From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 A14D126F28F for ; Wed, 27 Aug 2025 15:38:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756309131; cv=none; b=XpjyVb8rfDCwGDUvIqZ67SvYQftE7ao0HmQFhLhwHdd06lfx6kGpzhsXHDBLUp2RsUO64OQAwC+WF7aPYlOY1HsDnr4c0iGPBFpaINnF6iBDS8tSbnfdE+llBNGQL8c31ITo3qjeAV3CYHgiwssng4OdHxtDesTcyB2V3uCx0s4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756309131; c=relaxed/simple; bh=loYYaNJYfHTrXaySDdMRAmKAwbG/EVWwipbqdErAgrw=; h=From:To:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=N62SMSW5W62/qy69ZxCCLvra77lf1xGIhBUY65EQFs5yR+WVsmHJ93m+6Ozqzi5WLbTi82Hs+NemGSoQX81+Oxg2/VO6bIcKP3hqeisH04vnZfzDaze7gQ1YJkpVAeILR270SjirYEujoQJWcEp7AahBUXotB4ERNVskhmEMTBs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=THHQVdep; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="THHQVdep" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B7992C4CEEB; Wed, 27 Aug 2025 15:38:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1756309131; bh=loYYaNJYfHTrXaySDdMRAmKAwbG/EVWwipbqdErAgrw=; h=From:To:Subject:In-Reply-To:References:Date:From; b=THHQVdepxvZiuAozZYCcnkQggYeCE9mnQwgzUk64cPIdRYWwEGn4dPLgQPn/B1dZ6 boaPrCoj1+XZrT3g2pe2UrwAMDEIzhvUEthoPo8N0528/TzgQPU2hZ7ipmBtbMZkx/ cArg9eY125GDP5yupbOnWuPRkC2dtqOQZpjI36J4zdcD0XC9jzWhAx4tuijkz/sEX5 gaWtafxMEwwTpByvJvdBpgaFR/qDv0JYLVvaSQbVfDRSVc9pAwTwUcMKWr3aRxmWMZ 2u7J1O14xUw1q+UbLDBlYRvfXsLj3q1uteWLydIbTcUhS3u0LqNAXksFoWDaTaDF0S AyCbDpk5a8PxQ== From: Puranjay Mohan To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Xu Kuohai , Catalin Marinas , Will Deacon , Kumar Kartikeya Dwivedi , bpf@vger.kernel.org Subject: Re: [PATCH bpf-next v3 0/3] bpf: Report arena faults to BPF streams In-Reply-To: <20250827150113.15763-1-puranjay@kernel.org> References: <20250827150113.15763-1-puranjay@kernel.org> Date: Wed, 27 Aug 2025 15:38:47 +0000 Message-ID: Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain Puranjay Mohan writes: > Changes in v2->v3: > v2: https://lore.kernel.org/all/20250811111828.13836-1-puranjay@kernel.org/ > - Improved the selftest to check the exact fault address > - Dropped BPF_NO_KFUNC_PROTOTYPES and bpf_arena_alloc/free_pages() usage > - Rebased on bpf-next/master > > Changes in v1->v2: > v1: https://lore.kernel.org/all/20250806085847.18633-1-puranjay@kernel.org/ > - Changed variable and mask names for consistency (Yonghong) > - Added Acked-by: Yonghong Song on two patches > > This set adds the support of reporting page faults inside arena to BPF > stderr stream. The reported address is the one that a user would expect > to see if they pass it to bpf_printk(); > > Here is an example output from a stream and bpf_printk() > > ERROR: Arena WRITE access at unmapped address 0xdeaddead0000 > CPU: 9 UID: 0 PID: 502 Comm: test_progs > Call trace: > bpf_stream_stage_dump_stack+0xc0/0x150 > bpf_prog_report_arena_violation+0x98/0xf0 > ex_handler_bpf+0x5c/0x78 > fixup_exception+0xf8/0x160 > __do_kernel_fault+0x40/0x188 > do_bad_area+0x70/0x88 > do_translation_fault+0x54/0x98 > do_mem_abort+0x4c/0xa8 > el1_abort+0x44/0x70 > el1h_64_sync_handler+0x50/0x108 > el1h_64_sync+0x6c/0x70 > bpf_prog_a64a9778d31b8e88_stream_arena_write_fault+0x84/0xc8 > *(page) = 1; @ stream.c:100 > bpf_prog_test_run_syscall+0x100/0x328 > __sys_bpf+0x508/0xb98 > __arm64_sys_bpf+0x2c/0x48 > invoke_syscall+0x50/0x120 > el0_svc_common.constprop.0+0x48/0xf8 > do_el0_svc+0x28/0x40 > el0_svc+0x48/0xf8 > el0t_64_sync_handler+0xa0/0xe8 > el0t_64_sync+0x198/0x1a0 > > Same address is seen by using bpf_printk(): > > 1389.078831: bpf_trace_printk: Read Address: 0xdeaddead0000 > > To make this possible, some extra metadata has to be passed to the bpf > exception handler, so the bpf exception handling mechanism for both > x86-64 and arm64 have been improved in this set. > > The streams selftest has been updated to also test this new feature. > > Puranjay Mohan (3): > bpf: arm64: simplify exception table handling > bpf: Report arena faults to BPF stderr > selftests/bpf: Add tests for arena fault reporting > Please ignore this version!!! I forgot to fix a build issue in this version, it triggers when BPF_SYSCALL is disabled but JIT is enabled. I have sent another version to fix this. v4 including the fix: https://lore.kernel.org/all/20250827153728.28115-1-puranjay@kernel.org/ Thanks, Puranjay