08da5a2ca4
VT is very picky about when it can enter execution. Get all segments setup and get LDT and TR into valid state to allow VT execution under VMware and KVM (untested). This makes the boot decompression run under VT, which makes it several orders of magnitude faster on 64-bit Intel hardware. Before, I was seeing times up to a minute or more to decompress a 1.3MB kernel on a very fast box. Signed-off-by: Zachary Amsden <zach@vmware.com> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
312 lines
7.2 KiB
ArmAsm
312 lines
7.2 KiB
ArmAsm
/*
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* linux/boot/head.S
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*
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* Copyright (C) 1991, 1992, 1993 Linus Torvalds
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*/
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/*
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* head.S contains the 32-bit startup code.
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*
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* NOTE!!! Startup happens at absolute address 0x00001000, which is also where
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* the page directory will exist. The startup code will be overwritten by
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* the page directory. [According to comments etc elsewhere on a compressed
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* kernel it will end up at 0x1000 + 1Mb I hope so as I assume this. - AC]
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*
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* Page 0 is deliberately kept safe, since System Management Mode code in
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* laptops may need to access the BIOS data stored there. This is also
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* useful for future device drivers that either access the BIOS via VM86
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* mode.
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*/
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/*
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* High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996
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*/
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.code32
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.text
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#include <linux/linkage.h>
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#include <asm/segment.h>
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#include <asm/pgtable.h>
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#include <asm/page.h>
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#include <asm/msr.h>
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.section ".text.head"
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.code32
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.globl startup_32
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startup_32:
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cld
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cli
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movl $(__KERNEL_DS), %eax
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movl %eax, %ds
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movl %eax, %es
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movl %eax, %ss
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/* Calculate the delta between where we were compiled to run
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* at and where we were actually loaded at. This can only be done
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* with a short local call on x86. Nothing else will tell us what
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* address we are running at. The reserved chunk of the real-mode
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* data at 0x1e4 (defined as a scratch field) are used as the stack
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* for this calculation. Only 4 bytes are needed.
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*/
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leal (0x1e4+4)(%esi), %esp
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call 1f
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1: popl %ebp
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subl $1b, %ebp
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/* setup a stack and make sure cpu supports long mode. */
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movl $user_stack_end, %eax
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addl %ebp, %eax
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movl %eax, %esp
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call verify_cpu
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testl %eax, %eax
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jnz no_longmode
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/* Compute the delta between where we were compiled to run at
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* and where the code will actually run at.
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*/
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/* %ebp contains the address we are loaded at by the boot loader and %ebx
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* contains the address where we should move the kernel image temporarily
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* for safe in-place decompression.
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*/
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#ifdef CONFIG_RELOCATABLE
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movl %ebp, %ebx
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addl $(LARGE_PAGE_SIZE -1), %ebx
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andl $LARGE_PAGE_MASK, %ebx
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#else
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movl $CONFIG_PHYSICAL_START, %ebx
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#endif
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/* Replace the compressed data size with the uncompressed size */
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subl input_len(%ebp), %ebx
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movl output_len(%ebp), %eax
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addl %eax, %ebx
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/* Add 8 bytes for every 32K input block */
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shrl $12, %eax
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addl %eax, %ebx
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/* Add 32K + 18 bytes of extra slack and align on a 4K boundary */
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addl $(32768 + 18 + 4095), %ebx
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andl $~4095, %ebx
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/*
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* Prepare for entering 64 bit mode
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*/
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/* Load new GDT with the 64bit segments using 32bit descriptor */
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leal gdt(%ebp), %eax
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movl %eax, gdt+2(%ebp)
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lgdt gdt(%ebp)
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/* Enable PAE mode */
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xorl %eax, %eax
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orl $(1 << 5), %eax
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movl %eax, %cr4
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/*
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* Build early 4G boot pagetable
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*/
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/* Initialize Page tables to 0*/
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leal pgtable(%ebx), %edi
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xorl %eax, %eax
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movl $((4096*6)/4), %ecx
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rep stosl
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/* Build Level 4 */
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leal pgtable + 0(%ebx), %edi
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leal 0x1007 (%edi), %eax
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movl %eax, 0(%edi)
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/* Build Level 3 */
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leal pgtable + 0x1000(%ebx), %edi
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leal 0x1007(%edi), %eax
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movl $4, %ecx
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1: movl %eax, 0x00(%edi)
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addl $0x00001000, %eax
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addl $8, %edi
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decl %ecx
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jnz 1b
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/* Build Level 2 */
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leal pgtable + 0x2000(%ebx), %edi
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movl $0x00000183, %eax
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movl $2048, %ecx
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1: movl %eax, 0(%edi)
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addl $0x00200000, %eax
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addl $8, %edi
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decl %ecx
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jnz 1b
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/* Enable the boot page tables */
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leal pgtable(%ebx), %eax
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movl %eax, %cr3
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/* Enable Long mode in EFER (Extended Feature Enable Register) */
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movl $MSR_EFER, %ecx
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rdmsr
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btsl $_EFER_LME, %eax
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wrmsr
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/* Setup for the jump to 64bit mode
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*
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* When the jump is performend we will be in long mode but
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* in 32bit compatibility mode with EFER.LME = 1, CS.L = 0, CS.D = 1
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* (and in turn EFER.LMA = 1). To jump into 64bit mode we use
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* the new gdt/idt that has __KERNEL_CS with CS.L = 1.
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* We place all of the values on our mini stack so lret can
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* used to perform that far jump.
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*/
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pushl $__KERNEL_CS
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leal startup_64(%ebp), %eax
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pushl %eax
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/* Enter paged protected Mode, activating Long Mode */
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movl $0x80000001, %eax /* Enable Paging and Protected mode */
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movl %eax, %cr0
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/* Jump from 32bit compatibility mode into 64bit mode. */
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lret
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no_longmode:
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/* This isn't an x86-64 CPU so hang */
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1:
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hlt
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jmp 1b
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#include "../../kernel/verify_cpu.S"
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/* Be careful here startup_64 needs to be at a predictable
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* address so I can export it in an ELF header. Bootloaders
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* should look at the ELF header to find this address, as
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* it may change in the future.
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*/
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.code64
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.org 0x200
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ENTRY(startup_64)
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/* We come here either from startup_32 or directly from a
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* 64bit bootloader. If we come here from a bootloader we depend on
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* an identity mapped page table being provied that maps our
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* entire text+data+bss and hopefully all of memory.
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*/
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/* Setup data segments. */
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xorl %eax, %eax
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movl %eax, %ds
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movl %eax, %es
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movl %eax, %ss
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movl %eax, %fs
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movl %eax, %gs
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lldt %ax
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movl $0x20, %eax
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ltr %ax
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/* Compute the decompressed kernel start address. It is where
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* we were loaded at aligned to a 2M boundary. %rbp contains the
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* decompressed kernel start address.
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*
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* If it is a relocatable kernel then decompress and run the kernel
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* from load address aligned to 2MB addr, otherwise decompress and
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* run the kernel from CONFIG_PHYSICAL_START
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*/
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/* Start with the delta to where the kernel will run at. */
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#ifdef CONFIG_RELOCATABLE
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leaq startup_32(%rip) /* - $startup_32 */, %rbp
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addq $(LARGE_PAGE_SIZE - 1), %rbp
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andq $LARGE_PAGE_MASK, %rbp
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movq %rbp, %rbx
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#else
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movq $CONFIG_PHYSICAL_START, %rbp
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movq %rbp, %rbx
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#endif
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/* Replace the compressed data size with the uncompressed size */
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movl input_len(%rip), %eax
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subq %rax, %rbx
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movl output_len(%rip), %eax
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addq %rax, %rbx
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/* Add 8 bytes for every 32K input block */
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shrq $12, %rax
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addq %rax, %rbx
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/* Add 32K + 18 bytes of extra slack and align on a 4K boundary */
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addq $(32768 + 18 + 4095), %rbx
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andq $~4095, %rbx
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/* Copy the compressed kernel to the end of our buffer
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* where decompression in place becomes safe.
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*/
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leaq _end(%rip), %r8
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leaq _end(%rbx), %r9
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movq $_end /* - $startup_32 */, %rcx
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1: subq $8, %r8
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subq $8, %r9
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movq 0(%r8), %rax
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movq %rax, 0(%r9)
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subq $8, %rcx
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jnz 1b
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/*
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* Jump to the relocated address.
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*/
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leaq relocated(%rbx), %rax
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jmp *%rax
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.section ".text"
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relocated:
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/*
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* Clear BSS
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*/
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xorq %rax, %rax
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leaq _edata(%rbx), %rdi
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leaq _end(%rbx), %rcx
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subq %rdi, %rcx
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cld
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rep
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stosb
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/* Setup the stack */
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leaq user_stack_end(%rip), %rsp
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/* zero EFLAGS after setting rsp */
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pushq $0
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popfq
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/*
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* Do the decompression, and jump to the new kernel..
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*/
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pushq %rsi # Save the real mode argument
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movq %rsi, %rdi # real mode address
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leaq _heap(%rip), %rsi # _heap
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leaq input_data(%rip), %rdx # input_data
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movl input_len(%rip), %eax
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movq %rax, %rcx # input_len
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movq %rbp, %r8 # output
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call decompress_kernel
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popq %rsi
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/*
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* Jump to the decompressed kernel.
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*/
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jmp *%rbp
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.data
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gdt:
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.word gdt_end - gdt
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.long gdt
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.word 0
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.quad 0x0000000000000000 /* NULL descriptor */
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.quad 0x00af9a000000ffff /* __KERNEL_CS */
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.quad 0x00cf92000000ffff /* __KERNEL_DS */
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.quad 0x0080890000000000 /* TS descriptor */
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.quad 0x0000000000000000 /* TS continued */
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gdt_end:
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.bss
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/* Stack for uncompression */
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.balign 4
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user_stack:
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.fill 4096,4,0
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user_stack_end:
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