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[MIPS] TX49 MFC0 bug workaround 

If mfc0 $12 follows store and the mfc0 is last instruction of a
page and fetching the next instruction causes TLB miss, the result
of the mfc0 might wrongly contain EXL bit.
    
ERT-TX49H2-027, ERT-TX49H3-012, ERT-TX49HL3-006, ERT-TX49H4-008
    
Workaround: mask EXL bit of the result or place a nop before mfc0.  It
doesn't harm to always clear those bits, so we change the code to do so.
    
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Atsushi Nemoto 2006-02-03 01:34:01 +09:00 committed by Ralf Baechle
parent dbee90b7f9
commit c226f2601f
1 changed files with 17 additions and 6 deletions
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23
include/asm-mips/interrupt.h
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@ -47,6 +47,17 @@ static inline void local_irq_enable(void)
* R4000/R4400 need three nops, the R4600 two nops and the R10000 needs
* no nops at all.
*/
/*
* For TX49, operating only IE bit is not enough.
*
* If mfc0 $12 follows store and the mfc0 is last instruction of a
* page and fetching the next instruction causes TLB miss, the result
* of the mfc0 might wrongly contain EXL bit.
*
* ERT-TX49H2-027, ERT-TX49H3-012, ERT-TX49HL3-006, ERT-TX49H4-008
*
* Workaround: mask EXL bit of the result or place a nop before mfc0.
*/
__asm__ (
" .macro local_irq_disable\n"
" .set push \n"
@ -55,8 +66,8 @@ __asm__ (
" di \n"
#else
" mfc0 $1,$12 \n"
" ori $1,1 \n"
" xori $1,1 \n"
" ori $1,0x1f \n"
" xori $1,0x1f \n"
" .set noreorder \n"
" mtc0 $1,$12 \n"
#endif
@ -96,8 +107,8 @@ __asm__ (
" andi \\result, 1 \n"
#else
" mfc0 \\result, $12 \n"
" ori $1, \\result, 1 \n"
" xori $1, 1 \n"
" ori $1, \\result, 0x1f \n"
" xori $1, 0x1f \n"
" .set noreorder \n"
" mtc0 $1, $12 \n"
#endif
@ -136,8 +147,8 @@ __asm__ (
#else
" mfc0 $1, $12 \n"
" andi \\flags, 1 \n"
" ori $1, 1 \n"
" xori $1, 1 \n"
" ori $1, 0x1f \n"
" xori $1, 0x1f \n"
" or \\flags, $1 \n"
" mtc0 \\flags, $12 \n"
#endif