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 98B8931353F for ; Thu, 11 Sep 2025 14:58:13 +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=1757602695; cv=none; b=s0ukDnVG2/7jRKPGTBLnpvfdij0uok+jRjWUgYA9Zg+q3QYnHV/jjvPjq7DXvUjx0c5Ie3QDmUkAm4WV6v8sek/aHSLBAf3z4F7pvTnVV37JbPqdRjRLaDLjmiACJdygyPL4GHtQoEH6IVU/Y4H9k/XQdJxclo3wNTric+U9wKo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757602695; c=relaxed/simple; bh=EnAdwCERZJ/Z74qP6hatDxaYc/F9+WzCeBLkwXRCcSk=; h=From:To:Subject:Date:Message-ID:MIME-Version; b=C3CJF/NB4eFXpIgV2Hg+l8HpPfaZd2H2JsuOBEoPgg5Q3LpVBDkey/41akIMHb/IHdKjfpKXa2hx9FtZeud6TRqJ4g3c2y5Tdb0hvus4ZX6tpVThokpiqFAMI3DFDQdci8hZR6Qw3JQuUq64tty0HosxUh+TwtJLkrPgev31o38= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=tIVMaknP; 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="tIVMaknP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EB1F6C4CEF0; Thu, 11 Sep 2025 14:58:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1757602693; bh=EnAdwCERZJ/Z74qP6hatDxaYc/F9+WzCeBLkwXRCcSk=; h=From:To:Subject:Date:From; b=tIVMaknP8fg7S/7h9yTsxt0sx7/lRDqbKWprFBwg/KfIK1UQh5HM2GjEQ/99Y9QQV JCuh6DSGjHtOJWvS7lO1BfpDDj9jZCEWiQPc3DPr7l49MY089G41fGACxDHhavVUg6 hChxSrkTvmkKsfDN0DJFRexfYqgMJ7yk6/tqzSXRrv8FP0MjFlwcnD/zd3CssrqPr8 SYK6f9ifHnRpXsDSPfuXxJcAYzM4hiw8aGug82KHS3MLwRaA5MOCgjmzO3PKNGP0U0 iTBSdVgp1k0hLq59dyUrhEayEuyVz/fZvyHLuKnK+5lbkzzlBwhq2tSpaCcpkrw6c4 3Nv9v7CpiNdSw== 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 , Puranjay Mohan , Xu Kuohai , Catalin Marinas , Will Deacon , Kumar Kartikeya Dwivedi , bpf@vger.kernel.org Subject: [PATCH bpf-next v7 0/6] bpf: report arena faults to BPF streams Date: Thu, 11 Sep 2025 14:57:59 +0000 Message-ID: <20250911145808.58042-1-puranjay@kernel.org> X-Mailer: git-send-email 2.47.3 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Changes in v6->v7: v6: https://lore.kernel.org/all/20250908163638.23150-1-puranjay@kernel.org/ - Added comments about the usage of arena_reg in x86 and arm64 jits. (Alexei) - Used clear_lo32() for clearing the lower 32-bits of user_vm_start. (Alexei) - Moved update of the old tests to use __stderr to a separate commit (Eduard) - Used test__skip() in prog_tests/stream.c (Eduard) - Start a sub-test for read / write Changes in v5->v6: v5: https://lore.kernel.org/all/20250901193730.43543-1-puranjay@kernel.org/ - Introduces __stderr and __stdout for easy testing of bpf streams (Eduard) - Add more test cases for arena fault reporting (subprog and callback) - Fix main_prog_aux usage and return main_prog from find_from_stack_cb (Kumar) - Properly fix the build issue reported by kernel test robot Changes in v4->v5: v4: https://lore.kernel.org/all/20250827153728.28115-1-puranjay@kernel.org/ - Added patch 2 to introducing main_prog_aux for easier access to streams. - Fixed bug in fault handlers when arena_reg == dst_reg - Updated selftest to check test above edge case. - Added comments about the usage of barrier_var() in code and commit message. Changes in v3->v4: v3: https://lore.kernel.org/all/20250827150113.15763-1-puranjay@kernel.org/ - Fixed a build issue when CONFIG_BPF_JIT=y and # CONFIG_BPF_SYSCALL is not set 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 the stderr 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 printed by 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 test this new feature. Puranjay Mohan (6): bpf: arm64: simplify exception table handling bpf: core: introduce main_prog_aux for stream access bpf: Report arena faults to BPF stderr selftests: bpf: introduce __stderr and __stdout selftests: bpf: use __stderr in stream error tests selftests/bpf: Add tests for arena fault reporting arch/arm64/net/bpf_jit_comp.c | 85 +++++++--- arch/x86/net/bpf_jit_comp.c | 85 +++++++++- include/linux/bpf.h | 7 + kernel/bpf/arena.c | 30 ++++ kernel/bpf/core.c | 6 +- kernel/bpf/verifier.c | 1 + .../testing/selftests/bpf/prog_tests/stream.c | 131 ++++++--------- tools/testing/selftests/bpf/progs/bpf_misc.h | 10 ++ tools/testing/selftests/bpf/progs/stream.c | 158 ++++++++++++++++++ tools/testing/selftests/bpf/test_loader.c | 90 ++++++++++ 10 files changed, 491 insertions(+), 112 deletions(-) -- 2.47.3