Commit c68a78ff authored by Chuyi Zhou's avatar Chuyi Zhou Committed by Alexei Starovoitov
Browse files

bpf: Introduce task open coded iterator kfuncs 



This patch adds kfuncs bpf_iter_task_{new,next,destroy} which allow
creation and manipulation of struct bpf_iter_task in open-coded iterator
style. BPF programs can use these kfuncs or through bpf_for_each macro to
iterate all processes in the system.

The API design keep consistent with SEC("iter/task"). bpf_iter_task_new()
accepts a specific task and iterating type which allows:

1. iterating all process in the system (BPF_TASK_ITER_ALL_PROCS)

2. iterating all threads in the system (BPF_TASK_ITER_ALL_THREADS)

3. iterating all threads of a specific task (BPF_TASK_ITER_PROC_THREADS)

Signed-off-by: default avatarChuyi Zhou <zhouchuyi@bytedance.com>
Link: https://lore.kernel.org/r/20231018061746.111364-4-zhouchuyi@bytedance.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 9c66dc94

kernel/bpf/helpers.c

+3 −0
Original line number Diff line number Diff line
@@ -2563,6 +2563,9 @@ BTF_ID_FLAGS(func, bpf_iter_task_vma_destroy, KF_ITER_DESTROY) 
BTF_ID_FLAGS(func, bpf_iter_css_task_new, KF_ITER_NEW | KF_TRUSTED_ARGS)

BTF_ID_FLAGS(func, bpf_iter_css_task_next, KF_ITER_NEXT | KF_RET_NULL)

BTF_ID_FLAGS(func, bpf_iter_css_task_destroy, KF_ITER_DESTROY)

BTF_ID_FLAGS(func, bpf_iter_task_new, KF_ITER_NEW | KF_TRUSTED_ARGS)

BTF_ID_FLAGS(func, bpf_iter_task_next, KF_ITER_NEXT | KF_RET_NULL)

BTF_ID_FLAGS(func, bpf_iter_task_destroy, KF_ITER_DESTROY)

BTF_ID_FLAGS(func, bpf_dynptr_adjust)

BTF_ID_FLAGS(func, bpf_dynptr_is_null)

BTF_ID_FLAGS(func, bpf_dynptr_is_rdonly)

kernel/bpf/task_iter.c

+90 −0
Original line number Diff line number Diff line
@@ -952,6 +952,96 @@ __bpf_kfunc void bpf_iter_css_task_destroy(struct bpf_iter_css_task *it) 


__diag_pop();



struct bpf_iter_task {

	__u64 __opaque[3];

} __attribute__((aligned(8)));



struct bpf_iter_task_kern {

	struct task_struct *task;

	struct task_struct *pos;

	unsigned int flags;

} __attribute__((aligned(8)));



enum {

	/* all process in the system */

	BPF_TASK_ITER_ALL_PROCS,

	/* all threads in the system */

	BPF_TASK_ITER_ALL_THREADS,

	/* all threads of a specific process */

	BPF_TASK_ITER_PROC_THREADS

};



__diag_push();

__diag_ignore_all("-Wmissing-prototypes",

		  "Global functions as their definitions will be in vmlinux BTF");



__bpf_kfunc int bpf_iter_task_new(struct bpf_iter_task *it,

		struct task_struct *task, unsigned int flags)

{

	struct bpf_iter_task_kern *kit = (void *)it;



	BUILD_BUG_ON(sizeof(struct bpf_iter_task_kern) > sizeof(struct bpf_iter_task));

	BUILD_BUG_ON(__alignof__(struct bpf_iter_task_kern) !=

					__alignof__(struct bpf_iter_task));



	kit->task = kit->pos = NULL;

	switch (flags) {

	case BPF_TASK_ITER_ALL_THREADS:

	case BPF_TASK_ITER_ALL_PROCS:

	case BPF_TASK_ITER_PROC_THREADS:

		break;

	default:

		return -EINVAL;

	}



	if (flags == BPF_TASK_ITER_PROC_THREADS)

		kit->task = task;

	else

		kit->task = &init_task;

	kit->pos = kit->task;

	kit->flags = flags;

	return 0;

}



__bpf_kfunc struct task_struct *bpf_iter_task_next(struct bpf_iter_task *it)

{

	struct bpf_iter_task_kern *kit = (void *)it;

	struct task_struct *pos;

	unsigned int flags;



	flags = kit->flags;

	pos = kit->pos;



	if (!pos)

		return pos;



	if (flags == BPF_TASK_ITER_ALL_PROCS)

		goto get_next_task;



	kit->pos = next_thread(kit->pos);

	if (kit->pos == kit->task) {

		if (flags == BPF_TASK_ITER_PROC_THREADS) {

			kit->pos = NULL;

			return pos;

		}

	} else

		return pos;



get_next_task:

	kit->pos = next_task(kit->pos);

	kit->task = kit->pos;

	if (kit->pos == &init_task)

		kit->pos = NULL;



	return pos;

}



__bpf_kfunc void bpf_iter_task_destroy(struct bpf_iter_task *it)

{

}



__diag_pop();



DEFINE_PER_CPU(struct mmap_unlock_irq_work, mmap_unlock_work);



static void do_mmap_read_unlock(struct irq_work *entry)

tools/testing/selftests/bpf/bpf_experimental.h

+5 −0
Original line number Diff line number Diff line
@@ -465,5 +465,10 @@ extern int bpf_iter_css_task_new(struct bpf_iter_css_task *it, 
extern struct task_struct *bpf_iter_css_task_next(struct bpf_iter_css_task *it) __weak __ksym;

extern void bpf_iter_css_task_destroy(struct bpf_iter_css_task *it) __weak __ksym;



struct bpf_iter_task;

extern int bpf_iter_task_new(struct bpf_iter_task *it,

		struct task_struct *task, unsigned int flags) __weak __ksym;

extern struct task_struct *bpf_iter_task_next(struct bpf_iter_task *it) __weak __ksym;

extern void bpf_iter_task_destroy(struct bpf_iter_task *it) __weak __ksym;



#endif