Commit c226f260 authored by Atsushi Nemoto's avatar Atsushi Nemoto Committed by Ralf Baechle
Browse files

[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: default avatarAtsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent dbee90b7

include/asm-mips/interrupt.h

+17 −6
Original line number Diff line number Diff line
@@ -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

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