arm64/errata: add REVIDR handling to framework

In some cases, core variants that are affected by a certain erratum
also exist in versions that have the erratum fixed, and this fact is
recorded in a dedicated bit in system register REVIDR_EL1.

Since the architecture does not require that a certain bit retains
its meaning across different variants of the same model, each such
REVIDR bit is tightly coupled to a certain revision/variant value,
and so we need a list of revidr_mask/midr pairs to carry this
information.

So add the struct member and the associated macros and handling to
allow REVIDR fixes to be taken into account.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 060e3a4008abd18e4a5aa48bb5b6fa1674a735c3..fbf0aab94d67e52e4e8fc6475669b5f25eacc7d8 100644 (file)
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -105,6 +105,10 @@ struct arm64_cpu_capabilities {
                struct {        /* To be used for erratum handling only */
                        u32 midr_model;
                        u32 midr_range_min, midr_range_max;
+                       const struct arm64_midr_revidr {
+                               u32 midr_rv;            /* revision/variant */
+                               u32 revidr_mask;
+                       } * const fixed_revs;
                };
 
                struct {        /* Feature register checking */

diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index 52f15cd896e11ad631ac3092d9709337a9629bb4..b161abdd6e27e7cdcd963fd40a041ea69c26ea98 100644 (file)
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -24,10 +24,22 @@
 static bool __maybe_unused
 is_affected_midr_range(const struct arm64_cpu_capabilities *entry, int scope)
 {
+       const struct arm64_midr_revidr *fix;
+       u32 midr = read_cpuid_id(), revidr;
+
        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);
+       if (!MIDR_IS_CPU_MODEL_RANGE(midr, entry->midr_model,
+                                    entry->midr_range_min,
+                                    entry->midr_range_max))
+               return false;
+
+       midr &= MIDR_REVISION_MASK | MIDR_VARIANT_MASK;
+       revidr = read_cpuid(REVIDR_EL1);
+       for (fix = entry->fixed_revs; fix && fix->revidr_mask; fix++)
+               if (midr == fix->midr_rv && (revidr & fix->revidr_mask))
+                       return false;
+
+       return true;
 }
 
 static bool __maybe_unused
@@ -242,6 +254,9 @@ static int qcom_enable_link_stack_sanitization(void *data)
        .midr_range_min = 0, \
        .midr_range_max = (MIDR_VARIANT_MASK | MIDR_REVISION_MASK)
 
+#define MIDR_FIXED(rev, revidr_mask) \
+       .fixed_revs = (struct arm64_midr_revidr[]){{ (rev), (revidr_mask) }, {}}
+
 const struct arm64_cpu_capabilities arm64_errata[] = {
 #if    defined(CONFIG_ARM64_ERRATUM_826319) || \
        defined(CONFIG_ARM64_ERRATUM_827319) || \