On Tue, Mar 12, 2024 at 9:49 AM Alexei Starovoitov alexei.starovoitov@gmail.com wrote:
On Mon, Mar 11, 2024 at 2:34 AM Menglong Dong dongmenglong.8@bytedance.com wrote:
Refactor the struct modules_array to more general struct ptr_array, which is used to store the pointers.
Meanwhiles, introduce the bpf_try_add_ptr(), which checks the existing of the ptr before adding it to the array.
Seems it should be moved to another files in "lib", and I'm not sure where to add it now, and let's move it to kernel/bpf/syscall.c for now.
Signed-off-by: Menglong Dong dongmenglong.8@bytedance.com
include/linux/bpf.h | 10 +++++++++ kernel/bpf/syscall.c | 37 +++++++++++++++++++++++++++++++ kernel/trace/bpf_trace.c | 48 ++++++---------------------------------- 3 files changed, 54 insertions(+), 41 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 0f677fdcfcc7..997765cdf474 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -304,6 +304,16 @@ struct bpf_map { s64 __percpu *elem_count; };
+struct ptr_array {
void **ptrs;int cnt;int cap;+};
+int bpf_add_ptr(struct ptr_array *arr, void *ptr); +bool bpf_has_ptr(struct ptr_array *arr, struct module *mod); +int bpf_try_add_ptr(struct ptr_array *arr, void *ptr);
static inline const char *btf_field_type_name(enum btf_field_type type) { switch (type) { diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index f63f4da4db5e..4f230fd1f8e4 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -479,6 +479,43 @@ static void bpf_map_release_memcg(struct bpf_map *map) } #endif
+int bpf_add_ptr(struct ptr_array *arr, void *ptr) +{
void **ptrs;if (arr->cnt == arr->cap) {arr->cap = max(16, arr->cap * 3 / 2);ptrs = krealloc_array(arr->ptrs, arr->cap, sizeof(*ptrs), GFP_KERNEL);if (!ptrs)return -ENOMEM;arr->ptrs = ptrs;}arr->ptrs[arr->cnt] = ptr;arr->cnt++;return 0;+}
+bool bpf_has_ptr(struct ptr_array *arr, struct module *mod)
Don't you need 'void *mod' here?
Oops, it should be void *ptr here, my mistake~
+{
int i;for (i = arr->cnt - 1; i >= 0; i--) {if (arr->ptrs[i] == mod)return true;}return false;+}
...
kprobe_multi_put_modules(arr.mods, arr.mods_cnt);kfree(arr.mods);
kprobe_multi_put_modules((struct module **)arr.ptrs, arr.cnt);Do you really need to type cast? Compiler doesn't convert void** automatically?
Yeah, the compiler reports errors without this casting.