[PATCH 2/3] arm64: cpuinfo: print info for all CPUs
Ard Biesheuvel
ard.biesheuvel at linaro.org
Mon May 12 07:54:50 PDT 2014
Hi Mark,
On 12 May 2014 16:37, Mark Rutland <mark.rutland at arm.com> wrote:
> Currently reading /proc/cpuinfo will result in information being read
> out of the MIDR_EL1 of the current CPU, and the information is not
> associated with any particular logical CPU number.
>
> This is problematic for systems with heterogeneous CPUs (i.e.
> big.LITTLE) where fields will vary across CPUs, and the output will
> differ depending on the executing CPU. Additionally the output is
> different in format to the 32-bit ARM Linux port, where information is
> printed out for each CPU.
>
> This patch adds the necessary infrastructure to log the relevant
> registers (currently just MPIDR_EL1) and print out the logged
> information.
>
> Signed-off-by: Mark Rutland <mark.rutland at arm.com>
> Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
> Cc: Jacob Bramley <jacob.bramley at arm.com>
> ---
> arch/arm64/include/asm/cpu.h | 30 +++++++++++++++++++++++++++++
> arch/arm64/kernel/Makefile | 2 +-
> arch/arm64/kernel/cpuinfo.c | 30 +++++++++++++++++++++++++++++
> arch/arm64/kernel/setup.c | 46 +++++++++++++++++++++++---------------------
> arch/arm64/kernel/smp.c | 6 ++++++
> 5 files changed, 91 insertions(+), 23 deletions(-)
> create mode 100644 arch/arm64/include/asm/cpu.h
> create mode 100644 arch/arm64/kernel/cpuinfo.c
>
> diff --git a/arch/arm64/include/asm/cpu.h b/arch/arm64/include/asm/cpu.h
> new file mode 100644
> index 0000000..74bf9bb
> --- /dev/null
> +++ b/arch/arm64/include/asm/cpu.h
> @@ -0,0 +1,30 @@
> +/*
> + * arch/arm/include/asm/cpu.h
> + *
> + * Copyright (C) 2004-2014 ARM Ltd.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +#ifndef __ASM_ARM64_CPU_H
> +#define __ASM_ARM64_CPU_H
> +
> +#include <linux/percpu.h>
> +#include <linux/cpu.h>
> +
> +/*
> + * Records attributes of an individual CPU.
> + *
> + * This is used to cache data for /proc/cpuinfo.
> + */
> +struct cpuinfo_arm64 {
> + struct cpu cpu;
> + u32 reg_midr;
> +};
> +
> +DECLARE_PER_CPU(struct cpuinfo_arm64, cpu_data);
> +
> +void cpuinfo_store_cpu(void);
> +
> +#endif
> diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
> index 7d811d9..0e0431f 100644
> --- a/arch/arm64/kernel/Makefile
> +++ b/arch/arm64/kernel/Makefile
> @@ -9,7 +9,7 @@ AFLAGS_head.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
> arm64-obj-y := cputable.o debug-monitors.o entry.o irq.o fpsimd.o \
> entry-fpsimd.o process.o ptrace.o setup.o signal.o \
> sys.o stacktrace.o time.o traps.o io.o vdso.o \
> - hyp-stub.o psci.o cpu_ops.o insn.o
> + hyp-stub.o psci.o cpu_ops.o insn.o cpuinfo.o
>
> arm64-obj-$(CONFIG_COMPAT) += sys32.o kuser32.o signal32.o \
> sys_compat.o
> diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c
> new file mode 100644
> index 0000000..b9e18c5
> --- /dev/null
> +++ b/arch/arm64/kernel/cpuinfo.c
> @@ -0,0 +1,30 @@
> +/*
> + * Record CPU attributes for later retrieval
> + *
> + * Copyright (C) 2014 ARM Ltd.
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program. If not, see <http://www.gnu.org/licenses/>.
> + */
> +#include <asm/cpu.h>
> +
> +#include <linux/smp.h>
> +
> +DEFINE_PER_CPU(struct cpuinfo_arm64, cpu_data);
> +
> +void cpuinfo_store_cpu(void)
> +{
> + int cpu = smp_processor_id();
> + struct cpuinfo_arm64 *cpuinfo = &per_cpu(cpu_data, cpu);
> +
> + cpuinfo->reg_midr = read_cpuid_id();
> +}
> +
> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
> index 7450c58..b2c0554 100644
> --- a/arch/arm64/kernel/setup.c
> +++ b/arch/arm64/kernel/setup.c
> @@ -44,6 +44,7 @@
> #include <linux/of_platform.h>
>
> #include <asm/fixmap.h>
> +#include <asm/cpu.h>
> #include <asm/cputype.h>
> #include <asm/elf.h>
> #include <asm/cputable.h>
> @@ -391,6 +392,7 @@ void __init setup_arch(char **cmdline_p)
>
> cpu_logical_map(0) = read_cpuid_mpidr() & MPIDR_HWID_BITMASK;
> cpu_read_bootcpu_ops();
> + cpuinfo_store_cpu();
> #ifdef CONFIG_SMP
> smp_init_cpus();
> smp_build_mpidr_hash();
> @@ -412,14 +414,12 @@ static int __init arm64_device_init(void)
> }
> arch_initcall_sync(arm64_device_init);
>
> -static DEFINE_PER_CPU(struct cpu, cpu_data);
> -
> static int __init topology_init(void)
> {
> int i;
>
> for_each_possible_cpu(i) {
> - struct cpu *cpu = &per_cpu(cpu_data, i);
> + struct cpu *cpu = &per_cpu(cpu_data.cpu, i);
> cpu->hotpluggable = 1;
> register_cpu(cpu, i);
> }
> @@ -442,38 +442,40 @@ static const char *hwcap_str[] = {
>
> static int c_show(struct seq_file *m, void *v)
> {
> - int i;
> + int c;
>
> - seq_printf(m, "Processor\t: %s rev %d (%s)\n",
> - cpu_name, read_cpuid_id() & 15, ELF_PLATFORM);
> + for_each_online_cpu(c) {
> + int i;
> + struct cpuinfo_arm64 *cpuinfo = &per_cpu(cpu_data, c);
> + u32 midr = cpuinfo->reg_midr;
>
> - for_each_online_cpu(i) {
> /*
> * glibc reads /proc/cpuinfo to determine the number of
> * online processors, looking for lines beginning with
> * "processor". Give glibc what it expects.
> */
> #ifdef CONFIG_SMP
> - seq_printf(m, "processor\t: %d\n", i);
> + seq_printf(m, "processor\t: %d\n", c);
> #endif
> - }
> + seq_printf(m, "Type\t\t: %s rev %d (%s)\n",
> + cpu_name, MIDR_REVISION(midr), ELF_PLATFORM);
>
> - /* dump out the processor features */
> - seq_puts(m, "Features\t: ");
> + /* dump out the processor features */
> + seq_puts(m, "Features\t: ");
>
> - for (i = 0; hwcap_str[i]; i++)
> - if (elf_hwcap & (1 << i))
> - seq_printf(m, "%s ", hwcap_str[i]);
> + for (i = 0; hwcap_str[i]; i++)
> + if (elf_hwcap & (1 << i))
> + seq_printf(m, "%s ", hwcap_str[i]);
>
Considering that you are printing the contents of the same variable
every iteration, and the fact that your subsequent patch makes sure
elf_hwcap is in sync between all CPUs, doesn't it make more sense to
print this line only once?
--
Ard.
> - seq_printf(m, "\nCPU implementer\t: 0x%02x\n", read_cpuid_id() >> 24);
> - seq_printf(m, "CPU architecture: AArch64\n");
> - seq_printf(m, "CPU variant\t: 0x%x\n", (read_cpuid_id() >> 20) & 15);
> - seq_printf(m, "CPU part\t: 0x%03x\n", (read_cpuid_id() >> 4) & 0xfff);
> - seq_printf(m, "CPU revision\t: %d\n", read_cpuid_id() & 15);
> + seq_printf(m, "\nCPU implementer\t: 0x%02x\n",
> + MIDR_IMPLEMENTOR(midr));
> + seq_printf(m, "CPU architecture: AArch64\n");
> + seq_printf(m, "CPU variant\t: 0x%x\n", MIDR_VARIANT(midr));
> + seq_printf(m, "CPU part\t: 0x%03x\n", MIDR_PARTNUM(midr));
> + seq_printf(m, "CPU revision\t: %d\n", MIDR_REVISION(midr));
>
> - seq_puts(m, "\n");
> -
> - seq_printf(m, "Hardware\t: %s\n", machine_name);
> + seq_puts(m, "\n");
> + }
>
> return 0;
> }
> diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> index f0a141d..f74866d 100644
> --- a/arch/arm64/kernel/smp.c
> +++ b/arch/arm64/kernel/smp.c
> @@ -38,6 +38,7 @@
>
> #include <asm/atomic.h>
> #include <asm/cacheflush.h>
> +#include <asm/cpu.h>
> #include <asm/cputype.h>
> #include <asm/cpu_ops.h>
> #include <asm/mmu_context.h>
> @@ -160,6 +161,11 @@ asmlinkage void secondary_start_kernel(void)
> smp_store_cpu_info(cpu);
>
> /*
> + * Log the CPU info before it is marked online and might get read.
> + */
> + cpuinfo_store_cpu();
> +
> + /*
> * OK, now it's safe to let the boot CPU continue. Wait for
> * the CPU migration code to notice that the CPU is online
> * before we continue.
> --
> 1.8.1.1
>
>
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