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    Subject[PATCH 5.4 078/110] libbpf: Fix BTF-defined maps __type macro handling of arrays
    Date
    From: Andrii Nakryiko <andriin@fb.com>

    [ Upstream commit a53ba15d81995868651dd28a85d8045aef3d4e20 ]

    Due to a quirky C syntax of declaring pointers to array or function
    prototype, existing __type() macro doesn't work with map key/value types
    that are array or function prototype. One has to create a typedef first
    and use it to specify key/value type for a BPF map. By using typeof(),
    pointer to type is now handled uniformly for all kinds of types. Convert
    one of self-tests as a demonstration.

    Signed-off-by: Andrii Nakryiko <andriin@fb.com>
    Signed-off-by: Alexei Starovoitov <ast@kernel.org>
    Link: https://lore.kernel.org/bpf/20191004040211.2434033-1-andriin@fb.com
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    tools/testing/selftests/bpf/bpf_helpers.h | 2 +-
    tools/testing/selftests/bpf/progs/test_get_stack_rawtp.c | 3 +--
    2 files changed, 2 insertions(+), 3 deletions(-)

    diff --git a/tools/testing/selftests/bpf/bpf_helpers.h b/tools/testing/selftests/bpf/bpf_helpers.h
    index 54a50699bbfda..9f77cbaac01c1 100644
    --- a/tools/testing/selftests/bpf/bpf_helpers.h
    +++ b/tools/testing/selftests/bpf/bpf_helpers.h
    @@ -3,7 +3,7 @@
    #define __BPF_HELPERS__

    #define __uint(name, val) int (*name)[val]
    -#define __type(name, val) val *name
    +#define __type(name, val) typeof(val) *name

    /* helper macro to print out debug messages */
    #define bpf_printk(fmt, ...) \
    diff --git a/tools/testing/selftests/bpf/progs/test_get_stack_rawtp.c b/tools/testing/selftests/bpf/progs/test_get_stack_rawtp.c
    index f8ffa3f3d44bb..6cc4479ac9df6 100644
    --- a/tools/testing/selftests/bpf/progs/test_get_stack_rawtp.c
    +++ b/tools/testing/selftests/bpf/progs/test_get_stack_rawtp.c
    @@ -47,12 +47,11 @@ struct {
    * issue and avoid complicated C programming massaging.
    * This is an acceptable workaround since there is one entry here.
    */
    -typedef __u64 raw_stack_trace_t[2 * MAX_STACK_RAWTP];
    struct {
    __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
    __uint(max_entries, 1);
    __type(key, __u32);
    - __type(value, raw_stack_trace_t);
    + __type(value, __u64[2 * MAX_STACK_RAWTP]);
    } rawdata_map SEC(".maps");

    SEC("raw_tracepoint/sys_enter")
    --
    2.20.1


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