stackleak: Rename STACKLEAK to KSTACK_ERASE

In preparation for adding Clang sanitizer coverage stack depth tracking
that can support stack depth callbacks:

- Add the new top-level CONFIG_KSTACK_ERASE option which will be
  implemented either with the stackleak GCC plugin, or with the Clang
  stack depth callback support.
- Rename CONFIG_GCC_PLUGIN_STACKLEAK as needed to CONFIG_KSTACK_ERASE,
  but keep it for anything specific to the GCC plugin itself.
- Rename all exposed "STACKLEAK" names and files to "KSTACK_ERASE" (named
  for what it does rather than what it protects against), but leave as
  many of the internals alone as possible to avoid even more churn.

While here, also split "prev_lowest_stack" into CONFIG_KSTACK_ERASE_METRICS,
since that's the only place it is referenced from.

Suggested-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20250717232519.2984886-1-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>

3 files changed, 15 insertions, 15 deletions

diff --git a/kernel/Makefile b/kernel/Makefile
index 32e80dd626af..e4f01f1d4d0c 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -139,11 +139,11 @@ obj-$(CONFIG_WATCH_QUEUE) += watch_queue.o
 obj-$(CONFIG_RESOURCE_KUNIT_TEST) += resource_kunit.o
 obj-$(CONFIG_SYSCTL_KUNIT_TEST) += sysctl-test.o
 
-CFLAGS_stackleak.o += $(DISABLE_STACKLEAK_PLUGIN)
-obj-$(CONFIG_GCC_PLUGIN_STACKLEAK) += stackleak.o
-KASAN_SANITIZE_stackleak.o := n
-KCSAN_SANITIZE_stackleak.o := n
-KCOV_INSTRUMENT_stackleak.o := n
+CFLAGS_kstack_erase.o += $(DISABLE_KSTACK_ERASE)
+obj-$(CONFIG_KSTACK_ERASE) += kstack_erase.o
+KASAN_SANITIZE_kstack_erase.o := n
+KCSAN_SANITIZE_kstack_erase.o := n
+KCOV_INSTRUMENT_kstack_erase.o := n
 
 obj-$(CONFIG_SCF_TORTURE_TEST) += scftorture.o
 
diff --git a/kernel/fork.c b/kernel/fork.c
index 1ee8eb11f38b..1ec66911f6f6 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -93,7 +93,7 @@
 #include <linux/kcov.h>
 #include <linux/livepatch.h>
 #include <linux/thread_info.h>
-#include <linux/stackleak.h>
+#include <linux/kstack_erase.h>
 #include <linux/kasan.h>
 #include <linux/scs.h>
 #include <linux/io_uring.h>
diff --git a/kernel/stackleak.c b/kernel/kstack_erase.c
index bb65321761b4..201b846f8345 100644
--- a/kernel/stackleak.c
+++ b/kernel/kstack_erase.c
@@ -6,14 +6,14 @@
  *
  * Author: Alexander Popov <alex.popov@linux.com>
  *
- * STACKLEAK reduces the information which kernel stack leak bugs can
+ * KSTACK_ERASE reduces the information which kernel stack leak bugs can
  * reveal and blocks some uninitialized stack variable attacks.
  */
 
-#include <linux/stackleak.h>
+#include <linux/kstack_erase.h>
 #include <linux/kprobes.h>
 
-#ifdef CONFIG_STACKLEAK_RUNTIME_DISABLE
+#ifdef CONFIG_KSTACK_ERASE_RUNTIME_DISABLE
 #include <linux/jump_label.h>
 #include <linux/string_choices.h>
 #include <linux/sysctl.h>
@@ -68,7 +68,7 @@ late_initcall(stackleak_sysctls_init);
 #define skip_erasing()	static_branch_unlikely(&stack_erasing_bypass)
 #else
 #define skip_erasing()	false
-#endif /* CONFIG_STACKLEAK_RUNTIME_DISABLE */
+#endif /* CONFIG_KSTACK_ERASE_RUNTIME_DISABLE */
 
 #ifndef __stackleak_poison
 static __always_inline void __stackleak_poison(unsigned long erase_low,
@@ -91,7 +91,7 @@ static __always_inline void __stackleak_erase(bool on_task_stack)
 	erase_low = stackleak_find_top_of_poison(task_stack_low,
 						 current->lowest_stack);
 
-#ifdef CONFIG_STACKLEAK_METRICS
+#ifdef CONFIG_KSTACK_ERASE_METRICS
 	current->prev_lowest_stack = erase_low;
 #endif
 
@@ -113,7 +113,7 @@ static __always_inline void __stackleak_erase(bool on_task_stack)
 	else
 		erase_high = task_stack_high;
 
-	__stackleak_poison(erase_low, erase_high, STACKLEAK_POISON);
+	__stackleak_poison(erase_low, erase_high, KSTACK_ERASE_POISON);
 
 	/* Reset the 'lowest_stack' value for the next syscall */
 	current->lowest_stack = task_stack_high;
@@ -161,11 +161,11 @@ void __used __no_caller_saved_registers noinstr stackleak_track_stack(void)
 	unsigned long sp = current_stack_pointer;
 
 	/*
-	 * Having CONFIG_STACKLEAK_TRACK_MIN_SIZE larger than
-	 * STACKLEAK_SEARCH_DEPTH makes the poison search in
+	 * Having CONFIG_KSTACK_ERASE_TRACK_MIN_SIZE larger than
+	 * KSTACK_ERASE_SEARCH_DEPTH makes the poison search in
 	 * stackleak_erase() unreliable. Let's prevent that.
 	 */
-	BUILD_BUG_ON(CONFIG_STACKLEAK_TRACK_MIN_SIZE > STACKLEAK_SEARCH_DEPTH);
+	BUILD_BUG_ON(CONFIG_KSTACK_ERASE_TRACK_MIN_SIZE > KSTACK_ERASE_SEARCH_DEPTH);
 
 	/* 'lowest_stack' should be aligned on the register width boundary */
 	sp = ALIGN(sp, sizeof(unsigned long));