• Will Deacon's avatar
    scripts/faddr2line: Skip over mapping symbols in output from readelf · 60fd39af
    Will Deacon authored
    Mapping symbols emitted in the readelf output can confuse the
    'faddr2line' symbol size calculation, resulting in the erroneous
    rejection of valid offsets. This is especially prevalent when building
    an arm64 kernel with CONFIG_CFI_CLANG=y, where most functions are
    prefixed with a 32-bit data value in a '$d.n' section. For example:
    
    447538: ffff800080014b80   548 FUNC    GLOBAL DEFAULT    2 do_one_initcall
       104: ffff800080014c74     0 NOTYPE  LOCAL  DEFAULT    2 $x.73
       106: ffff800080014d30     0 NOTYPE  LOCAL  DEFAULT    2 $x.75
       111: ffff800080014da4     0 NOTYPE  LOCAL  DEFAULT    2 $d.78
       112: ffff800080014da8     0 NOTYPE  LOCAL  DEFAULT    2 $x.79
        36: ffff800080014de0   200 FUNC    LOCAL  DEFAULT    2 run_init_process
    
    Adding a warning to do_one_initcall() results in:
    
      | WARNING: CPU: 0 PID: 1 at init/main.c:1236 do_one_initcall+0xf4/0x260
    
    Which 'faddr2line' refuses to accept:
    
    $ ./scripts/faddr2line vmlinux do_one_initcall+0xf4/0x260
    skipping do_one_initcall address at 0xffff800080014c74 due to size mismatch (0x260 != 0x224)
    no match for do_one_initcall+0xf4/0x260
    
    Filter out these entries from readelf using a shell reimplementation of
    is_mapping_symbol(), so that the size of a symbol is calculated as a
    delta to the next symbol present in ksymtab.
    Suggested-by: default avatarMasahiro Yamada <masahiroy@kernel.org>
    Signed-off-by: default avatarWill Deacon <will@kernel.org>
    Reviewed-by: default avatarNick Desaulniers <ndesaulniers@google.com>
    Link: https://lore.kernel.org/r/20231002165750.1661-4-will@kernel.orgSigned-off-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
    60fd39af
faddr2line 8.63 KB