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Message-Id: <1471525832-21209-4-git-send-email-suzuki.poulose@arm.com>
Date: Thu, 18 Aug 2016 14:10:27 +0100
From: Suzuki K Poulose <suzuki.poulose@....com>
To: linux-arm-kernel@...ts.infradead.org
Cc: linux-kernel@...r.kernel.org, will.deacon@....com,
catalin.marinas@....com, mark.rutland@....com,
andre.przywara@....com, Suzuki K Poulose <suzuki.poulose@....com>
Subject: [PATCH 3/8] arm64: Rearrange CPU errata workaround checks
Right now we run through the work around checks on a CPU
from __cpuinfo_store_cpu. There are some problems with that:
1) We initialise the system wide CPU feature registers only after the
Boot CPU updates its cpuinfo. Now, if a work around depends on the
variance of a CPU ID feature (e.g, check for Cache Line size mismatch),
we have no way of performing it cleanly for the boot CPU.
2) It is out of place, invoked from __cpuinfo_store_cpu() in cpuinfo.c. It
is not an obvious place for that.
This patch rearranges the CPU specific capability(aka work around) checks.
1) At the moment we use verify_local_cpu_capabilities() to check if a new
CPU has all the system advertised features. Use this for the secondary CPUs
to perform the work around check. For that we rename
verify_local_cpu_capabilities() => check_local_cpu_capabilities()
which:
If the system wide capabilities haven't been initialised (i.e, the CPU
is activated at the boot), update the system wide detected work arounds.
Otherwise (i.e a CPU hotplugged in later) verify that this CPU conforms to the
system wide capabilities.
2) Boot CPU updates the work arounds from smp_prepare_boot_cpu() after we have
initialised the system wide CPU feature values.
Cc: Mark Rutland <mark.rutland@....com>
Cc: Andre Przywara <andre.przywara@....com>
Cc: Will Deacon <will.deacon@....com>
Cc: Catalin Marinas <catalin.marinas@....com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
---
arch/arm64/include/asm/cpufeature.h | 4 ++--
arch/arm64/kernel/cpufeature.c | 30 ++++++++++++++++++++----------
arch/arm64/kernel/cpuinfo.c | 2 --
arch/arm64/kernel/smp.c | 8 +++++++-
4 files changed, 29 insertions(+), 15 deletions(-)
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index aadd946..692b8d3 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -193,11 +193,11 @@ void __init setup_cpu_features(void);
void update_cpu_capabilities(const struct arm64_cpu_capabilities *caps,
const char *info);
void enable_cpu_capabilities(const struct arm64_cpu_capabilities *caps);
+void check_local_cpu_capabilities(void);
+
void update_cpu_errata_workarounds(void);
void __init enable_errata_workarounds(void);
-
void verify_local_cpu_errata_workarounds(void);
-void verify_local_cpu_capabilities(void);
u64 read_system_reg(u32 id);
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index a591c35..fcf87ca 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1005,23 +1005,33 @@ verify_local_cpu_features(const struct arm64_cpu_capabilities *caps)
* cannot do anything to fix it up and could cause unexpected failures. So
* we park the CPU.
*/
-void verify_local_cpu_capabilities(void)
+static void verify_local_cpu_capabilities(void)
{
+ verify_local_cpu_errata_workarounds();
+ verify_local_cpu_features(arm64_features);
+ verify_local_elf_hwcaps(arm64_elf_hwcaps);
+ if (system_supports_32bit_el0())
+ verify_local_elf_hwcaps(compat_elf_hwcaps);
+}
+void check_local_cpu_capabilities(void)
+{
+ /*
+ * All secondary CPUs should conform to the early CPU features
+ * in use by the kernel based on boot CPU.
+ */
check_early_cpu_features();
/*
- * If we haven't computed the system capabilities, there is nothing
- * to verify.
+ * If we haven't finalised the system capabilities, this CPU gets
+ * a chance to update the errata work arounds.
+ * Otherwise, this CPU should verify that it has all the system
+ * advertised capabilities.
*/
if (!sys_caps_initialised)
- return;
-
- verify_local_cpu_errata_workarounds();
- verify_local_cpu_features(arm64_features);
- verify_local_elf_hwcaps(arm64_elf_hwcaps);
- if (system_supports_32bit_el0())
- verify_local_elf_hwcaps(compat_elf_hwcaps);
+ update_cpu_errata_workarounds();
+ else
+ verify_local_cpu_capabilities();
}
static void __init setup_feature_capabilities(void)
diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c
index 4fa7b73..b3d5b3e 100644
--- a/arch/arm64/kernel/cpuinfo.c
+++ b/arch/arm64/kernel/cpuinfo.c
@@ -363,8 +363,6 @@ static void __cpuinfo_store_cpu(struct cpuinfo_arm64 *info)
}
cpuinfo_detect_icache_policy(info);
-
- update_cpu_errata_workarounds();
}
void cpuinfo_store_cpu(void)
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 76a6d92..289c43b 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -239,7 +239,7 @@ asmlinkage void secondary_start_kernel(void)
* this CPU ticks all of those. If it doesn't, the CPU will
* fail to come online.
*/
- verify_local_cpu_capabilities();
+ check_local_cpu_capabilities();
if (cpu_ops[cpu]->cpu_postboot)
cpu_ops[cpu]->cpu_postboot();
@@ -439,6 +439,12 @@ void __init smp_prepare_boot_cpu(void)
set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
cpuinfo_store_boot_cpu();
save_boot_cpu_run_el();
+ /*
+ * Run the errata work around checks on the boot CPU, once we have
+ * initialised the cpu feature infrastructure from
+ * cpuinfo_store_boot_cpu() above.
+ */
+ update_cpu_errata_workarounds();
}
static u64 __init of_get_cpu_mpidr(struct device_node *dn)
--
2.7.4
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