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5ddafcc3 |
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10-May-2024 |
Cupertino Miranda <cupertino.miranda@oracle.com> |
selftests/bpf: Fix a few tests for GCC related warnings. This patch corrects a few warnings to allow selftests to compile for GCC. -- progs/cpumask_failure.c -- progs/bpf_misc.h:136:22: error: ‘cpumask’ is used uninitialized [-Werror=uninitialized] 136 | #define __sink(expr) asm volatile("" : "+g"(expr)) | ^~~ progs/cpumask_failure.c:68:9: note: in expansion of macro ‘__sink’ 68 | __sink(cpumask); The macro __sink(cpumask) with the '+' contraint modifier forces the the compiler to expect a read and write from cpumask. GCC detects that cpumask is never initialized and reports an error. This patch removes the spurious non required definitions of cpumask. -- progs/dynptr_fail.c -- progs/dynptr_fail.c:1444:9: error: ‘ptr1’ may be used uninitialized [-Werror=maybe-uninitialized] 1444 | bpf_dynptr_clone(&ptr1, &ptr2); Many of the tests in the file are related to the detection of uninitialized pointers by the verifier. GCC is able to detect possible uninitialized values, and reports this as an error. The patch initializes all of the previous uninitialized structs. -- progs/test_tunnel_kern.c -- progs/test_tunnel_kern.c:590:9: error: array subscript 1 is outside array bounds of ‘struct geneve_opt[1]’ [-Werror=array-bounds=] 590 | *(int *) &gopt.opt_data = bpf_htonl(0xdeadbeef); | ^~~~~~~~~~~~~~~~~~~~~~~ progs/test_tunnel_kern.c:575:27: note: at offset 4 into object ‘gopt’ of size 4 575 | struct geneve_opt gopt; This tests accesses beyond the defined data for the struct geneve_opt which contains as last field "u8 opt_data[0]" which clearly does not get reserved space (in stack) in the function header. This pattern is repeated in ip6geneve_set_tunnel and geneve_set_tunnel functions. GCC is able to see this and emits a warning. The patch introduces a local struct that allocates enough space to safely allow the write to opt_data field. -- progs/jeq_infer_not_null_fail.c -- progs/jeq_infer_not_null_fail.c:21:40: error: array subscript ‘struct bpf_map[0]’ is partly outside array bounds of ‘struct <anonymous>[1]’ [-Werror=array-bounds=] 21 | struct bpf_map *inner_map = map->inner_map_meta; | ^~ progs/jeq_infer_not_null_fail.c:14:3: note: object ‘m_hash’ of size 32 14 | } m_hash SEC(".maps"); This example defines m_hash in the context of the compilation unit and casts it to struct bpf_map which is much smaller than the size of struct bpf_map. It errors out in GCC when it attempts to access an element that would be defined in struct bpf_map outsize of the defined limits for m_hash. This patch disables the warning through a GCC pragma. This changes were tested in bpf-next master selftests without any regressions. Signed-off-by: Cupertino Miranda <cupertino.miranda@oracle.com> Cc: jose.marchesi@oracle.com Cc: david.faust@oracle.com Cc: Yonghong Song <yonghong.song@linux.dev> Cc: Eduard Zingerman <eddyz87@gmail.com> Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com> Link: https://lore.kernel.org/r/20240510183850.286661-2-cupertino.miranda@oracle.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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67efbd57 |
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30-Mar-2023 |
David Vernet <void@manifault.com> |
selftests/bpf: Add testcases for ptr_*_or_null_ in bpf_kptr_xchg The second argument of the bpf_kptr_xchg() helper function is ARG_PTR_TO_BTF_ID_OR_NULL. A recent patch fixed a bug whereby the verifier would fail with an internal error message if a program invoked the helper with a PTR_TO_BTF_ID | PTR_MAYBE_NULL register. This testcase adds some testcases to ensure that it fails gracefully moving forward. Before the fix, these testcases would have failed an error resembling the following: ; p = bpf_kfunc_call_test_acquire(&(unsigned long){0}); 99: (7b) *(u64 *)(r10 -16) = r7 ; frame1: ... 100: (bf) r1 = r10 ; frame1: ... 101: (07) r1 += -16 ; frame1: ... ; p = bpf_kfunc_call_test_acquire(&(unsigned long){0}); 102: (85) call bpf_kfunc_call_test_acquire#13908 ; frame1: R0_w=ptr_or_null_prog_test_ref_kfunc... ; p = bpf_kptr_xchg(&v->ref_ptr, p); 103: (bf) r1 = r6 ; frame1: ... 104: (bf) r2 = r0 ; frame1: R0_w=ptr_or_null_prog_test_ref_kfunc... 105: (85) call bpf_kptr_xchg#194 verifier internal error: invalid PTR_TO_BTF_ID register for type match Signed-off-by: David Vernet <void@manifault.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20230330145203.80506-2-void@manifault.com
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1b403ce7 |
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15-Mar-2023 |
David Vernet <void@manifault.com> |
bpf: Remove bpf_cpumask_kptr_get() kfunc Now that struct bpf_cpumask is RCU safe, there's no need for this kfunc. Rather than doing the following: private(MASK) static struct bpf_cpumask __kptr *global; int BPF_PROG(prog, s32 cpu, ...) { struct bpf_cpumask *cpumask; bpf_rcu_read_lock(); cpumask = bpf_cpumask_kptr_get(&global); if (!cpumask) { bpf_rcu_read_unlock(); return -1; } bpf_cpumask_setall(cpumask); ... bpf_cpumask_release(cpumask); bpf_rcu_read_unlock(); } Programs can instead simply do (assume same global cpumask): int BPF_PROG(prog, ...) { struct bpf_cpumask *cpumask; bpf_rcu_read_lock(); cpumask = global; if (!cpumask) { bpf_rcu_read_unlock(); return -1; } bpf_cpumask_setall(cpumask); ... bpf_rcu_read_unlock(); } In other words, no extra atomic acquire / release, and less boilerplate code. This patch removes both the kfunc, as well as its selftests and documentation. Signed-off-by: David Vernet <void@manifault.com> Link: https://lore.kernel.org/r/20230316054028.88924-5-void@manifault.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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a5a197df |
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15-Mar-2023 |
David Vernet <void@manifault.com> |
bpf/selftests: Test using global cpumask kptr with RCU Now that struct bpf_cpumask * is considered an RCU-safe type according to the verifier, we should add tests that validate its common usages. This patch adds those tests to the cpumask test suite. A subsequent changes will remove bpf_cpumask_kptr_get(), and will adjust the selftest and BPF documentation accordingly. Signed-off-by: David Vernet <void@manifault.com> Link: https://lore.kernel.org/r/20230316054028.88924-4-void@manifault.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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c8ed6685 |
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08-Mar-2023 |
Andrii Nakryiko <andrii@kernel.org> |
selftests/bpf: fix lots of silly mistakes pointed out by compiler Once we enable -Wall for BPF sources, compiler will complain about lots of unused variables, variables that are set but never read, etc. Fix all these issues first before enabling -Wall in Makefile. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20230309054015.4068562-4-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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6fcd486b |
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02-Mar-2023 |
Alexei Starovoitov <ast@kernel.org> |
bpf: Refactor RCU enforcement in the verifier. bpf_rcu_read_lock/unlock() are only available in clang compiled kernels. Lack of such key mechanism makes it impossible for sleepable bpf programs to use RCU pointers. Allow bpf_rcu_read_lock/unlock() in GCC compiled kernels (though GCC doesn't support btf_type_tag yet) and allowlist certain field dereferences in important data structures like tast_struct, cgroup, socket that are used by sleepable programs either as RCU pointer or full trusted pointer (which is valid outside of RCU CS). Use BTF_TYPE_SAFE_RCU and BTF_TYPE_SAFE_TRUSTED macros for such tagging. They will be removed once GCC supports btf_type_tag. With that refactor check_ptr_to_btf_access(). Make it strict in enforcing PTR_TRUSTED and PTR_UNTRUSTED while deprecating old PTR_TO_BTF_ID without modifier flags. There is a chance that this strict enforcement might break existing programs (especially on GCC compiled kernels), but this cleanup has to start sooner than later. Note PTR_TO_CTX access still yields old deprecated PTR_TO_BTF_ID. Once it's converted to strict PTR_TRUSTED or PTR_UNTRUSTED the kfuncs and helpers will be able to default to KF_TRUSTED_ARGS. KF_RCU will remain as a weaker version of KF_TRUSTED_ARGS where obj refcnt could be 0. Adjust rcu_read_lock selftest to run on gcc and clang compiled kernels. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: David Vernet <void@manifault.com> Link: https://lore.kernel.org/bpf/20230303041446.3630-7-alexei.starovoitov@gmail.com
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7b6abcfa |
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25-Jan-2023 |
David Vernet <void@manifault.com> |
selftests/bpf: Add selftest suite for cpumask kfuncs A recent patch added a new set of kfuncs for allocating, freeing, manipulating, and querying cpumasks. This patch adds a new 'cpumask' selftest suite which verifies their behavior. Signed-off-by: David Vernet <void@manifault.com> Link: https://lore.kernel.org/r/20230125143816.721952-5-void@manifault.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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