The patch titled
Subject: kasan: clean up feature flags for HW_TAGS mode
has been removed from the -mm tree. Its filename was
kasan-clean-up-feature-flags-for-hw_tags-mode.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Subject: 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@xxxxxxxxxx
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Acked-by: Marco Elver <elver@xxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Evgenii Stepanov <eugenis@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Peter Collingbourne <pcc@xxxxxxxxxx>
Cc: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/kasan/hw_tags.c | 38 +++++++++++++++++++++-----------------
mm/kasan/kasan.h | 2 +-
2 files changed, 22 insertions(+), 18 deletions(-)
--- a/mm/kasan/hw_tags.c~kasan-clean-up-feature-flags-for-hw_tags-mode
+++ a/mm/kasan/hw_tags.c
@@ -42,16 +42,22 @@ static enum kasan_arg kasan_arg __ro_aft
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");
--- a/mm/kasan/kasan.h~kasan-clean-up-feature-flags-for-hw_tags-mode
+++ a/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,
_
Patches currently in -mm which might be from andreyknvl@xxxxxxxxxx are
stacktrace-add-interface-based-on-shadow-call-stack.patch
arm64-scs-save-scs_sp-values-per-cpu-when-switching-stacks.patch
arm64-implement-stack_trace_save_shadow.patch
kasan-use-stack_trace_save_shadow.patch
