena *page; int ret; @@ -289,7 +282,6 @@ int basic_reserve1(void *ctx) page = bpf_arena_alloc_pages(&arena, NULL, 1, NUMA_NO_NODE, 0); if (page) return 4; -#endif return 0; } @@ -297,7 +289,6 @@ SEC("socket") __success __retval(0) int basic_reserve2_nosleep(void *ctx) { -#if defined(__BPF_FEATURE_ADDR_SPACE_CAST) char __arena *page; int ret; @@ -309,7 +300,6 @@ int basic_reserve2_nosleep(void *ctx) page = bpf_arena_alloc_pages(&arena, page, 1, NUMA_NO_NODE, 0); if ((u64)page) return 2; -#endif return 0; } @@ -317,7 +307,6 @@ SEC("syscall") __success __retval(0) int basic_reserve2(void *ctx) { -#if defined(__BPF_FEATURE_ADDR_SPACE_CAST) char __arena *page; int ret; @@ -329,7 +318,6 @@ int basic_reserve2(void *ctx) page = bpf_arena_alloc_pages(&arena, page, 1, NUMA_NO_NODE, 0); if ((u64)page) return 2; -#endif return 0; } @@ -338,7 +326,6 @@ SEC("socket") __success __retval(0) int reserve_twice_nosleep(void *ctx) { -#if defined(__BPF_FEATURE_ADDR_SPACE_CAST) char __arena *page; int ret; @@ -351,7 +338,6 @@ int reserve_twice_nosleep(void *ctx) ret = bpf_arena_reserve_pages(&arena, page, 1); if (ret != -EBUSY) return 2; -#endif return 0; } @@ -359,7 +345,6 @@ SEC("syscall") __success __retval(0) int reserve_twice(void *ctx) { -#if defined(__BPF_FEATURE_ADDR_SPACE_CAST) char __arena *page; int ret; @@ -372,7 +357,6 @@ int reserve_twice(void *ctx) ret = bpf_arena_reserve_pages(&arena, page, 1); if (ret != -EBUSY) return 2; -#endif return 0; } @@ -381,7 +365,6 @@ SEC("socket") __success __retval(0) int reserve_invalid_region_nosleep(void *ctx) { -#if defined(__BPF_FEATURE_ADDR_SPACE_CAST) char __arena *page; int ret; @@ -403,7 +386,6 @@ int reserve_invalid_region_nosleep(void *ctx) ret = bpf_arena_reserve_pages(&arena, page, (1ULL << 32) - 1); if (ret != -EINVAL) return 4; -#endif return 0; } @@ -411,7 +393,6 @@ SEC("syscall") __success __retval(0) int reserve_invalid_region(void *ctx) { -#if defined(__BPF_FEATURE_ADDR_SPACE_CAST) char __arena *page; int ret; @@ -433,7 +414,6 @@ int reserve_invalid_region(void *ctx) ret = bpf_arena_reserve_pages(&arena, page, (1ULL << 32) - 1); if (ret != -EINVAL) return 4; -#endif return 0; } @@ -478,7 +458,6 @@ SEC("syscall") __success __retval(0) int arena_kfuncs_under_bpf_lock(void *ctx) { -#if defined(__BPF_FEATURE_ADDR_SPACE_CAST) char __arena *page; int ret; @@ -503,7 +482,6 @@ int arena_kfuncs_under_bpf_lock(void *ctx) bpf_arena_free_pages(&arena, page, 1); bpf_spin_unlock(&arena_bpf_test_lock); -#endif return 0; } @@ -765,6 +743,7 @@ u32 __arena volatile *check_arena_arg_quals2(u32 volatile __arena *arg1, u32 __a SEC("syscall") __success __retval(0) +__skip_without_arena int check_arena_arg_ret(void *ctx) { u32 __arena *page = bpf_arena_alloc_pages(&arena, NULL, 1, NUMA_NO_NODE, 0); diff --git a/tools/testing/selftests/bpf/progs/verifier_arena_large.c b/tools/testing/selftests/bpf/progs/verifier_arena_large.c index 34f0a0f88e12..6ef99793cac1 100644 --- a/tools/testing/selftests/bpf/progs/verifier_arena_large.c +++ b/tools/testing/selftests/bpf/progs/verifier_arena_large.c @@ -22,9 +22,9 @@ struct { SEC("syscall") __success __retval(0) +__skip_without_arena int big_alloc1(void *ctx) { -#if defined(__BPF_FEATURE_ADDR_SPACE_CAST) volatile char __arena *page1, *page2, *no_page, *page3; u64 base; @@ -79,16 +79,15 @@ int big_alloc1(void *ctx) return 13; if (*(page2 - PAGE_SIZE) != 0) return 14; -#endif return 0; } /* Try to access a reserved page. Behavior should be identical with accessing unallocated pages. */ SEC("syscall") __success __retval(0) +__skip_without_arena int access_reserved(void *ctx) { -#if defined(__BPF_FEATURE_ADDR_SPACE_CAST) volatile char __arena *page; char __arena *base; const size_t len = 4; @@ -118,7 +117,6 @@ int access_reserved(void *ctx) if (*page) return 2 + 2 * i + 1; } -#endif return 0; } @@ -127,7 +125,6 @@ SEC("syscall") __success __retval(0) int request_partially_reserved(void *ctx) { -#if defined(__BPF_FEATURE_ADDR_SPACE_CAST) volatile char __arena *page; char __arena *base; int ret; @@ -142,7 +139,6 @@ int request_partially_reserved(void *ctx) page = bpf_arena_alloc_pages(&arena, base, 5, NUMA_NO_NODE, 0); if ((u64)page != 0ULL) return 2; -#endif return 0; } @@ -150,7 +146,6 @@ SEC("syscall") __success __retval(0) int free_reserved(void *ctx) { -#if defined(__BPF_FEATURE_ADDR_SPACE_CAST) char __arena *addr; char __arena *page; int ret; @@ -177,7 +172,6 @@ int free_reserved(void *ctx) page = bpf_arena_alloc_pages(&arena, addr + __PAGE_SIZE, 2, NUMA_NO_NODE, 0); if (!page) return 3; -#endif return 0; } @@ -292,7 +286,6 @@ SEC("socket") __success __retval(0) int big_alloc3(void *ctx) { -#if defined(__BPF_FEATURE_ADDR_SPACE_CAST) char __arena *pages; u64 i; int err = 0; @@ -314,8 +307,6 @@ int big_alloc3(void *ctx) bpf_arena_free_pages(&arena, pages, LARGE_PAGE_CNT); return err; -#endif - return 0; } /* SYSCALL programs are always sleepable. */ @@ -323,7 +314,6 @@ SEC("syscall") __success __retval(0) int big_alloc4(void *ctx) { -#if defined(__BPF_FEATURE_ADDR_SPACE_CAST) char __arena *pages; u64 i; int err = 0; @@ -345,8 +335,6 @@ int big_alloc4(void *ctx) bpf_arena_free_pages(&arena, pages, LARGE_PAGE_CNT); return err; -#endif - return 0; } #else -- 2.53.0-Meta