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objtool: Rework instruction -> symbol mapping

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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@infradead.org>
This commit is contained in:
Peter Zijlstra 2022-09-22 22:03:50 +02:00
parent 08ef8c4011
commit dbcdbdfdf1
2 changed files with 66 additions and 51 deletions
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105
tools/objtool/check.c
View file

@ -62,12 +62,12 @@ static struct instruction *next_insn_same_func(struct objtool_file *file,
struct instruction *insn) struct instruction *insn)
{ {
struct instruction *next = list_next_entry(insn, list); struct instruction *next = list_next_entry(insn, list);
struct symbol *func = insn->func; struct symbol *func = insn_func(insn);
if (!func) if (!func)
return NULL; return NULL;
if (&next->list != &file->insn_list && next->func == func) if (&next->list != &file->insn_list && insn_func(next) == func)
return next; return next;
/* Check if we're already in the subfunction: */ /* 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); 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 prev;
return NULL; return NULL;
@ -133,7 +133,7 @@ static bool is_sibling_call(struct instruction *insn)
* sibling call detection consistency between vmlinux.o and individual * sibling call detection consistency between vmlinux.o and individual
* objects. * objects.
*/ */
if (!insn->func) if (!insn_func(insn))
return false; return false;
/* An indirect jump is either a sibling call or a jump to a table. */ /* 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; return false;
insn = find_insn(file, func->sec, func->offset); insn = find_insn(file, func->sec, func->offset);
if (!insn->func) if (!insn_func(insn))
return false; return false;
func_for_each_insn(file, func, insn) { 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 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) { 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; continue;
if (!find_insn(file, sec, func->offset)) { 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) { sym_for_each_insn(file, func, insn) {
insn->func = func; insn->sym = func;
if (insn->type == INSN_ENDBR && list_empty(&insn->call_node)) { if (func->type == STT_FUNC &&
if (insn->offset == insn->func->offset) { insn->type == INSN_ENDBR &&
list_empty(&insn->call_node)) {
if (insn->offset == func->offset) {
list_add_tail(&insn->call_node, &file->endbr_list); list_add_tail(&insn->call_node, &file->endbr_list);
file->nr_endbr++; file->nr_endbr++;
} else { } 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) 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) 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; return true;
if (opts.ibt) { if (opts.ibt) {
struct instruction *prev = prev_insn_same_sym(file, insn); struct instruction *prev = prev_insn_same_sym(file, insn);
if (prev && prev->type == INSN_ENDBR && if (prev && prev->type == INSN_ENDBR &&
insn->offset == insn->func->offset + prev->len) insn->offset == insn_func(insn)->offset + prev->len)
return true; return true;
} }
@ -1450,7 +1455,7 @@ static int add_jump_destinations(struct objtool_file *file)
} else if (reloc->sym->return_thunk) { } else if (reloc->sym->return_thunk) {
add_return_call(file, insn, true); add_return_call(file, insn, true);
continue; continue;
} else if (insn->func) { } else if (insn_func(insn)) {
/* /*
* External sibling call or internal sibling call with * External sibling call or internal sibling call with
* STT_FUNC reloc. * STT_FUNC reloc.
@ -1492,8 +1497,8 @@ static int add_jump_destinations(struct objtool_file *file)
/* /*
* Cross-function jump. * Cross-function jump.
*/ */
if (insn->func && jump_dest->func && if (insn_func(insn) && insn_func(jump_dest) &&
insn->func != jump_dest->func) { insn_func(insn) != insn_func(jump_dest)) {
/* /*
* For GCC 8+, create parent/child links for any cold * 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 * case where the parent function's only reference to a
* subfunction is through a jump table. * subfunction is through a jump table.
*/ */
if (!strstr(insn->func->name, ".cold") && if (!strstr(insn_func(insn)->name, ".cold") &&
strstr(jump_dest->func->name, ".cold")) { strstr(insn_func(jump_dest)->name, ".cold")) {
insn->func->cfunc = jump_dest->func; insn_func(insn)->cfunc = insn_func(jump_dest);
jump_dest->func->pfunc = insn->func; insn_func(jump_dest)->pfunc = insn_func(insn);
} else if (!same_function(insn, jump_dest) && } else if (!same_function(insn, jump_dest) &&
is_first_func_insn(file, 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 * Internal sibling call without reloc or with
* STT_SECTION reloc. * STT_SECTION reloc.
*/ */
add_call_dest(file, insn, jump_dest->func, true); add_call_dest(file, insn, insn_func(jump_dest), true);
continue; continue;
} }
} }
@ -1572,7 +1577,7 @@ static int add_call_destinations(struct objtool_file *file)
return -1; 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", WARN_FUNC("unsupported call to non-function",
insn->sec, insn->offset); insn->sec, insn->offset);
return -1; 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->offset = special_alt->new_off + special_alt->new_len;
nop->len = special_alt->orig_len - special_alt->new_len; nop->len = special_alt->orig_len - special_alt->new_len;
nop->type = INSN_NOP; nop->type = INSN_NOP;
nop->func = orig_insn->func; nop->sym = orig_insn->sym;
nop->alt_group = new_alt_group; nop->alt_group = new_alt_group;
nop->ignore = orig_insn->ignore_alts; nop->ignore = orig_insn->ignore_alts;
} }
@ -1688,7 +1693,7 @@ static int handle_group_alt(struct objtool_file *file,
last_new_insn = insn; last_new_insn = insn;
insn->ignore = orig_insn->ignore_alts; insn->ignore = orig_insn->ignore_alts;
insn->func = orig_insn->func; insn->sym = orig_insn->sym;
insn->alt_group = new_alt_group; 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 reloc *reloc = table;
struct instruction *dest_insn; struct instruction *dest_insn;
struct alternative *alt; struct alternative *alt;
struct symbol *pfunc = insn->func->pfunc; struct symbol *pfunc = insn_func(insn)->pfunc;
unsigned int prev_offset = 0; unsigned int prev_offset = 0;
/* /*
@ -1909,7 +1914,7 @@ static int add_jump_table(struct objtool_file *file, struct instruction *insn,
break; break;
/* Make sure the destination is in the same function: */ /* 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; break;
alt = malloc(sizeof(*alt)); alt = malloc(sizeof(*alt));
@ -1949,7 +1954,7 @@ static struct reloc *find_jump_table(struct objtool_file *file,
* it. * it.
*/ */
for (; 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)) { insn = insn->first_jump_src ?: prev_insn_same_sym(file, insn)) {
if (insn != orig_insn && insn->type == INSN_JUMP_DYNAMIC) 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) if (!table_reloc)
continue; continue;
dest_insn = find_insn(file, table_reloc->sym->sec, table_reloc->addend); 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; continue;
return table_reloc; return table_reloc;
@ -2415,6 +2420,13 @@ static int decode_sections(struct objtool_file *file)
if (ret) if (ret)
return ret; return ret;
/*
* Must be before add_{jump_call}_destination.
*/
ret = classify_symbols(file);
if (ret)
return ret;
ret = decode_instructions(file); ret = decode_instructions(file);
if (ret) if (ret)
return ret; return ret;
@ -2433,13 +2445,6 @@ static int decode_sections(struct objtool_file *file)
if (ret) if (ret)
return ret; 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' * Must be before add_jump_destinations(), which depends on 'func'
* being set for alternatives, to enable proper sibling call detection. * 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 */ /* stack operations don't make sense with an undefined CFA */
if (cfa->base == CFI_UNDEFINED) { if (cfa->base == CFI_UNDEFINED) {
if (insn->func) { if (insn_func(insn)) {
WARN_FUNC("undefined stack state", insn->sec, insn->offset); WARN_FUNC("undefined stack state", insn->sec, insn->offset);
return -1; return -1;
} }
@ -2994,7 +2999,7 @@ static int update_cfi_state(struct instruction *insn,
} }
/* detect when asm code uses rbp as a scratch register */ /* 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) cfa->base != CFI_BP)
cfi->bp_scratch = true; cfi->bp_scratch = true;
break; break;
@ -3390,13 +3395,13 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
while (1) { while (1) {
next_insn = next_insn_to_validate(file, insn); 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 */ /* Ignore KCFI type preambles, which always fall through */
if (!strncmp(func->name, "__cfi_", 6)) if (!strncmp(func->name, "__cfi_", 6))
return 0; return 0;
WARN("%s() falls through to next function %s()", WARN("%s() falls through to next function %s()",
func->name, insn->func->name); func->name, insn_func(insn)->name);
return 1; 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)) { while (&insn->list != &file->insn_list && (!sec || insn->sec == sec)) {
if (insn->hint && !insn->visited && !insn->ignore) { 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) if (ret && opts.backtrace)
BT_FUNC("<=== (hint)", insn); BT_FUNC("<=== (hint)", insn);
warnings += ret; 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 * In this case we'll find a piece of code (whole function) that is not
* covered by a !section symbol. Ignore them. * 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); int size = find_symbol_hole_containing(insn->sec, insn->offset);
unsigned long end = insn->offset + size; 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 this hole jumps to a .cold function, mark it ignore too.
*/ */
if (insn->jump_dest && insn->jump_dest->func && if (insn->jump_dest && insn_func(insn->jump_dest) &&
strstr(insn->jump_dest->func->name, ".cold")) { strstr(insn_func(insn->jump_dest)->name, ".cold")) {
struct instruction *dest = insn->jump_dest; 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; dest->ignore = true;
} }
} }
@ -3896,10 +3901,10 @@ static bool ignore_unreachable_insn(struct objtool_file *file, struct instructio
return false; return false;
} }
if (!insn->func) if (!insn_func(insn))
return false; return false;
if (insn->func->static_call_tramp) if (insn_func(insn)->static_call_tramp)
return true; 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->type == INSN_JUMP_UNCONDITIONAL) {
if (insn->jump_dest && if (insn->jump_dest &&
insn->jump_dest->func == insn->func) { insn_func(insn->jump_dest) == insn_func(insn)) {
insn = insn->jump_dest; insn = insn->jump_dest;
continue; continue;
} }
@ -3938,7 +3943,7 @@ static bool ignore_unreachable_insn(struct objtool_file *file, struct instructio
break; 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; break;
insn = list_next_entry(insn, list); 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; 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) if (ret && opts.backtrace)
BT_FUNC("<=== (sym)", insn); BT_FUNC("<=== (sym)", insn);
return ret; return ret;
@ -4104,7 +4109,7 @@ static int validate_ibt_insn(struct objtool_file *file, struct instruction *insn
continue; 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 * Anything from->to self is either _THIS_IP_ or
* IRET-to-self. * IRET-to-self.

12
tools/objtool/include/objtool/check.h
View file

@ -67,11 +67,21 @@ struct instruction {
struct reloc *jump_table; struct reloc *jump_table;
struct reloc *reloc; struct reloc *reloc;
struct list_head alts; struct list_head alts;
struct symbol *func; struct symbol *sym;
struct list_head stack_ops; struct list_head stack_ops;
struct cfi_state *cfi; 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 0x01
#define VISITED_BRANCH_UACCESS 0x02 #define VISITED_BRANCH_UACCESS 0x02
#define VISITED_BRANCH_MASK 0x03 #define VISITED_BRANCH_MASK 0x03