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>

18 files changed, 20 insertions, 20 deletions

diff --git a/arch/Kconfig b/arch/Kconfig
index a3308a220f86..4d1908f6f084 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -630,11 +630,11 @@ config SECCOMP_CACHE_DEBUG
 
 	  If unsure, say N.
 
-config HAVE_ARCH_STACKLEAK
+config HAVE_ARCH_KSTACK_ERASE
 	bool
 	help
 	  An architecture should select this if it has the code which
-	  fills the used part of the kernel stack with the STACKLEAK_POISON
+	  fills the used part of the kernel stack with the KSTACK_ERASE_POISON
 	  value before returning from system calls.
 
 config HAVE_STACKPROTECTOR
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 3072731fe09c..cb0b2e2211ca 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -87,11 +87,11 @@ config ARM
 	select HAVE_ARCH_KGDB if !CPU_ENDIAN_BE32 && MMU
 	select HAVE_ARCH_KASAN if MMU && !XIP_KERNEL
 	select HAVE_ARCH_KASAN_VMALLOC if HAVE_ARCH_KASAN
+	select HAVE_ARCH_KSTACK_ERASE
 	select HAVE_ARCH_MMAP_RND_BITS if MMU
 	select HAVE_ARCH_PFN_VALID
 	select HAVE_ARCH_SECCOMP
 	select HAVE_ARCH_SECCOMP_FILTER if AEABI && !OABI_COMPAT
-	select HAVE_ARCH_STACKLEAK
 	select HAVE_ARCH_THREAD_STRUCT_WHITELIST
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE if ARM_LPAE
diff --git a/arch/arm/boot/compressed/Makefile b/arch/arm/boot/compressed/Makefile
index d61369b1eabe..f9075edfd773 100644
--- a/arch/arm/boot/compressed/Makefile
+++ b/arch/arm/boot/compressed/Makefile
@@ -9,7 +9,7 @@ OBJS		=
 
 HEAD	= head.o
 OBJS	+= misc.o decompress.o
-CFLAGS_decompress.o += $(DISABLE_STACKLEAK_PLUGIN)
+CFLAGS_decompress.o += $(DISABLE_KSTACK_ERASE)
 ifeq ($(CONFIG_DEBUG_UNCOMPRESS),y)
 OBJS	+= debug.o
 AFLAGS_head.o += -DDEBUG
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index f379c852dcb7..88336a1292bb 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -119,7 +119,7 @@ no_work_pending:
 
 	ct_user_enter save = 0
 
-#ifdef CONFIG_GCC_PLUGIN_STACKLEAK
+#ifdef CONFIG_KSTACK_ERASE
 	bl	stackleak_erase_on_task_stack
 #endif
 	restore_user_regs fast = 0, offset = 0
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 55fc331af337..e2a9e013b6a9 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -187,12 +187,12 @@ config ARM64
 	select HAVE_ARCH_KCSAN if EXPERT
 	select HAVE_ARCH_KFENCE
 	select HAVE_ARCH_KGDB
+	select HAVE_ARCH_KSTACK_ERASE
 	select HAVE_ARCH_MMAP_RND_BITS
 	select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT
 	select HAVE_ARCH_PREL32_RELOCATIONS
 	select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
 	select HAVE_ARCH_SECCOMP_FILTER
-	select HAVE_ARCH_STACKLEAK
 	select HAVE_ARCH_THREAD_STRUCT_WHITELIST
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 5ae2a34b50bd..67331437b2aa 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -614,7 +614,7 @@ SYM_CODE_END(ret_to_kernel)
 SYM_CODE_START_LOCAL(ret_to_user)
 	ldr	x19, [tsk, #TSK_TI_FLAGS]	// re-check for single-step
 	enable_step_tsk x19, x2
-#ifdef CONFIG_GCC_PLUGIN_STACKLEAK
+#ifdef CONFIG_KSTACK_ERASE
 	bl	stackleak_erase_on_task_stack
 #endif
 	kernel_exit 0
diff --git a/arch/arm64/kernel/pi/Makefile b/arch/arm64/kernel/pi/Makefile
index 4d11a8c29181..f440bf57b1a5 100644
--- a/arch/arm64/kernel/pi/Makefile
+++ b/arch/arm64/kernel/pi/Makefile
@@ -2,7 +2,7 @@
 # Copyright 2022 Google LLC
 
 KBUILD_CFLAGS	:= $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) -fpie \
-		   -Os -DDISABLE_BRANCH_PROFILING $(DISABLE_STACKLEAK_PLUGIN) \
+		   -Os -DDISABLE_BRANCH_PROFILING $(DISABLE_KSTACK_ERASE) \
 		   $(DISABLE_LATENT_ENTROPY_PLUGIN) \
 		   $(call cc-option,-mbranch-protection=none) \
 		   -I$(srctree)/scripts/dtc/libfdt -fno-stack-protector \
diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile
index a76522d63c3e..0b0a68b663d4 100644
--- a/arch/arm64/kvm/hyp/nvhe/Makefile
+++ b/arch/arm64/kvm/hyp/nvhe/Makefile
@@ -12,7 +12,7 @@ asflags-y := -D__KVM_NVHE_HYPERVISOR__ -D__DISABLE_EXPORTS
 ccflags-y := -D__KVM_NVHE_HYPERVISOR__ -D__DISABLE_EXPORTS -D__DISABLE_TRACE_MMIO__
 ccflags-y += -fno-stack-protector	\
 	     -DDISABLE_BRANCH_PROFILING	\
-	     $(DISABLE_STACKLEAK_PLUGIN)
+	     $(DISABLE_KSTACK_ERASE)
 
 hostprogs := gen-hyprel
 HOST_EXTRACFLAGS += -I$(objtree)/include
diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index 4b19f93379a1..1514789bea4a 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -120,11 +120,11 @@ config LOONGARCH
 	select HAVE_ARCH_KASAN
 	select HAVE_ARCH_KFENCE
 	select HAVE_ARCH_KGDB if PERF_EVENTS
+	select HAVE_ARCH_KSTACK_ERASE
 	select HAVE_ARCH_MMAP_RND_BITS if MMU
 	select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
 	select HAVE_ARCH_SECCOMP
 	select HAVE_ARCH_SECCOMP_FILTER
-	select HAVE_ARCH_STACKLEAK
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
 	select HAVE_ARCH_USERFAULTFD_MINOR if USERFAULTFD
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 36061f4732b7..cfc084fc9e6f 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -135,13 +135,13 @@ config RISCV
 	select HAVE_ARCH_KASAN if MMU && 64BIT
 	select HAVE_ARCH_KASAN_VMALLOC if MMU && 64BIT
 	select HAVE_ARCH_KFENCE if MMU && 64BIT
+	select HAVE_ARCH_KSTACK_ERASE
 	select HAVE_ARCH_KGDB if !XIP_KERNEL
 	select HAVE_ARCH_KGDB_QXFER_PKT
 	select HAVE_ARCH_MMAP_RND_BITS if MMU
 	select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT
 	select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
 	select HAVE_ARCH_SECCOMP_FILTER
-	select HAVE_ARCH_STACKLEAK
 	select HAVE_ARCH_THREAD_STRUCT_WHITELIST
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE if 64BIT && MMU
diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S
index 75656afa2d6b..3a0ec6fd5956 100644
--- a/arch/riscv/kernel/entry.S
+++ b/arch/riscv/kernel/entry.S
@@ -220,7 +220,7 @@ SYM_CODE_START_NOALIGN(ret_from_exception)
 #endif
 	bnez s0, 1f
 
-#ifdef CONFIG_GCC_PLUGIN_STACKLEAK
+#ifdef CONFIG_KSTACK_ERASE
 	call	stackleak_erase_on_task_stack
 #endif
 
diff --git a/arch/riscv/kernel/pi/Makefile b/arch/riscv/kernel/pi/Makefile
index 81d69d45c06c..7dd15be69c90 100644
--- a/arch/riscv/kernel/pi/Makefile
+++ b/arch/riscv/kernel/pi/Makefile
@@ -2,7 +2,7 @@
 # This file was copied from arm64/kernel/pi/Makefile.
 
 KBUILD_CFLAGS	:= $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) -fpie \
-		   -Os -DDISABLE_BRANCH_PROFILING $(DISABLE_STACKLEAK_PLUGIN) \
+		   -Os -DDISABLE_BRANCH_PROFILING $(DISABLE_KSTACK_ERASE) \
 		   $(call cc-option,-mbranch-protection=none) \
 		   -I$(srctree)/scripts/dtc/libfdt -fno-stack-protector \
 		   -include $(srctree)/include/linux/hidden.h \
diff --git a/arch/riscv/purgatory/Makefile b/arch/riscv/purgatory/Makefile
index fb9c917c9b45..240592e3f5c2 100644
--- a/arch/riscv/purgatory/Makefile
+++ b/arch/riscv/purgatory/Makefile
@@ -53,7 +53,7 @@ targets += purgatory.ro purgatory.chk
 
 PURGATORY_CFLAGS_REMOVE := -mcmodel=kernel
 PURGATORY_CFLAGS := -mcmodel=medany -ffreestanding -fno-zero-initialized-in-bss
-PURGATORY_CFLAGS += $(DISABLE_STACKLEAK_PLUGIN) -DDISABLE_BRANCH_PROFILING
+PURGATORY_CFLAGS += $(DISABLE_KSTACK_ERASE) -DDISABLE_BRANCH_PROFILING
 PURGATORY_CFLAGS += -fno-stack-protector -g0
 
 # Default KBUILD_CFLAGS can have -pg option set when FTRACE is enabled. That
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 0c16dc443e2f..a8e74ed8e3cc 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -176,10 +176,10 @@ config S390
 	select HAVE_ARCH_KCSAN
 	select HAVE_ARCH_KMSAN
 	select HAVE_ARCH_KFENCE
+	select HAVE_ARCH_KSTACK_ERASE
 	select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
 	select HAVE_ARCH_SECCOMP_FILTER
 	select HAVE_ARCH_SOFT_DIRTY
-	select HAVE_ARCH_STACKLEAK
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
 	select HAVE_ARCH_VMAP_STACK
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index 0f00f4b06d51..75b0fbb236d0 100644
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -124,7 +124,7 @@ _LPP_OFFSET	= __LC_LPP
 #endif
 
 	.macro STACKLEAK_ERASE
-#ifdef CONFIG_GCC_PLUGIN_STACKLEAK
+#ifdef CONFIG_KSTACK_ERASE
 	brasl	%r14,stackleak_erase_on_task_stack
 #endif
 	.endm
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 340e5468980e..bc3708cad46b 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -204,13 +204,13 @@ config X86
 	select HAVE_ARCH_KFENCE
 	select HAVE_ARCH_KMSAN			if X86_64
 	select HAVE_ARCH_KGDB
+	select HAVE_ARCH_KSTACK_ERASE
 	select HAVE_ARCH_MMAP_RND_BITS		if MMU
 	select HAVE_ARCH_MMAP_RND_COMPAT_BITS	if MMU && COMPAT
 	select HAVE_ARCH_COMPAT_MMAP_BASES	if MMU && COMPAT
 	select HAVE_ARCH_PREL32_RELOCATIONS
 	select HAVE_ARCH_SECCOMP_FILTER
 	select HAVE_ARCH_THREAD_STRUCT_WHITELIST
-	select HAVE_ARCH_STACKLEAK
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
diff --git a/arch/x86/entry/calling.h b/arch/x86/entry/calling.h
index d83236b96f22..94519688b007 100644
--- a/arch/x86/entry/calling.h
+++ b/arch/x86/entry/calling.h
@@ -369,7 +369,7 @@ For 32-bit we have the following conventions - kernel is built with
 .endm
 
 .macro STACKLEAK_ERASE_NOCLOBBER
-#ifdef CONFIG_GCC_PLUGIN_STACKLEAK
+#ifdef CONFIG_KSTACK_ERASE
 	PUSH_AND_CLEAR_REGS
 	call stackleak_erase
 	POP_REGS
@@ -388,7 +388,7 @@ For 32-bit we have the following conventions - kernel is built with
 #endif /* !CONFIG_X86_64 */
 
 .macro STACKLEAK_ERASE
-#ifdef CONFIG_GCC_PLUGIN_STACKLEAK
+#ifdef CONFIG_KSTACK_ERASE
 	call stackleak_erase
 #endif
 .endm
diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile
index ebdfd7b84feb..e0a607a14e7e 100644
--- a/arch/x86/purgatory/Makefile
+++ b/arch/x86/purgatory/Makefile
@@ -35,7 +35,7 @@ targets += purgatory.ro purgatory.chk
 PURGATORY_CFLAGS_REMOVE := -mcmodel=kernel
 PURGATORY_CFLAGS := -mcmodel=small -ffreestanding -fno-zero-initialized-in-bss -g0
 PURGATORY_CFLAGS += -fpic -fvisibility=hidden
-PURGATORY_CFLAGS += $(DISABLE_STACKLEAK_PLUGIN) -DDISABLE_BRANCH_PROFILING
+PURGATORY_CFLAGS += $(DISABLE_KSTACK_ERASE) -DDISABLE_BRANCH_PROFILING
 PURGATORY_CFLAGS += -fno-stack-protector
 
 # Default KBUILD_CFLAGS can have -pg option set when FTRACE is enabled. That