This patch prepare decompression code to boot-time switching between 4- and 5-level paging. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> --- arch/x86/boot/compressed/head_64.S | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index 3ed26769810b..89d886c95afc 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -109,6 +109,31 @@ ENTRY(startup_32) movl $LOAD_PHYSICAL_ADDR, %ebx 1: +#ifdef CONFIG_X86_5LEVEL + pushl %ebx + + /* Check if leaf 7 is supported*/ + movl $0, %eax + cpuid + cmpl $7, %eax + jb 1f + + /* + * Check if la57 is supported. + * The feature is enumerated with CPUID.(EAX=07H, ECX=0):ECX[bit 16] + */ + movl $7, %eax + movl $0, %ecx + cpuid + andl $(1 << 16), %ecx + jz 1f + + /* p4d page table is not folded if la57 is present */ + movl $0, p4d_folded(%ebp) +1: + popl %ebx +#endif + /* Target address to relocate to for decompression */ movl BP_init_size(%esi), %eax subl $_end, %eax @@ -125,9 +150,14 @@ ENTRY(startup_32) /* Enable PAE and LA57 mode */ movl %cr4, %eax orl $X86_CR4_PAE, %eax + #ifdef CONFIG_X86_5LEVEL + testl $1, p4d_folded(%ebp) + jnz 1f orl $X86_CR4_LA57, %eax +1: #endif + movl %eax, %cr4 /* @@ -147,11 +177,15 @@ ENTRY(startup_32) movl %eax, 0(%edi) #ifdef CONFIG_X86_5LEVEL + testl $1, p4d_folded(%ebp) + jnz 1f + /* Build Level 4 */ addl $0x1000, %edx leal pgtable(%ebx,%edx), %edi leal 0x1007 (%edi), %eax movl %eax, 0(%edi) +1: #endif /* Build Level 3 */ @@ -464,6 +498,9 @@ gdt: .quad 0x0000000000000000 /* TS continued */ gdt_end: +p4d_folded: + .word 1 + #ifdef CONFIG_EFI_STUB efi_config: .quad 0 -- 2.11.0 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
