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3a6bfbc91d
The arch_mutex_cpu_relax() function, introduced by 34b133f, is
hacky and ugly. It was added a few years ago to address the fact
that common cpu_relax() calls include yielding on s390, and thus
impact the optimistic spinning functionality of mutexes. Nowadays
we use this function well beyond mutexes: rwsem, qrwlock, mcs and
lockref. Since the macro that defines the call is in the mutex header,
any users must include mutex.h and the naming is misleading as well.
This patch (i) renames the call to cpu_relax_lowlatency ("relax, but
only if you can do it with very low latency") and (ii) defines it in
each arch's asm/processor.h local header, just like for regular cpu_relax
functions. On all archs, except s390, cpu_relax_lowlatency is simply cpu_relax,
and thus we can take it out of mutex.h. While this can seem redundant,
I believe it is a good choice as it allows us to move out arch specific
logic from generic locking primitives and enables future(?) archs to
transparently define it, similarly to System Z.
Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Anton Blanchard <anton@samba.org>
Cc: Aurelien Jacquiot <a-jacquiot@ti.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Bharat Bhushan <r65777@freescale.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chen Liqin <liqin.linux@gmail.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Howells <dhowells@redhat.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Deepthi Dharwar <deepthi@linux.vnet.ibm.com>
Cc: Dominik Dingel <dingel@linux.vnet.ibm.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Hirokazu Takata <takata@linux-m32r.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James E.J. Bottomley <jejb@parisc-linux.org>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: Joe Perches <joe@perches.com>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Joseph Myers <joseph@codesourcery.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Koichi Yasutake <yasutake.koichi@jp.panasonic.com>
Cc: Lennox Wu <lennox.wu@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Salter <msalter@redhat.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Neuling <mikey@neuling.org>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Mikael Starvik <starvik@axis.com>
Cc: Nicolas Pitre <nico@linaro.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Qais Yousef <qais.yousef@imgtec.com>
Cc: Qiaowei Ren <qiaowei.ren@intel.com>
Cc: Rafael Wysocki <rafael.j.wysocki@intel.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Steven Miao <realmz6@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Stratos Karafotis <stratosk@semaphore.gr>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vasily Kulikov <segoon@openwall.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Vineet Gupta <Vineet.Gupta1@synopsys.com>
Cc: Waiman Long <Waiman.Long@hp.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Wolfram Sang <wsa@the-dreams.de>
Cc: adi-buildroot-devel@lists.sourceforge.net
Cc: linux390@de.ibm.com
Cc: linux-alpha@vger.kernel.org
Cc: linux-am33-list@redhat.com
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-c6x-dev@linux-c6x.org
Cc: linux-cris-kernel@axis.com
Cc: linux-hexagon@vger.kernel.org
Cc: linux-ia64@vger.kernel.org
Cc: linux@lists.openrisc.net
Cc: linux-m32r-ja@ml.linux-m32r.org
Cc: linux-m32r@ml.linux-m32r.org
Cc: linux-m68k@lists.linux-m68k.org
Cc: linux-metag@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: linux-parisc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-s390@vger.kernel.org
Cc: linux-sh@vger.kernel.org
Cc: linux-xtensa@linux-xtensa.org
Cc: sparclinux@vger.kernel.org
Link: http://lkml.kernel.org/r/1404079773.2619.4.camel@buesod1.americas.hpqcorp.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
128 lines
3.4 KiB
C
128 lines
3.4 KiB
C
/* include/asm/processor.h
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*
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* Copyright (C) 1994 David S. Miller (davem@caip.rutgers.edu)
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*/
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#ifndef __ASM_SPARC_PROCESSOR_H
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#define __ASM_SPARC_PROCESSOR_H
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/*
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* Sparc32 implementation of macro that returns current
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* instruction pointer ("program counter").
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*/
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#define current_text_addr() ({ void *pc; __asm__("sethi %%hi(1f), %0; or %0, %%lo(1f), %0;\n1:" : "=r" (pc)); pc; })
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#include <asm/psr.h>
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#include <asm/ptrace.h>
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#include <asm/head.h>
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#include <asm/signal.h>
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#include <asm/page.h>
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/*
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* The sparc has no problems with write protection
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*/
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#define wp_works_ok 1
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#define wp_works_ok__is_a_macro /* for versions in ksyms.c */
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/* Whee, this is STACK_TOP + PAGE_SIZE and the lowest kernel address too...
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* That one page is used to protect kernel from intruders, so that
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* we can make our access_ok test faster
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*/
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#define TASK_SIZE PAGE_OFFSET
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#ifdef __KERNEL__
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#define STACK_TOP (PAGE_OFFSET - PAGE_SIZE)
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#define STACK_TOP_MAX STACK_TOP
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#endif /* __KERNEL__ */
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struct task_struct;
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#ifdef __KERNEL__
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struct fpq {
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unsigned long *insn_addr;
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unsigned long insn;
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};
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#endif
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typedef struct {
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int seg;
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} mm_segment_t;
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/* The Sparc processor specific thread struct. */
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struct thread_struct {
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struct pt_regs *kregs;
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unsigned int _pad1;
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/* Special child fork kpsr/kwim values. */
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unsigned long fork_kpsr __attribute__ ((aligned (8)));
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unsigned long fork_kwim;
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/* Floating point regs */
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unsigned long float_regs[32] __attribute__ ((aligned (8)));
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unsigned long fsr;
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unsigned long fpqdepth;
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struct fpq fpqueue[16];
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unsigned long flags;
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mm_segment_t current_ds;
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};
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#define SPARC_FLAG_KTHREAD 0x1 /* task is a kernel thread */
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#define SPARC_FLAG_UNALIGNED 0x2 /* is allowed to do unaligned accesses */
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#define INIT_THREAD { \
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.flags = SPARC_FLAG_KTHREAD, \
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.current_ds = KERNEL_DS, \
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}
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/* Return saved PC of a blocked thread. */
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unsigned long thread_saved_pc(struct task_struct *t);
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/* Do necessary setup to start up a newly executed thread. */
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static inline void start_thread(struct pt_regs * regs, unsigned long pc,
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unsigned long sp)
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{
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register unsigned long zero asm("g1");
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regs->psr = (regs->psr & (PSR_CWP)) | PSR_S;
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regs->pc = ((pc & (~3)) - 4);
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regs->npc = regs->pc + 4;
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regs->y = 0;
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zero = 0;
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__asm__ __volatile__("std\t%%g0, [%0 + %3 + 0x00]\n\t"
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"std\t%%g0, [%0 + %3 + 0x08]\n\t"
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"std\t%%g0, [%0 + %3 + 0x10]\n\t"
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"std\t%%g0, [%0 + %3 + 0x18]\n\t"
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"std\t%%g0, [%0 + %3 + 0x20]\n\t"
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"std\t%%g0, [%0 + %3 + 0x28]\n\t"
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"std\t%%g0, [%0 + %3 + 0x30]\n\t"
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"st\t%1, [%0 + %3 + 0x38]\n\t"
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"st\t%%g0, [%0 + %3 + 0x3c]"
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: /* no outputs */
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: "r" (regs),
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"r" (sp - sizeof(struct reg_window32)),
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"r" (zero),
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"i" ((const unsigned long)(&((struct pt_regs *)0)->u_regs[0]))
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: "memory");
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}
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/* Free all resources held by a thread. */
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#define release_thread(tsk) do { } while(0)
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unsigned long get_wchan(struct task_struct *);
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#define task_pt_regs(tsk) ((tsk)->thread.kregs)
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#define KSTK_EIP(tsk) ((tsk)->thread.kregs->pc)
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#define KSTK_ESP(tsk) ((tsk)->thread.kregs->u_regs[UREG_FP])
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#ifdef __KERNEL__
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extern struct task_struct *last_task_used_math;
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int do_mathemu(struct pt_regs *regs, struct task_struct *fpt);
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#define cpu_relax() barrier()
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#define cpu_relax_lowlatency() cpu_relax()
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extern void (*sparc_idle)(void);
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#endif
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#endif /* __ASM_SPARC_PROCESSOR_H */
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