[tip: x86/core] objtool: Rework instruction -> symbol mapping
From: tip-bot2 for Peter Zijlstra
Date: Mon Oct 17 2022 - 10:55:25 EST
The following commit has been merged into the x86/core branch of tip:
Commit-ID: dbcdbdfdf137b49144204571f1a5e5dc01b8aaad
Gitweb: https://git.kernel.org/tip/dbcdbdfdf137b49144204571f1a5e5dc01b8aaad
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Thu, 22 Sep 2022 22:03:50 +02:00
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Mon, 17 Oct 2022 16:41:08 +02:00
objtool: Rework instruction -> symbol mapping
Currently insn->func contains a instruction -> symbol link for
STT_FUNC symbols. A NULL value is assumed to mean STT_NOTYPE.
However, there are also instructions not covered by any symbol at all.
This can happen due to __weak symbols for example.
Since the current scheme cannot differentiate between no symbol and
STT_NOTYPE symbol, change things around. Make insn->sym point to any
symbol type such that !insn->sym means no symbol and add a helper
insn_func() that check the sym->type to retain the old functionality.
This then prepares the way to add code that depends on the distinction
between STT_NOTYPE and no symbol at all.
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
tools/objtool/check.c | 105 +++++++++++++------------
tools/objtool/include/objtool/check.h | 12 ++-
2 files changed, 66 insertions(+), 51 deletions(-)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 3f46f46..e532efb 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -62,12 +62,12 @@ static struct instruction *next_insn_same_func(struct objtool_file *file,
struct instruction *insn)
{
struct instruction *next = list_next_entry(insn, list);
- struct symbol *func = insn->func;
+ struct symbol *func = insn_func(insn);
if (!func)
return NULL;
- if (&next->list != &file->insn_list && next->func == func)
+ if (&next->list != &file->insn_list && insn_func(next) == func)
return next;
/* Check if we're already in the subfunction: */
@@ -83,7 +83,7 @@ static struct instruction *prev_insn_same_sym(struct objtool_file *file,
{
struct instruction *prev = list_prev_entry(insn, list);
- if (&prev->list != &file->insn_list && prev->func == insn->func)
+ if (&prev->list != &file->insn_list && insn_func(prev) == insn_func(insn))
return prev;
return NULL;
@@ -133,7 +133,7 @@ static bool is_sibling_call(struct instruction *insn)
* sibling call detection consistency between vmlinux.o and individual
* objects.
*/
- if (!insn->func)
+ if (!insn_func(insn))
return false;
/* An indirect jump is either a sibling call or a jump to a table. */
@@ -207,7 +207,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
return false;
insn = find_insn(file, func->sec, func->offset);
- if (!insn->func)
+ if (!insn_func(insn))
return false;
func_for_each_insn(file, func, insn) {
@@ -243,7 +243,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
return false;
}
- return __dead_end_function(file, dest->func, recursion+1);
+ return __dead_end_function(file, insn_func(dest), recursion+1);
}
}
@@ -427,7 +427,10 @@ static int decode_instructions(struct objtool_file *file)
}
list_for_each_entry(func, &sec->symbol_list, list) {
- if (func->type != STT_FUNC || func->alias != func)
+ if (func->type != STT_NOTYPE && func->type != STT_FUNC)
+ continue;
+
+ if (func->return_thunk || func->alias != func)
continue;
if (!find_insn(file, sec, func->offset)) {
@@ -437,9 +440,11 @@ static int decode_instructions(struct objtool_file *file)
}
sym_for_each_insn(file, func, insn) {
- insn->func = func;
- if (insn->type == INSN_ENDBR && list_empty(&insn->call_node)) {
- if (insn->offset == insn->func->offset) {
+ insn->sym = func;
+ if (func->type == STT_FUNC &&
+ insn->type == INSN_ENDBR &&
+ list_empty(&insn->call_node)) {
+ if (insn->offset == func->offset) {
list_add_tail(&insn->call_node, &file->endbr_list);
file->nr_endbr++;
} else {
@@ -1397,19 +1402,19 @@ static void add_return_call(struct objtool_file *file, struct instruction *insn,
static bool same_function(struct instruction *insn1, struct instruction *insn2)
{
- return insn1->func->pfunc == insn2->func->pfunc;
+ return insn_func(insn1)->pfunc == insn_func(insn2)->pfunc;
}
static bool is_first_func_insn(struct objtool_file *file, struct instruction *insn)
{
- if (insn->offset == insn->func->offset)
+ if (insn->offset == insn_func(insn)->offset)
return true;
if (opts.ibt) {
struct instruction *prev = prev_insn_same_sym(file, insn);
if (prev && prev->type == INSN_ENDBR &&
- insn->offset == insn->func->offset + prev->len)
+ insn->offset == insn_func(insn)->offset + prev->len)
return true;
}
@@ -1450,7 +1455,7 @@ static int add_jump_destinations(struct objtool_file *file)
} else if (reloc->sym->return_thunk) {
add_return_call(file, insn, true);
continue;
- } else if (insn->func) {
+ } else if (insn_func(insn)) {
/*
* External sibling call or internal sibling call with
* STT_FUNC reloc.
@@ -1492,8 +1497,8 @@ static int add_jump_destinations(struct objtool_file *file)
/*
* Cross-function jump.
*/
- if (insn->func && jump_dest->func &&
- insn->func != jump_dest->func) {
+ if (insn_func(insn) && insn_func(jump_dest) &&
+ insn_func(insn) != insn_func(jump_dest)) {
/*
* For GCC 8+, create parent/child links for any cold
@@ -1510,10 +1515,10 @@ static int add_jump_destinations(struct objtool_file *file)
* case where the parent function's only reference to a
* subfunction is through a jump table.
*/
- if (!strstr(insn->func->name, ".cold") &&
- strstr(jump_dest->func->name, ".cold")) {
- insn->func->cfunc = jump_dest->func;
- jump_dest->func->pfunc = insn->func;
+ if (!strstr(insn_func(insn)->name, ".cold") &&
+ strstr(insn_func(jump_dest)->name, ".cold")) {
+ insn_func(insn)->cfunc = insn_func(jump_dest);
+ insn_func(jump_dest)->pfunc = insn_func(insn);
} else if (!same_function(insn, jump_dest) &&
is_first_func_insn(file, jump_dest)) {
@@ -1521,7 +1526,7 @@ static int add_jump_destinations(struct objtool_file *file)
* Internal sibling call without reloc or with
* STT_SECTION reloc.
*/
- add_call_dest(file, insn, jump_dest->func, true);
+ add_call_dest(file, insn, insn_func(jump_dest), true);
continue;
}
}
@@ -1572,7 +1577,7 @@ static int add_call_destinations(struct objtool_file *file)
return -1;
}
- if (insn->func && insn->call_dest->type != STT_FUNC) {
+ if (insn_func(insn) && insn->call_dest->type != STT_FUNC) {
WARN_FUNC("unsupported call to non-function",
insn->sec, insn->offset);
return -1;
@@ -1668,7 +1673,7 @@ static int handle_group_alt(struct objtool_file *file,
nop->offset = special_alt->new_off + special_alt->new_len;
nop->len = special_alt->orig_len - special_alt->new_len;
nop->type = INSN_NOP;
- nop->func = orig_insn->func;
+ nop->sym = orig_insn->sym;
nop->alt_group = new_alt_group;
nop->ignore = orig_insn->ignore_alts;
}
@@ -1688,7 +1693,7 @@ static int handle_group_alt(struct objtool_file *file,
last_new_insn = insn;
insn->ignore = orig_insn->ignore_alts;
- insn->func = orig_insn->func;
+ insn->sym = orig_insn->sym;
insn->alt_group = new_alt_group;
/*
@@ -1882,7 +1887,7 @@ static int add_jump_table(struct objtool_file *file, struct instruction *insn,
struct reloc *reloc = table;
struct instruction *dest_insn;
struct alternative *alt;
- struct symbol *pfunc = insn->func->pfunc;
+ struct symbol *pfunc = insn_func(insn)->pfunc;
unsigned int prev_offset = 0;
/*
@@ -1909,7 +1914,7 @@ static int add_jump_table(struct objtool_file *file, struct instruction *insn,
break;
/* Make sure the destination is in the same function: */
- if (!dest_insn->func || dest_insn->func->pfunc != pfunc)
+ if (!insn_func(dest_insn) || insn_func(dest_insn)->pfunc != pfunc)
break;
alt = malloc(sizeof(*alt));
@@ -1949,7 +1954,7 @@ static struct reloc *find_jump_table(struct objtool_file *file,
* it.
*/
for (;
- insn && insn->func && insn->func->pfunc == func;
+ insn && insn_func(insn) && insn_func(insn)->pfunc == func;
insn = insn->first_jump_src ?: prev_insn_same_sym(file, insn)) {
if (insn != orig_insn && insn->type == INSN_JUMP_DYNAMIC)
@@ -1966,7 +1971,7 @@ static struct reloc *find_jump_table(struct objtool_file *file,
if (!table_reloc)
continue;
dest_insn = find_insn(file, table_reloc->sym->sec, table_reloc->addend);
- if (!dest_insn || !dest_insn->func || dest_insn->func->pfunc != func)
+ if (!dest_insn || !insn_func(dest_insn) || insn_func(dest_insn)->pfunc != func)
continue;
return table_reloc;
@@ -2415,6 +2420,13 @@ static int decode_sections(struct objtool_file *file)
if (ret)
return ret;
+ /*
+ * Must be before add_{jump_call}_destination.
+ */
+ ret = classify_symbols(file);
+ if (ret)
+ return ret;
+
ret = decode_instructions(file);
if (ret)
return ret;
@@ -2434,13 +2446,6 @@ static int decode_sections(struct objtool_file *file)
return ret;
/*
- * Must be before add_{jump_call}_destination.
- */
- ret = classify_symbols(file);
- if (ret)
- return ret;
-
- /*
* Must be before add_jump_destinations(), which depends on 'func'
* being set for alternatives, to enable proper sibling call detection.
*/
@@ -2648,7 +2653,7 @@ static int update_cfi_state(struct instruction *insn,
/* stack operations don't make sense with an undefined CFA */
if (cfa->base == CFI_UNDEFINED) {
- if (insn->func) {
+ if (insn_func(insn)) {
WARN_FUNC("undefined stack state", insn->sec, insn->offset);
return -1;
}
@@ -2994,7 +2999,7 @@ static int update_cfi_state(struct instruction *insn,
}
/* detect when asm code uses rbp as a scratch register */
- if (opts.stackval && insn->func && op->src.reg == CFI_BP &&
+ if (opts.stackval && insn_func(insn) && op->src.reg == CFI_BP &&
cfa->base != CFI_BP)
cfi->bp_scratch = true;
break;
@@ -3390,13 +3395,13 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
while (1) {
next_insn = next_insn_to_validate(file, insn);
- if (func && insn->func && func != insn->func->pfunc) {
+ if (func && insn_func(insn) && func != insn_func(insn)->pfunc) {
/* Ignore KCFI type preambles, which always fall through */
if (!strncmp(func->name, "__cfi_", 6))
return 0;
WARN("%s() falls through to next function %s()",
- func->name, insn->func->name);
+ func->name, insn_func(insn)->name);
return 1;
}
@@ -3638,7 +3643,7 @@ static int validate_unwind_hints(struct objtool_file *file, struct section *sec)
while (&insn->list != &file->insn_list && (!sec || insn->sec == sec)) {
if (insn->hint && !insn->visited && !insn->ignore) {
- ret = validate_branch(file, insn->func, insn, state);
+ ret = validate_branch(file, insn_func(insn), insn, state);
if (ret && opts.backtrace)
BT_FUNC("<=== (hint)", insn);
warnings += ret;
@@ -3861,7 +3866,7 @@ static bool ignore_unreachable_insn(struct objtool_file *file, struct instructio
* In this case we'll find a piece of code (whole function) that is not
* covered by a !section symbol. Ignore them.
*/
- if (opts.link && !insn->func) {
+ if (opts.link && !insn_func(insn)) {
int size = find_symbol_hole_containing(insn->sec, insn->offset);
unsigned long end = insn->offset + size;
@@ -3885,10 +3890,10 @@ static bool ignore_unreachable_insn(struct objtool_file *file, struct instructio
/*
* If this hole jumps to a .cold function, mark it ignore too.
*/
- if (insn->jump_dest && insn->jump_dest->func &&
- strstr(insn->jump_dest->func->name, ".cold")) {
+ if (insn->jump_dest && insn_func(insn->jump_dest) &&
+ strstr(insn_func(insn->jump_dest)->name, ".cold")) {
struct instruction *dest = insn->jump_dest;
- func_for_each_insn(file, dest->func, dest)
+ func_for_each_insn(file, insn_func(dest), dest)
dest->ignore = true;
}
}
@@ -3896,10 +3901,10 @@ static bool ignore_unreachable_insn(struct objtool_file *file, struct instructio
return false;
}
- if (!insn->func)
+ if (!insn_func(insn))
return false;
- if (insn->func->static_call_tramp)
+ if (insn_func(insn)->static_call_tramp)
return true;
/*
@@ -3930,7 +3935,7 @@ static bool ignore_unreachable_insn(struct objtool_file *file, struct instructio
if (insn->type == INSN_JUMP_UNCONDITIONAL) {
if (insn->jump_dest &&
- insn->jump_dest->func == insn->func) {
+ insn_func(insn->jump_dest) == insn_func(insn)) {
insn = insn->jump_dest;
continue;
}
@@ -3938,7 +3943,7 @@ static bool ignore_unreachable_insn(struct objtool_file *file, struct instructio
break;
}
- if (insn->offset + insn->len >= insn->func->offset + insn->func->len)
+ if (insn->offset + insn->len >= insn_func(insn)->offset + insn_func(insn)->len)
break;
insn = list_next_entry(insn, list);
@@ -3967,7 +3972,7 @@ static int validate_symbol(struct objtool_file *file, struct section *sec,
state->uaccess = sym->uaccess_safe;
- ret = validate_branch(file, insn->func, insn, *state);
+ ret = validate_branch(file, insn_func(insn), insn, *state);
if (ret && opts.backtrace)
BT_FUNC("<=== (sym)", insn);
return ret;
@@ -4104,7 +4109,7 @@ static int validate_ibt_insn(struct objtool_file *file, struct instruction *insn
continue;
}
- if (dest->func && dest->func == insn->func) {
+ if (insn_func(dest) && insn_func(dest) == insn_func(insn)) {
/*
* Anything from->to self is either _THIS_IP_ or
* IRET-to-self.
diff --git a/tools/objtool/include/objtool/check.h b/tools/objtool/include/objtool/check.h
index 036129c..acd7fae 100644
--- a/tools/objtool/include/objtool/check.h
+++ b/tools/objtool/include/objtool/check.h
@@ -67,11 +67,21 @@ struct instruction {
struct reloc *jump_table;
struct reloc *reloc;
struct list_head alts;
- struct symbol *func;
+ struct symbol *sym;
struct list_head stack_ops;
struct cfi_state *cfi;
};
+static inline struct symbol *insn_func(struct instruction *insn)
+{
+ struct symbol *sym = insn->sym;
+
+ if (sym && sym->type != STT_FUNC)
+ sym = NULL;
+
+ return sym;
+}
+
#define VISITED_BRANCH 0x01
#define VISITED_BRANCH_UACCESS 0x02
#define VISITED_BRANCH_MASK 0x03