Commit ff05ab23 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

x86/nospec, objtool: Introduce ANNOTATE_IGNORE_ALTERNATIVE 



To facillitate other usage of ignoring alternatives; rename
ANNOTATE_NOSPEC_IGNORE to ANNOTATE_IGNORE_ALTERNATIVE.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent b69656fa

arch/x86/include/asm/alternative-asm.h

+11 −0
Original line number Diff line number Diff line
@@ -19,6 +19,17 @@ 
	.endm

#endif



/*

 * 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



/*

 * Issue one struct alt_instr descriptor entry (need to put it into

 * the section .altinstructions, see below). This entry contains

arch/x86/include/asm/alternative.h

+10 −0
Original line number Diff line number Diff line
@@ -45,6 +45,16 @@ 
#define LOCK_PREFIX ""

#endif



/*

 * 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"



struct alt_instr {

	s32 instr_offset;	/* original instruction */

	s32 repl_offset;	/* offset to replacement instruction */

arch/x86/include/asm/nospec-branch.h

+9 −19
Original line number Diff line number Diff line
@@ -10,6 +10,15 @@ 
#include <asm/cpufeatures.h>

#include <asm/msr-index.h>



/*

 * This should be used immediately before a retpoline alternative. It tells

 * objtool where the retpolines are so that it can make sense of the control

 * flow by just reading the original instruction(s) and ignoring the

 * alternatives.

 */

#define ANNOTATE_NOSPEC_ALTERNATIVE \

	ANNOTATE_IGNORE_ALTERNATIVE



/*

 * Fill the CPU return stack buffer.

 *
@@ -56,19 +65,6 @@ 


#ifdef __ASSEMBLY__



/*

 * This should be used immediately before a retpoline alternative.  It tells

 * objtool where the retpolines are so that it can make sense of the control

 * flow by just reading the original instruction(s) and ignoring the

 * alternatives.

 */

.macro ANNOTATE_NOSPEC_ALTERNATIVE

	.Lannotate_\@:

	.pushsection .discard.nospec

	.long .Lannotate_\@ - .

	.popsection

.endm



/*

 * This should be used immediately before an indirect jump/call. It tells

 * objtool the subsequent indirect jump/call is vouched safe for retpoline
@@ -152,12 +148,6 @@ 


#else /* __ASSEMBLY__ */



#define ANNOTATE_NOSPEC_ALTERNATIVE				\

	"999:\n\t"						\

	".pushsection .discard.nospec\n\t"			\

	".long 999b - .\n\t"					\

	".popsection\n\t"



#define ANNOTATE_RETPOLINE_SAFE					\

	"999:\n\t"						\

	".pushsection .discard.retpoline_safe\n\t"		\

tools/objtool/check.c

+4 −4
Original line number Diff line number Diff line
@@ -457,13 +457,13 @@ static void add_ignores(struct objtool_file *file) 
 * But it at least allows objtool to understand the control flow *around* the

 * retpoline.

 */

static int add_nospec_ignores(struct objtool_file *file)

static int add_ignore_alternatives(struct objtool_file *file)

{

	struct section *sec;

	struct rela *rela;

	struct instruction *insn;



	sec = find_section_by_name(file->elf, ".rela.discard.nospec");

	sec = find_section_by_name(file->elf, ".rela.discard.ignore_alts");

	if (!sec)

		return 0;
@@ -475,7 +475,7 @@ static int add_nospec_ignores(struct objtool_file *file) 


		insn = find_insn(file, rela->sym->sec, rela->addend);

		if (!insn) {

			WARN("bad .discard.nospec entry");

			WARN("bad .discard.ignore_alts entry");

			return -1;

		}
@@ -1239,7 +1239,7 @@ static int decode_sections(struct objtool_file *file) 


	add_ignores(file);



	ret = add_nospec_ignores(file);

	ret = add_ignore_alternatives(file);

	if (ret)

		return ret;

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