Commit 8925ec4c authored by Will Deacon's avatar Will Deacon Committed by Russell King
Browse files

ARM: 6385/1: setup: detect aliasing I-cache when D-cache is non-aliasing 



Currently, the Kernel assumes that if a CPU has a non-aliasing D-cache
then the I-cache is also non-aliasing. This may not be true on ARM cores
from v6 onwards, which may have aliasing I-caches but non-aliasing
D-caches.

This patch adds a cpu_has_aliasing_icache function, which is called from
cacheid_init and adds CACHEID_VIPT_I_ALIASING to the cacheid when
appropriate. A utility macro, icache_is_vipt_aliasing(), is also
provided.

Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent f8b63c18

arch/arm/include/asm/cachetype.h

+6 −2
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ 
#define CACHEID_VIPT_ALIASING		(1 << 2)

#define CACHEID_VIPT			(CACHEID_VIPT_ALIASING|CACHEID_VIPT_NONALIASING)

#define CACHEID_ASID_TAGGED		(1 << 3)

#define CACHEID_VIPT_I_ALIASING		(1 << 4)



extern unsigned int cacheid;
@@ -14,15 +15,18 @@ extern unsigned int cacheid; 
#define cache_is_vipt_nonaliasing()	cacheid_is(CACHEID_VIPT_NONALIASING)

#define cache_is_vipt_aliasing()	cacheid_is(CACHEID_VIPT_ALIASING)

#define icache_is_vivt_asid_tagged()	cacheid_is(CACHEID_ASID_TAGGED)

#define icache_is_vipt_aliasing()	cacheid_is(CACHEID_VIPT_I_ALIASING)



/*

 * __LINUX_ARM_ARCH__ is the minimum supported CPU architecture

 * Mask out support which will never be present on newer CPUs.

 * - v6+ is never VIVT

 * - v7+ VIPT never aliases

 * - v7+ VIPT never aliases on D-side

 */

#if __LINUX_ARM_ARCH__ >= 7

#define __CACHEID_ARCH_MIN	(CACHEID_VIPT_NONALIASING | CACHEID_ASID_TAGGED)

#define __CACHEID_ARCH_MIN	(CACHEID_VIPT_NONALIASING |\

				 CACHEID_ASID_TAGGED |\

				 CACHEID_VIPT_I_ALIASING)

#elif __LINUX_ARM_ARCH__ >= 6

#define	__CACHEID_ARCH_MIN	(~CACHEID_VIVT)

#else

arch/arm/kernel/setup.c

+36 −3
Original line number Diff line number Diff line
@@ -238,6 +238,34 @@ int cpu_architecture(void) 
	return cpu_arch;

}



static int cpu_has_aliasing_icache(unsigned int arch)

{

	int aliasing_icache;

	unsigned int id_reg, num_sets, line_size;



	/* arch specifies the register format */

	switch (arch) {

	case CPU_ARCH_ARMv7:

		asm("mcr	p15, 2, %1, c0, c0, 0	@ set CSSELR\n"

		    "isb\n"

		    "mrc	p15, 1, %0, c0, c0, 0	@ read CCSIDR"

		    : "=r" (id_reg)

		    : "r" (1));

		line_size = 4 << ((id_reg & 0x7) + 2);

		num_sets = ((id_reg >> 13) & 0x7fff) + 1;

		aliasing_icache = (line_size * num_sets) > PAGE_SIZE;

		break;

	case CPU_ARCH_ARMv6:

		aliasing_icache = read_cpuid_cachetype() & (1 << 11);

		break;

	default:

		/* I-cache aliases will be handled by D-cache aliasing code */

		aliasing_icache = 0;

	}



	return aliasing_icache;

}



static void __init cacheid_init(void)

{

	unsigned int cachetype = read_cpuid_cachetype();
@@ -249,10 +277,15 @@ static void __init cacheid_init(void) 
			cacheid = CACHEID_VIPT_NONALIASING;

			if ((cachetype & (3 << 14)) == 1 << 14)

				cacheid |= CACHEID_ASID_TAGGED;

		} else if (cachetype & (1 << 23))

			else if (cpu_has_aliasing_icache(CPU_ARCH_ARMv7))

				cacheid |= CACHEID_VIPT_I_ALIASING;

		} else if (cachetype & (1 << 23)) {

			cacheid = CACHEID_VIPT_ALIASING;

		else

		} else {

			cacheid = CACHEID_VIPT_NONALIASING;

			if (cpu_has_aliasing_icache(CPU_ARCH_ARMv6))

				cacheid |= CACHEID_VIPT_I_ALIASING;

		}

	} else {

		cacheid = CACHEID_VIVT;

	}
@@ -263,7 +296,7 @@ static void __init cacheid_init(void) 
		cache_is_vipt_nonaliasing() ? "VIPT nonaliasing" : "unknown",

		cache_is_vivt() ? "VIVT" :

		icache_is_vivt_asid_tagged() ? "VIVT ASID tagged" :

		cache_is_vipt_aliasing() ? "VIPT aliasing" :

		icache_is_vipt_aliasing() ? "VIPT aliasing" :

		cache_is_vipt_nonaliasing() ? "VIPT nonaliasing" : "unknown");

}

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