| Message ID | 1427716167-25078-2-git-send-email-ard.biesheuvel@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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@linaro.org> > --- > 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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." */ + "_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; + int l = strlen(sym_name) - strlen(special_suffixes[i]); + + if (l >= 0 && strcmp(sym_name + l, special_suffixes[i]) == 0) + return 0; + } + return 1; }
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@linaro.org> --- scripts/kallsyms.c | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-)