lkml.org 
[lkml]   [2023]   [Oct]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    Subject[PATCH v6 1/2] bpftool: Align output skeleton ELF code
    From
    libbpf accesses the ELF data requiring at least 8 byte alignment,
    however, the data is generated into a C string that doesn't guarantee
    alignment. Fix this by assigning to an aligned char array. Use sizeof
    on the array, less one for the \0 terminator, rather than generating a
    constant.

    Fixes: a6cc6b34b93e ("bpftool: Provide a helper method for accessing skeleton's embedded ELF data")
    Signed-off-by: Ian Rogers <irogers@google.com>
    Acked-by: Quentin Monnet <quentin@isovalent.com>
    Reviewed-by: Alan Maguire <alan.maguire@oracle.com>
    ---
    tools/bpf/bpftool/gen.c | 15 +++++++++------
    1 file changed, 9 insertions(+), 6 deletions(-)

    diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c
    index 04c47745b3ea..882bf8e6e70e 100644
    --- a/tools/bpf/bpftool/gen.c
    +++ b/tools/bpf/bpftool/gen.c
    @@ -1209,7 +1209,7 @@ static int do_skeleton(int argc, char **argv)
    codegen("\
    \n\
    \n\
    - s->data = %2$s__elf_bytes(&s->data_sz); \n\
    + s->data = %1$s__elf_bytes(&s->data_sz); \n\
    \n\
    obj->skeleton = s; \n\
    return 0; \n\
    @@ -1218,12 +1218,12 @@ static int do_skeleton(int argc, char **argv)
    return err; \n\
    } \n\
    \n\
    - static inline const void *%2$s__elf_bytes(size_t *sz) \n\
    + static inline const void *%1$s__elf_bytes(size_t *sz) \n\
    { \n\
    - *sz = %1$d; \n\
    - return (const void *)\"\\ \n\
    - "
    - , file_sz, obj_name);
    + static const char data[] __attribute__((__aligned__(8))) = \"\\\n\
    + ",
    + obj_name
    + );

    /* embed contents of BPF object file */
    print_hex(obj_data, file_sz);
    @@ -1231,6 +1231,9 @@ static int do_skeleton(int argc, char **argv)
    codegen("\
    \n\
    \"; \n\
    + \n\
    + *sz = sizeof(data) - 1; \n\
    + return (const void *)data; \n\
    } \n\
    \n\
    #ifdef __cplusplus \n\
    --
    2.42.0.609.gbb76f46606-goog
    \
     
     \ /
      Last update: 2023-10-07 06:45    [W:6.403 / U:0.024 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site