[PATCH 5/8] objtool: Rewrite add_ignores()

From: Peter Zijlstra
Date: Thu Feb 28 2019 - 10:05:42 EST


The whole add_ignores() thing was wildly weird; rewrite it according
to 'modern' ways.

Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
tools/objtool/check.c | 51 +++++++++++++++++++-------------------------------
tools/objtool/check.h | 1
2 files changed, 20 insertions(+), 32 deletions(-)

--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -105,29 +105,6 @@ static struct instruction *next_insn_sam
insn = next_insn_same_sec(file, insn))

/*
- * Check if the function has been manually whitelisted with the
- * STACK_FRAME_NON_STANDARD macro, or if it should be automatically whitelisted
- * due to its use of a context switching instruction.
- */
-static bool ignore_func(struct objtool_file *file, struct symbol *func)
-{
- struct rela *rela;
-
- /* check for STACK_FRAME_NON_STANDARD */
- if (file->whitelist && file->whitelist->rela)
- list_for_each_entry(rela, &file->whitelist->rela->rela_list, list) {
- if (rela->sym->type == STT_SECTION &&
- rela->sym->sec == func->sec &&
- rela->addend == func->offset)
- return true;
- if (rela->sym->type == STT_FUNC && rela->sym == func)
- return true;
- }
-
- return false;
-}
-
-/*
* This checks to see if the given function is a "noreturn" function.
*
* For global functions which are outside the scope of this object file, we
@@ -436,18 +413,31 @@ static void add_ignores(struct objtool_f
struct instruction *insn;
struct section *sec;
struct symbol *func;
+ struct rela *rela;

- for_each_sec(file, sec) {
- list_for_each_entry(func, &sec->symbol_list, list) {
- if (func->type != STT_FUNC)
- continue;
+ sec = find_section_by_name(file->elf, ".rela.discard.func_stack_frame_non_standard");
+ if (!sec)
+ return;

- if (!ignore_func(file, func))
+ list_for_each_entry(rela, &sec->rela_list, list) {
+ switch (rela->sym->type) {
+ case STT_FUNC:
+ func = rela->sym;
+ break;
+
+ case STT_SECTION:
+ func = find_symbol_by_offset(rela->sym->sec, rela->addend);
+ if (!func || func->type != STT_FUNC)
continue;
+ break;

- func_for_each_insn_all(file, func, insn)
- insn->ignore = true;
+ default:
+ WARN("unexpected relation symbol type in %s: %d", sec->name, rela->sym->type);
+ continue;
}
+
+ func_for_each_insn_all(file, func, insn)
+ insn->ignore = true;
}
}

@@ -2198,7 +2188,6 @@ int check(const char *_objname, bool orc

INIT_LIST_HEAD(&file.insn_list);
hash_init(file.insn_hash);
- file.whitelist = find_section_by_name(file.elf, ".discard.func_stack_frame_non_standard");
file.c_file = find_section_by_name(file.elf, ".comment");
file.ignore_unreachables = no_unreachable;
file.hints = false;
--- a/tools/objtool/check.h
+++ b/tools/objtool/check.h
@@ -60,7 +60,6 @@ struct objtool_file {
struct elf *elf;
struct list_head insn_list;
DECLARE_HASHTABLE(insn_hash, 16);
- struct section *whitelist;
bool ignore_unreachables, c_file, hints, rodata;
};