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/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2003, 2004 Ralf Baechle <ralf@linux-mips.org>
* Copyright (C) MIPS Technologies, Inc.
* written by Ralf Baechle <ralf@linux-mips.org>
*/
#ifndef _ASM_HAZARDS_H
#define _ASM_HAZARDS_H
#include <linux/config.h>
#ifdef __ASSEMBLY__
.macro _ssnop
sll $0, $0, 1
.endm
.macro _ehb
sll $0, $0, 3
.endm
/*
* RM9000 hazards. When the JTLB is updated by tlbwi or tlbwr, a subsequent
* use of the JTLB for instructions should not occur for 4 cpu cycles and use
* for data translations should not occur for 3 cpu cycles.
*/
#ifdef CONFIG_CPU_RM9000
.macro mtc0_tlbw_hazard
.set push
.set mips32
_ssnop; _ssnop; _ssnop; _ssnop
.set pop
.endm
.macro tlbw_eret_hazard
.set push
.set mips32
_ssnop; _ssnop; _ssnop; _ssnop
.set pop
.endm
#else
/*
* The taken branch will result in a two cycle penalty for the two killed
* instructions on R4000 / R4400. Other processors only have a single cycle
* hazard so this is nice trick to have an optimal code for a range of
* processors.
*/
.macro mtc0_tlbw_hazard
b . + 8
.endm
.macro tlbw_eret_hazard
.endm
#endif
/*
* mtc0->mfc0 hazard
* The 24K has a 2 cycle mtc0/mfc0 execution hazard.
* It is a MIPS32R2 processor so ehb will clear the hazard.
*/
#ifdef CONFIG_CPU_MIPSR2
/*
* Use a macro for ehb unless explicit support for MIPSR2 is enabled
*/
#define irq_enable_hazard
_ehb
#define irq_disable_hazard
_ehb
#elif defined(CONFIG_CPU_R10000) || defined(CONFIG_CPU_RM9000)
/*
* R10000 rocks - all hazards handled in hardware, so this becomes a nobrainer.
*/
#define irq_enable_hazard
#define irq_disable_hazard
#else
/*
* Classic MIPS needs 1 - 3 nops or ssnops
*/
#define irq_enable_hazard
#define irq_disable_hazard \
_ssnop; _ssnop; _ssnop
#endif
#else /* __ASSEMBLY__ */
__asm__(
" .macro _ssnop \n"
" sll $0, $0, 1 \n"
" .endm \n"
" \n"
" .macro _ehb \n"
" sll $0, $0, 3 \n"
" .endm \n");
#ifdef CONFIG_CPU_RM9000
/*
* RM9000 hazards. When the JTLB is updated by tlbwi or tlbwr, a subsequent
* use of the JTLB for instructions should not occur for 4 cpu cycles and use
* for data translations should not occur for 3 cpu cycles.
*/
#define mtc0_tlbw_hazard() \
__asm__ __volatile__( \
" .set mips32 \n" \
" _ssnop \n" \
" _ssnop \n" \
" _ssnop \n" \
" _ssnop \n" \
" .set mips0 \n")
#define tlbw_use_hazard() \
__asm__ __volatile__( \
" .set mips32 \n" \
" _ssnop \n" \
" _ssnop \n" \
" _ssnop \n" \
" _ssnop \n" \
" .set mips0 \n")
#else
/*
* Overkill warning ...
*/
#define mtc0_tlbw_hazard() \
__asm__ __volatile__( \
" .set noreorder \n" \
" nop \n" \
" nop \n" \
" nop \n" \
" nop \n" \
" nop \n" \
" nop \n" \
" .set reorder \n")
#define tlbw_use_hazard() \
__asm__ __volatile__( \
" .set noreorder \n" \
" nop \n" \
" nop \n" \
" nop \n" \
" nop \n" \
" nop \n" \
" nop \n" \
" .set reorder \n")
#endif
/*
* Interrupt enable/disable hazards
* Some processors have hazards when modifying
* the status register to change the interrupt state
*/
#ifdef CONFIG_CPU_MIPSR2
__asm__(" .macro irq_enable_hazard \n"
" _ehb \n"
" .endm \n"
" \n"
" .macro irq_disable_hazard \n"
" _ehb \n"
" .endm \n");
#elif defined(CONFIG_CPU_R10000) || defined(CONFIG_CPU_RM9000)
/*
* R10000 rocks - all hazards handled in hardware, so this becomes a nobrainer.
*/
__asm__(
" .macro irq_enable_hazard \n"
" .endm \n"
" \n"
" .macro irq_disable_hazard \n"
" .endm \n");
#else
/*
* Default for classic MIPS processors. Assume worst case hazards but don't
* care about the irq_enable_hazard - sooner or later the hardware will
* enable it and we don't care when exactly.
*/
__asm__(
" # \n"
" # There is a hazard but we do not care \n"
" # \n"
" .macro\tirq_enable_hazard \n"
" .endm \n"
" \n"
" .macro\tirq_disable_hazard \n"
" _ssnop \n"
" _ssnop \n"
" _ssnop \n"
" .endm \n");
#endif
#define irq_enable_hazard() \
__asm__ __volatile__("irq_enable_hazard")
#define irq_disable_hazard() \
__asm__ __volatile__("irq_disable_hazard")
/*
* Back-to-back hazards -
*
* What is needed to separate a move to cp0 from a subsequent read from the
* same cp0 register?
*/
#ifdef CONFIG_CPU_MIPSR2
__asm__(" .macro back_to_back_c0_hazard \n"
" _ehb \n"
" .endm \n");
#elif defined(CONFIG_CPU_R10000) || defined(CONFIG_CPU_RM9000) || \
defined(CONFIG_CPU_SB1)
__asm__(" .macro back_to_back_c0_hazard \n"
" .endm \n");
#else
__asm__(" .macro back_to_back_c0_hazard \n"
" .set noreorder \n"
" _ssnop \n"
" _ssnop \n"
" _ssnop \n"
" .set reorder \n"
" .endm");
#endif
#define back_to_back_c0_hazard() \
__asm__ __volatile__("back_to_back_c0_hazard")
/*
* Instruction execution hazard
*/
#ifdef CONFIG_CPU_MIPSR2
/*
* gcc has a tradition of misscompiling the previous construct using the
* address of a label as argument to inline assembler. Gas otoh has the
* annoying difference between la and dla which are only usable for 32-bit
* rsp. 64-bit code, so can't be used without conditional compilation.
* The alterantive is switching the assembler to 64-bit code which happens
* to work right even for 32-bit code ...
*/
#define instruction_hazard() \
do { \
unsigned long tmp; \
\
__asm__ __volatile__( \
" .set mips64r2 \n" \
" dla %0, 1f \n" \
" jr.hb %0 \n" \
" .set mips0 \n" \
"1: \n" \
: "=r" (tmp)); \
} while (0)
#else
#define instruction_hazard() do { } while (0)
#endif
#endif /* __ASSEMBLY__ */
#endif /* _ASM_HAZARDS_H */
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