From: Varad Gautam <varad.gautam@xxxxxxxx> Move the code for transitioning from unpaged 32-bit mode to paged 64-bit mode to trampoline.S, it can be shared across EFI and non-EFI builds. Leave 5-level paging behind for the time being, EFI doesn't yet support support disabling paging, which is required to get from 4-level to 5-level paging. Signed-off-by: Varad Gautam <varad.gautam@xxxxxxxx> [sean: move to trampolines.S instead of start32.S, reword changelog] Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx> --- x86/cstart64.S | 60 --------------------------------------- x86/trampolines.S | 71 +++++++++++++++++++++++++++++++++++++++++++++-- 2 files changed, 69 insertions(+), 62 deletions(-) diff --git a/x86/cstart64.S b/x86/cstart64.S index 8ac6e9c..0a561ce 100644 --- a/x86/cstart64.S +++ b/x86/cstart64.S @@ -56,36 +56,12 @@ mb_flags = 0x0 .long mb_magic, mb_flags, 0 - (mb_magic + mb_flags) mb_cmdline = 16 -MSR_GS_BASE = 0xc0000101 - -.macro setup_percpu_area - lea -4096(%esp), %eax - mov $0, %edx - mov $MSR_GS_BASE, %ecx - wrmsr -.endm - .macro load_tss movq %rsp, %rdi call setup_tss ltr %ax .endm -.macro setup_segments - mov $MSR_GS_BASE, %ecx - rdmsr - - mov $0x10, %bx - mov %bx, %ds - mov %bx, %es - mov %bx, %fs - mov %bx, %gs - mov %bx, %ss - - /* restore MSR_GS_BASE */ - wrmsr -.endm - .globl start start: mov %ebx, mb_boot_info @@ -118,33 +94,6 @@ switch_to_5level: call enter_long_mode jmpl $8, $lvl5 -prepare_64: - lgdt gdt_descr - setup_segments - - xor %eax, %eax - mov %eax, %cr4 - -enter_long_mode: - mov %cr4, %eax - bts $5, %eax // pae - mov %eax, %cr4 - - mov pt_root, %eax - mov %eax, %cr3 - -efer = 0xc0000080 - mov $efer, %ecx - rdmsr - bts $8, %eax - wrmsr - - mov %cr0, %eax - bts $0, %eax - bts $31, %eax - mov %eax, %cr0 - ret - smp_stacktop: .long stacktop - 4096 .align 16 @@ -155,15 +104,6 @@ gdt32: .quad 0x00cf93000000ffff // flat 32-bit data segment gdt32_end: -.code32 -ap_start32: - setup_segments - mov $-4096, %esp - lock xaddl %esp, smp_stacktop - setup_percpu_area - call prepare_64 - ljmpl $8, $ap_start64 - .code64 save_id: movl $(APIC_DEFAULT_PHYS_BASE + APIC_ID), %eax diff --git a/x86/trampolines.S b/x86/trampolines.S index 9640c66..deb5057 100644 --- a/x86/trampolines.S +++ b/x86/trampolines.S @@ -1,6 +1,9 @@ -/* Common bootstrapping code to transition from 16-bit to 32-bit code. */ +/* + * Common bootstrapping code to transition from 16-bit to 32-bit code, and to + * transition from 32-bit to 64-bit code (x86-64 only) + */ -/* EFI provides it's own SIPI sequence to handle relocation. */ + /* EFI provides it's own SIPI sequence to handle relocation. */ #ifndef CONFIG_EFI .code16 .globl rm_trampoline @@ -28,3 +31,67 @@ ap_rm_gdt_descr: .globl rm_trampoline_end rm_trampoline_end: #endif + +/* The 32-bit => 64-bit trampoline is x86-64 only. */ +#ifdef __x86_64__ +.code32 + +MSR_GS_BASE = 0xc0000101 + +.macro setup_percpu_area + lea -4096(%esp), %eax + mov $0, %edx + mov $MSR_GS_BASE, %ecx + wrmsr +.endm + +.macro setup_segments + mov $MSR_GS_BASE, %ecx + rdmsr + + mov $0x10, %bx + mov %bx, %ds + mov %bx, %es + mov %bx, %fs + mov %bx, %gs + mov %bx, %ss + + /* restore MSR_GS_BASE */ + wrmsr +.endm + +prepare_64: + lgdt gdt_descr + setup_segments + + xor %eax, %eax + mov %eax, %cr4 + +enter_long_mode: + mov %cr4, %eax + bts $5, %eax // pae + mov %eax, %cr4 + + mov pt_root, %eax + mov %eax, %cr3 + +efer = 0xc0000080 + mov $efer, %ecx + rdmsr + bts $8, %eax + wrmsr + + mov %cr0, %eax + bts $0, %eax + bts $31, %eax + mov %eax, %cr0 + ret + +ap_start32: + setup_segments + mov $-4096, %esp + lock xaddl %esp, smp_stacktop + setup_percpu_area + call prepare_64 + ljmpl $8, $ap_start64 +#endif -- 2.36.1.476.g0c4daa206d-goog
