Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit bb0a008d authored by Nadav Amit's avatar Nadav Amit Committed by Ingo Molnar
Browse files

x86/jump-label: Remove support for custom text poker 



There are only two types of text poking: early and breakpoint based. The use
of a function pointer to perform text poking complicates the code and is
probably inefficient due to the use of indirect branches.

Signed-off-by: default avatarNadav Amit <namit@vmware.com>
Signed-off-by: default avatarRick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: <akpm@linux-foundation.org>
Cc: <ard.biesheuvel@linaro.org>
Cc: <deneen.t.dock@intel.com>
Cc: <kernel-hardening@lists.openwall.com>
Cc: <kristen@linux.intel.com>
Cc: <linux_dti@icloud.com>
Cc: <will.deacon@arm.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190426001143.4983-13-namit@vmware.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent f2c65fb3

arch/x86/kernel/jump_label.c

+10 −16
Original line number Diff line number Diff line
@@ -37,7 +37,6 @@ static void bug_at(unsigned char *ip, int line) 


static void __ref __jump_label_transform(struct jump_entry *entry,

					 enum jump_label_type type,

					 void *(*poker)(void *, const void *, size_t),

					 int init)

{

	union jump_code_union jmp;
@@ -50,14 +49,6 @@ static void __ref __jump_label_transform(struct jump_entry *entry, 
	jmp.offset = jump_entry_target(entry) -

		     (jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE);



	/*

	 * As long as only a single processor is running and the code is still

	 * not marked as RO, text_poke_early() can be used; Checking that

	 * system_state is SYSTEM_BOOTING guarantees it.

	 */

	if (system_state == SYSTEM_BOOTING)

		poker = text_poke_early;



	if (type == JUMP_LABEL_JMP) {

		if (init) {

			expect = default_nop; line = __LINE__;
@@ -80,15 +71,18 @@ static void __ref __jump_label_transform(struct jump_entry *entry, 
		bug_at((void *)jump_entry_code(entry), line);



	/*

	 * Make text_poke_bp() a default fallback poker.

	 * As long as only a single processor is running and the code is still

	 * not marked as RO, text_poke_early() can be used; Checking that

	 * system_state is SYSTEM_BOOTING guarantees it. It will be set to

	 * SYSTEM_SCHEDULING before other cores are awaken and before the

	 * code is write-protected.

	 *

	 * At the time the change is being done, just ignore whether we

	 * are doing nop -> jump or jump -> nop transition, and assume

	 * always nop being the 'currently valid' instruction

	 *

	 */

	if (poker) {

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

	if (init || system_state == SYSTEM_BOOTING) {

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

				JUMP_LABEL_NOP_SIZE);

		return;

	}
@@ -101,7 +95,7 @@ void arch_jump_label_transform(struct jump_entry *entry, 
			       enum jump_label_type type)

{

	mutex_lock(&text_mutex);

	__jump_label_transform(entry, type, NULL, 0);

	__jump_label_transform(entry, type, 0);

	mutex_unlock(&text_mutex);

}
@@ -131,5 +125,5 @@ __init_or_module void arch_jump_label_transform_static(struct jump_entry *entry, 
			jlstate = JL_STATE_NO_UPDATE;

	}

	if (jlstate == JL_STATE_UPDATE)

		__jump_label_transform(entry, type, text_poke_early, 1);

		__jump_label_transform(entry, type, 1);

}