Commit 7dd6662a authored by Paul Mundt's avatar Paul Mundt
Browse files

sh: delay slot future proofing via EXPMASK on SH-4A parts. 



This implements EXPMASK initialization code for SH-4A parts, where it is
possible to disable compat features that will go away in newer cores.
Presently this includes disabling support for non-nop instructions in the
rte delay slot, as well as a sleep instruction being placed in a delay
slot (neither of which the kernel does any longer). As a result of this,
any future offenders will have illegal slot exceptions generated for
them.

Associative writes for the memory-mapped cache array are still left
enabled, until such a point that special cache operations for SH-4A are
provided to move off of the current (and rather dated) SH-4 versions.

Signed-off-by: default avatarPaul Mundt <lethal@linux-sh.org>
parent 7a90e00d

arch/sh/kernel/cpu/init.c

+33 −1
Original line number Diff line number Diff line
@@ -3,7 +3,7 @@ 
 *

 * CPU init code

 *

 * Copyright (C) 2002 - 2007  Paul Mundt

 * Copyright (C) 2002 - 2009  Paul Mundt

 * Copyright (C) 2003  Richard Curnow

 *

 * This file is subject to the terms and conditions of the GNU General Public
@@ -62,6 +62,37 @@ static void __init speculative_execution_init(void) 
#define speculative_execution_init()	do { } while (0)

#endif



#ifdef CONFIG_CPU_SH4A

#define EXPMASK			0xff2f0004

#define EXPMASK_RTEDS		(1 << 0)

#define EXPMASK_BRDSSLP		(1 << 1)

#define EXPMASK_MMCAW		(1 << 4)



static void __init expmask_init(void)

{

	unsigned long expmask = __raw_readl(EXPMASK);



	/*

	 * Future proofing.

	 *

	 * Disable support for slottable sleep instruction

	 * and non-nop instructions in the rte delay slot.

	 */

	expmask &= ~(EXPMASK_RTEDS | EXPMASK_BRDSSLP);



	/*

	 * Enable associative writes to the memory-mapped cache array

	 * until the cache flush ops have been rewritten.

	 */

	expmask |= EXPMASK_MMCAW;



	__raw_writel(expmask, EXPMASK);

	ctrl_barrier();

}

#else

#define expmask_init()	do { } while (0)

#endif



/* 2nd-level cache init */

void __uses_jump_to_uncached __attribute__ ((weak)) l2_cache_init(void)

{
@@ -321,4 +352,5 @@ asmlinkage void __init sh_cpu_init(void) 
#endif



	speculative_execution_init();

	expmask_init();

}

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