[PATCH 18/18] x86/traps: Use a new on_thread_stack() helper to clean up an assertion

Andy Lutomirski
2017-10-26T08:28:15Z

Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
arch/x86/include/asm/processor.h | 6 ++++++
arch/x86/kernel/traps.c | 3 +--
2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 562c575d8bc3..26fc33231cbd 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -541,6 +541,12 @@ static inline unsigned long current_top_of_stack(void)
#endif
}

+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/kernel/traps.c b/arch/x86/kernel/traps.c
index 67db4f43309e..42a9c4458f5d 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -141,8 +141,7 @@ 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();
}
--
2.13.6