[PATCH] m32r: Fix clearing of thread info fault code

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From	Michael Büsch <m@bues.ch>
Newsgroups	linux.kernel
Subject	[PATCH] m32r: Fix clearing of thread info fault code
Date	Thu, 18 Jun 2015 21:30:01 +0200
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The expression (~0 >> x) will always yield all-ones, because the right
shift is an arithmetic right shift that will always shift ones in.
Hence the old fault code bits will not be cleared before being ORed
with the new fault code.

Fix this by forcing a logical right shift instead of an arithmetic
right shift by using an unsigned long constant.

Reported-by: Ilia Mirkin <imirkin@alum.mit.edu>
Signed-off-by: Michael Buesch <m@bues.ch>

---

The code also assumes sizeof(ti->flags) == 4. But that probably is ok for this arch.

This patch is untested, because I do not have the hardware.


Index: linux/arch/m32r/include/asm/thread_info.h
===================================================================
--- linux.orig/arch/m32r/include/asm/thread_info.h
+++ linux/arch/m32r/include/asm/thread_info.h
@@ -77,7 +77,7 @@ static inline struct thread_info *curren
 static inline void set_thread_fault_code(unsigned int val)
 {
 	struct thread_info *ti = current_thread_info();
-	ti->flags = (ti->flags & (~0 >> (32 - TI_FLAG_FAULT_CODE_SHIFT)))
+	ti->flags = (ti->flags & (~0UL >> (32 - TI_FLAG_FAULT_CODE_SHIFT)))
 		| (val << TI_FLAG_FAULT_CODE_SHIFT);
 }

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[PATCH] m32r: Fix clearing of thread info fault code Michael Büsch <m@bues.ch> - 2015-06-18 21:30 +0200

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