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Commit 3f4aa45c authored by Vladimir Murzin's avatar Vladimir Murzin Committed by Russell King
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ARM: 8226/1: cacheflush: get rid of restarting block 



We cannot restart cacheflush safely if a process provides user-defined
signal handler and signal is pending. In this case -EINTR is returned
and it is expected that process re-invokes syscall. However, there are
a few problems with that:
 * looks like nobody bothers checking return value from cacheflush
 * but if it did, we don't provide the restart address for that, so the
   process has to use the same range again
 * ...and again, what might lead to looping forever

So, remove cacheflush restarting code and terminate cache flushing
as early as fatal signal is pending.

Cc: stable@vger.kernel.org # 3.12+
Reported-by: default avatarChanho Min <chanho.min@lge.com>
Signed-off-by: default avatarVladimir Murzin <vladimir.murzin@arm.com>
Acked-by: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 995ab518

arch/arm/include/asm/thread_info.h

+0 −11
Original line number Diff line number Diff line
@@ -44,16 +44,6 @@ struct cpu_context_save { 
	__u32	extra[2];		/* Xscale 'acc' register, etc */

};



struct arm_restart_block {

	union {

		/* For user cache flushing */

		struct {

			unsigned long start;

			unsigned long end;

		} cache;

	};

};



/*

 * low level task data that entry.S needs immediate access to.

 * __switch_to() assumes cpu_context follows immediately after cpu_domain.
@@ -79,7 +69,6 @@ struct thread_info { 
	unsigned long		thumbee_state;	/* ThumbEE Handler Base register */

#endif

	struct restart_block	restart_block;

	struct arm_restart_block	arm_restart_block;

};



#define INIT_THREAD_INFO(tsk)						\

arch/arm/kernel/traps.c

+2 −29
Original line number Diff line number Diff line
@@ -533,8 +533,6 @@ static int bad_syscall(int n, struct pt_regs *regs) 
	return regs->ARM_r0;

}



static long do_cache_op_restart(struct restart_block *);



static inline int

__do_cache_op(unsigned long start, unsigned long end)

{
@@ -543,24 +541,8 @@ __do_cache_op(unsigned long start, unsigned long end) 
	do {

		unsigned long chunk = min(PAGE_SIZE, end - start);



		if (signal_pending(current)) {

			struct thread_info *ti = current_thread_info();



			ti->restart_block = (struct restart_block) {

				.fn	= do_cache_op_restart,

			};



			ti->arm_restart_block = (struct arm_restart_block) {

				{

					.cache = {

						.start	= start,

						.end	= end,

					},

				},

			};



			return -ERESTART_RESTARTBLOCK;

		}

		if (fatal_signal_pending(current))

			return 0;



		ret = flush_cache_user_range(start, start + chunk);

		if (ret)
@@ -573,15 +555,6 @@ __do_cache_op(unsigned long start, unsigned long end) 
	return 0;

}



static long do_cache_op_restart(struct restart_block *unused)

{

	struct arm_restart_block *restart_block;



	restart_block = &current_thread_info()->arm_restart_block;

	return __do_cache_op(restart_block->cache.start,

			     restart_block->cache.end);

}



static inline int

do_cache_op(unsigned long start, unsigned long end, int flags)

{