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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: Chanho Min <chanho.min@lge.com>
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Vladimir Murzin 2014-11-27 11:39:04 +01:00 committed by Russell King
parent 995ab5189d
commit 3f4aa45cee
2 changed files with 2 additions and 40 deletions
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11
arch/arm/include/asm/thread_info.h
View File

@ -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) \

31
arch/arm/kernel/traps.c
View File

@ -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)
{