Re: [Xen-devel] [PATCH] x86/DMI: use proper structures in favor of byte offsets

[Chris Dalton <cid@xxxxxx>]

Hi Jan,

Not a comment on the patch changes directly but on the code covered by 
the patch: in my experience on some EFI bioses you can't assume that the 
SMBIOS tables are in a region beginning 0xF0000. The location needs to 
be retrieved from the EFI system table, but I guess you have this in hand.
Chris

On 21/06/11 09:01, Jan Beulich wrote:
> Besides being (in my eyes) desirable cleanup, this at once represents
> another prerequisite for native EFI booting support.
>
> Signed-off-by: Jan Beulich<jbeulich@xxxxxxxxxx>
>
> --- a/xen/arch/x86/dmi_scan.c
> +++ b/xen/arch/x86/dmi_scan.c
> @@ -10,11 +10,31 @@
>   #include<asm/system.h>
>   #include<xen/dmi.h>
>
> -#define bt_ioremap(b,l)  ((u8 *)__acpi_map_table(b,l))
> +#define bt_ioremap(b,l)  ((void *)__acpi_map_table(b,l))
>   #define bt_iounmap(b,l)  ((void)0)
>   #define memcpy_fromio    memcpy
>   #define alloc_bootmem(l) xmalloc_bytes(l)
>
> +struct dmi_eps {
> +       char anchor[5];                 /* "_DMI_" */
> +       u8 checksum;
> +       u16 size;
> +       u32 address;
> +       u16 num_structures;
> +       u8 revision;
> +} __attribute__((packed));
> +
> +struct smbios_eps {
> +       char anchor[4];                 /* "_SM_" */
> +       u8 checksum;
> +       u8 length;
> +       u8 major, minor;
> +       u16 max_size;
> +       u8 revision;
> +       u8 _rsrvd_[5];
> +       struct dmi_eps dmi;
> +} __attribute__((packed));
> +
>   struct dmi_header
>   {
>         u8      type;
> @@ -90,62 +110,70 @@ static int __init dmi_table(u32 base, in
>   }
>
>
> -inline static int __init dmi_checksum(u8 *buf)
> +static inline bool_t __init dmi_checksum(const void __iomem *buf,
> +                                        unsigned int len)
>   {
> -       u8 sum=0;
> -       int a;
> +       u8 sum = 0;
> +       const u8 *p = buf;
> +       unsigned int a;
>         
> -       for(a=0; a<15; a++)
> -               sum+=buf[a];
> -       return (sum==0);
> +       for (a = 0; a<  len; a++)
> +               sum += p[a];
> +       return sum == 0;
>   }
>
>   int __init dmi_get_table(u32 *base, u32 *len)
>   {
> -       u8 buf[15];
> +       struct dmi_eps eps;
>         char __iomem *p, *q;
>
>         p = maddr_to_virt(0xF0000);
>         for (q = p; q<  p + 0x10000; q += 16) {
> -               memcpy_fromio(buf, q, 15);
> -               if (memcmp(buf, "_DMI_", 5)==0&&  dmi_checksum(buf)) {
> -                       *base=buf[11]<<24|buf[10]<<16|buf[9]<<8|buf[8];
> -                       *len=buf[7]<<8|buf[6];
> +               memcpy_fromio(&eps, q, 15);
> +               if (memcmp(eps.anchor, "_DMI_", 5) == 0&&
> +                   dmi_checksum(&eps, sizeof(eps))) {
> +                       *base = eps.address;
> +                       *len = eps.size;
>                         return 0;
>                 }
>         }
>         return -1;
>   }
>
> +static int __init _dmi_iterate(const struct dmi_eps *dmi,
> +                              const struct smbios_eps __iomem *smbios,
> +                              void (*decode)(struct dmi_header *))
> +{
> +       u16 num = dmi->num_structures;
> +       u16 len = dmi->size;
> +       u32 base = dmi->address;
> +
> +       /*
> +        * DMI version 0.0 means that the real version is taken from
> +        * the SMBIOS version, which we may not know at this point.
> +        */
> +       if (dmi->revision)
> +               printk(KERN_INFO "DMI %d.%d present.\n",
> +                      dmi->revision>>  4,  dmi->revision&  0x0f);
> +       else if (!smbios)
> +               printk(KERN_INFO "DMI present.\n");
> +       dmi_printk((KERN_INFO "%d structures occupying %d bytes.\n",
> +                   num, len));
> +       dmi_printk((KERN_INFO "DMI table at 0x%08X.\n", base));
> +       return dmi_table(base, len, num, decode);
> +}
> +
>   static int __init dmi_iterate(void (*decode)(struct dmi_header *))
>   {
> -       u8 buf[15];
> +       struct dmi_eps eps;
>         char __iomem *p, *q;
>
>         p = maddr_to_virt(0xF0000);
>         for (q = p; q<  p + 0x10000; q += 16) {
> -               memcpy_fromio(buf, q, 15);
> -               if (memcmp(buf, "_DMI_", 5)==0&&  dmi_checksum(buf)) {
> -                       u16 num=buf[13]<<8|buf[12];
> -                       u16 len=buf[7]<<8|buf[6];
> -                       u32 base=buf[11]<<24|buf[10]<<16|buf[9]<<8|buf[8];
> -
> -                       /*
> -                        * DMI version 0.0 means that the real version is taken 
> from
> -                        * the SMBIOS version, which we don't know at this 
> point.
> -                        */
> -                       if(buf[14]!=0)
> -                               printk(KERN_INFO "DMI %d.%d present.\n",
> -                                       buf[14]>>4, buf[14]&0x0F);
> -                       else
> -                               printk(KERN_INFO "DMI present.\n");
> -                       dmi_printk((KERN_INFO "%d structures occupying %d 
> bytes.\n",
> -                               num, len));
> -                       dmi_printk((KERN_INFO "DMI table at 0x%08X.\n",
> -                               base));
> -                       if(dmi_table(base,len, num, decode)==0)
> -                               return 0;
> -               }
> +               memcpy_fromio(&eps, q, sizeof(eps));
> +               if (memcmp(eps.anchor, "_DMI_", 5) == 0&&
> +                   dmi_checksum(&eps, sizeof(eps)))
> +                       return _dmi_iterate(&eps, NULL, decode);
>         }
>         return -1;
>   }
>
>
>
>
>
>
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