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objtool: Refactor function alias logic 

- Add an alias check in validate_functions().  With this change, aliases
  no longer need uaccess_safe set.

- Add an alias check in decode_instructions().  With this change, the
  "if (!insn->func)" check is no longer needed.

- Don't create aliases for zero-length functions, as it can have
  unexpected results.  The next patch will spit out a warning for
  zero-length functions anyway.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/26a99c31426540f19c9a58b9e10727c385a147bc.1563413318.git.jpoimboe@redhat.com
This commit is contained in:
Josh Poimboeuf 2019-07-17 20:36:48 -05:00 committed by Thomas Gleixner
parent c705cecc84
commit e10cd8fe8d
2 changed files with 10 additions and 8 deletions
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16
tools/objtool/check.c
View File

@ -276,7 +276,7 @@ static int decode_instructions(struct objtool_file *file)
}
list_for_each_entry(func, &sec->symbol_list, list) {
if (func->type != STT_FUNC)
if (func->type != STT_FUNC || func->alias != func)
continue;
if (!find_insn(file, sec, func->offset)) {
@ -286,8 +286,7 @@ static int decode_instructions(struct objtool_file *file)
}
func_for_each_insn(file, func, insn)
if (!insn->func)
insn->func = func;
insn->func = func;
}
}
@ -508,7 +507,7 @@ static void add_uaccess_safe(struct objtool_file *file)
if (!func)
continue;
func->alias->uaccess_safe = true;
func->uaccess_safe = true;
}
}
@ -1887,7 +1886,7 @@ static bool insn_state_match(struct instruction *insn, struct insn_state *state)
static inline bool func_uaccess_safe(struct symbol *func)
{
if (func)
return func->alias->uaccess_safe;
return func->uaccess_safe;
return false;
}
@ -2355,14 +2354,17 @@ static int validate_functions(struct objtool_file *file)
for_each_sec(file, sec) {
list_for_each_entry(func, &sec->symbol_list, list) {
if (func->type != STT_FUNC || func->pfunc != func)
if (func->type != STT_FUNC)
continue;
if (func->pfunc != func || func->alias != func)
continue;
insn = find_insn(file, sec, func->offset);
if (!insn || insn->ignore || insn->visited)
continue;
state.uaccess = func->alias->uaccess_safe;
state.uaccess = func->uaccess_safe;
ret = validate_branch(file, func, insn, state);
if (ret && backtrace)

2
tools/objtool/elf.c
View File

@ -278,7 +278,7 @@ static int read_symbols(struct elf *elf)
}
if (sym->offset == s->offset) {
if (sym->len == s->len && alias == sym)
if (sym->len && sym->len == s->len && alias == sym)
alias = s;
if (sym->len >= s->len) {