| Message ID | 1403795926-17139-4-git-send-email-mark.rutland@arm.com |
|---|---|
| State | New |
| Headers | show |
On 26 June 2014 17:18, Mark Rutland <mark.rutland@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. > > This patch reorganises the code responsible for /proc/cpuinfo to print > information per-cpu. As hwcaps are expected to be identical across all > CPUs, this information is printed once. > > Signed-off-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> > --- > arch/arm64/kernel/setup.c | 29 +++++++++++++++-------------- > 1 file changed, 15 insertions(+), 14 deletions(-) > > diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c > index edb146d..b00b7a3 100644 > --- a/arch/arm64/kernel/setup.c > +++ b/arch/arm64/kernel/setup.c > @@ -448,20 +448,30 @@ static const char *hwcap_str[] = { > > static int c_show(struct seq_file *m, void *v) > { > - int i; > + int c, i; > > - seq_printf(m, "Processor\t: %s rev %d (%s)\n", > - cpu_name, read_cpuid_id() & 15, ELF_PLATFORM); > + for_each_online_cpu(c) { > + 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); > + seq_printf(m, "CPU 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"); > } > > /* dump out the processor features */ > @@ -470,17 +480,8 @@ static int c_show(struct seq_file *m, void *v) > for (i = 0; hwcap_str[i]; i++) > if (elf_hwcap & (1 << i)) > seq_printf(m, "%s ", hwcap_str[i]); > - > - 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_puts(m, "\n"); > > - seq_printf(m, "Hardware\t: %s\n", machine_name); > - > return 0; > } > > -- > 1.9.1 >
diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c index edb146d..b00b7a3 100644 --- a/arch/arm64/kernel/setup.c +++ b/arch/arm64/kernel/setup.c @@ -448,20 +448,30 @@ static const char *hwcap_str[] = { static int c_show(struct seq_file *m, void *v) { - int i; + int c, i; - seq_printf(m, "Processor\t: %s rev %d (%s)\n", - cpu_name, read_cpuid_id() & 15, ELF_PLATFORM); + for_each_online_cpu(c) { + 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); + seq_printf(m, "CPU 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"); } /* dump out the processor features */ @@ -470,17 +480,8 @@ static int c_show(struct seq_file *m, void *v) for (i = 0; hwcap_str[i]; i++) if (elf_hwcap & (1 << i)) seq_printf(m, "%s ", hwcap_str[i]); - - 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_puts(m, "\n"); - seq_printf(m, "Hardware\t: %s\n", machine_name); - return 0; }
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. This patch reorganises the code responsible for /proc/cpuinfo to print information per-cpu. As hwcaps are expected to be identical across all CPUs, this information is printed once. Signed-off-by: Mark Rutland <mark.rutland@arm.com> --- arch/arm64/kernel/setup.c | 29 +++++++++++++++-------------- 1 file changed, 15 insertions(+), 14 deletions(-)