From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f50.google.com (mail-pj1-f50.google.com [209.85.216.50]) (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 0FDE54CC266 for ; Mon, 7 Sep 2026 13:06:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.50 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788786424; cv=none; b=JlfjOy+uQSa6Ub4z822m5fYBZndfCTuK/5J+ApUgLXc4VN9HoKrcMTiEwxuTiwc7GBo0pAjBL1yHyv2IMHqwIXCM8piMpltzyQWTdFj5Bo37rCGzIy/iPMnmNnUAHAdGZIgrPyCTLbgo2QuqVPS+6ZCjcxvwLBQiun/qlJYwqeo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788786424; c=relaxed/simple; bh=Aq2Yj8WlY/n8sjOdlrRc6EEnwqw44OPa3KHFRf4++So=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=C8OyuB7O8rYAiGUWfH7TCpTOU/4/7WBufd85BqyP63Oux6l4G4ybbWLbrex9RxE2stB8JnqSZrYBDyNhdGpwP0Rd2QXUThfyqdY/81GCWaFi0OtnO4BOAzCIICfynieKcjOerbK+R2Ct7c8MmqKsVmSkPJtc6ubuW66W4XLPXVs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=Hs2ov4Uk; arc=none smtp.client-ip=209.85.216.50 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="Hs2ov4Uk" Received: by mail-pj1-f50.google.com with SMTP id 98e67ed59e1d1-39b2ad862bdso3780202a91.2 for ; Mon, 07 Sep 2026 06:06:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1788786407; x=1789391207; 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:content-type; bh=YnZZQEjTT3ispo9t2Rp3ilMwMqDfcn5R3yYWSok4gBU=; b=Hs2ov4UkFW+3Ps6wOnyI0xRBCDAmGThte3uzHkEIoQ4hk7Q4nQVnnEsy+77xUC0awn nRn1dtYLhkuPIBrYPe3guKnvth68e4aq3ydEYZqy4u7tniI8rFfFI9QaCFK6BBkZ3Wqh aqCpc7OqNlMWOPPVsgv//a11tcQrx5uQ+LRbcZ1HSKAglqMQI0HZuvTHe2OE0jhRNlAi 8KWaCjtCPyNkmDL+bD/POxZHQ1GBtB/G+15RSfnfXwXcdOmquP6HajZ0+YDZA7A5JxOi Z+Tj4W8yscWftdJtvvw/KAF8KO8eM5nNtWRkm0A4wdBvGWDlBLP6JKX6M6dea+klLvam Cj1g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1788786407; x=1789391207; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to:content-type; bh=YnZZQEjTT3ispo9t2Rp3ilMwMqDfcn5R3yYWSok4gBU=; b=St4mIgW4If4b908M+FKqrAjXqYJNYJ7PlHac0GvERVIUEpgDK+JtfU9y8C2C3YyY4t XQsoDT1bQR89ac/FltZHH6t7gPyNSveh/rJPCYjeKZx9W51MNIwbUDHbUgpz38GyPq50 AZhzXmhkARWBKPQg8xj3MzN39TRIW7dHlFW51X9aRO5Oi5vnNB3qVh2sRm0zq6wiWm+G l+Lks9T4JFKtsTiOzSTp3MBog1O4dkaurWziZMCOl1sAJn3JizYmNq1a5KKn/qrZHKyJ tRiAU0Zt+vFCSpVjchCJHGKdgOeQG36Q/TV52mT+yk9QoBuS7EfSuBNgPtY4huDTMozs h7tQ== X-Forwarded-Encrypted: i=1; AKwUvByIq0mWZOW0Ab7Y0QbOcqAH2vx20ulC4/oiTZdHm1QIGqMcoPwtOfYRqTWyURKRpShFh6WmjHNjRSwD3j4=@vger.kernel.org X-Gm-Message-State: AFuF++ktbhAp+Vq2KBF5mekpmvHhRRRShl/vqOeirTGZEE3A9/MLsxrs d5vfJu7kS8WFki3VaqygzJL1f2cByEKc3t/rf25nYwJsRaAVS0typjA= X-Gm-Gg: AYBFou2/wtleL8BXUMJiDtZijT0X6aQT20/EJMmMAFIWQPNXak28mTi9hNYCm2QWedB LoGhiZsQlRU9hVGlNqFp461MaTdALnZdx6wQE5udJRw73rFlPcYHpMGZo8q3x3NNPaBq42ORWrj O49IhjvF2dbeKRzXSWwlwaUiPOZfxWxHFfeOI5Qh8kx9PAd5n8bAAYWiNcmB0wqrjigDt3gHqQS Hntpl4G1pOSWDOf6Twzn/3Zi172nMMwDHntSU9bQD2QRKQ0VONSa9+46qnJxn3FYacrkAXNjYMg YLslx24t+RxR9SBSnnWFYho7GKnWVElhswm9FvZS5ltoE1O4uBPO3HyZamw/JWtjhSFiHrGzSSZ m/JM2khPwiRElFsF9gOCmiRVhh3TeouCBwPTe8Tg6PBi9mlXxQ1aGse/NnFuD36IzKgIP0BGibt 63+nKNNZh/qV1lTrnL5m2C7h872A10L7pfaEXsHZwRB1NqKiguw1OV+z1AAnqWtpEKdTwy4sQvq zn4LM0HhKcVcwaA X-Received: by 2002:a17:90b:3809:b0:381:a766:efc9 with SMTP id 98e67ed59e1d1-39b261014e2mr32056634a91.7.1788786407241; Mon, 07 Sep 2026 06:06:47 -0700 (PDT) Received: from ydg-Zenbook-14-UM3406GA ([2001:2d8:6467:d689:c773:5f09:906c:a72b]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-39b07b197a9sm26742398a91.0.2026.09.07.06.06.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 07 Sep 2026 06:06:46 -0700 (PDT) From: Donggeun Yoo To: Alexei Starovoitov , Andrii Nakryiko , Catalin Marinas , Daniel Borkmann , Eduard Zingerman , Emil Tsalapatis , Ihor Solodrai , Jiri Olsa , Kumar Kartikeya Dwivedi , Mark Rutland , Martin KaFai Lau , Puranjay Mohan , Shuah Khan , Song Liu , Will Deacon , Xu Kuohai , Yonghong Song Cc: bpf@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, donggeunyoo.kernel@gmail.com Subject: [PATCH bpf v3 2/2] selftests/bpf: cover the exception callback using its own BPF stack Date: Mon, 7 Sep 2026 22:06:24 +0900 Message-ID: <20260907130624.611942-3-donggeunyoo.kernel@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260907130624.611942-1-donggeunyoo.kernel@gmail.com> References: <20260907130624.611942-1-donggeunyoo.kernel@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The existing exception tests do not reach a callback that materializes BPF_REG_FP into a register. They either throw from the main program, where BPF_REG_FP already holds the value the callback needs, or use a callback whose only stack accesses are frame pointer relative, which the arm64 JIT rewrites to be stack pointer relative. Add a test that throws from a subprogram using its own BPF stack, with a callback that hands the address of a local variable to bpf_probe_read_kernel(). The helper and the callback have to name the same slot for the value read back to be the one the helper stored. Signed-off-by: Donggeun Yoo --- .../selftests/bpf/prog_tests/exceptions.c | 1 + .../testing/selftests/bpf/progs/exceptions.c | 30 +++++++++++++++++++ 2 files changed, 31 insertions(+) diff --git a/tools/testing/selftests/bpf/prog_tests/exceptions.c b/tools/testing/selftests/bpf/prog_tests/exceptions.c index 3588d6f97fd4..639866ce09a9 100644 --- a/tools/testing/selftests/bpf/prog_tests/exceptions.c +++ b/tools/testing/selftests/bpf/prog_tests/exceptions.c @@ -55,6 +55,7 @@ static void test_exceptions_success(void) RUN_SUCCESS(exception_ext, 0); RUN_SUCCESS(exception_ext_mod_cb_runtime, 35); RUN_SUCCESS(exception_throw_subprog, 1); + RUN_SUCCESS(exception_throw_subprog_stack_cb, 0x1234); RUN_SUCCESS(exception_assert_nz_gfunc, 1); RUN_SUCCESS(exception_assert_zero_gfunc, 1); RUN_SUCCESS(exception_assert_neg_gfunc, 1); diff --git a/tools/testing/selftests/bpf/progs/exceptions.c b/tools/testing/selftests/bpf/progs/exceptions.c index c8d716fbd419..91c81971e58c 100644 --- a/tools/testing/selftests/bpf/progs/exceptions.c +++ b/tools/testing/selftests/bpf/progs/exceptions.c @@ -212,6 +212,36 @@ int exception_throw_subprog(struct __sk_buff *ctx) return 0; } +u64 exception_cb_stack_src = 0x1234; + +/* + * The address handed to the helper has to be this callback's own stack + * slot, not one from a frame that is already gone. + */ +__noinline int exception_cb_stack(u64 cookie) +{ + volatile u64 val = 0xdead; + + bpf_probe_read_kernel((void *)&val, sizeof(val), &exception_cb_stack_src); + return val; +} + +/* Throws from a subprogram that has a stack of its own. */ +__noinline static int throwing_subprog_stack(struct __sk_buff *ctx) +{ + volatile u64 pad[4] = {}; + + bpf_throw(pad[0]); + return 0; +} + +SEC("tc") +__exception_cb(exception_cb_stack) +int exception_throw_subprog_stack_cb(struct __sk_buff *ctx) +{ + return throwing_subprog_stack(ctx); +} + __noinline int assert_nz_gfunc(u64 c) { volatile u64 cookie = c; -- 2.53.0