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Commit c47a1900 authored by Suzuki K Poulose's avatar Suzuki K Poulose Committed by Will Deacon
Browse files

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@arm.com>
Cc: Andre Przywara <andre.przywara@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarSuzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent 89ba2645

arch/arm64/include/asm/cpufeature.h

+2 −2
Original line number Diff line number Diff line
@@ -202,11 +202,11 @@ 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);

arch/arm64/kernel/cpufeature.c

+20 −10
Original line number Diff line number Diff line
@@ -1009,23 +1009,33 @@ 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)

arch/arm64/kernel/cpuinfo.c

+0 −2
Original line number Diff line number Diff line
@@ -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)

arch/arm64/kernel/smp.c

+7 −1
Original line number Diff line number Diff line
@@ -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();
@@ -444,6 +444,12 @@ void __init smp_prepare_boot_cpu(void) 
	jump_label_init();

	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)