Commit f0cd57c3 authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

objtool: Convert ANNOTATE_IGNORE_ALTERNATIVE to ANNOTATE 



Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20241128094311.465691316@infradead.org
parent 18aa6118

arch/x86/include/asm/alternative.h

+3 −11
Original line number Diff line number Diff line
@@ -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

include/linux/objtool_types.h

+1 −0
Original line number Diff line number Diff line
@@ -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 */

tools/include/linux/objtool_types.h

+1 −0
Original line number Diff line number Diff line
@@ -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 */

tools/objtool/check.c

+10 −35
Original line number Diff line number Diff line
@@ -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;