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Subject[RFC 17/17] x86/traps: Use a new on_thread_stack() helper to clean up an assertion
Date
Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
arch/x86/include/asm/processor.h | 17 +++++++++++++++++
arch/x86/include/asm/thread_info.h | 11 -----------
arch/x86/kernel/traps.c | 3 +--
3 files changed, 18 insertions(+), 13 deletions(-)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 4c137472f530..b6f8dc11c222 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -534,6 +534,23 @@ static inline unsigned long current_top_of_stack(void)
#endif
}

+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;
+}
+
+static inline bool on_thread_stack(void)
+{
+ return (unsigned long)(current_top_of_stack() -
+ current_stack_pointer()) < THREAD_SIZE;
+}
+
#ifdef CONFIG_PARAVIRT
#include <asm/paravirt.h>
#else
diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
index e00e1bd6e7b3..90e1f9b84534 100644
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -155,17 +155,6 @@ struct thread_info {
*/
#ifndef __ASSEMBLY__

-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;
-}
-
/*
* Walks up the stack frames to make sure that the specified object is
* entirely contained by a single stack frame.
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index bf54309b85da..0347ed41c92d 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -153,8 +153,7 @@ void ist_begin_non_atomic(struct pt_regs *regs)
* will catch asm bugs and any attempt to use ist_preempt_enable
* from double_fault.
*/
- BUG_ON((unsigned long)(current_top_of_stack() -
- current_stack_pointer()) >= THREAD_SIZE);
+ BUG_ON(!on_thread_stack());

preempt_enable_no_resched();
}
--
2.13.5
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