Re: [PATCH][EFI] Run EFI in physical mode

[huang ying]

On Sat, Aug 14, 2010 at 3:18 AM, Takao Indoh <indou.takao@xxxxxxxxxxxxxx> wrote:
> diff -Nurp linux-2.6.35.org/arch/x86/kernel/efi_64.c linux-2.6.35/arch/x86/kernel/efi_64.c
> --- linux-2.6.35.org/arch/x86/kernel/efi_64.c  2010-08-01 18:11:14.000000000 -0400
> +++ linux-2.6.35/arch/x86/kernel/efi_64.c    2010-08-13 14:39:25.819105004 -0400
> @@ -39,7 +39,9 @@
> Â#include <asm/fixmap.h>
>
> Âstatic pgd_t save_pgd __initdata;
> -static unsigned long efi_flags __initdata;
> +static unsigned long efi_flags;
> +static pgd_t efi_pgd[PTRS_PER_PGD] __page_aligned_bss;
> +static unsigned long save_cr3;
>
> Âstatic void __init early_mapping_set_exec(unsigned long start,
> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Âunsigned long end,
> @@ -98,6 +100,19 @@ void __init efi_call_phys_epilog(void)
> Â Â Â Âearly_runtime_code_mapping_set_exec(0);
> Â}
>
> +void efi_call_phys_prelog_in_physmode(void)
> +{
> + Â Â Â local_irq_save(efi_flags);
> + Â Â Â save_cr3 = read_cr3();
> + Â Â Â write_cr3(virt_to_phys(efi_pgd));
> +}
> +
> +void efi_call_phys_epilog_in_physmode(void)
> +{
> + Â Â Â write_cr3(save_cr3);
> + Â Â Â local_irq_restore(efi_flags);
> +}

efi_flags and save_cr3 should be per-CPU, because they now will be
used after SMP is enabled.

efi_pgd should be dynamically allocated instead of statically
allocated, because EFI may be not enabled on some platform.

And I think it is better to unify early physical mode with run-time
physical mode. Just allocate the page table with early page allocator
(lmb?).

Best Regards,
Huang Ying
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