diff options
Diffstat (limited to 'arch/x86/kernel/head_64.S')
| -rw-r--r-- | arch/x86/kernel/head_64.S | 45 |
1 files changed, 25 insertions, 20 deletions
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index 7eb2a1c87969..04bddaaba8e2 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -26,15 +26,6 @@ #include <asm/nospec-branch.h> #include <asm/fixmap.h> -#ifdef CONFIG_PARAVIRT_XXL -#include <asm/asm-offsets.h> -#include <asm/paravirt.h> -#define GET_CR2_INTO(reg) GET_CR2_INTO_AX ; _ASM_MOV %_ASM_AX, reg -#else -#define INTERRUPT_RETURN iretq -#define GET_CR2_INTO(reg) _ASM_MOV %cr2, reg -#endif - /* * We are not able to switch in one step to the final KERNEL ADDRESS SPACE * because we need identity-mapped pages. @@ -161,6 +152,21 @@ SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL) /* Setup early boot stage 4-/5-level pagetables. */ addq phys_base(%rip), %rax + + /* + * For SEV guests: Verify that the C-bit is correct. A malicious + * hypervisor could lie about the C-bit position to perform a ROP + * attack on the guest by writing to the unencrypted stack and wait for + * the next RET instruction. + * %rsi carries pointer to realmode data and is callee-clobbered. Save + * and restore it. + */ + pushq %rsi + movq %rax, %rdi + call sev_verify_cbit + popq %rsi + + /* Switch to new page-table */ movq %rax, %cr3 /* Ensure I am executing from virtual addresses */ @@ -279,6 +285,7 @@ SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL) SYM_CODE_END(secondary_startup_64) #include "verify_cpu.S" +#include "sev_verify_cbit.S" #ifdef CONFIG_HOTPLUG_CPU /* @@ -524,21 +531,19 @@ SYM_DATA_END(level3_kernel_pgt) SYM_DATA_START_PAGE_ALIGNED(level2_kernel_pgt) /* - * 512 MB kernel mapping. We spend a full page on this pagetable - * anyway. + * Kernel high mapping. * - * The kernel code+data+bss must not be bigger than that. + * The kernel code+data+bss must be located below KERNEL_IMAGE_SIZE in + * virtual address space, which is 1 GiB if RANDOMIZE_BASE is enabled, + * 512 MiB otherwise. * - * (NOTE: at +512MB starts the module area, see MODULES_VADDR. - * If you want to increase this then increase MODULES_VADDR - * too.) + * (NOTE: after that starts the module area, see MODULES_VADDR.) * - * This table is eventually used by the kernel during normal - * runtime. Care must be taken to clear out undesired bits - * later, like _PAGE_RW or _PAGE_GLOBAL in some cases. + * This table is eventually used by the kernel during normal runtime. + * Care must be taken to clear out undesired bits later, like _PAGE_RW + * or _PAGE_GLOBAL in some cases. */ - PMDS(0, __PAGE_KERNEL_LARGE_EXEC, - KERNEL_IMAGE_SIZE/PMD_SIZE) + PMDS(0, __PAGE_KERNEL_LARGE_EXEC, KERNEL_IMAGE_SIZE/PMD_SIZE) SYM_DATA_END(level2_kernel_pgt) SYM_DATA_START_PAGE_ALIGNED(level2_fixmap_pgt) |