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objtool: Convert {.UN}REACHABLE to ANNOTATE

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Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20241128094312.353431347@infradead.org
This commit is contained in:
Peter Zijlstra 2024-11-28 10:39:05 +01:00
parent 06e2474598
commit e7a174fb43
8 changed files with 36 additions and 76 deletions
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2
arch/loongarch/include/asm/bug.h
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@ -45,7 +45,7 @@
#define __WARN_FLAGS(flags) \
do { \
instrumentation_begin(); \
__BUG_FLAGS(BUGFLAG_WARNING|(flags), ASM_REACHABLE); \
__BUG_FLAGS(BUGFLAG_WARNING|(flags), ANNOTATE_REACHABLE);\
instrumentation_end(); \
} while (0)

4
arch/x86/entry/entry_64.S
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@ -311,7 +311,7 @@ SYM_CODE_END(xen_error_entry)
call \cfunc
/* For some configurations \cfunc ends up being a noreturn. */
REACHABLE
ANNOTATE_REACHABLE
jmp error_return
.endm
@ -532,7 +532,7 @@ SYM_CODE_START(\asmsym)
call \cfunc
/* For some configurations \cfunc ends up being a noreturn. */
REACHABLE
ANNOTATE_REACHABLE
jmp paranoid_exit

2
arch/x86/include/asm/bug.h
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@ -92,7 +92,7 @@ do { \
do { \
__auto_type __flags = BUGFLAG_WARNING|(flags); \
instrumentation_begin(); \
_BUG_FLAGS(ASM_UD2, __flags, ASM_REACHABLE); \
_BUG_FLAGS(ASM_UD2, __flags, ANNOTATE_REACHABLE); \
instrumentation_end(); \
} while (0)

2
arch/x86/include/asm/irq_stack.h
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@ -101,7 +101,7 @@
#define ASM_CALL_ARG0 \
"call %c[__func] \n" \
ASM_REACHABLE
ANNOTATE_REACHABLE
#define ASM_CALL_ARG1 \
"movq %[arg1], %%rdi \n" \

18
include/linux/objtool.h
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@ -111,14 +111,6 @@
#endif
.endm
.macro REACHABLE
.Lhere_\@:
.pushsection .discard.reachable
.long .Lhere_\@
.popsection
.endm
.macro ANNOTATE type:req
.Lhere_\@:
.pushsection .discard.annotate_insn,"M",@progbits,8
@ -138,14 +130,11 @@
#define STACK_FRAME_NON_STANDARD_FP(func)
#define __ASM_ANNOTATE(label, type)
#define ASM_ANNOTATE(type)
#define ASM_REACHABLE
#else
.macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 signal=0
.endm
.macro STACK_FRAME_NON_STANDARD func:req
.endm
.macro REACHABLE
.endm
.macro ANNOTATE type:req
.endm
#endif
@ -187,6 +176,12 @@
* it will be ignored.
*/
#define ANNOTATE_UNRET_BEGIN ASM_ANNOTATE(ANNOTYPE_UNRET_BEGIN)
/*
* This should be used directly after an instruction that is considered
* terminating, like a noreturn CALL or UD2 when we know they are not -- eg
* WARN using UD2.
*/
#define ANNOTATE_REACHABLE ASM_ANNOTATE(ANNOTYPE_REACHABLE)
#else
#define ANNOTATE_NOENDBR ANNOTATE type=ANNOTYPE_NOENDBR
@ -196,6 +191,7 @@
#define ANNOTATE_IGNORE_ALTERNATIVE ANNOTATE type=ANNOTYPE_IGNORE_ALTS
#define ANNOTATE_INTRA_FUNCTION_CALL ANNOTATE type=ANNOTYPE_INTRA_FUNCTION_CALL
#define ANNOTATE_UNRET_BEGIN ANNOTATE type=ANNOTYPE_UNRET_BEGIN
#define ANNOTATE_REACHABLE ANNOTATE type=ANNOTYPE_REACHABLE
#endif
#if defined(CONFIG_NOINSTR_VALIDATION) && \

1
include/linux/objtool_types.h
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@ -64,5 +64,6 @@ struct unwind_hint {
#define ANNOTYPE_UNRET_BEGIN 5
#define ANNOTYPE_IGNORE_ALTS 6
#define ANNOTYPE_INTRA_FUNCTION_CALL 7
#define ANNOTYPE_REACHABLE 8
#endif /* _LINUX_OBJTOOL_TYPES_H */

1
tools/include/linux/objtool_types.h
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@ -64,5 +64,6 @@ struct unwind_hint {
#define ANNOTYPE_UNRET_BEGIN 5
#define ANNOTYPE_IGNORE_ALTS 6
#define ANNOTYPE_INTRA_FUNCTION_CALL 7
#define ANNOTYPE_REACHABLE 8
#endif /* _LINUX_OBJTOOL_TYPES_H */

82
tools/objtool/check.c
View File

@ -627,56 +627,6 @@ static struct instruction *find_last_insn(struct objtool_file *file,
return insn;
}
/*
* Mark "ud2" instructions and manually annotated dead ends.
*/
static int add_dead_ends(struct objtool_file *file)
{
struct section *rsec;
struct reloc *reloc;
struct instruction *insn;
uint64_t offset;
/*
* UD2 defaults to being a dead-end, allow them to be annotated for
* non-fatal, eg WARN.
*/
rsec = find_section_by_name(file->elf, ".rela.discard.reachable");
if (!rsec)
return 0;
for_each_reloc(rsec, reloc) {
if (reloc->sym->type == STT_SECTION) {
offset = reloc_addend(reloc);
} else if (reloc->sym->local_label) {
offset = reloc->sym->offset;
} else {
WARN("unexpected relocation symbol type in %s", rsec->name);
return -1;
}
insn = find_insn(file, reloc->sym->sec, offset);
if (insn)
insn = prev_insn_same_sec(file, insn);
else if (offset == reloc->sym->sec->sh.sh_size) {
insn = find_last_insn(file, reloc->sym->sec);
if (!insn) {
WARN("can't find reachable insn at %s+0x%" PRIx64,
reloc->sym->sec->name, offset);
return -1;
}
} else {
WARN("can't find reachable insn at %s+0x%" PRIx64,
reloc->sym->sec->name, offset);
return -1;
}
insn->dead_end = false;
}
return 0;
}
static int create_static_call_sections(struct objtool_file *file)
{
struct static_call_site *site;
@ -2306,6 +2256,7 @@ static int read_annotate(struct objtool_file *file,
struct section *sec;
struct instruction *insn;
struct reloc *reloc;
uint64_t offset;
int type, ret;
sec = find_section_by_name(file->elf, ".discard.annotate_insn");
@ -2327,8 +2278,19 @@ static int read_annotate(struct objtool_file *file,
for_each_reloc(sec->rsec, reloc) {
type = *(u32 *)(sec->data->d_buf + (reloc_idx(reloc) * sec->sh.sh_entsize) + 4);
insn = find_insn(file, reloc->sym->sec,
reloc->sym->offset + reloc_addend(reloc));
offset = reloc->sym->offset + reloc_addend(reloc);
insn = find_insn(file, reloc->sym->sec, offset);
/*
* Reachable annotations are 'funneh' and act on the previous instruction :/
*/
if (type == ANNOTYPE_REACHABLE) {
if (insn)
insn = prev_insn_same_sec(file, insn);
else if (offset == reloc->sym->sec->sh.sh_size)
insn = find_last_insn(file, reloc->sym->sec);
}
if (!insn) {
WARN("bad .discard.annotate_insn entry: %d of type %d", reloc_idx(reloc), type);
return -1;
@ -2420,6 +2382,10 @@ static int __annotate_late(struct objtool_file *file, int type, struct instructi
insn->unret = 1;
break;
case ANNOTYPE_REACHABLE:
insn->dead_end = false;
break;
default:
break;
}
@ -2566,14 +2532,6 @@ static int decode_sections(struct objtool_file *file)
if (ret)
return ret;
/*
* Must be after add_call_destinations() such that it can override
* dead_end_function() marks.
*/
ret = add_dead_ends(file);
if (ret)
return ret;
ret = add_jump_table_alts(file);
if (ret)
return ret;
@ -2582,6 +2540,10 @@ static int decode_sections(struct objtool_file *file)
if (ret)
return ret;
/*
* Must be after add_call_destinations() such that it can override
* dead_end_function() marks.
*/
ret = read_annotate(file, __annotate_late);
if (ret)
return ret;