From 950ad93df2fce70445e655ed2e74f5c1a8653ab2 Mon Sep 17 00:00:00 2001 From: Emil Tsalapatis Date: Sun, 9 Mar 2025 19:04:24 -0400 Subject: [PATCH 1/4] bpf: add kfunc for populating cpumask bits Add a helper kfunc that sets the bitmap of a bpf_cpumask from BPF memory. Signed-off-by: Emil Tsalapatis (Meta) Acked-by: Hou Tao Acked-by: Tejun Heo Link: https://lore.kernel.org/r/20250309230427.26603-2-emil@etsalapatis.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/cpumask.c | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) diff --git a/kernel/bpf/cpumask.c b/kernel/bpf/cpumask.c index cfa1c18e3a48..77900cbbbd75 100644 --- a/kernel/bpf/cpumask.c +++ b/kernel/bpf/cpumask.c @@ -420,6 +420,38 @@ __bpf_kfunc u32 bpf_cpumask_weight(const struct cpumask *cpumask) return cpumask_weight(cpumask); } +/** + * bpf_cpumask_populate() - Populate the CPU mask from the contents of + * a BPF memory region. + * + * @cpumask: The cpumask being populated. + * @src: The BPF memory holding the bit pattern. + * @src__sz: Length of the BPF memory region in bytes. + * + * Return: + * * 0 if the struct cpumask * instance was populated successfully. + * * -EACCES if the memory region is too small to populate the cpumask. + * * -EINVAL if the memory region is not aligned to the size of a long + * and the architecture does not support efficient unaligned accesses. + */ +__bpf_kfunc int bpf_cpumask_populate(struct cpumask *cpumask, void *src, size_t src__sz) +{ + unsigned long source = (unsigned long)src; + + /* The memory region must be large enough to populate the entire CPU mask. */ + if (src__sz < bitmap_size(nr_cpu_ids)) + return -EACCES; + + /* If avoiding unaligned accesses, the input region must be aligned to the nearest long. */ + if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && + !IS_ALIGNED(source, sizeof(long))) + return -EINVAL; + + bitmap_copy(cpumask_bits(cpumask), src, nr_cpu_ids); + + return 0; +} + __bpf_kfunc_end_defs(); BTF_KFUNCS_START(cpumask_kfunc_btf_ids) @@ -448,6 +480,7 @@ BTF_ID_FLAGS(func, bpf_cpumask_copy, KF_RCU) BTF_ID_FLAGS(func, bpf_cpumask_any_distribute, KF_RCU) BTF_ID_FLAGS(func, bpf_cpumask_any_and_distribute, KF_RCU) BTF_ID_FLAGS(func, bpf_cpumask_weight, KF_RCU) +BTF_ID_FLAGS(func, bpf_cpumask_populate, KF_RCU) BTF_KFUNCS_END(cpumask_kfunc_btf_ids) static const struct btf_kfunc_id_set cpumask_kfunc_set = { From 918ba2636d4ea97d0aebaad37353b2412d4c2935 Mon Sep 17 00:00:00 2001 From: Emil Tsalapatis Date: Sun, 9 Mar 2025 19:04:25 -0400 Subject: [PATCH 2/4] selftests: bpf: add bpf_cpumask_populate selftests Add selftests for the bpf_cpumask_populate helper that sets a bpf_cpumask to a bit pattern provided by a BPF program. Signed-off-by: Emil Tsalapatis (Meta) Acked-by: Hou Tao Link: https://lore.kernel.org/r/20250309230427.26603-3-emil@etsalapatis.com Signed-off-by: Alexei Starovoitov --- .../selftests/bpf/prog_tests/cpumask.c | 3 + .../selftests/bpf/progs/cpumask_common.h | 1 + .../selftests/bpf/progs/cpumask_failure.c | 38 ++++++ .../selftests/bpf/progs/cpumask_success.c | 119 ++++++++++++++++++ 4 files changed, 161 insertions(+) diff --git a/tools/testing/selftests/bpf/prog_tests/cpumask.c b/tools/testing/selftests/bpf/prog_tests/cpumask.c index e58a04654238..9b09beba988b 100644 --- a/tools/testing/selftests/bpf/prog_tests/cpumask.c +++ b/tools/testing/selftests/bpf/prog_tests/cpumask.c @@ -25,6 +25,9 @@ static const char * const cpumask_success_testcases[] = { "test_global_mask_nested_deep_rcu", "test_global_mask_nested_deep_array_rcu", "test_cpumask_weight", + "test_populate_reject_small_mask", + "test_populate_reject_unaligned", + "test_populate", }; static void verify_success(const char *prog_name) diff --git a/tools/testing/selftests/bpf/progs/cpumask_common.h b/tools/testing/selftests/bpf/progs/cpumask_common.h index 4ece7873ba60..86085b79f5ca 100644 --- a/tools/testing/selftests/bpf/progs/cpumask_common.h +++ b/tools/testing/selftests/bpf/progs/cpumask_common.h @@ -61,6 +61,7 @@ u32 bpf_cpumask_any_distribute(const struct cpumask *src) __ksym __weak; u32 bpf_cpumask_any_and_distribute(const struct cpumask *src1, const struct cpumask *src2) __ksym __weak; u32 bpf_cpumask_weight(const struct cpumask *cpumask) __ksym __weak; +int bpf_cpumask_populate(struct cpumask *cpumask, void *src, size_t src__sz) __ksym __weak; void bpf_rcu_read_lock(void) __ksym __weak; void bpf_rcu_read_unlock(void) __ksym __weak; diff --git a/tools/testing/selftests/bpf/progs/cpumask_failure.c b/tools/testing/selftests/bpf/progs/cpumask_failure.c index b40b52548ffb..8a2fd596c8a3 100644 --- a/tools/testing/selftests/bpf/progs/cpumask_failure.c +++ b/tools/testing/selftests/bpf/progs/cpumask_failure.c @@ -222,3 +222,41 @@ int BPF_PROG(test_invalid_nested_array, struct task_struct *task, u64 clone_flag return 0; } + +SEC("tp_btf/task_newtask") +__failure __msg("type=scalar expected=fp") +int BPF_PROG(test_populate_invalid_destination, struct task_struct *task, u64 clone_flags) +{ + struct bpf_cpumask *invalid = (struct bpf_cpumask *)0x123456; + u64 bits; + int ret; + + ret = bpf_cpumask_populate((struct cpumask *)invalid, &bits, sizeof(bits)); + if (!ret) + err = 2; + + return 0; +} + +SEC("tp_btf/task_newtask") +__failure __msg("leads to invalid memory access") +int BPF_PROG(test_populate_invalid_source, struct task_struct *task, u64 clone_flags) +{ + void *garbage = (void *)0x123456; + struct bpf_cpumask *local; + int ret; + + local = create_cpumask(); + if (!local) { + err = 1; + return 0; + } + + ret = bpf_cpumask_populate((struct cpumask *)local, garbage, 8); + if (!ret) + err = 2; + + bpf_cpumask_release(local); + + return 0; +} diff --git a/tools/testing/selftests/bpf/progs/cpumask_success.c b/tools/testing/selftests/bpf/progs/cpumask_success.c index 80ee469b0b60..91a5357769a8 100644 --- a/tools/testing/selftests/bpf/progs/cpumask_success.c +++ b/tools/testing/selftests/bpf/progs/cpumask_success.c @@ -770,3 +770,122 @@ int BPF_PROG(test_refcount_null_tracking, struct task_struct *task, u64 clone_fl bpf_cpumask_release(mask2); return 0; } + +SEC("tp_btf/task_newtask") +int BPF_PROG(test_populate_reject_small_mask, struct task_struct *task, u64 clone_flags) +{ + struct bpf_cpumask *local; + u8 toofewbits; + int ret; + + if (!is_test_task()) + return 0; + + local = create_cpumask(); + if (!local) + return 0; + + /* The kfunc should prevent this operation */ + ret = bpf_cpumask_populate((struct cpumask *)local, &toofewbits, sizeof(toofewbits)); + if (ret != -EACCES) + err = 2; + + bpf_cpumask_release(local); + + return 0; +} + +/* Mask is guaranteed to be large enough for bpf_cpumask_t. */ +#define CPUMASK_TEST_MASKLEN (sizeof(cpumask_t)) + +/* Add an extra word for the test_populate_reject_unaligned test. */ +u64 bits[CPUMASK_TEST_MASKLEN / 8 + 1]; +extern bool CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS __kconfig __weak; + +SEC("tp_btf/task_newtask") +int BPF_PROG(test_populate_reject_unaligned, struct task_struct *task, u64 clone_flags) +{ + struct bpf_cpumask *mask; + char *src; + int ret; + + if (!is_test_task()) + return 0; + + /* Skip if unaligned accesses are fine for this arch. */ + if (CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) + return 0; + + mask = bpf_cpumask_create(); + if (!mask) { + err = 1; + return 0; + } + + /* Misalign the source array by a byte. */ + src = &((char *)bits)[1]; + + ret = bpf_cpumask_populate((struct cpumask *)mask, src, CPUMASK_TEST_MASKLEN); + if (ret != -EINVAL) + err = 2; + + bpf_cpumask_release(mask); + + return 0; +} + + +SEC("tp_btf/task_newtask") +int BPF_PROG(test_populate, struct task_struct *task, u64 clone_flags) +{ + struct bpf_cpumask *mask; + bool bit; + int ret; + int i; + + if (!is_test_task()) + return 0; + + /* Set only odd bits. */ + __builtin_memset(bits, 0xaa, CPUMASK_TEST_MASKLEN); + + mask = bpf_cpumask_create(); + if (!mask) { + err = 1; + return 0; + } + + /* Pass the entire bits array, the kfunc will only copy the valid bits. */ + ret = bpf_cpumask_populate((struct cpumask *)mask, bits, CPUMASK_TEST_MASKLEN); + if (ret) { + err = 2; + goto out; + } + + /* + * Test is there to appease the verifier. We cannot directly + * access NR_CPUS, the upper bound for nr_cpus, so we infer + * it from the size of cpumask_t. + */ + if (nr_cpus < 0 || nr_cpus >= CPUMASK_TEST_MASKLEN * 8) { + err = 3; + goto out; + } + + bpf_for(i, 0, nr_cpus) { + /* Odd-numbered bits should be set, even ones unset. */ + bit = bpf_cpumask_test_cpu(i, (const struct cpumask *)mask); + if (bit == (i % 2 != 0)) + continue; + + err = 4; + break; + } + +out: + bpf_cpumask_release(mask); + + return 0; +} + +#undef CPUMASK_TEST_MASKLEN From 014eb5c2d6351b428b10fb063a89c64436925eb2 Mon Sep 17 00:00:00 2001 From: Emil Tsalapatis Date: Sun, 9 Mar 2025 19:04:26 -0400 Subject: [PATCH 3/4] bpf: fix missing kdoc string fields in cpumask.c Some bpf_cpumask-related kfuncs have kdoc strings that are missing return values. Add a the missing descriptions for the return values. Reported-by: Alexei Starovoitov Signed-off-by: Emil Tsalapatis (Meta) Acked-by: Hou Tao Link: https://lore.kernel.org/r/20250309230427.26603-4-emil@etsalapatis.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/cpumask.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/kernel/bpf/cpumask.c b/kernel/bpf/cpumask.c index 77900cbbbd75..9876c5fe6c2a 100644 --- a/kernel/bpf/cpumask.c +++ b/kernel/bpf/cpumask.c @@ -45,6 +45,10 @@ __bpf_kfunc_start_defs(); * * bpf_cpumask_create() allocates memory using the BPF memory allocator, and * will not block. It may return NULL if no memory is available. + * + * Return: + * * A pointer to a new struct bpf_cpumask instance on success. + * * NULL if the BPF memory allocator is out of memory. */ __bpf_kfunc struct bpf_cpumask *bpf_cpumask_create(void) { @@ -71,6 +75,10 @@ __bpf_kfunc struct bpf_cpumask *bpf_cpumask_create(void) * Acquires a reference to a BPF cpumask. The cpumask returned by this function * must either be embedded in a map as a kptr, or freed with * bpf_cpumask_release(). + * + * Return: + * * The struct bpf_cpumask pointer passed to the function. + * */ __bpf_kfunc struct bpf_cpumask *bpf_cpumask_acquire(struct bpf_cpumask *cpumask) { @@ -106,6 +114,9 @@ CFI_NOSEAL(bpf_cpumask_release_dtor); * * Find the index of the first nonzero bit of the cpumask. A struct bpf_cpumask * pointer may be safely passed to this function. + * + * Return: + * * The index of the first nonzero bit in the struct cpumask. */ __bpf_kfunc u32 bpf_cpumask_first(const struct cpumask *cpumask) { @@ -119,6 +130,9 @@ __bpf_kfunc u32 bpf_cpumask_first(const struct cpumask *cpumask) * * Find the index of the first unset bit of the cpumask. A struct bpf_cpumask * pointer may be safely passed to this function. + * + * Return: + * * The index of the first zero bit in the struct cpumask. */ __bpf_kfunc u32 bpf_cpumask_first_zero(const struct cpumask *cpumask) { @@ -133,6 +147,9 @@ __bpf_kfunc u32 bpf_cpumask_first_zero(const struct cpumask *cpumask) * * Find the index of the first nonzero bit of the AND of two cpumasks. * struct bpf_cpumask pointers may be safely passed to @src1 and @src2. + * + * Return: + * * The index of the first bit that is nonzero in both cpumask instances. */ __bpf_kfunc u32 bpf_cpumask_first_and(const struct cpumask *src1, const struct cpumask *src2) @@ -414,6 +431,9 @@ __bpf_kfunc u32 bpf_cpumask_any_and_distribute(const struct cpumask *src1, * @cpumask: The cpumask being queried. * * Count the number of set bits in the given cpumask. + * + * Return: + * * The number of bits set in the mask. */ __bpf_kfunc u32 bpf_cpumask_weight(const struct cpumask *cpumask) { From c06707ff07689b0ff026e68caabe6f2a85f40caf Mon Sep 17 00:00:00 2001 From: Emil Tsalapatis Date: Sun, 9 Mar 2025 19:04:27 -0400 Subject: [PATCH 4/4] selftests: bpf: fix duplicate selftests in cpumask_success. The BPF cpumask selftests are currently run twice in test_progs/cpumask.c, once by traversing cpumask_success_testcases, and once by invoking RUN_TESTS(cpumask_success). Remove the invocation of RUN_TESTS to properly run the selftests only once. Now that the tests are run only through cpumask_success_testscases, add to it the missing test_refcount_null_tracking testcase. Also remove the __success annotation from it, since it is now loaded and invoked by the runner. Signed-off-by: Emil Tsalapatis (Meta) Acked-by: Hou Tao Link: https://lore.kernel.org/r/20250309230427.26603-5-emil@etsalapatis.com Signed-off-by: Alexei Starovoitov --- tools/testing/selftests/bpf/prog_tests/cpumask.c | 2 +- tools/testing/selftests/bpf/progs/cpumask_success.c | 1 - 2 files changed, 1 insertion(+), 2 deletions(-) diff --git a/tools/testing/selftests/bpf/prog_tests/cpumask.c b/tools/testing/selftests/bpf/prog_tests/cpumask.c index 9b09beba988b..6c45330a5ca3 100644 --- a/tools/testing/selftests/bpf/prog_tests/cpumask.c +++ b/tools/testing/selftests/bpf/prog_tests/cpumask.c @@ -25,6 +25,7 @@ static const char * const cpumask_success_testcases[] = { "test_global_mask_nested_deep_rcu", "test_global_mask_nested_deep_array_rcu", "test_cpumask_weight", + "test_refcount_null_tracking", "test_populate_reject_small_mask", "test_populate_reject_unaligned", "test_populate", @@ -81,6 +82,5 @@ void test_cpumask(void) verify_success(cpumask_success_testcases[i]); } - RUN_TESTS(cpumask_success); RUN_TESTS(cpumask_failure); } diff --git a/tools/testing/selftests/bpf/progs/cpumask_success.c b/tools/testing/selftests/bpf/progs/cpumask_success.c index 91a5357769a8..0e04c31b91c0 100644 --- a/tools/testing/selftests/bpf/progs/cpumask_success.c +++ b/tools/testing/selftests/bpf/progs/cpumask_success.c @@ -749,7 +749,6 @@ int BPF_PROG(test_cpumask_weight, struct task_struct *task, u64 clone_flags) } SEC("tp_btf/task_newtask") -__success int BPF_PROG(test_refcount_null_tracking, struct task_struct *task, u64 clone_flags) { struct bpf_cpumask *mask1, *mask2;