x86/kernel/head_64.S

1 /* SPDX-License-Identifier: GPL-2.0 */
3  *  linux/arch/x86/kernel/head_64.S -- start in 32bit and switch to 64bit
21 #include <asm/processor-flags.h>
25 #include <asm/nospec-branch.h>
33  * because we need identity-mapped pages.
51 	 * arch/x86/boot/compressed/head_64.S.
53 	 * We only come here initially at boot nothing else comes here.
61 	/* Set up the stack for verify_cpu() */
65 	 * Set up GSBASE.
66 	 * Note that on SMP the boot CPU uses the init data section until
67 	 * the per-CPU areas are set up.
89 	 * be done now, since this also includes setup of the SEV-SNP CPUID table,
101 	 * Derive the kernel's physical-to-virtual offset from the physical and
124 	 * For SEV guests: Verify that the C-bit is correct. A malicious
125 	 * hypervisor could lie about the C-bit position to perform a ROP
159 	 * after the boot processor executes this code.
167 	 * SEV-ES guests. In those guests the call to verify_cpu() would cause
171 	 * All non SEV-ES systems, especially Intel systems, need to execute
178 	/* Clear %R15 which holds the boot_params pointer on the boot CPU */
183 	addq	$(init_top_pgt - __START_KERNEL_map), %rax
230 	 * Set CR4.PGE to re-enable global translations.
237 	 * For parallel boot, the APIC ID is read from the APIC, and then
238 	 * used to look up the CPU number.  For booting a single CPU, the
242 	 * Bit 0-23	CPU# if STARTUP_xx flags are not set
249 	 * in bit 0-23. This is also the boot CPU case (CPU number 0).
277 	/* Read the APIC ID from the fix-mapped MMIO space. */
316 	xorl	%edx, %edx /* zero-extended to clear all of RDX */
320 	 * Setup a boot time stack - Any secondary CPU will have lost its stack
321 	 * by now because the cr3-switch above unmaps the real-mode stack.
323 	 * RDX contains the per-cpu offset
330 	 * protection. For the boot CPU the pointer is NULL!
345 	movw	$(GDT_SIZE-1), (%rsp)
351 	/* set up data segments */
366 	 * Set up GSBASE.
367 	 * Note that, on SMP, the boot cpu uses init data section until
368 	 * the per cpu areas are set up.
428  * restarting the boot CPU or for restarting SEV guest CPUs after CPU hot
429  * unplug. Everything is set up already except the stack.
445  * VC Exception handler used during early boot when running on kernel
449  * Therefore this handler ends up in the .text section so that it stays around
503 	.fill early_idt_handler_array + i*EARLY_IDT_HANDLER_SIZE - ., 1, 0xcc
518 	/* The vector number is currently in the pt_regs->di slot. */
519 	pushq %rsi				/* pt_regs->si */
521 	movq %rdi, 8(%rsp)			/* pt_regs->di = RDI */
522 	pushq %rdx				/* pt_regs->dx */
523 	pushq %rcx				/* pt_regs->cx */
524 	pushq %rax				/* pt_regs->ax */
525 	pushq %r8				/* pt_regs->r8 */
526 	pushq %r9				/* pt_regs->r9 */
527 	pushq %r10				/* pt_regs->r10 */
528 	pushq %r11				/* pt_regs->r11 */
529 	pushq %rbx				/* pt_regs->bx */
530 	pushq %rbp				/* pt_regs->bp */
531 	pushq %r12				/* pt_regs->r12 */
532 	pushq %r13				/* pt_regs->r13 */
533 	pushq %r14				/* pt_regs->r14 */
534 	pushq %r15				/* pt_regs->r15 */
546  * VC Exception handler used during very early boot. The
548  * paravirtualized INTERRUPT_RETURN and pv-ops don't work that early.
552  * This handler will end up in the .init.text section and not be
553  * available to boot secondary CPUs.
573 	/* Pure iret required here - don't use INTERRUPT_RETURN */
590 /* This ensures they are 8k-aligned: */
604 	.quad	level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC
618 	.quad   level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
620 	.quad   level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
622 	/* (2^48-(2*1024*1024*1024))/(2^39) = 511 */
623 	.quad   level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC
628 	.quad	level2_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
652 	.quad	level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC
658 	/* (2^48-(2*1024*1024*1024)-((2^39)*511))/(2^30) = 510 */
659 	.quad	level2_kernel_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
660 	.quad	level2_fixmap_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC
681 	.fill	(512 - 4 - FIXMAP_PMD_NUM),8,0
684 	.quad level1_fixmap_pgt + (pgtno << PAGE_SHIFT) - __START_KERNEL_map \
708 #include "../xen/xen-head.S"