* Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> 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.shutemov@xxxxxxxxxxxxxxx> > --- > 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
