[U-Boot] [PATCH 1/4] x86: Display more detailed CPU information on boot

Simon Glass sjg at chromium.org
Fri Nov 7 03:22:59 CET 2014


Hi Bin,

On 4 November 2014 07:58, Bin Meng <bmeng.cn at gmail.com> wrote:
> Currently only basic CPU information (x86 or x86_64) is displayed
> on boot. This commit adds more detailed information output including
> CPU vendor name, device id, family, model and stepping as well as
> the CPU brand string, all of which are extracted from CPUID result.
>
> The CPU identification happens in x86_cpu_init_f() and corresponding
> fields are saved in the global data. Later print_cpuinfo() just uses
> these fields to display CPU information without the need to probe
> again in real time.
>
> Signed-off-by: Bin Meng <bmeng.cn at gmail.com>
> ---
>  arch/x86/cpu/cpu.c                 | 282 +++++++++++++++++++++++++++++++------
>  arch/x86/include/asm/cpu.h         | 142 +++++++++++++++++++
>  arch/x86/include/asm/global_data.h |   5 +
>  3 files changed, 385 insertions(+), 44 deletions(-)
>
> diff --git a/arch/x86/cpu/cpu.c b/arch/x86/cpu/cpu.c
> index 2e25253..e9058f7 100644
> --- a/arch/x86/cpu/cpu.c
> +++ b/arch/x86/cpu/cpu.c
> @@ -13,6 +13,9 @@
>   * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
>   * Alex Zuepke <azu at sysgo.de>
>   *
> + * Part of this file is adapted from coreboot
> + * src/arch/x86/lib/cpu.c
> + *
>   * SPDX-License-Identifier:    GPL-2.0+
>   */
>
> @@ -27,6 +30,8 @@
>  #include <asm/interrupt.h>
>  #include <linux/compiler.h>
>
> +DECLARE_GLOBAL_DATA_PTR;
> +
>  /*
>   * Constructor for a conventional segment GDT (or LDT) entry
>   * This is a macro so it can be used in initialisers
> @@ -43,6 +48,51 @@ struct gdt_ptr {
>         u32 ptr;
>  } __packed;
>
> +struct cpu_device_id {
> +       unsigned vendor;
> +       unsigned device;
> +};
> +
> +struct cpuinfo_x86 {
> +        uint8_t    x86;            /* CPU family */
> +        uint8_t    x86_vendor;     /* CPU vendor */
> +        uint8_t    x86_model;
> +        uint8_t    x86_mask;
> +};
> +
> +/* List of cpu vendor strings along with their normalized

Can we put /* on its own line?

/*
 * List of CPU vendor strings ...
 * ...
 */

> + * id values.
> + */
> +static struct {
> +       int vendor;
> +       const char *name;
> +} x86_vendors[] = {
> +       { X86_VENDOR_INTEL,     "GenuineIntel", },
> +       { X86_VENDOR_CYRIX,     "CyrixInstead", },
> +       { X86_VENDOR_AMD,       "AuthenticAMD", },
> +       { X86_VENDOR_UMC,       "UMC UMC UMC ", },
> +       { X86_VENDOR_NEXGEN,    "NexGenDriven", },
> +       { X86_VENDOR_CENTAUR,   "CentaurHauls", },
> +       { X86_VENDOR_RISE,      "RiseRiseRise", },
> +       { X86_VENDOR_TRANSMETA, "GenuineTMx86", },
> +       { X86_VENDOR_TRANSMETA, "TransmetaCPU", },
> +       { X86_VENDOR_NSC,       "Geode by NSC", },
> +       { X86_VENDOR_SIS,       "SiS SiS SiS ", },
> +};
> +
> +static const char *x86_vendor_name[] = {
> +       [X86_VENDOR_INTEL]     = "Intel",
> +       [X86_VENDOR_CYRIX]     = "Cyrix",
> +       [X86_VENDOR_AMD]       = "AMD",
> +       [X86_VENDOR_UMC]       = "UMC",
> +       [X86_VENDOR_NEXGEN]    = "NexGen",
> +       [X86_VENDOR_CENTAUR]   = "Centaur",
> +       [X86_VENDOR_RISE]      = "Rise",
> +       [X86_VENDOR_TRANSMETA] = "Transmeta",
> +       [X86_VENDOR_NSC]       = "NSC",
> +       [X86_VENDOR_SIS]       = "SiS",
> +};
> +
>  static void load_ds(u32 segment)
>  {
>         asm volatile("movl %0, %%ds" : : "r" (segment * X86_GDT_ENTRY_SIZE));
> @@ -115,6 +165,131 @@ int __weak x86_cleanup_before_linux(void)
>         return 0;
>  }
>
> +/*
> + * Cyrix CPUs without cpuid or with cpuid not yet enabled can be detected
> + * by the fact that they preserve the flags across the division of 5/2.
> + * PII and PPro exhibit this behavior too, but they have cpuid available.
> + */
> +
> +/*
> + * Perform the Cyrix 5/2 test. A Cyrix won't change
> + * the flags, while other 486 chips will.
> + */
> +static inline int test_cyrix_52div(void)
> +{
> +       unsigned int test;
> +
> +       __asm__ __volatile__(
> +            "sahf\n\t"         /* clear flags (%eax = 0x0005) */
> +            "div %b2\n\t"      /* divide 5 by 2 */
> +            "lahf"             /* store flags into %ah */
> +            : "=a" (test)
> +            : "0" (5), "q" (2)
> +            : "cc");
> +
> +       /* AH is 0x02 on Cyrix after the divide.. */
> +       return (unsigned char) (test >> 8) == 0x02;
> +}
> +
> +/*
> + *     Detect a NexGen CPU running without BIOS hypercode new enough
> + *     to have CPUID. (Thanks to Herbert Oppmann)
> + */
> +
> +static int deep_magic_nexgen_probe(void)
> +{
> +       int ret;
> +
> +       __asm__ __volatile__ (
> +               "       movw    $0x5555, %%ax\n"
> +               "       xorw    %%dx,%%dx\n"
> +               "       movw    $2, %%cx\n"
> +               "       divw    %%cx\n"
> +               "       movl    $0, %%eax\n"
> +               "       jnz     1f\n"
> +               "       movl    $1, %%eax\n"
> +               "1:\n"
> +               : "=a" (ret) : : "cx", "dx" );
> +       return  ret;
> +}
> +
> +static bool has_cpuid(void)
> +{
> +       return flag_is_changeable_p(X86_EFLAGS_ID);
> +}
> +
> +static void identify_cpu(struct cpu_device_id *cpu)
> +{
> +       char vendor_name[16];
> +       int i;
> +
> +       vendor_name[0] = '\0'; /* Unset */
> +
> +       /* Find the id and vendor_name */
> +       if (!has_cpuid()) {
> +               /* Its a 486 if we can modify the AC flag */
> +               if (flag_is_changeable_p(X86_EFLAGS_AC)) {
> +                       cpu->device = 0x00000400; /* 486 */
> +               } else {
> +                       cpu->device = 0x00000300; /* 386 */
> +               }
> +               if ((cpu->device == 0x00000400) && test_cyrix_52div()) {
> +                       memcpy(vendor_name, "CyrixInstead", 13);
> +                       /* If we ever care we can enable cpuid here */
> +               }
> +               /* Detect NexGen with old hypercode */
> +               else if (deep_magic_nexgen_probe()) {
> +                       memcpy(vendor_name, "NexGenDriven", 13);
> +               }
> +       }
> +       if (has_cpuid()) {
> +               int  cpuid_level;
> +               struct cpuid_result result;

blank line between declaration &code

> +               result = cpuid(0x00000000);
> +               cpuid_level    = result.eax;
> +               vendor_name[ 0] = (result.ebx >>  0) & 0xff;
> +               vendor_name[ 1] = (result.ebx >>  8) & 0xff;
> +               vendor_name[ 2] = (result.ebx >> 16) & 0xff;
> +               vendor_name[ 3] = (result.ebx >> 24) & 0xff;
> +               vendor_name[ 4] = (result.edx >>  0) & 0xff;
> +               vendor_name[ 5] = (result.edx >>  8) & 0xff;
> +               vendor_name[ 6] = (result.edx >> 16) & 0xff;
> +               vendor_name[ 7] = (result.edx >> 24) & 0xff;
> +               vendor_name[ 8] = (result.ecx >>  0) & 0xff;
> +               vendor_name[ 9] = (result.ecx >>  8) & 0xff;
> +               vendor_name[10] = (result.ecx >> 16) & 0xff;
> +               vendor_name[11] = (result.ecx >> 24) & 0xff;

I think the byte loop approach is better (see cpu_get_name() in my
series). Can it be done? If you put this name bit in a separate
function it will be cleaner, too.


> +               vendor_name[12] = '\0';
> +
> +               /* Intel-defined flags: level 0x00000001 */
> +               if (cpuid_level >= 0x00000001) {
> +                       cpu->device = cpuid_eax(0x00000001);
> +               }
> +               else {
> +                       /* Have CPUID level 0 only unheard of */
> +                       cpu->device = 0x00000400;
> +               }
> +       }
> +       cpu->vendor = X86_VENDOR_UNKNOWN;
> +       for(i = 0; i < ARRAY_SIZE(x86_vendors); i++) {
> +               if (memcmp(vendor_name, x86_vendors[i].name, 12) == 0) {
> +                       cpu->vendor = x86_vendors[i].vendor;
> +                       break;
> +               }
> +       }
> +}
> +
> +static inline void get_fms(struct cpuinfo_x86 *c, uint32_t tfms)
> +{
> +       c->x86 = (tfms >> 8) & 0xf;
> +       c->x86_model = (tfms >> 4) & 0xf;
> +       c->x86_mask = tfms & 0xf;
> +       if (c->x86 == 0xf)
> +               c->x86 += (tfms >> 20) & 0xff;
> +       if (c->x86 >= 0x6)
> +               c->x86_model += ((tfms >> 16) & 0xF) << 4;
> +}
> +
>  int x86_cpu_init_f(void)
>  {
>         const u32 em_rst = ~X86_CR0_EM;
> @@ -128,6 +303,20 @@ int x86_cpu_init_f(void)
>              "movl %%eax, %%cr0\n" \
>              : : "i" (em_rst), "i" (mp_ne_set) : "eax");
>
> +       /* identify CPU via cpuid and store the decoded info into gd->arch */
> +       if (has_cpuid()) {

Why not move this into print_cpuinfo()? Then you can print debug
information if the CPU is not known. Or will it always be known? For
some reason for me it always says '<invalid cpu vendor>'

> +               struct cpu_device_id cpu;
> +               struct cpuinfo_x86 c;
> +
> +               identify_cpu(&cpu);
> +               get_fms(&c, cpu.device);
> +               gd->arch.x86 = c.x86;
> +               gd->arch.x86_vendor = cpu.vendor;
> +               gd->arch.x86_model = c.x86_model;
> +               gd->arch.x86_mask = c.x86_mask;
> +               gd->arch.x86_device = cpu.device;
> +       }
> +
>         return 0;
>  }
>  int cpu_init_f(void) __attribute__((weak, alias("x86_cpu_init_f")));
> @@ -279,55 +468,14 @@ void cpu_disable_paging_pae(void)
>                 : "eax");
>  }
>
> -static bool has_cpuid(void)
> -{
> -       unsigned long flag;
> -
> -       asm volatile("pushf\n" \
> -               "pop %%eax\n"
> -               "mov %%eax, %%ecx\n"    /* ecx = flags */
> -               "xor %1, %%eax\n"
> -               "push %%eax\n"
> -               "popf\n"                /* flags ^= $2 */
> -               "pushf\n"
> -               "pop %%eax\n"           /* eax = flags */
> -               "push %%ecx\n"
> -               "popf\n"                /* flags = ecx */
> -               "xor %%ecx, %%eax\n"
> -               "mov %%eax, %0"
> -               : "=r" (flag)
> -               : "i" (1 << 21)
> -               : "eax", "ecx", "memory");
> -
> -       return flag != 0;
> -}
> -
>  static bool can_detect_long_mode(void)
>  {
> -       unsigned long flag;
> -
> -       asm volatile("mov $0x80000000, %%eax\n"
> -               "cpuid\n"
> -               "mov %%eax, %0"
> -               : "=r" (flag)
> -               :
> -               : "eax", "ebx", "ecx", "edx", "memory");
> -
> -       return flag > 0x80000000UL;
> +       return cpuid_eax(0x80000000) > 0x80000000UL;
>  }
>
>  static bool has_long_mode(void)
>  {
> -       unsigned long flag;
> -
> -       asm volatile("mov $0x80000001, %%eax\n"
> -               "cpuid\n"
> -               "mov %%edx, %0"
> -               : "=r" (flag)
> -               :
> -               : "eax", "ebx", "ecx", "edx", "memory");
> -
> -       return flag & (1 << 29) ? true : false;
> +       return cpuid_edx(0x80000001) & (1 << 29) ? true : false;
>  }
>
>  int cpu_has_64bit(void)
> @@ -336,9 +484,55 @@ int cpu_has_64bit(void)
>                 has_long_mode();
>  }
>
> +static const char *cpu_vendor_name(int vendor)
> +{
> +       const char *name;
> +       name = "<invalid cpu vendor>";
> +       if ((vendor < (ARRAY_SIZE(x86_vendor_name))) &&
> +               (x86_vendor_name[vendor] != 0))
> +       {
> +               name = x86_vendor_name[vendor];
> +       }
> +       return name;
> +}
> +
> +static void fill_processor_name(char *processor_name)
> +{
> +       struct cpuid_result regs;
> +       char temp_processor_name[49];
> +       char *processor_name_start;
> +       unsigned int *name_as_ints = (unsigned int *)temp_processor_name;
> +       int i;
> +
> +       for (i = 0; i < 3; i++) {
> +               regs = cpuid(0x80000002 + i);
> +               name_as_ints[i * 4 + 0] = regs.eax;
> +               name_as_ints[i * 4 + 1] = regs.ebx;
> +               name_as_ints[i * 4 + 2] = regs.ecx;
> +               name_as_ints[i * 4 + 3] = regs.edx;
> +       }
> +
> +       temp_processor_name[48] = 0;
> +
> +       /* Skip leading spaces. */
> +       processor_name_start = temp_processor_name;
> +       while (*processor_name_start == ' ')
> +               processor_name_start++;
> +
> +       memset(processor_name, 0, 49);
> +       strcpy(processor_name, processor_name_start);
> +}
> +
>  int print_cpuinfo(void)
>  {
> -       printf("CPU:   %s\n", cpu_has_64bit() ? "x86_64" : "x86");
> +       char processor_name[49];
> +
> +       printf("CPU: %s, vendor %s, device %xh\n", cpu_has_64bit() ? "x86_64" : "x86",
> +               cpu_vendor_name(gd->arch.x86_vendor), gd->arch.x86_device);
> +       printf("CPU: family %02xh, model %02xh, stepping %02xh\n",
> +               gd->arch.x86, gd->arch.x86_model, gd->arch.x86_mask);
> +       fill_processor_name(processor_name);
> +       printf("CPU: %s\n", processor_name);
>
>         return 0;
>  }
> diff --git a/arch/x86/include/asm/cpu.h b/arch/x86/include/asm/cpu.h
> index 6c6774a..6cd9f5b 100644
> --- a/arch/x86/include/asm/cpu.h
> +++ b/arch/x86/include/asm/cpu.h
> @@ -1,12 +1,154 @@
>  /*
>   * Copyright (c) 2014 The Chromium OS Authors.
>   *
> + * Part of this file is adapted from coreboot
> + * src/arch/x86/include/arch/cpu.h and
> + * src/arch/x86/lib/cpu.c
> + *
>   * SPDX-License-Identifier:    GPL-2.0+
>   */
>
>  #ifndef __X86_CPU_H
>  #define __X86_CPU_H

_ASM_CPU_H

>
> +#define X86_VENDOR_INVALID    0
> +#define X86_VENDOR_INTEL      1
> +#define X86_VENDOR_CYRIX      2
> +#define X86_VENDOR_AMD        3
> +#define X86_VENDOR_UMC        4
> +#define X86_VENDOR_NEXGEN     5
> +#define X86_VENDOR_CENTAUR    6
> +#define X86_VENDOR_RISE       7
> +#define X86_VENDOR_TRANSMETA  8
> +#define X86_VENDOR_NSC        9
> +#define X86_VENDOR_SIS       10
> +#define X86_VENDOR_ANY     0xfe
> +#define X86_VENDOR_UNKNOWN 0xff

Can we use an enum for this?

> +
> +struct cpuid_result {
> +       uint32_t eax;
> +       uint32_t ebx;
> +       uint32_t ecx;
> +       uint32_t edx;
> +};
> +
> +/*
> + * Generic CPUID function
> + */
> +static inline struct cpuid_result cpuid(int op)
> +{
> +       struct cpuid_result result;
> +       asm volatile(
> +               "mov %%ebx, %%edi;"
> +               "cpuid;"
> +               "mov %%ebx, %%esi;"
> +               "mov %%edi, %%ebx;"
> +               : "=a" (result.eax),
> +                 "=S" (result.ebx),
> +                 "=c" (result.ecx),
> +                 "=d" (result.edx)
> +               : "0" (op)
> +               : "edi");
> +       return result;
> +}
> +
> +/*
> + * Generic Extended CPUID function
> + */
> +static inline struct cpuid_result cpuid_ext(int op, unsigned ecx)
> +{
> +       struct cpuid_result result;
> +       asm volatile(
> +               "mov %%ebx, %%edi;"
> +               "cpuid;"
> +               "mov %%ebx, %%esi;"
> +               "mov %%edi, %%ebx;"
> +               : "=a" (result.eax),
> +                 "=S" (result.ebx),
> +                 "=c" (result.ecx),
> +                 "=d" (result.edx)
> +               : "0" (op), "2" (ecx)
> +               : "edi");
> +       return result;
> +}
> +
> +/*
> + * CPUID functions returning a single datum
> + */
> +static inline unsigned int cpuid_eax(unsigned int op)
> +{
> +       unsigned int eax;
> +
> +       __asm__("mov %%ebx, %%edi;"
> +               "cpuid;"
> +               "mov %%edi, %%ebx;"
> +               : "=a" (eax)
> +               : "0" (op)
> +               : "ecx", "edx", "edi");
> +       return eax;
> +}
> +
> +static inline unsigned int cpuid_ebx(unsigned int op)
> +{
> +       unsigned int eax, ebx;
> +
> +       __asm__("mov %%ebx, %%edi;"
> +               "cpuid;"
> +               "mov %%ebx, %%esi;"
> +               "mov %%edi, %%ebx;"
> +               : "=a" (eax), "=S" (ebx)
> +               : "0" (op)
> +               : "ecx", "edx", "edi");
> +       return ebx;
> +}
> +
> +static inline unsigned int cpuid_ecx(unsigned int op)
> +{
> +       unsigned int eax, ecx;
> +
> +       __asm__("mov %%ebx, %%edi;"
> +               "cpuid;"
> +               "mov %%edi, %%ebx;"
> +               : "=a" (eax), "=c" (ecx)
> +               : "0" (op)
> +               : "edx", "edi");
> +       return ecx;
> +}
> +
> +static inline unsigned int cpuid_edx(unsigned int op)
> +{
> +       unsigned int eax, edx;
> +
> +       __asm__("mov %%ebx, %%edi;"
> +               "cpuid;"
> +               "mov %%edi, %%ebx;"
> +               : "=a" (eax), "=d" (edx)
> +               : "0" (op)
> +               : "ecx", "edi");
> +       return edx;
> +}
> +
> +/* Standard macro to see if a specific flag is changeable */
> +static inline int flag_is_changeable_p(uint32_t flag)
> +{
> +       uint32_t f1, f2;
> +
> +       asm(
> +               "pushfl\n\t"
> +               "pushfl\n\t"
> +               "popl %0\n\t"
> +               "movl %0,%1\n\t"
> +               "xorl %2,%0\n\t"
> +               "pushl %0\n\t"
> +               "popfl\n\t"
> +               "pushfl\n\t"
> +               "popl %0\n\t"
> +               "popfl\n\t"
> +               : "=&r" (f1), "=&r" (f2)
> +               : "ir" (flag));
> +       return ((f1^f2) & flag) != 0;
> +}

Does this have to be inline?

> +
>   /**
>   * cpu_enable_paging_pae() - Enable PAE-paging
>   *
> diff --git a/arch/x86/include/asm/global_data.h b/arch/x86/include/asm/global_data.h
> index 3e8e2cd..721e7dc 100644
> --- a/arch/x86/include/asm/global_data.h
> +++ b/arch/x86/include/asm/global_data.h
> @@ -13,6 +13,11 @@
>  /* Architecture-specific global data */
>  struct arch_global_data {
>         struct global_data *gd_addr;            /* Location of Global Data */
> +       uint8_t  x86;                   /* CPU family */
> +       uint8_t  x86_vendor;            /* CPU vendor */
> +       uint8_t  x86_model;
> +       uint8_t  x86_mask;
> +       uint32_t x86_device;
>         uint64_t tsc_base;              /* Initial value returned by rdtsc() */
>         uint32_t tsc_base_kclocks;      /* Initial tsc as a kclocks value */
>         uint32_t tsc_prev;              /* For show_boot_progress() */
> --
> 1.8.2.1
>

Regards,
Simon


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