[PATCH] arm64: add architecture specified current_pt_regs

[Zhi-zhou Zhang]

From: zhizhou <zhizhou.zh at gmail.com>

This patch is based on the implementation of arm. The generic
current_pt_regs is implemented with current->stack. It need to access
memory that would be too expensive.

Signed-off-by: zhizhou <zhizhou.zh at gmail.com>
---
 arch/arm64/include/asm/ptrace.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h
index e9e5467..1865d54 100644
--- a/arch/arm64/include/asm/ptrace.h
+++ b/arch/arm64/include/asm/ptrace.h
@@ -185,5 +185,9 @@ static inline int valid_user_regs(struct user_pt_regs *regs)
 
 extern unsigned long profile_pc(struct pt_regs *regs);
 
+#define current_pt_regs(void) ({ (struct pt_regs *)			\
+	((current_stack_pointer | (THREAD_SIZE - 1)) - 0xf) - 1;	\
+})
+
 #endif /* __ASSEMBLY__ */
 #endif
-- 
2.5.0