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objtool: Convert ANNOTATE_IGNORE_ALTERNATIVE to ANNOTATE

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Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20241128094311.465691316@infradead.org
This commit is contained in:
Peter Zijlstra 2024-11-28 10:38:57 +01:00
parent 18aa6118a1
commit f0cd57c35a
4 changed files with 15 additions and 46 deletions
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14
arch/x86/include/asm/alternative.h
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@ -4,6 +4,7 @@
#include <linux/types.h>
#include <linux/stringify.h>
#include <linux/objtool.h>
#include <asm/asm.h>
#define ALT_FLAGS_SHIFT 16
@ -58,11 +59,7 @@
* objtool annotation to ignore the alternatives and only consider the original
* instruction(s).
*/
#define ANNOTATE_IGNORE_ALTERNATIVE \
"999:\n\t" \
".pushsection .discard.ignore_alts\n\t" \
".long 999b\n\t" \
".popsection\n\t"
#define ANNOTATE_IGNORE_ALTERNATIVE ASM_ANNOTATE(ANNOTYPE_IGNORE_ALTS)
/*
* The patching flags are part of the upper bits of the @ft_flags parameter when
@ -314,12 +311,7 @@ void nop_func(void);
* objtool annotation to ignore the alternatives and only consider the original
* instruction(s).
*/
.macro ANNOTATE_IGNORE_ALTERNATIVE
.Lannotate_\@:
.pushsection .discard.ignore_alts
.long .Lannotate_\@
.popsection
.endm
#define ANNOTATE_IGNORE_ALTERNATIVE ANNOTATE type=ANNOTYPE_IGNORE_ALTS
/*
* Issue one struct alt_instr descriptor entry (need to put it into

1
include/linux/objtool_types.h
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@ -62,5 +62,6 @@ struct unwind_hint {
#define ANNOTYPE_INSTR_BEGIN 3
#define ANNOTYPE_INSTR_END 4
#define ANNOTYPE_UNRET_BEGIN 5
#define ANNOTYPE_IGNORE_ALTS 6
#endif /* _LINUX_OBJTOOL_TYPES_H */

1
tools/include/linux/objtool_types.h
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@ -62,5 +62,6 @@ struct unwind_hint {
#define ANNOTYPE_INSTR_BEGIN 3
#define ANNOTYPE_INSTR_END 4
#define ANNOTYPE_UNRET_BEGIN 5
#define ANNOTYPE_IGNORE_ALTS 6
#endif /* _LINUX_OBJTOOL_TYPES_H */

45
tools/objtool/check.c
View File

@ -1309,40 +1309,6 @@ static void add_uaccess_safe(struct objtool_file *file)
}
}
/*
* FIXME: For now, just ignore any alternatives which add retpolines. This is
* a temporary hack, as it doesn't allow ORC to unwind from inside a retpoline.
* But it at least allows objtool to understand the control flow *around* the
* retpoline.
*/
static int add_ignore_alternatives(struct objtool_file *file)
{
struct section *rsec;
struct reloc *reloc;
struct instruction *insn;
rsec = find_section_by_name(file->elf, ".rela.discard.ignore_alts");
if (!rsec)
return 0;
for_each_reloc(rsec, reloc) {
if (reloc->sym->type != STT_SECTION) {
WARN("unexpected relocation symbol type in %s", rsec->name);
return -1;
}
insn = find_insn(file, reloc->sym->sec, reloc_addend(reloc));
if (!insn) {
WARN("bad .discard.ignore_alts entry");
return -1;
}
insn->ignore_alts = true;
}
return 0;
}
/*
* Symbols that replace INSN_CALL_DYNAMIC, every (tail) call to such a symbol
* will be added to the .retpoline_sites section.
@ -2414,6 +2380,15 @@ static int read_annotate(struct objtool_file *file, int (*func)(int type, struct
return 0;
}
static int __annotate_ignore_alts(int type, struct instruction *insn)
{
if (type != ANNOTYPE_IGNORE_ALTS)
return 0;
insn->ignore_alts = true;
return 0;
}
static int __annotate_noendbr(int type, struct instruction *insn)
{
if (type != ANNOTYPE_NOENDBR)
@ -2626,7 +2601,7 @@ static int decode_sections(struct objtool_file *file)
add_ignores(file);
add_uaccess_safe(file);
ret = add_ignore_alternatives(file);
ret = read_annotate(file, __annotate_ignore_alts);
if (ret)
return ret;