* Kirill A. Shutemov <kirill.shute...@linux.intel.com> wrote:
> This patch adds support for 5-level paging during early boot.
> It generalizes boot for 4- and 5-level paging on 64-bit systems with
> compile-time switch between them.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shute...@linux.intel.com>
> ---
> arch/x86/boot/compressed/head_64.S | 23 ++++++++++++---
> arch/x86/include/asm/pgtable_64.h | 2 ++
> arch/x86/include/uapi/asm/processor-flags.h | 2 ++
> arch/x86/kernel/head64.c | 44
> +++++++++++++++++++++++++----
> arch/x86/kernel/head_64.S | 29 +++++++++++++++----
> 5 files changed, 85 insertions(+), 15 deletions(-)
>
> diff --git a/arch/x86/boot/compressed/head_64.S
> b/arch/x86/boot/compressed/head_64.S
> index d2ae1f821e0c..3ed26769810b 100644
> --- a/arch/x86/boot/compressed/head_64.S
> +++ b/arch/x86/boot/compressed/head_64.S
> @@ -122,9 +122,12 @@ ENTRY(startup_32)
> addl %ebp, gdt+2(%ebp)
> lgdt gdt(%ebp)
>
> - /* Enable PAE mode */
> + /* Enable PAE and LA57 mode */
> movl %cr4, %eax
> orl $X86_CR4_PAE, %eax
> +#ifdef CONFIG_X86_5LEVEL
> + orl $X86_CR4_LA57, %eax
> +#endif
> movl %eax, %cr4
>
> /*
> @@ -136,13 +139,24 @@ ENTRY(startup_32)
> movl $(BOOT_INIT_PGT_SIZE/4), %ecx
> rep stosl
>
> + xorl %edx, %edx
> +
> + /* Build Top Level */
> + leal pgtable(%ebx,%edx,1), %edi
> + leal 0x1007 (%edi), %eax
> + movl %eax, 0(%edi)
> +
> +#ifdef CONFIG_X86_5LEVEL
> /* Build Level 4 */
> - leal pgtable + 0(%ebx), %edi
> + addl $0x1000, %edx
> + leal pgtable(%ebx,%edx), %edi
> leal 0x1007 (%edi), %eax
> movl %eax, 0(%edi)
> +#endif
>
> /* Build Level 3 */
> - leal pgtable + 0x1000(%ebx), %edi
> + addl $0x1000, %edx
> + leal pgtable(%ebx,%edx), %edi
> leal 0x1007(%edi), %eax
> movl $4, %ecx
> 1: movl %eax, 0x00(%edi)
> @@ -152,7 +166,8 @@ ENTRY(startup_32)
> jnz 1b
>
> /* Build Level 2 */
> - leal pgtable + 0x2000(%ebx), %edi
> + addl $0x1000, %edx
> + leal pgtable(%ebx,%edx), %edi
> movl $0x00000183, %eax
> movl $2048, %ecx
> 1: movl %eax, 0(%edi)
I realize that you had difficulties converting this to C, but it's not going to
get any easier in the future either, with one more paging mode/level added!
If you are stuck on where it breaks I'd suggest doing it gradually: first add a
trivial .c, build and link it in and call it separately. Then once that works,
move functionality from asm to C step by step and test it at every step.
I've applied the first two patches of this series, but we really should convert
this assembly bit to C too.
Thanks,
Ingo
