diff options
Diffstat (limited to 'arch/x86/realmode/rm/trampoline_64.S')
| -rw-r--r-- | arch/x86/realmode/rm/trampoline_64.S | 58 |
1 files changed, 53 insertions, 5 deletions
diff --git a/arch/x86/realmode/rm/trampoline_64.S b/arch/x86/realmode/rm/trampoline_64.S index e38d61d6562e..14d9c7daf90f 100644 --- a/arch/x86/realmode/rm/trampoline_64.S +++ b/arch/x86/realmode/rm/trampoline_64.S @@ -37,6 +37,26 @@ .text .code16 +.macro LOCK_AND_LOAD_REALMODE_ESP lock_pa=0 lock_rip=0 + /* + * Make sure only one CPU fiddles with the realmode stack + */ +.Llock_rm\@: + .if \lock_pa + lock btsl $0, pa_tr_lock + .elseif \lock_rip + lock btsl $0, tr_lock(%rip) + .else + lock btsl $0, tr_lock + .endif + jnc 2f + pause + jmp .Llock_rm\@ +2: + # Setup stack + movl $rm_stack_end, %esp +.endm + .balign PAGE_SIZE SYM_CODE_START(trampoline_start) cli # We should be safe anyway @@ -49,8 +69,7 @@ SYM_CODE_START(trampoline_start) mov %ax, %es mov %ax, %ss - # Setup stack - movl $rm_stack_end, %esp + LOCK_AND_LOAD_REALMODE_ESP call verify_cpu # Verify the cpu supports long mode testl %eax, %eax # Check for return code @@ -93,8 +112,7 @@ SYM_CODE_START(sev_es_trampoline_start) mov %ax, %es mov %ax, %ss - # Setup stack - movl $rm_stack_end, %esp + LOCK_AND_LOAD_REALMODE_ESP jmp .Lswitch_to_protected SYM_CODE_END(sev_es_trampoline_start) @@ -177,7 +195,7 @@ SYM_CODE_START(pa_trampoline_compat) * In compatibility mode. Prep ESP and DX for startup_32, then disable * paging and complete the switch to legacy 32-bit mode. */ - movl $rm_stack_end, %esp + LOCK_AND_LOAD_REALMODE_ESP lock_pa=1 movw $__KERNEL_DS, %dx movl $(CR0_STATE & ~X86_CR0_PG), %eax @@ -204,6 +222,35 @@ SYM_CODE_START(trampoline_start64) lidt tr_idt(%rip) lgdt tr_gdt64(%rip) + /* Check if paging mode has to be changed */ + movq %cr4, %rax + xorl tr_cr4(%rip), %eax + testl $X86_CR4_LA57, %eax + jnz .L_switch_paging + + /* Paging mode is correct proceed in 64-bit mode */ + + LOCK_AND_LOAD_REALMODE_ESP lock_rip=1 + + movw $__KERNEL_DS, %dx + movl %edx, %ss + addl $pa_real_mode_base, %esp + movl %edx, %ds + movl %edx, %es + movl %edx, %fs + movl %edx, %gs + + movl $pa_trampoline_pgd, %eax + movq %rax, %cr3 + + pushq $__KERNEL_CS + pushq tr_start(%rip) + lretq +.L_switch_paging: + /* + * To switch between 4- and 5-level paging modes, it is necessary + * to disable paging. This must be done in the compatibility mode. + */ ljmpl *tr_compat(%rip) SYM_CODE_END(trampoline_start64) @@ -241,6 +288,7 @@ SYM_DATA_START(trampoline_header) SYM_DATA(tr_efer, .space 8) SYM_DATA(tr_cr4, .space 4) SYM_DATA(tr_flags, .space 4) + SYM_DATA(tr_lock, .space 4) SYM_DATA_END(trampoline_header) #include "trampoline_common.S" |