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Commit 4dcafb42 authored by Suzuki K. Poulose's avatar Suzuki K. Poulose Committed by Kyle Yan
Browse files

arm64: Add assembly helpers for MIDR range check 



Add a helper to check the MIDR of the running CPU against a given
MODEL and a range of revision and variants (just like we do in
is_affected_midr_range()). This will be useful for early checks
for MIDR to detect CPU errata.

Change-Id: I8cee3c92d2903d401d0b4235312904b706b38f7f
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: default avatarSuzuki K Poulose <suzuki.poulose@arm.com>
Patch-mainline: linux-arm-kernel @ 01/16/2018, 10:23
[kyan@codeaurora.org: resolve trivial merge conflicts]
Signed-off-by: default avatarKyle Yan <kyan@codeaurora.org>
parent eb8323cc

arch/arm64/include/asm/assembler.h

+40 −0
Original line number Diff line number Diff line
@@ -25,6 +25,7 @@ 


#include <asm/asm-offsets.h>

#include <asm/cpufeature.h>

#include <asm/cputype.h>

#include <asm/page.h>

#include <asm/pgtable-hwdef.h>

#include <asm/ptrace.h>
@@ -452,4 +453,43 @@ alternative_endif 
	mrs	\rd, sp_el0

	.endm



/*

 * Check the MIDR_EL1 of the current CPU for a given model and a range of

 * variant/revision. See asm/cputype.h for the macros used below.

 *

 *	model:		MIDR_CPU_MODEL of CPU

 *	rv_min:		Minimum of MIDR_CPU_VAR_REV()

 *	rv_max:		Maximum of MIDR_CPU_VAR_REV()

 *	res:		Result register.

 *	tmp1, tmp2, tmp3: Temporary registers

 *

 * Corrupts: res, tmp1, tmp2, tmp3

 * Returns:  0, if the CPU id doesn't match. Non-zero otherwise

 */

	.macro	cpu_midr_match model, rv_min, rv_max, res, tmp1, tmp2, tmp3

	mrs		\res, midr_el1

	mov_q		\tmp1, (MIDR_REVISION_MASK | MIDR_VARIANT_MASK)

	mov_q		\tmp2, MIDR_CPU_MODEL_MASK

	and		\tmp3, \res, \tmp2	// Extract model

	and		\tmp1, \res, \tmp1	// rev & variant

	mov_q		\tmp2, \model

	cmp		\tmp3, \tmp2

	cset		\res, eq

	cbz		\res, .Ldone\@		// Model matches ?



	.if (\rv_min != 0)			// Skip min check if rv_min == 0

	mov_q		\tmp3, \rv_min

	cmp		\tmp1, \tmp3

	cset		\res, ge

	.endif					// \rv_min != 0

	/* Skip rv_max check if rv_min == rv_max && rv_min != 0 */

	.if ((\rv_min != \rv_max) || \rv_min == 0)

	mov_q		\tmp2, \rv_max

	cmp		\tmp1, \tmp2

	cset		\tmp2, le

	and		\res, \res, \tmp2

	.endif

.Ldone\@:

	.endm



#endif	/* __ASM_ASSEMBLER_H */