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authorAndrey Konovalov <andreyknvl@google.com>2022-03-24 18:11:44 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2022-03-24 19:06:48 -0700
commit241944d1628e77f578d309ec57528b01cdef78d3 (patch)
tree2dd26740eb3736e55ec712e4ef07bcb3f64b157d /mm/kasan
parent1eeac51e6201c1c0980fcdae73dbbe34811f8503 (diff)
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: Andrey Konovalov <andreyknvl@google.com> Acked-by: Marco 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: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/kasan')
-rw-r--r--mm/kasan/hw_tags.c38
-rw-r--r--mm/kasan/kasan.h2
2 files changed, 22 insertions, 18 deletions
diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c
index 6509809dd5d8..6a3146d1ccc5 100644
--- a/mm/kasan/hw_tags.c
+++ b/mm/kasan/hw_tags.c
@@ -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");
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index 020f3e57a03f..efda13a9ce6a 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -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,