Commit 9fc0f798 authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Thomas Gleixner
Browse files

x86/jump_label: Switch to jump_entry accessors 



In preparation of switching x86 to use place-relative references for
the code, target and key members of struct jump_entry, replace direct
references to the struct members with invocations of the new accessors.
This will allow us to make the switch by modifying the accessors only.

This incorporates a cleanup of __jump_label_transform() proposed by
Peter.

Signed-off-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-s390@vger.kernel.org
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Jessica Yu <jeyu@kernel.org>
Link: https://lkml.kernel.org/r/20180919065144.25010-6-ard.biesheuvel@linaro.org
parent b40a142b

arch/x86/kernel/jump_label.c

+25 −37
Original line number Diff line number Diff line
@@ -42,55 +42,40 @@ static void __ref __jump_label_transform(struct jump_entry *entry, 
					 void *(*poker)(void *, const void *, size_t),

					 int init)

{

	union jump_code_union code;

	union jump_code_union jmp;

	const unsigned char default_nop[] = { STATIC_KEY_INIT_NOP };

	const unsigned char *ideal_nop = ideal_nops[NOP_ATOMIC5];

	const void *expect, *code;

	int line;



	jmp.jump = 0xe9;

	jmp.offset = jump_entry_target(entry) -

		     (jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE);



	if (early_boot_irqs_disabled)

		poker = text_poke_early;



	if (type == JUMP_LABEL_JMP) {

		if (init) {

			/*

			 * Jump label is enabled for the first time.

			 * So we expect a default_nop...

			 */

			if (unlikely(memcmp((void *)entry->code, default_nop, 5)

				     != 0))

				bug_at((void *)entry->code, __LINE__);

			expect = default_nop; line = __LINE__;

		} else {

			/*

			 * ...otherwise expect an ideal_nop. Otherwise

			 * something went horribly wrong.

			 */

			if (unlikely(memcmp((void *)entry->code, ideal_nop, 5)

				     != 0))

				bug_at((void *)entry->code, __LINE__);

			expect = ideal_nop; line = __LINE__;

		}



		code.jump = 0xe9;

		code.offset = entry->target -

				(entry->code + JUMP_LABEL_NOP_SIZE);

		code = &jmp.code;

	} else {

		/*

		 * We are disabling this jump label. If it is not what

		 * we think it is, then something must have gone wrong.

		 * If this is the first initialization call, then we

		 * are converting the default nop to the ideal nop.

		 */

		if (init) {

			if (unlikely(memcmp((void *)entry->code, default_nop, 5) != 0))

				bug_at((void *)entry->code, __LINE__);

			expect = default_nop; line = __LINE__;

		} else {

			code.jump = 0xe9;

			code.offset = entry->target -

				(entry->code + JUMP_LABEL_NOP_SIZE);

			if (unlikely(memcmp((void *)entry->code, &code, 5) != 0))

				bug_at((void *)entry->code, __LINE__);

			expect = &jmp.code; line = __LINE__;

		}

		memcpy(&code, ideal_nops[NOP_ATOMIC5], JUMP_LABEL_NOP_SIZE);



		code = ideal_nop;

	}



	if (memcmp((void *)jump_entry_code(entry), expect, JUMP_LABEL_NOP_SIZE))

		bug_at((void *)jump_entry_code(entry), line);



	/*

	 * Make text_poke_bp() a default fallback poker.

	 *
@@ -99,11 +84,14 @@ static void __ref __jump_label_transform(struct jump_entry *entry, 
	 * always nop being the 'currently valid' instruction

	 *

	 */

	if (poker)

		(*poker)((void *)entry->code, &code, JUMP_LABEL_NOP_SIZE);

	else

		text_poke_bp((void *)entry->code, &code, JUMP_LABEL_NOP_SIZE,

			     (void *)entry->code + JUMP_LABEL_NOP_SIZE);

	if (poker) {

		(*poker)((void *)jump_entry_code(entry), code,

			 JUMP_LABEL_NOP_SIZE);

		return;

	}



	text_poke_bp((void *)jump_entry_code(entry), code, JUMP_LABEL_NOP_SIZE,

		     (void *)jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE);

}



void arch_jump_label_transform(struct jump_entry *entry,

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