linux-kernel - [PATCH 3.16 21/76] x86: Clean up current_stack

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Message-ID: <lsq.1520823972.347392980@decadent.org.uk>
Date:   Mon, 12 Mar 2018 03:06:12 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Andy Lutomirski" <luto@...capital.net>,
        "Borislav Petkov" <bp@...e.de>
Subject: [PATCH 3.16 21/76] x86: Clean up current_stack_pointer

3.16.56-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Andy Lutomirski <luto@...capital.net>

commit 83653c16da91112236292871b820cb8b367220e3 upstream.

There's no good reason for it to be a macro, and x86_64 will want to
use it, so it should be in a header.

Acked-by: Borislav Petkov <bp@...e.de>
Signed-off-by: Andy Lutomirski <luto@...capital.net>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 arch/x86/include/asm/thread_info.h | 11 +++++++++++
 arch/x86/kernel/irq_32.c           | 13 +++----------
 2 files changed, 14 insertions(+), 10 deletions(-)

--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -170,6 +170,17 @@ static inline struct thread_info *curren
 	return ti;
 }
 
+static inline unsigned long current_stack_pointer(void)
+{
+	unsigned long sp;
+#ifdef CONFIG_X86_64
+	asm("mov %%rsp,%0" : "=g" (sp));
+#else
+	asm("mov %%esp,%0" : "=g" (sp));
+#endif
+	return sp;
+}
+
 #else /* !__ASSEMBLY__ */
 
 /* how to get the thread information struct from ASM */
--- a/arch/x86/kernel/irq_32.c
+++ b/arch/x86/kernel/irq_32.c
@@ -69,16 +69,9 @@ static void call_on_stack(void *func, vo
 		     : "memory", "cc", "edx", "ecx", "eax");
 }
 
-/* how to get the current stack pointer from C */
-#define current_stack_pointer ({		\
-	unsigned long sp;			\
-	asm("mov %%esp,%0" : "=g" (sp));	\
-	sp;					\
-})
-
 static inline void *current_stack(void)
 {
-	return (void *)(current_stack_pointer & ~(THREAD_SIZE - 1));
+	return (void *)(current_stack_pointer() & ~(THREAD_SIZE - 1));
 }
 
 static inline int
@@ -103,7 +96,7 @@ execute_on_irq_stack(int overflow, struc
 
 	/* Save the next esp at the bottom of the stack */
 	prev_esp = (u32 *)irqstk;
-	*prev_esp = current_stack_pointer;
+	*prev_esp = current_stack_pointer();
 
 	if (unlikely(overflow))
 		call_on_stack(print_stack_overflow, isp);
@@ -156,7 +149,7 @@ void do_softirq_own_stack(void)
 
 	/* Push the previous esp onto the stack */
 	prev_esp = (u32 *)irqstk;
-	*prev_esp = current_stack_pointer;
+	*prev_esp = current_stack_pointer();
 
 	call_on_stack(__do_softirq, isp);
 }