Commit 301bcfac authored by Andre Przywara's avatar Andre Przywara Committed by Will Deacon
Browse files

arm64: add Cortex-A53 cache errata workaround 



The ARM errata 819472, 826319, 827319 and 824069 define the same
workaround for these hardware issues in certain Cortex-A53 parts.
Use the new alternatives framework and the CPU MIDR detection to
patch "cache clean" into "cache clean and invalidate" instructions if
an affected CPU is detected at runtime.

Signed-off-by: default avatarAndre Przywara <andre.przywara@arm.com>
[will: add __maybe_unused to squash gcc warning]
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent e116a375

arch/arm64/include/asm/alternative-asm.h

+13 −0
Original line number Diff line number Diff line
@@ -11,6 +11,19 @@ 
	.byte \alt_len

.endm



.macro alternative_insn insn1 insn2 cap

661:	\insn1

662:	.pushsection .altinstructions, "a"

	altinstruction_entry 661b, 663f, \cap, 662b-661b, 664f-663f

	.popsection

	.pushsection .altinstr_replacement, "ax"

663:	\insn2

664:	.popsection

	.if ((664b-663b) != (662b-661b))

		.error "Alternatives instruction length mismatch"

	.endif

.endm



#endif  /*  __ASSEMBLY__  */



#endif /* __ASM_ALTERNATIVE_ASM_H */

arch/arm64/include/asm/cpufeature.h

+7 −1
Original line number Diff line number Diff line
@@ -21,7 +21,11 @@ 
#define MAX_CPU_FEATURES	(8 * sizeof(elf_hwcap))

#define cpu_feature(x)		ilog2(HWCAP_ ## x)



#define NCAPS			0

#define ARM64_WORKAROUND_CLEAN_CACHE	0



#define NCAPS				1



#ifndef __ASSEMBLY__



extern DECLARE_BITMAP(cpu_hwcaps, NCAPS);
@@ -48,4 +52,6 @@ static inline void cpus_set_cap(unsigned int num) 


void check_local_cpu_errata(void);



#endif /* __ASSEMBLY__ */



#endif

arch/arm64/include/asm/cputype.h

+5 −0
Original line number Diff line number Diff line
@@ -57,6 +57,11 @@ 
#define MIDR_IMPLEMENTOR(midr)	\

	(((midr) & MIDR_IMPLEMENTOR_MASK) >> MIDR_IMPLEMENTOR_SHIFT)



#define MIDR_CPU_PART(imp, partnum) \

	(((imp)			<< MIDR_IMPLEMENTOR_SHIFT) | \

	(0xf			<< MIDR_ARCHITECTURE_SHIFT) | \

	((partnum)		<< MIDR_PARTNUM_SHIFT))



#define ARM_CPU_IMP_ARM		0x41

#define ARM_CPU_IMP_APM		0x50

arch/arm64/kernel/cpu_errata.c

+32 −1
Original line number Diff line number Diff line
@@ -23,6 +23,8 @@ 
#include <asm/cputype.h>

#include <asm/cpufeature.h>



#define MIDR_CORTEX_A53 MIDR_CPU_PART(ARM_CPU_IMP_ARM, ARM_CPU_PART_CORTEX_A53)



/*

 * Add a struct or another datatype to the union below if you need

 * different means to detect an affected CPU.
@@ -39,8 +41,37 @@ struct arm64_cpu_capabilities { 
	};

};



#define CPU_MODEL_MASK (MIDR_IMPLEMENTOR_MASK | MIDR_PARTNUM_MASK | \

			MIDR_ARCHITECTURE_MASK)



static bool __maybe_unused

is_affected_midr_range(struct arm64_cpu_capabilities *entry)

{

	u32 midr = read_cpuid_id();



	if ((midr & CPU_MODEL_MASK) != entry->midr_model)

		return false;



	midr &= MIDR_REVISION_MASK | MIDR_VARIANT_MASK;



	return (midr >= entry->midr_range_min && midr <= entry->midr_range_max);

}



#define MIDR_RANGE(model, min, max) \

	.is_affected = is_affected_midr_range, \

	.midr_model = model, \

	.midr_range_min = min, \

	.midr_range_max = max



struct arm64_cpu_capabilities arm64_errata[] = {

	{}

	{

	/* Cortex-A53 r0p[012] */

		.desc = "ARM errata 826319, 827319, 824069",

		.capability = ARM64_WORKAROUND_CLEAN_CACHE,

		MIDR_RANGE(MIDR_CORTEX_A53, 0x00, 0x02),

	},

	{

	}

};



void check_local_cpu_errata(void)

arch/arm64/mm/cache.S

+3 −1
Original line number Diff line number Diff line
@@ -20,6 +20,8 @@ 
#include <linux/linkage.h>

#include <linux/init.h>

#include <asm/assembler.h>

#include <asm/cpufeature.h>

#include <asm/alternative-asm.h>



#include "proc-macros.S"
@@ -210,7 +212,7 @@ __dma_clean_range: 
	dcache_line_size x2, x3

	sub	x3, x2, #1

	bic	x0, x0, x3

1:	dc	cvac, x0			// clean D / U line

1:	alternative_insn "dc cvac, x0", "dc civac, x0", ARM64_WORKAROUND_CLEAN_CACHE

	add	x0, x0, x2

	cmp	x0, x1

	b.lo	1b

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