Commit 241944d1 authored by Andrey Konovalov's avatar Andrey Konovalov Committed by Linus Torvalds
Browse files

kasan: clean up feature flags for HW_TAGS mode 

 - Untie kasan_init_hw_tags() code from the default values of
   kasan_arg_mode and kasan_arg_stacktrace.

 - Move static_branch_enable(&kasan_flag_enabled) to the end of
   kasan_init_hw_tags_cpu().

 - Remove excessive comments in kasan_arg_mode switch.

 - Add new comments.

Link: https://lkml.kernel.org/r/76ebb340265be57a218564a497e1f52ff36a3879.1643047180.git.andreyknvl@google.com


Signed-off-by: default avatarAndrey Konovalov <andreyknvl@google.com>
Acked-by: default avatarMarco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1eeac51e

mm/kasan/hw_tags.c

+21 −17
Original line number Diff line number Diff line
@@ -42,16 +42,22 @@ static enum kasan_arg kasan_arg __ro_after_init; 
static enum kasan_arg_mode kasan_arg_mode __ro_after_init;

static enum kasan_arg_stacktrace kasan_arg_stacktrace __initdata;



/* Whether KASAN is enabled at all. */

/*

 * Whether KASAN is enabled at all.

 * The value remains false until KASAN is initialized by kasan_init_hw_tags().

 */

DEFINE_STATIC_KEY_FALSE(kasan_flag_enabled);

EXPORT_SYMBOL(kasan_flag_enabled);



/* Whether the selected mode is synchronous/asynchronous/asymmetric.*/

/*

 * Whether the selected mode is synchronous, asynchronous, or asymmetric.

 * Defaults to KASAN_MODE_SYNC.

 */

enum kasan_mode kasan_mode __ro_after_init;

EXPORT_SYMBOL_GPL(kasan_mode);



/* Whether to collect alloc/free stack traces. */

DEFINE_STATIC_KEY_FALSE(kasan_flag_stacktrace);

DEFINE_STATIC_KEY_TRUE(kasan_flag_stacktrace);



/* kasan=off/on */

static int __init early_kasan_flag(char *arg)
@@ -127,7 +133,11 @@ void kasan_init_hw_tags_cpu(void) 
	 * as this function is only called for MTE-capable hardware.

	 */



	/* If KASAN is disabled via command line, don't initialize it. */

	/*

	 * If KASAN is disabled via command line, don't initialize it.

	 * When this function is called, kasan_flag_enabled is not yet

	 * set by kasan_init_hw_tags(). Thus, check kasan_arg instead.

	 */

	if (kasan_arg == KASAN_ARG_OFF)

		return;
@@ -154,42 +164,36 @@ void __init kasan_init_hw_tags(void) 
	if (kasan_arg == KASAN_ARG_OFF)

		return;



	/* Enable KASAN. */

	static_branch_enable(&kasan_flag_enabled);



	switch (kasan_arg_mode) {

	case KASAN_ARG_MODE_DEFAULT:

		/*

		 * Default to sync mode.

		 */

		fallthrough;

		/* Default is specified by kasan_mode definition. */

		break;

	case KASAN_ARG_MODE_SYNC:

		/* Sync mode enabled. */

		kasan_mode = KASAN_MODE_SYNC;

		break;

	case KASAN_ARG_MODE_ASYNC:

		/* Async mode enabled. */

		kasan_mode = KASAN_MODE_ASYNC;

		break;

	case KASAN_ARG_MODE_ASYMM:

		/* Asymm mode enabled. */

		kasan_mode = KASAN_MODE_ASYMM;

		break;

	}



	switch (kasan_arg_stacktrace) {

	case KASAN_ARG_STACKTRACE_DEFAULT:

		/* Default to enabling stack trace collection. */

		static_branch_enable(&kasan_flag_stacktrace);

		/* Default is specified by kasan_flag_stacktrace definition. */

		break;

	case KASAN_ARG_STACKTRACE_OFF:

		/* Do nothing, kasan_flag_stacktrace keeps its default value. */

		static_branch_disable(&kasan_flag_stacktrace);

		break;

	case KASAN_ARG_STACKTRACE_ON:

		static_branch_enable(&kasan_flag_stacktrace);

		break;

	}



	/* KASAN is now initialized, enable it. */

	static_branch_enable(&kasan_flag_enabled);



	pr_info("KernelAddressSanitizer initialized (hw-tags, mode=%s, stacktrace=%s)\n",

		kasan_mode_info(),

		kasan_stack_collection_enabled() ? "on" : "off");

mm/kasan/kasan.h

+1 −1
Original line number Diff line number Diff line
@@ -12,7 +12,7 @@ 
#include <linux/static_key.h>

#include "../slab.h"



DECLARE_STATIC_KEY_FALSE(kasan_flag_stacktrace);

DECLARE_STATIC_KEY_TRUE(kasan_flag_stacktrace);



enum kasan_mode {

	KASAN_MODE_SYNC,