On 2015-03-30 13:49, Ard Biesheuvel wrote:
> When linking large kernels on ARM, the linker will insert veneers
> (i.e., PLT like stubs) when function symbols are out of reach for
> the ordinary relative branch/branch-and-link instructions.
>
> However, due to the fact that the kallsyms region sits in .rodata,
> which is between .text and .init.text, additional veneers may be
> emitted in the second pass due to the fact that the size of the
> kallsyms region itself has pushed the .init.text section further
> down, resulting in additional veneers to be emitted.
>
> So ignore the veneers when generating the symbol table. Veneers
> have no corresponding source code, and they will not turn up in
> backtraces anyway.
>
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
> ---
> scripts/kallsyms.c | 17 ++++++++++++++---
> 1 file changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
> index c6d33bd15b04..6668c87d599f 100644
> --- a/scripts/kallsyms.c
> +++ b/scripts/kallsyms.c
> @@ -212,6 +212,12 @@ static int symbol_valid(struct sym_entry *s)
> "_SDA_BASE_", /* ppc */
> "_SDA2_BASE_", /* ppc */
> NULL };
> +
> + static char *special_suffixes[] = {
> + "_compiled.", /* gcc < 3.0: "gcc[0-9]_compiled." */
Your newly added comment suggests that this can go away, since we have
been requiring at least gcc 3.2 since some time. But it can be removed
in a follow-up cleanup.
> + "_veneer", /* arm */
> + NULL };
> +
> int i;
> int offset = 1;
>
> @@ -244,13 +250,18 @@ static int symbol_valid(struct sym_entry *s)
> }
>
> /* Exclude symbols which vary between passes. */
> - if (strstr((char *)s->sym + offset, "_compiled."))
> - return 0;
> -
> for (i = 0; special_symbols[i]; i++)
> if( strcmp((char *)s->sym + offset, special_symbols[i]) == 0 )
> return 0;
>
> + for (i = 0; special_suffixes[i]; i++) {
> + char *sym_name = (char *)s->sym + offset;
You should declare and set this useful helper a few lines earlier and
use it in the other statements that test the symbol name.
Michal
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