Commit 00387808 authored by Song Liu's avatar Song Liu Committed by Alexei Starovoitov
Browse files

selftests/bpf: Fix tests after fields reorder in struct file 



The change in struct file [1] moved f_ref to the 3rd cache line.
It made *(u64 *)file dereference invalid from the verifier point of view,
because btf_struct_walk() walks into f_lock field, which is 4-byte long.

Fix the selftests to deference the file pointer as a 4-byte access.

[1] commit e249056c ("fs: place f_ref to 3rd cache line in struct file to resolve false sharing")
Reported-by: default avatarJakub Kicinski <kuba@kernel.org>
Signed-off-by: default avatarSong Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20250327185528.1740787-1-song@kernel.org


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 5d0b2046

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

+1 −1
Original line number Diff line number Diff line
@@ -117,7 +117,7 @@ int BPF_PROG(handle_fexit_ret, int arg, struct file *ret) 


	bpf_probe_read_kernel(&buf, 8, ret);

	bpf_probe_read_kernel(&buf, 8, (char *)ret + 256);

	*(volatile long long *)ret;

	*(volatile int *)ret;

	*(volatile int *)&ret->f_mode;

	return 0;

}

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

+3 −3
Original line number Diff line number Diff line
@@ -21,7 +21,7 @@ static __u64 test_cb(struct bpf_map *map, __u32 *key, __u64 *val, void *data) 
SEC("fexit/bpf_testmod_return_ptr")

int BPF_PROG(handle_fexit_ret_subprogs, int arg, struct file *ret)

{

	*(volatile long *)ret;

	*(volatile int *)ret;

	*(volatile int *)&ret->f_mode;

	bpf_for_each_map_elem(&test_array, test_cb, NULL, 0);

	triggered++;
@@ -31,7 +31,7 @@ int BPF_PROG(handle_fexit_ret_subprogs, int arg, struct file *ret) 
SEC("fexit/bpf_testmod_return_ptr")

int BPF_PROG(handle_fexit_ret_subprogs2, int arg, struct file *ret)

{

	*(volatile long *)ret;

	*(volatile int *)ret;

	*(volatile int *)&ret->f_mode;

	bpf_for_each_map_elem(&test_array, test_cb, NULL, 0);

	triggered++;
@@ -41,7 +41,7 @@ int BPF_PROG(handle_fexit_ret_subprogs2, int arg, struct file *ret) 
SEC("fexit/bpf_testmod_return_ptr")

int BPF_PROG(handle_fexit_ret_subprogs3, int arg, struct file *ret)

{

	*(volatile long *)ret;

	*(volatile int *)ret;

	*(volatile int *)&ret->f_mode;

	bpf_for_each_map_elem(&test_array, test_cb, NULL, 0);

	triggered++;