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>

2 files changed, 14 insertions, 14 deletions

diff --git a/drivers/misc/lkdtm/Makefile b/drivers/misc/lkdtm/Makefile
index 39468bd27b85..03ebe33185f9 100644
--- a/drivers/misc/lkdtm/Makefile
+++ b/drivers/misc/lkdtm/Makefile
@@ -8,7 +8,7 @@ lkdtm-$(CONFIG_LKDTM)		+= perms.o
 lkdtm-$(CONFIG_LKDTM)		+= refcount.o
 lkdtm-$(CONFIG_LKDTM)		+= rodata_objcopy.o
 lkdtm-$(CONFIG_LKDTM)		+= usercopy.o
-lkdtm-$(CONFIG_LKDTM)		+= stackleak.o
+lkdtm-$(CONFIG_LKDTM)		+= kstack_erase.o
 lkdtm-$(CONFIG_LKDTM)		+= cfi.o
 lkdtm-$(CONFIG_LKDTM)		+= fortify.o
 lkdtm-$(CONFIG_PPC_64S_HASH_MMU)	+= powerpc.o
diff --git a/drivers/misc/lkdtm/stackleak.c b/drivers/misc/lkdtm/kstack_erase.c
index f1d022160913..4fd9b0bfb874 100644
--- a/drivers/misc/lkdtm/stackleak.c
+++ b/drivers/misc/lkdtm/kstack_erase.c
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 /*
  * This code tests that the current task stack is properly erased (filled
- * with STACKLEAK_POISON).
+ * with KSTACK_ERASE_POISON).
  *
  * Authors:
  *   Alexander Popov <alex.popov@linux.com>
@@ -9,9 +9,9 @@
  */
 
 #include "lkdtm.h"
-#include <linux/stackleak.h>
+#include <linux/kstack_erase.h>
 
-#if defined(CONFIG_GCC_PLUGIN_STACKLEAK)
+#if defined(CONFIG_KSTACK_ERASE)
 /*
  * Check that stackleak tracks the lowest stack pointer and erases the stack
  * below this as expected.
@@ -85,7 +85,7 @@ static void noinstr check_stackleak_irqoff(void)
 	while (poison_low > task_stack_low) {
 		poison_low -= sizeof(unsigned long);
 
-		if (*(unsigned long *)poison_low == STACKLEAK_POISON)
+		if (*(unsigned long *)poison_low == KSTACK_ERASE_POISON)
 			continue;
 
 		instrumentation_begin();
@@ -96,7 +96,7 @@ static void noinstr check_stackleak_irqoff(void)
 	}
 
 	instrumentation_begin();
-	pr_info("stackleak stack usage:\n"
+	pr_info("kstack erase stack usage:\n"
 		"  high offset: %lu bytes\n"
 		"  current:     %lu bytes\n"
 		"  lowest:      %lu bytes\n"
@@ -121,7 +121,7 @@ out:
 	instrumentation_end();
 }
 
-static void lkdtm_STACKLEAK_ERASING(void)
+static void lkdtm_KSTACK_ERASE(void)
 {
 	unsigned long flags;
 
@@ -129,19 +129,19 @@ static void lkdtm_STACKLEAK_ERASING(void)
 	check_stackleak_irqoff();
 	local_irq_restore(flags);
 }
-#else /* defined(CONFIG_GCC_PLUGIN_STACKLEAK) */
-static void lkdtm_STACKLEAK_ERASING(void)
+#else /* defined(CONFIG_KSTACK_ERASE) */
+static void lkdtm_KSTACK_ERASE(void)
 {
-	if (IS_ENABLED(CONFIG_HAVE_ARCH_STACKLEAK)) {
-		pr_err("XFAIL: stackleak is not enabled (CONFIG_GCC_PLUGIN_STACKLEAK=n)\n");
+	if (IS_ENABLED(CONFIG_HAVE_ARCH_KSTACK_ERASE)) {
+		pr_err("XFAIL: stackleak is not enabled (CONFIG_KSTACK_ERASE=n)\n");
 	} else {
-		pr_err("XFAIL: stackleak is not supported on this arch (HAVE_ARCH_STACKLEAK=n)\n");
+		pr_err("XFAIL: stackleak is not supported on this arch (HAVE_ARCH_KSTACK_ERASE=n)\n");
 	}
 }
-#endif /* defined(CONFIG_GCC_PLUGIN_STACKLEAK) */
+#endif /* defined(CONFIG_KSTACK_ERASE) */
 
 static struct crashtype crashtypes[] = {
-	CRASHTYPE(STACKLEAK_ERASING),
+	CRASHTYPE(KSTACK_ERASE),
 };
 
 struct crashtype_category stackleak_crashtypes = {