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objtool: Handle function aliases

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Function aliases result in different symbols for the same set of
instructions; track a canonical symbol so there is a unique point of
access.

This again prepares the way for function attributes. And in particular
the need for aliases comes from how KASAN uses them.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra 2019-02-28 14:17:50 +01:00 committed by Ingo Molnar
parent a4d09dde90
commit 09f30d83d3
2 changed files with 12 additions and 5 deletions
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15
tools/objtool/elf.c
View File

@ -219,7 +219,7 @@ static int read_sections(struct elf *elf)
static int read_symbols(struct elf *elf) static int read_symbols(struct elf *elf)
{ {
struct section *symtab, *sec; struct section *symtab, *sec;
struct symbol *sym, *pfunc; struct symbol *sym, *pfunc, *alias;
struct list_head *entry, *tmp; struct list_head *entry, *tmp;
int symbols_nr, i; int symbols_nr, i;
char *coldstr; char *coldstr;
@ -239,6 +239,7 @@ static int read_symbols(struct elf *elf)
return -1; return -1;
} }
memset(sym, 0, sizeof(*sym)); memset(sym, 0, sizeof(*sym));
alias = sym;
sym->idx = i; sym->idx = i;
@ -288,11 +289,17 @@ static int read_symbols(struct elf *elf)
break; break;
} }
if (sym->offset == s->offset && sym->len >= s->len) { if (sym->offset == s->offset) {
entry = tmp; if (sym->len == s->len && alias == sym)
break; alias = s;
if (sym->len >= s->len) {
entry = tmp;
break;
}
} }
} }
sym->alias = alias;
list_add(&sym->list, entry); list_add(&sym->list, entry);
hash_add(sym->sec->symbol_hash, &sym->hash, sym->idx); hash_add(sym->sec->symbol_hash, &sym->hash, sym->idx);
} }

2
tools/objtool/elf.h
View File

@ -61,7 +61,7 @@ struct symbol {
unsigned char bind, type; unsigned char bind, type;
unsigned long offset; unsigned long offset;
unsigned int len; unsigned int len;
struct symbol *pfunc, *cfunc; struct symbol *pfunc, *cfunc, *alias;
}; };
struct rela { struct rela {