riscv: Rename "sp_in_global" to "current_stack_pointer"

To follow the existing per-arch conventions, rename "sp_in_global" to
"current_stack_pointer". This will let it be used in non-arch places
(like HARDENED_USERCOPY).
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

arch/riscv/Kconfig

@@ -16,6 +16,7 @@ config RISCV
 	select ARCH_ENABLE_HUGEPAGE_MIGRATION if HUGETLB_PAGE && MIGRATION
 	select ARCH_ENABLE_SPLIT_PMD_PTLOCK if PGTABLE_LEVELS > 2
 	select ARCH_HAS_BINFMT_FLAT
+	select ARCH_HAS_CURRENT_STACK_POINTER
 	select ARCH_HAS_DEBUG_VM_PGTABLE
 	select ARCH_HAS_DEBUG_VIRTUAL if MMU
 	select ARCH_HAS_DEBUG_WX

arch/riscv/include/asm/current.h

@@ -33,6 +33,8 @@ static __always_inline struct task_struct *get_current(void)
 
 #define current get_current()
 
+register unsigned long current_stack_pointer __asm__("sp");
+
 #endif /* __ASSEMBLY__ */
 
 #endif /* _ASM_RISCV_CURRENT_H */

arch/riscv/kernel/stacktrace.c

@@ -14,8 +14,6 @@
 
 #include <asm/stacktrace.h>
 
-register unsigned long sp_in_global __asm__("sp");
-
 #ifdef CONFIG_FRAME_POINTER
 
 void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
@@ -30,7 +28,7 @@ void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
 		pc = instruction_pointer(regs);
 	} else if (task == NULL || task == current) {
 		fp = (unsigned long)__builtin_frame_address(0);
-		sp = sp_in_global;
+		sp = current_stack_pointer;
 		pc = (unsigned long)walk_stackframe;
 	} else {
 		/* task blocked in __switch_to */
@@ -78,7 +76,7 @@ void notrace walk_stackframe(struct task_struct *task,
 		sp = user_stack_pointer(regs);
 		pc = instruction_pointer(regs);
 	} else if (task == NULL || task == current) {
-		sp = sp_in_global;
+		sp = current_stack_pointer;
 		pc = (unsigned long)walk_stackframe;
 	} else {
 		/* task blocked in __switch_to */