From: Menglong Dong <imagedong@xxxxxxxxxxx> I think there is something wrong with BPF_PROBE_MEM in ___bpf_prog_run() in big-endian machine. Let's make a test and see what will happen if we want to load a 'u16' with BPF_PROBE_MEM. Let's make the src value '0x0001', the value of dest register will become 0x0001000000000000, as the value will be loaded to the first 2 byte of DST with following code: bpf_probe_read_kernel(&DST, SIZE, (const void *)(long) (SRC + insn->off)); Obviously, the value in DST is not correct. In fact, we can compare BPF_PROBE_MEM with LDX_MEM_H: DST = *(SIZE *)(unsigned long) (SRC + insn->off); If the memory load is done by LDX_MEM_H, the value in DST will be 0x1 now. And I think this error results in the test case 'test_bpf_sk_storage_map' failing: test_bpf_sk_storage_map:PASS:bpf_iter_bpf_sk_storage_map__open_and_load 0 nsec test_bpf_sk_storage_map:PASS:socket 0 nsec test_bpf_sk_storage_map:PASS:map_update 0 nsec test_bpf_sk_storage_map:PASS:socket 0 nsec test_bpf_sk_storage_map:PASS:map_update 0 nsec test_bpf_sk_storage_map:PASS:socket 0 nsec test_bpf_sk_storage_map:PASS:map_update 0 nsec test_bpf_sk_storage_map:PASS:attach_iter 0 nsec test_bpf_sk_storage_map:PASS:create_iter 0 nsec test_bpf_sk_storage_map:PASS:read 0 nsec test_bpf_sk_storage_map:FAIL:ipv6_sk_count got 0 expected 3 $10/26 bpf_iter/bpf_sk_storage_map:FAIL The code of the test case is simply, it will load sk->sk_family to the register with BPF_PROBE_MEM and check if it is AF_INET6. With this patch, now the test case 'bpf_iter' can pass: $10 bpf_iter:OK Reviewed-by: Jiang Biao <benbjiang@xxxxxxxxxxx> Reviewed-by: Hao Peng <flyingpeng@xxxxxxxxxxx> Signed-off-by: Menglong Dong <imagedong@xxxxxxxxxxx> --- kernel/bpf/core.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 13e9dbeeedf3..09e3f374739a 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -1945,14 +1945,15 @@ static u64 ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn) LDST(W, u32) LDST(DW, u64) #undef LDST -#define LDX_PROBE(SIZEOP, SIZE) \ +#define LDX_PROBE(SIZEOP, SIZE, TYPE) \ LDX_PROBE_MEM_##SIZEOP: \ bpf_probe_read_kernel(&DST, SIZE, (const void *)(long) (SRC + insn->off)); \ + DST = *((TYPE *)&DST); \ CONT; - LDX_PROBE(B, 1) - LDX_PROBE(H, 2) - LDX_PROBE(W, 4) - LDX_PROBE(DW, 8) + LDX_PROBE(B, 1, u8) + LDX_PROBE(H, 2, u16) + LDX_PROBE(W, 4, u32) + LDX_PROBE(DW, 8, u64) #undef LDX_PROBE #define ATOMIC_ALU_OP(BOP, KOP) \ -- 2.36.1
