diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index fc313e29fe2c..d598d65db32c 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -304,20 +304,6 @@ ENTRY(startup_64) /* Set up the stack */ leaq boot_stack_end(%rbx), %rsp -#ifdef CONFIG_X86_5LEVEL - /* - * Check if we need to enable 5-level paging. - * RSI holds real mode data and need to be preserved across - * a function call. - */ - pushq %rsi - call l5_paging_required - popq %rsi - - /* If l5_paging_required() returned zero, we're done here. */ - cmpq $0, %rax - je lvl5 - /* * At this point we are in long mode with 4-level paging enabled, * but we want to enable 5-level paging. @@ -325,13 +311,29 @@ ENTRY(startup_64) * The problem is that we cannot do it directly. Setting LA57 in * long mode would trigger #GP. So we need to switch off long mode * first. - * - * NOTE: This is not going to work if bootloader put us above 4G - * limit. - * - * The first step is go into compatibility mode. */ + /* + * paging_prepare() sets up the trampoline and checks if we need to + * enable 5-level paging. + * + * Address of the trampoline is returned in RAX. + * Non zero RDX on return means we need to enable 5-level paging. + * + * RSI holds real mode data and needs to be preserved across + * this function call. + */ + pushq %rsi + call paging_prepare + popq %rsi + + /* 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 @@ -352,7 +354,6 @@ ENTRY(startup_64) pushq %rax lretq lvl5: -#endif /* Zero EFLAGS */ pushq $0 @@ -490,7 +491,6 @@ relocated: jmp *%rax .code32 -#ifdef CONFIG_X86_5LEVEL compatible_mode: /* Setup data and stack segments */ movl $__KERNEL_DS, %eax @@ -526,7 +526,6 @@ compatible_mode: movl %eax, %cr0 lret -#endif no_longmode: /* This isn't an x86-64 CPU so hang */ @@ -585,7 +584,5 @@ boot_stack_end: .balign 4096 pgtable: .fill BOOT_PGT_SIZE, 1, 0 -#ifdef CONFIG_X86_5LEVEL lvl5_pgtable: .fill PAGE_SIZE, 1, 0 -#endif diff --git a/arch/x86/boot/compressed/pgtable_64.c b/arch/x86/boot/compressed/pgtable_64.c index b4469a37e9a1..3f1697fcc7a8 100644 --- a/arch/x86/boot/compressed/pgtable_64.c +++ b/arch/x86/boot/compressed/pgtable_64.c @@ -9,20 +9,19 @@ */ unsigned long __force_order; -int l5_paging_required(void) +struct paging_config { + unsigned long trampoline_start; + unsigned long l5_required; +}; + +struct paging_config paging_prepare(void) { - /* Check if leaf 7 is supported. */ + struct paging_config paging_config = {}; - if (native_cpuid_eax(0) < 7) - return 0; + /* Check if LA57 is desired and supported */ + if (IS_ENABLED(CONFIG_X86_5LEVEL) && native_cpuid_eax(0) >= 7 && + (native_cpuid_ecx(7) & (1 << (X86_FEATURE_LA57 & 31)))) + paging_config.l5_required = 1; - /* Check if la57 is supported. */ - if (!(native_cpuid_ecx(7) & (1 << (X86_FEATURE_LA57 & 31)))) - return 0; - - /* Check if 5-level paging has already been enabled. */ - if (native_read_cr4() & X86_CR4_LA57) - return 0; - - return 1; + return paging_config; }