hazards.h
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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
#ifdef __ASSEMBLY__
#define ASMMACRO(name, code...) .macro name; code; .endm
#else
#define ASMMACRO(name, code...) \
__asm__(".macro " #name "; " #code "; .endm"); \
\
static inline void name(void) \
{ \
__asm__ __volatile__ (#name); \
}
#endif
ASMMACRO(_ssnop,
sll $0, $0, 1
)
ASMMACRO(_ehb,
sll $0, $0, 3
)
/*
* TLB hazards
*/
#if defined(CONFIG_CPU_MIPSR2)
/*
* MIPSR2 defines ehb for hazard avoidance
*/
ASMMACRO(mtc0_tlbw_hazard,
_ehb
)
ASMMACRO(tlbw_use_hazard,
_ehb
)
ASMMACRO(tlb_probe_hazard,
_ehb
)
ASMMACRO(irq_enable_hazard,
)
ASMMACRO(irq_disable_hazard,
_ehb
)
ASMMACRO(back_to_back_c0_hazard,
_ehb
)
/*
* 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)
#elif defined(CONFIG_CPU_R10000)
/*
* R10000 rocks - all hazards handled in hardware, so this becomes a nobrainer.
*/
ASMMACRO(mtc0_tlbw_hazard,
)
ASMMACRO(tlbw_use_hazard,
)
ASMMACRO(tlb_probe_hazard,
)
ASMMACRO(irq_enable_hazard,
)
ASMMACRO(irq_disable_hazard,
)
ASMMACRO(back_to_back_c0_hazard,
)
#define instruction_hazard() do { } while (0)
#elif defined(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.
*/
ASMMACRO(mtc0_tlbw_hazard,
_ssnop; _ssnop; _ssnop; _ssnop
)
ASMMACRO(tlbw_use_hazard,
_ssnop; _ssnop; _ssnop; _ssnop
)
ASMMACRO(tlb_probe_hazard,
_ssnop; _ssnop; _ssnop; _ssnop
)
ASMMACRO(irq_enable_hazard,
)
ASMMACRO(irq_disable_hazard,
)
ASMMACRO(back_to_back_c0_hazard,
)
#define instruction_hazard() do { } while (0)
#elif defined(CONFIG_CPU_SB1)
/*
* Mostly like R4000 for historic reasons
*/
ASMMACRO(mtc0_tlbw_hazard,
)
ASMMACRO(tlbw_use_hazard,
)
ASMMACRO(tlb_probe_hazard,
)
ASMMACRO(irq_enable_hazard,
)
ASMMACRO(irq_disable_hazard,
_ssnop; _ssnop; _ssnop
)
ASMMACRO(back_to_back_c0_hazard,
)
#define instruction_hazard() do { } while (0)
#else
/*
* Finally the catchall case for all other processors including R4000, R4400,
* R4600, R4700, R5000, RM7000, NEC VR41xx etc.
*
* 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.
*/
ASMMACRO(mtc0_tlbw_hazard,
nop
)
ASMMACRO(tlbw_use_hazard,
nop; nop; nop
)
ASMMACRO(tlb_probe_hazard,
nop; nop; nop
)
ASMMACRO(irq_enable_hazard,
)
ASMMACRO(irq_disable_hazard,
nop; nop; nop
)
ASMMACRO(back_to_back_c0_hazard,
_ssnop; _ssnop; _ssnop;
)
#define instruction_hazard() do { } while (0)
#endif
#endif /* _ASM_HAZARDS_H */