freebsd-dev/sys/powerpc/aim/swtch32.S
Nathan Whitehorn bc96dccc69 Fix final bugs in memory barriers on PowerPC:
- Use isync/lwsync unconditionally for acquire/release. Use of isync
  guarantees a complete memory barrier, which is important for serialization
  of bus space accesses with mutexes on multi-processor systems.
- Go back to using sync as the I/O memory barrier, which solves the same
  problem as above with respect to mutex release using lwsync, while not
  penalizing non-I/O operations like a return to sync on the atomic release
  operations would.
- Place an acquisition barrier around thread lock acquisition in
  cpu_switchin().
2012-05-04 16:00:22 +00:00

199 lines
6.5 KiB
ArmAsm

/* $FreeBSD$ */
/* $NetBSD: locore.S,v 1.24 2000/05/31 05:09:17 thorpej Exp $ */
/*-
* Copyright (C) 2001 Benno Rice
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY Benno Rice ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*-
* Copyright (C) 1995, 1996 Wolfgang Solfrank.
* Copyright (C) 1995, 1996 TooLs GmbH.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by TooLs GmbH.
* 4. The name of TooLs GmbH may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "assym.s"
#include "opt_sched.h"
#include <sys/syscall.h>
#include <machine/trap.h>
#include <machine/param.h>
#include <machine/asm.h>
/*
* void cpu_throw(struct thread *old, struct thread *new)
*/
ENTRY(cpu_throw)
mr %r2, %r4
b cpu_switchin
/*
* void cpu_switch(struct thread *old,
* struct thread *new,
* struct mutex *mtx);
*
* Switch to a new thread saving the current state in the old thread.
*/
ENTRY(cpu_switch)
lwz %r6,TD_PCB(%r3) /* Get the old thread's PCB ptr */
stmw %r12,PCB_CONTEXT(%r6) /* Save the non-volatile GP regs.
These can now be used for scratch */
mfcr %r16 /* Save the condition register */
stw %r16,PCB_CR(%r6)
mflr %r16 /* Save the link register */
stw %r16,PCB_LR(%r6)
stw %r1,PCB_SP(%r6) /* Save the stack pointer */
mr %r14,%r3 /* Copy the old thread ptr... */
mr %r2,%r4 /* and the new thread ptr in curthread */
mr %r16,%r5 /* and the new lock */
mr %r17,%r6 /* and the PCB */
lwz %r7,PCB_FLAGS(%r17)
/* Save FPU context if needed */
andi. %r7, %r7, PCB_FPU
beq .L1
bl save_fpu
.L1:
mr %r3,%r14 /* restore old thread ptr */
lwz %r7,PCB_FLAGS(%r17)
/* Save Altivec context if needed */
andi. %r7, %r7, PCB_VEC
beq .L2
bl save_vec
.L2:
mr %r3,%r14 /* restore old thread ptr */
bl pmap_deactivate /* Deactivate the current pmap */
sync /* Make sure all of that finished */
stw %r16,TD_LOCK(%r14) /* ULE: update old thread's lock */
cpu_switchin:
#if defined(SMP) && defined(SCHED_ULE)
/* Wait for the new thread to become unblocked */
lis %r6,blocked_lock@ha
addi %r6,%r6,blocked_lock@l
blocked_loop:
lwz %r7,TD_LOCK(%r2)
cmpw %r6,%r7
beq- blocked_loop
isync
#endif
mfsprg %r7,0 /* Get the pcpu pointer */
stw %r2,PC_CURTHREAD(%r7) /* Store new current thread */
lwz %r17,TD_PCB(%r2) /* Store new current PCB */
stw %r17,PC_CURPCB(%r7)
mr %r3,%r2 /* Get new thread ptr */
bl pmap_activate /* Activate the new address space */
lwz %r6, PCB_FLAGS(%r17)
/* Restore FPU context if needed */
andi. %r6, %r6, PCB_FPU
beq .L3
mr %r3,%r2 /* Pass curthread to enable_fpu */
bl enable_fpu
.L3:
lwz %r6, PCB_FLAGS(%r17)
/* Restore Altivec context if needed */
andi. %r6, %r6, PCB_VEC
beq .L4
mr %r3,%r2 /* Pass curthread to enable_vec */
bl enable_vec
/* thread to restore is in r3 */
.L4:
mr %r3,%r17 /* Recover PCB ptr */
lmw %r12,PCB_CONTEXT(%r3) /* Load the non-volatile GP regs */
lwz %r5,PCB_CR(%r3) /* Load the condition register */
mtcr %r5
lwz %r5,PCB_LR(%r3) /* Load the link register */
mtlr %r5
lwz %r5,PCB_AIM_USR_VSID(%r3) /* Load the USER_SR segment reg */
isync
mtsr USER_SR,%r5
isync
lwz %r1,PCB_SP(%r3) /* Load the stack pointer */
/*
* Perform a dummy stwcx. to clear any reservations we may have
* inherited from the previous thread. It doesn't matter if the
* stwcx succeeds or not. pcb_context[0] can be clobbered.
*/
stwcx. %r1, 0, %r3
blr
/*
* savectx(pcb)
* Update pcb, saving current processor state
*/
ENTRY(savectx)
stmw %r12,PCB_CONTEXT(%r3) /* Save the non-volatile GP regs */
mfcr %r4 /* Save the condition register */
stw %r4,PCB_CR(%r3)
blr
/*
* fork_trampoline()
* Set up the return from cpu_fork()
*/
ENTRY(fork_trampoline)
lwz %r3,CF_FUNC(%r1)
lwz %r4,CF_ARG0(%r1)
lwz %r5,CF_ARG1(%r1)
bl fork_exit
addi %r1,%r1,CF_SIZE-FSP /* Allow 8 bytes in front of
trapframe to simulate FRAME_SETUP
does when allocating space for
a frame pointer/saved LR */
b trapexit