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Davidlohr Bueso
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 <[email protected]>
Signed-off-by: Peter Zijlstra <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Anton Blanchard <[email protected]>
Cc: Aurelien Jacquiot <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Bharat Bhushan <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Chen Liqin <[email protected]>
Cc: Chris Metcalf <[email protected]>
Cc: Christian Borntraeger <[email protected]>
Cc: Chris Zankel <[email protected]>
Cc: David Howells <[email protected]>
Cc: David S. Miller <[email protected]>
Cc: Deepthi Dharwar <[email protected]>
Cc: Dominik Dingel <[email protected]>
Cc: Fenghua Yu <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Cc: Guan Xuetao <[email protected]>
Cc: Haavard Skinnemoen <[email protected]>
Cc: Hans-Christian Egtvedt <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Helge Deller <[email protected]>
Cc: Hirokazu Takata <[email protected]>
Cc: Ivan Kokshaysky <[email protected]>
Cc: James E.J. Bottomley <[email protected]>
Cc: James Hogan <[email protected]>
Cc: Jason Wang <[email protected]>
Cc: Jesper Nilsson <[email protected]>
Cc: Joe Perches <[email protected]>
Cc: Jonas Bonn <[email protected]>
Cc: Joseph Myers <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Koichi Yasutake <[email protected]>
Cc: Lennox Wu <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mark Salter <[email protected]>
Cc: Martin Schwidefsky <[email protected]>
Cc: Matt Turner <[email protected]>
Cc: Max Filippov <[email protected]>
Cc: Michael Neuling <[email protected]>
Cc: Michal Simek <[email protected]>
Cc: Mikael Starvik <[email protected]>
Cc: Nicolas Pitre <[email protected]>
Cc: Paolo Bonzini <[email protected]>
Cc: Paul Burton <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Paul Gortmaker <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Qais Yousef <[email protected]>
Cc: Qiaowei Ren <[email protected]>
Cc: Rafael Wysocki <[email protected]>
Cc: Ralf Baechle <[email protected]>
Cc: Richard Henderson <[email protected]>
Cc: Richard Kuo <[email protected]>
Cc: Russell King <[email protected]>
Cc: Steven Miao <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Stratos Karafotis <[email protected]>
Cc: Tim Chen <[email protected]>
Cc: Tony Luck <[email protected]>
Cc: Vasily Kulikov <[email protected]>
Cc: Vineet Gupta <[email protected]>
Cc: Vineet Gupta <[email protected]>
Cc: Waiman Long <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Wolfram Sang <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
138 lines
3.5 KiB
C
138 lines
3.5 KiB
C
/*
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* Port on Texas Instruments TMS320C6x architecture
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*
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* Copyright (C) 2004, 2009, 2010, 2011 Texas Instruments Incorporated
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* Author: Aurelien Jacquiot ([email protected])
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*
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* Updated for 2.6.34: Mark Salter <[email protected]>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#ifndef _ASM_C6X_PROCESSOR_H
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#define _ASM_C6X_PROCESSOR_H
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#include <asm/ptrace.h>
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#include <asm/page.h>
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#include <asm/current.h>
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/*
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* Default 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() \
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({ \
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void *__pc; \
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asm("mvc .S2 pce1,%0\n" : "=b"(__pc)); \
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__pc; \
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})
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/*
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* User space process size. This is mostly meaningless for NOMMU
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* but some C6X processors may have RAM addresses up to 0xFFFFFFFF.
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* Since calls like mmap() can return an address or an error, we
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* have to allow room for error returns when code does something
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* like:
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*
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* addr = do_mmap(...)
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* if ((unsigned long)addr >= TASK_SIZE)
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* ... its an error code, not an address ...
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*
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* Here, we allow for 4096 error codes which means we really can't
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* use the last 4K page on systems with RAM extending all the way
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* to the end of the 32-bit address space.
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*/
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#define TASK_SIZE 0xFFFFF000
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/*
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* This decides where the kernel will search for a free chunk of vm
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* space during mmap's. We won't be using it
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*/
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#define TASK_UNMAPPED_BASE 0
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struct thread_struct {
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unsigned long long b15_14;
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unsigned long long a15_14;
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unsigned long long b13_12;
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unsigned long long a13_12;
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unsigned long long b11_10;
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unsigned long long a11_10;
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unsigned long long ricl_icl;
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unsigned long usp; /* user stack pointer */
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unsigned long pc; /* kernel pc */
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unsigned long wchan;
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};
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#define INIT_THREAD \
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{ \
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.usp = 0, \
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.wchan = 0, \
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}
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#define INIT_MMAP { \
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&init_mm, 0, 0, NULL, PAGE_SHARED, VM_READ | VM_WRITE | VM_EXEC, 1, \
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NULL, NULL }
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#define task_pt_regs(task) \
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((struct pt_regs *)(THREAD_START_SP + task_stack_page(task)) - 1)
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#define alloc_kernel_stack() __get_free_page(GFP_KERNEL)
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#define free_kernel_stack(page) free_page((page))
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/* Forward declaration, a strange C thing */
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struct task_struct;
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extern void start_thread(struct pt_regs *regs, unsigned int pc,
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unsigned long usp);
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/* Free all resources held by a thread. */
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static inline void release_thread(struct task_struct *dead_task)
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{
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}
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#define copy_segments(tsk, mm) do { } while (0)
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#define release_segments(mm) do { } while (0)
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/*
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* saved PC of a blocked thread.
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*/
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#define thread_saved_pc(tsk) (task_pt_regs(tsk)->pc)
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/*
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* saved kernel SP and DP of a blocked thread.
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*/
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#ifdef _BIG_ENDIAN
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#define thread_saved_ksp(tsk) \
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(*(unsigned long *)&(tsk)->thread.b15_14)
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#define thread_saved_dp(tsk) \
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(*(((unsigned long *)&(tsk)->thread.b15_14) + 1))
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#else
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#define thread_saved_ksp(tsk) \
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(*(((unsigned long *)&(tsk)->thread.b15_14) + 1))
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#define thread_saved_dp(tsk) \
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(*(unsigned long *)&(tsk)->thread.b15_14)
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#endif
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extern unsigned long get_wchan(struct task_struct *p);
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#define KSTK_EIP(task) (task_pt_regs(task)->pc)
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#define KSTK_ESP(task) (task_pt_regs(task)->sp)
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#define cpu_relax() do { } while (0)
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#define cpu_relax_lowlatency() cpu_relax()
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extern const struct seq_operations cpuinfo_op;
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/* Reset the board */
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#define HARD_RESET_NOW()
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extern unsigned int c6x_core_freq;
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extern void (*c6x_restart)(void);
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extern void (*c6x_halt)(void);
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#endif /* ASM_C6X_PROCESSOR_H */
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