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Revision e88d2468718b0789b4c33da2f7e1cef2a1eee279 authored by David S. Miller on 15 November 2011, 20:57:00 UTC, committed by David S. Miller on 15 November 2011, 20:57:00 UTC 
sparc: Stash orig_i0 into %g6 instead of %g2
 
As per the comments added by this commit, %g2 turns out to not be a
usable place to save away orig_i0 for syscall restart handling.

In fact all of %g2, %g3, %g4, and %g5 are assumed to be saved across
a system call by various bits of code in glibc.

%g1 can't be used because that holds the syscall number, which would
need to be saved and restored for syscall restart handling too, and
that would only compound our problems :-)

This leaves us with %g6 and %g7 which are for "system use".  %g7 is
used as the "thread register" by glibc, but %g6 is used as a compiler
and assembler temporary scratch register.  And in no instance is %g6
used to hold a value across a system call.

Therefore %g6 is safe for storing away orig_i0, at least for now.

Signed-off-by: David S. Miller <davem@davemloft.net>
1 parent 1d299bc
Raw File
mutex-debug.h 
/*
 * Mutexes: blocking mutual exclusion locks
 *
 * started by Ingo Molnar:
 *
 *  Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
 *
 * This file contains mutex debugging related internal declarations,
 * prototypes and inline functions, for the CONFIG_DEBUG_MUTEXES case.
 * More details are in kernel/mutex-debug.c.
 */

/*
 * This must be called with lock->wait_lock held.
 */
extern void debug_mutex_lock_common(struct mutex *lock,
				    struct mutex_waiter *waiter);
extern void debug_mutex_wake_waiter(struct mutex *lock,
				    struct mutex_waiter *waiter);
extern void debug_mutex_free_waiter(struct mutex_waiter *waiter);
extern void debug_mutex_add_waiter(struct mutex *lock,
				   struct mutex_waiter *waiter,
				   struct thread_info *ti);
extern void mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter,
				struct thread_info *ti);
extern void debug_mutex_unlock(struct mutex *lock);
extern void debug_mutex_init(struct mutex *lock, const char *name,
			     struct lock_class_key *key);

static inline void mutex_set_owner(struct mutex *lock)
{
	lock->owner = current;
}

static inline void mutex_clear_owner(struct mutex *lock)
{
	lock->owner = NULL;
}

#define spin_lock_mutex(lock, flags)			\
	do {						\
		struct mutex *l = container_of(lock, struct mutex, wait_lock); \
							\
		DEBUG_LOCKS_WARN_ON(in_interrupt());	\
		local_irq_save(flags);			\
		arch_spin_lock(&(lock)->rlock.raw_lock);\
		DEBUG_LOCKS_WARN_ON(l->magic != l);	\
	} while (0)

#define spin_unlock_mutex(lock, flags)				\
	do {							\
		arch_spin_unlock(&(lock)->rlock.raw_lock);	\
		local_irq_restore(flags);			\
		preempt_check_resched();			\
	} while (0)
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