Merge branch 'for-next/scs' into for-next/core

Support for Clang's Shadow Call Stack in the kernel
(Sami Tolvanen and Will Deacon)
* for-next/scs:
  arm64: entry-ftrace.S: Update comment to indicate that x18 is live
  scs: Move DEFINE_SCS macro into core code
  scs: Remove references to asm/scs.h from core code
  scs: Move scs_overflow_check() out of architecture code
  arm64: scs: Use 'scs_sp' register alias for x18
  scs: Move accounting into alloc/free functions
  arm64: scs: Store absolute SCS stack pointer value in thread_info
  efi/libstub: Disable Shadow Call Stack
  arm64: scs: Add shadow stacks for SDEI
  arm64: Implement Shadow Call Stack
  arm64: Disable SCS for hypervisor code
  arm64: vdso: Disable Shadow Call Stack
  arm64: efi: Restore register x18 if it was corrupted
  arm64: Preserve register x18 when CPU is suspended
  arm64: Reserve register x18 from general allocation with SCS
  scs: Disable when function graph tracing is enabled
  scs: Add support for stack usage debugging
  scs: Add page accounting for shadow call stack allocations
  scs: Add support for Clang's Shadow Call Stack (SCS)

arch/arm64/include/asm/kvm_hyp.h

@@ -12,7 +12,7 @@
 #include <asm/alternative.h>
 #include <asm/sysreg.h>
 
-#define __hyp_text __section(.hyp.text) notrace
+#define __hyp_text __section(.hyp.text) notrace __noscs
 
 #define read_sysreg_elx(r,nvh,vh)					\
 	({								\

arch/arm64/include/asm/scs.h

@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_SCS_H
+#define _ASM_SCS_H
+
+#ifdef __ASSEMBLY__
+
+#include <asm/asm-offsets.h>
+
+#ifdef CONFIG_SHADOW_CALL_STACK
+	scs_sp	.req	x18
+
+	.macro scs_load tsk, tmp
+	ldr	scs_sp, [\tsk, #TSK_TI_SCS_SP]
+	.endm
+
+	.macro scs_save tsk, tmp
+	str	scs_sp, [\tsk, #TSK_TI_SCS_SP]
+	.endm
+#else
+	.macro scs_load tsk, tmp
+	.endm
+
+	.macro scs_save tsk, tmp
+	.endm
+#endif /* CONFIG_SHADOW_CALL_STACK */
+
+#endif /* __ASSEMBLY __ */
+
+#endif /* _ASM_SCS_H */

arch/arm64/include/asm/suspend.h

@@ -2,7 +2,7 @@
 #ifndef __ASM_SUSPEND_H
 #define __ASM_SUSPEND_H
 
-#define NR_CTX_REGS 12
+#define NR_CTX_REGS 13
 #define NR_CALLEE_SAVED_REGS 12
 
 /*

arch/arm64/include/asm/thread_info.h

@@ -41,6 +41,10 @@ struct thread_info {
 #endif
 		} preempt;
 	};
+#ifdef CONFIG_SHADOW_CALL_STACK
+	void			*scs_base;
+	void			*scs_sp;
+#endif
 };
 
 #define thread_saved_pc(tsk)	\
@@ -100,11 +104,20 @@ void arch_release_task_struct(struct task_struct *tsk);
 				 _TIF_SYSCALL_TRACEPOINT | _TIF_SECCOMP | \
 				 _TIF_SYSCALL_EMU)
 
+#ifdef CONFIG_SHADOW_CALL_STACK
+#define INIT_SCS							\
+	.scs_base	= init_shadow_call_stack,			\
+	.scs_sp		= init_shadow_call_stack,
+#else
+#define INIT_SCS
+#endif
+
 #define INIT_THREAD_INFO(tsk)						\
 {									\
 	.flags		= _TIF_FOREIGN_FPSTATE,				\
 	.preempt_count	= INIT_PREEMPT_COUNT,				\
 	.addr_limit	= KERNEL_DS,					\
+	INIT_SCS							\
 }
 
 #endif /* __ASM_THREAD_INFO_H */