Commit 4cc0991a authored by Song Liu's avatar Song Liu Committed by Alexei Starovoitov
Browse files

bpf: Fix bpf_prog_pack build for ppc64_defconfig 



bpf_prog_pack causes build error with powerpc ppc64_defconfig:

kernel/bpf/core.c:830:23: error: variably modified 'bitmap' at file scope
  830 |         unsigned long bitmap[BITS_TO_LONGS(BPF_PROG_CHUNK_COUNT)];
      |                       ^~~~~~

This is because the marco expands as:

unsigned long bitmap[((((((1UL) << (16 + __pte_index_size)) / (1 << 6))) \
     + ((sizeof(long) * 8)) - 1) / ((sizeof(long) * 8)))];

where __pte_index_size is a global variable.

Fix it by turning bitmap into a 0-length array.

Fixes: 57631054 ("bpf: Introduce bpf_prog_pack allocator")
Reported-by: default avatarStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: default avatarSong Liu <song@kernel.org>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220211024939.2962537-1-song@kernel.org
parent a5a358ab

kernel/bpf/core.c

+2 −2
Original line number Diff line number Diff line
@@ -827,7 +827,7 @@ int bpf_jit_add_poke_descriptor(struct bpf_prog *prog, 
struct bpf_prog_pack {

	struct list_head list;

	void *ptr;

	unsigned long bitmap[BITS_TO_LONGS(BPF_PROG_CHUNK_COUNT)];

	unsigned long bitmap[];

};



#define BPF_PROG_MAX_PACK_PROG_SIZE	BPF_PROG_PACK_SIZE
@@ -840,7 +840,7 @@ static struct bpf_prog_pack *alloc_new_pack(void) 
{

	struct bpf_prog_pack *pack;



	pack = kzalloc(sizeof(*pack), GFP_KERNEL);

	pack = kzalloc(sizeof(*pack) + BITS_TO_BYTES(BPF_PROG_CHUNK_COUNT), GFP_KERNEL);

	if (!pack)

		return NULL;

	pack->ptr = module_alloc(BPF_PROG_PACK_SIZE);