linux-kernel - [PATCH 4.9 10/43] arm64: Add helpers for checking CPU MIDR against a range

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Date:   Wed,  6 Apr 2022 20:26:19 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Will Deacon <will.deacon@....com>,
        Mark Rutland <mark.rutland@....com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Dave Martin <dave.martin@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        James Morse <james.morse@....com>
Subject: [PATCH 4.9 10/43] arm64: Add helpers for checking CPU MIDR against a range

From: Suzuki K Poulose <suzuki.poulose@....com>

[ Upstream commit 1df310505d6d544802016f6bae49aab836ae8510 ]

Add helpers for checking if the given CPU midr falls in a range
of variants/revisions for a given model.

Cc: Will Deacon <will.deacon@....com>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Ard Biesheuvel <ard.biesheuvel@...aro.org>
Reviewed-by: Dave Martin <dave.martin@....com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
Signed-off-by: Will Deacon <will.deacon@....com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: James Morse <james.morse@....com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/arm64/include/asm/cpufeature.h |    4 ++--
 arch/arm64/include/asm/cputype.h    |   30 ++++++++++++++++++++++++++++++
 arch/arm64/kernel/cpu_errata.c      |   14 +++++---------
 3 files changed, 37 insertions(+), 11 deletions(-)

--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -10,6 +10,7 @@
 #define __ASM_CPUFEATURE_H
 
 #include <asm/cpucaps.h>
+#include <asm/cputype.h>
 #include <asm/hwcap.h>
 #include <asm/sysreg.h>
 
@@ -229,8 +230,7 @@ struct arm64_cpu_capabilities {
 	void (*cpu_enable)(const struct arm64_cpu_capabilities *cap);
 	union {
 		struct {	/* To be used for erratum handling only */
-			u32 midr_model;
-			u32 midr_range_min, midr_range_max;
+			struct midr_range midr_range;
 		};
 
 		struct {	/* Feature register checking */
--- a/arch/arm64/include/asm/cputype.h
+++ b/arch/arm64/include/asm/cputype.h
@@ -114,6 +114,36 @@
 #define read_cpuid(reg)			read_sysreg_s(SYS_ ## reg)
 
 /*
+ * Represent a range of MIDR values for a given CPU model and a
+ * range of variant/revision values.
+ *
+ * @model	- CPU model as defined by MIDR_CPU_MODEL
+ * @rv_min	- Minimum value for the revision/variant as defined by
+ *		  MIDR_CPU_VAR_REV
+ * @rv_max	- Maximum value for the variant/revision for the range.
+ */
+struct midr_range {
+	u32 model;
+	u32 rv_min;
+	u32 rv_max;
+};
+
+#define MIDR_RANGE(m, v_min, r_min, v_max, r_max)		\
+	{							\
+		.model = m,					\
+		.rv_min = MIDR_CPU_VAR_REV(v_min, r_min),	\
+		.rv_max = MIDR_CPU_VAR_REV(v_max, r_max),	\
+	}
+
+#define MIDR_ALL_VERSIONS(m) MIDR_RANGE(m, 0, 0, 0xf, 0xf)
+
+static inline bool is_midr_in_range(u32 midr, struct midr_range const *range)
+{
+	return MIDR_IS_CPU_MODEL_RANGE(midr, range->model,
+				 range->rv_min, range->rv_max);
+}
+
+/*
  * The CPU ID never changes at run time, so we might as well tell the
  * compiler that it's constant.  Use this function to read the CPU ID
  * rather than directly reading processor_id or read_cpuid() directly.
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -27,10 +27,10 @@
 static bool __maybe_unused
 is_affected_midr_range(const struct arm64_cpu_capabilities *entry, int scope)
 {
+	u32 midr = read_cpuid_id();
+
 	WARN_ON(scope != SCOPE_LOCAL_CPU || preemptible());
-	return MIDR_IS_CPU_MODEL_RANGE(read_cpuid_id(), entry->midr_model,
-				       entry->midr_range_min,
-				       entry->midr_range_max);
+	return is_midr_in_range(midr, &entry->midr_range);
 }
 
 static bool
@@ -370,15 +370,11 @@ static bool has_ssbd_mitigation(const st
 
 #define CAP_MIDR_RANGE(model, v_min, r_min, v_max, r_max)	\
 	.matches = is_affected_midr_range,			\
-	.midr_model = model,					\
-	.midr_range_min = MIDR_CPU_VAR_REV(v_min, r_min),	\
-	.midr_range_max = MIDR_CPU_VAR_REV(v_max, r_max)
+	.midr_range = MIDR_RANGE(model, v_min, r_min, v_max, r_max)
 
 #define CAP_MIDR_ALL_VERSIONS(model)					\
 	.matches = is_affected_midr_range,				\
-	.midr_model = model,						\
-	.midr_range_min = MIDR_CPU_VAR_REV(0, 0),			\
-	.midr_range_max = (MIDR_VARIANT_MASK | MIDR_REVISION_MASK)
+	.midr_range = MIDR_ALL_VERSIONS(model)
 
 #define MIDR_FIXED(rev, revidr_mask) \
 	.fixed_revs = (struct arm64_midr_revidr[]){{ (rev), (revidr_mask) }, {}}