diff options
Diffstat (limited to 'arch/x86/boot')
| -rw-r--r-- | arch/x86/boot/compressed/head_64.S | 47 |
1 files changed, 23 insertions, 24 deletions
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index 12915511be61..959ca07a58d9 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -336,23 +336,6 @@ ENTRY(startup_64) /* Save the trampoline address in RCX */ movq %rax, %rcx - /* Check if we need to enable 5-level paging */ - cmpq $0, %rdx - jz lvl5 - - /* Clear additional page table */ - leaq lvl5_pgtable(%rbx), %rdi - xorq %rax, %rax - movq $(PAGE_SIZE/8), %rcx - rep stosq - - /* - * Setup current CR3 as the first and only entry in a new top level - * page table. - */ - movq %cr3, %rdi - leaq 0x7 (%rdi), %rax - movq %rax, lvl5_pgtable(%rbx) /* Switch to compatibility mode (CS.L = 0 CS.D = 1) via far return */ pushq $__KERNEL32_CS @@ -524,13 +507,31 @@ compatible_mode: btrl $X86_CR0_PG_BIT, %eax movl %eax, %cr0 - /* Point CR3 to 5-level paging */ - leal lvl5_pgtable(%ebx), %eax - movl %eax, %cr3 + /* Check what paging mode we want to be in after the trampoline */ + cmpl $0, %edx + jz 1f - /* Enable PAE and LA57 mode */ + /* We want 5-level paging: don't touch CR3 if it already points to 5-level page tables */ movl %cr4, %eax - orl $(X86_CR4_PAE | X86_CR4_LA57), %eax + testl $X86_CR4_LA57, %eax + jnz 3f + jmp 2f +1: + /* We want 4-level paging: don't touch CR3 if it already points to 4-level page tables */ + movl %cr4, %eax + testl $X86_CR4_LA57, %eax + jz 3f +2: + /* Point CR3 to the trampoline's new top level page table */ + leal TRAMPOLINE_32BIT_PGTABLE_OFFSET(%ecx), %eax + movl %eax, %cr3 +3: + /* Enable PAE and LA57 (if required) paging modes */ + movl $X86_CR4_PAE, %eax + cmpl $0, %edx + jz 1f + orl $X86_CR4_LA57, %eax +1: movl %eax, %cr4 /* Calculate address we are running at */ @@ -611,5 +612,3 @@ boot_stack_end: .balign 4096 pgtable: .fill BOOT_PGT_SIZE, 1, 0 -lvl5_pgtable: - .fill PAGE_SIZE, 1, 0 |