Commit f11f7cf9 authored by Alexei Starovoitov's avatar Alexei Starovoitov
Browse files

Merge branch 'bpf-add-bpf_stream_print_stack-kfunc' 

Emil Tsalapatis says:

====================
bpf: Add bpf_stream_print_stack kfunc

Add a new bpf_stream_print_stack kfunc for printing a BPF program stack
into a BPF stream. Update the verifier to allow the new kfunc to be
called with BPF spinlocks held, along with bpf_stream_vprintk.

Patchset spun out of the larger libarena + ASAN patchset.
(https://lore.kernel.org/bpf/20260127181610.86376-1-emil@etsalapatis.com/)

Changeset:
	- Update bpf_stream_print_stack to take stream_id arg (Kumar)
	- Added selftest for the bpf_stream_print_stack
	- Add selftest for calling the streams kfuncs under lock

v2->v1: (https://lore.kernel.org/bpf/20260202193311.446717-1-emil@etsalapatis.com/

)
	- Updated Signed-off-by to be consistent with past submissions
	- Updated From email to be consistent with Signed-off-by

Acked-by: default avatarKumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: default avatarEmil Tsalapatis <emil@etsalapatis.com>
====================

Link: https://patch.msgid.link/20260203180424.14057-1-emil@etsalapatis.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parents f941479a 4d99137e

kernel/bpf/helpers.c

+1 −0
Original line number Diff line number Diff line
@@ -4562,6 +4562,7 @@ BTF_ID_FLAGS(func, bpf_strncasestr); 
BTF_ID_FLAGS(func, bpf_cgroup_read_xattr, KF_RCU)

#endif

BTF_ID_FLAGS(func, bpf_stream_vprintk, KF_IMPLICIT_ARGS)

BTF_ID_FLAGS(func, bpf_stream_print_stack, KF_IMPLICIT_ARGS)

BTF_ID_FLAGS(func, bpf_task_work_schedule_signal, KF_IMPLICIT_ARGS)

BTF_ID_FLAGS(func, bpf_task_work_schedule_resume, KF_IMPLICIT_ARGS)

BTF_ID_FLAGS(func, bpf_dynptr_from_file)

kernel/bpf/stream.c

+19 −0
Original line number Diff line number Diff line
@@ -245,6 +245,25 @@ __bpf_kfunc int bpf_stream_vprintk(int stream_id, const char *fmt__str, const vo 
	return ret;

}



/* Directly trigger a stack dump from the program. */

__bpf_kfunc int bpf_stream_print_stack(int stream_id, struct bpf_prog_aux *aux)

{

	struct bpf_stream_stage ss;

	struct bpf_prog *prog;



	/* Make sure the stream ID is valid. */

	if (!bpf_stream_get(stream_id, aux))

		return -ENOENT;



	prog = aux->main_prog_aux->prog;



	bpf_stream_stage(ss, prog, stream_id, ({

		bpf_stream_dump_stack(ss);

	}));



	return 0;

}



__bpf_kfunc_end_defs();



/* Added kfunc to common_btf_ids */

kernel/bpf/verifier.c

+12 −1
Original line number Diff line number Diff line
@@ -12455,6 +12455,8 @@ enum special_kfunc_type { 
	KF_bpf_arena_free_pages,

	KF_bpf_arena_reserve_pages,

	KF_bpf_session_is_return,

	KF_bpf_stream_vprintk,

	KF_bpf_stream_print_stack,

};









BTF_ID_LIST(special_kfunc_list)








@@ -12533,6 +12535,8 @@ BTF_ID(func, bpf_arena_alloc_pages)







BTF_ID(func, bpf_arena_free_pages)









BTF_ID(func, bpf_arena_reserve_pages)









BTF_ID(func, bpf_session_is_return)









BTF_ID(func, bpf_stream_vprintk)









BTF_ID(func, bpf_stream_print_stack)

















static bool is_task_work_add_kfunc(u32 func_id)









{








@@ -12977,10 +12981,17 @@ static bool is_bpf_arena_kfunc(u32 btf_id)







	       btf_id == special_kfunc_list[KF_bpf_arena_reserve_pages];









}

















static bool is_bpf_stream_kfunc(u32 btf_id)









{









	return btf_id == special_kfunc_list[KF_bpf_stream_vprintk] ||









	       btf_id == special_kfunc_list[KF_bpf_stream_print_stack];









}

















static bool kfunc_spin_allowed(u32 btf_id)









{









	return is_bpf_graph_api_kfunc(btf_id) || is_bpf_iter_num_api_kfunc(btf_id) ||









	       is_bpf_res_spin_lock_kfunc(btf_id) || is_bpf_arena_kfunc(btf_id);









	       is_bpf_res_spin_lock_kfunc(btf_id) || is_bpf_arena_kfunc(btf_id) ||









	       is_bpf_stream_kfunc(btf_id);









}

















static bool is_sync_callback_calling_kfunc(u32 btf_id)
































tools/testing/selftests/bpf/progs/stream.c



+53
−0






























Original line number
Diff line number
Diff line







@@ -42,6 +42,10 @@ int size;







u64 fault_addr;









void *arena_ptr;



















#define private(name) SEC(".bss." #name) __hidden __attribute__((aligned(8)))



















private(STREAM) struct bpf_spin_lock block;



















SEC("syscall")









__success __retval(0)









int stream_exhaust(void *ctx)








@@ -234,4 +238,53 @@ int stream_arena_callback_fault(void *ctx)







	return 0;









}



















SEC("syscall")









__arch_x86_64









__arch_arm64









__success __retval(0)









__stderr("CPU: {{[0-9]+}} UID: 0 PID: {{[0-9]+}} Comm: {{.*}}")









__stderr("Call trace:\n"









"{{([a-zA-Z_][a-zA-Z0-9_]*\\+0x[0-9a-fA-F]+/0x[0-9a-fA-F]+\n"









"|[ \t]+[^\n]+\n)*}}")









int stream_print_stack_kfunc(void *ctx)









{









	return bpf_stream_print_stack(BPF_STDERR);









}



















SEC("syscall")









__success __retval(-2)









int stream_print_stack_invalid_id(void *ctx)









{









	/* Try to pass an invalid stream ID. */









	return bpf_stream_print_stack((enum bpf_stream_id)0xbadcafe);









}



















SEC("syscall")









__arch_x86_64









__arch_arm64









__success __retval(0)









__stdout(_STR)









__stderr("CPU: {{[0-9]+}} UID: 0 PID: {{[0-9]+}} Comm: {{.*}}")









__stderr("Call trace:\n"









"{{([a-zA-Z_][a-zA-Z0-9_]*\\+0x[0-9a-fA-F]+/0x[0-9a-fA-F]+\n"









"|[ \t]+[^\n]+\n)*}}")









int stream_print_kfuncs_locked(void *ctx)









{









	int ret;



















	bpf_spin_lock(&block);



















	ret = bpf_stream_printk(BPF_STDOUT, _STR);









	if (ret)









		goto out;



















	ret = bpf_stream_print_stack(BPF_STDERR);



















out:









	bpf_spin_unlock(&block);



















	return ret;









}





























char _license[] SEC("license") = "GPL";