diff options
Diffstat (limited to 'arch/x86_64/boot/compressed/head.S')
| -rw-r--r-- | arch/x86_64/boot/compressed/head.S | 322 |
1 files changed, 234 insertions, 88 deletions
diff --git a/arch/x86_64/boot/compressed/head.S b/arch/x86_64/boot/compressed/head.S index 6f55565e4d42..c353a9266ea4 100644 --- a/arch/x86_64/boot/compressed/head.S +++ b/arch/x86_64/boot/compressed/head.S @@ -26,116 +26,262 @@ #include <linux/linkage.h> #include <asm/segment.h> +#include <asm/pgtable.h> #include <asm/page.h> +#include <asm/msr.h> +.section ".text.head" .code32 .globl startup_32 - + startup_32: cld cli - movl $(__KERNEL_DS),%eax - movl %eax,%ds - movl %eax,%es - movl %eax,%fs - movl %eax,%gs - - lss stack_start,%esp - xorl %eax,%eax -1: incl %eax # check that A20 really IS enabled - movl %eax,0x000000 # loop forever if it isn't - cmpl %eax,0x100000 - je 1b + movl $(__KERNEL_DS), %eax + movl %eax, %ds + movl %eax, %es + movl %eax, %ss + +/* Calculate the delta between where we were compiled to run + * at and where we were actually loaded at. This can only be done + * with a short local call on x86. Nothing else will tell us what + * address we are running at. The reserved chunk of the real-mode + * data at 0x34-0x3f are used as the stack for this calculation. + * Only 4 bytes are needed. + */ + leal 0x40(%esi), %esp + call 1f +1: popl %ebp + subl $1b, %ebp + +/* Compute the delta between where we were compiled to run at + * and where the code will actually run at. + */ +/* %ebp contains the address we are loaded at by the boot loader and %ebx + * contains the address where we should move the kernel image temporarily + * for safe in-place decompression. + */ + +#ifdef CONFIG_RELOCATABLE + movl %ebp, %ebx + addl $(LARGE_PAGE_SIZE -1), %ebx + andl $LARGE_PAGE_MASK, %ebx +#else + movl $CONFIG_PHYSICAL_START, %ebx +#endif + + /* Replace the compressed data size with the uncompressed size */ + subl input_len(%ebp), %ebx + movl output_len(%ebp), %eax + addl %eax, %ebx + /* Add 8 bytes for every 32K input block */ + shrl $12, %eax + addl %eax, %ebx + /* Add 32K + 18 bytes of extra slack and align on a 4K boundary */ + addl $(32768 + 18 + 4095), %ebx + andl $~4095, %ebx /* - * Initialize eflags. Some BIOS's leave bits like NT set. This would - * confuse the debugger if this code is traced. - * XXX - best to initialize before switching to protected mode. + * Prepare for entering 64 bit mode */ - pushl $0 - popfl + + /* Load new GDT with the 64bit segments using 32bit descriptor */ + leal gdt(%ebp), %eax + movl %eax, gdt+2(%ebp) + lgdt gdt(%ebp) + + /* Enable PAE mode */ + xorl %eax, %eax + orl $(1 << 5), %eax + movl %eax, %cr4 + + /* + * Build early 4G boot pagetable + */ + /* Initialize Page tables to 0*/ + leal pgtable(%ebx), %edi + xorl %eax, %eax + movl $((4096*6)/4), %ecx + rep stosl + + /* Build Level 4 */ + leal pgtable + 0(%ebx), %edi + leal 0x1007 (%edi), %eax + movl %eax, 0(%edi) + + /* Build Level 3 */ + leal pgtable + 0x1000(%ebx), %edi + leal 0x1007(%edi), %eax + movl $4, %ecx +1: movl %eax, 0x00(%edi) + addl $0x00001000, %eax + addl $8, %edi + decl %ecx + jnz 1b + + /* Build Level 2 */ + leal pgtable + 0x2000(%ebx), %edi + movl $0x00000183, %eax + movl $2048, %ecx +1: movl %eax, 0(%edi) + addl $0x00200000, %eax + addl $8, %edi + decl %ecx + jnz 1b + + /* Enable the boot page tables */ + leal pgtable(%ebx), %eax + movl %eax, %cr3 + + /* Enable Long mode in EFER (Extended Feature Enable Register) */ + movl $MSR_EFER, %ecx + rdmsr + btsl $_EFER_LME, %eax + wrmsr + + /* Setup for the jump to 64bit mode + * + * When the jump is performend we will be in long mode but + * in 32bit compatibility mode with EFER.LME = 1, CS.L = 0, CS.D = 1 + * (and in turn EFER.LMA = 1). To jump into 64bit mode we use + * the new gdt/idt that has __KERNEL_CS with CS.L = 1. + * We place all of the values on our mini stack so lret can + * used to perform that far jump. + */ + pushl $__KERNEL_CS + leal startup_64(%ebp), %eax + pushl %eax + + /* Enter paged protected Mode, activating Long Mode */ + movl $0x80000001, %eax /* Enable Paging and Protected mode */ + movl %eax, %cr0 + + /* Jump from 32bit compatibility mode into 64bit mode. */ + lret + + /* Be careful here startup_64 needs to be at a predictable + * address so I can export it in an ELF header. Bootloaders + * should look at the ELF header to find this address, as + * it may change in the future. + */ + .code64 + .org 0x100 +ENTRY(startup_64) + /* We come here either from startup_32 or directly from a + * 64bit bootloader. If we come here from a bootloader we depend on + * an identity mapped page table being provied that maps our + * entire text+data+bss and hopefully all of memory. + */ + + /* Setup data segments. */ + xorl %eax, %eax + movl %eax, %ds + movl %eax, %es + movl %eax, %ss + + /* Compute the decompressed kernel start address. It is where + * we were loaded at aligned to a 2M boundary. %rbp contains the + * decompressed kernel start address. + * + * If it is a relocatable kernel then decompress and run the kernel + * from load address aligned to 2MB addr, otherwise decompress and + * run the kernel from CONFIG_PHYSICAL_START + */ + + /* Start with the delta to where the kernel will run at. */ +#ifdef CONFIG_RELOCATABLE + leaq startup_32(%rip) /* - $startup_32 */, %rbp + addq $(LARGE_PAGE_SIZE - 1), %rbp + andq $LARGE_PAGE_MASK, %rbp + movq %rbp, %rbx +#else + movq $CONFIG_PHYSICAL_START, %rbp + movq %rbp, %rbx +#endif + + /* Replace the compressed data size with the uncompressed size */ + movl input_len(%rip), %eax + subq %rax, %rbx + movl output_len(%rip), %eax + addq %rax, %rbx + /* Add 8 bytes for every 32K input block */ + shrq $12, %rax + addq %rax, %rbx + /* Add 32K + 18 bytes of extra slack and align on a 4K boundary */ + addq $(32768 + 18 + 4095), %rbx + andq $~4095, %rbx + +/* Copy the compressed kernel to the end of our buffer + * where decompression in place becomes safe. + */ + leaq _end(%rip), %r8 + leaq _end(%rbx), %r9 + movq $_end /* - $startup_32 */, %rcx +1: subq $8, %r8 + subq $8, %r9 + movq 0(%r8), %rax + movq %rax, 0(%r9) + subq $8, %rcx + jnz 1b + +/* + * Jump to the relocated address. + */ + leaq relocated(%rbx), %rax + jmp *%rax + +.section ".text" +relocated: + /* * Clear BSS */ - xorl %eax,%eax - movl $_edata,%edi - movl $_end,%ecx - subl %edi,%ecx + xorq %rax, %rax + leaq _edata(%rbx), %rdi + leaq _end(%rbx), %rcx + subq %rdi, %rcx cld rep stosb + + /* Setup the stack */ + leaq user_stack_end(%rip), %rsp + + /* zero EFLAGS after setting rsp */ + pushq $0 + popfq + /* * Do the decompression, and jump to the new kernel.. */ - subl $16,%esp # place for structure on the stack - movl %esp,%eax - pushl %esi # real mode pointer as second arg - pushl %eax # address of structure as first arg - call decompress_kernel - orl %eax,%eax - jnz 3f - addl $8,%esp - xorl %ebx,%ebx - ljmp $(__KERNEL_CS), $__PHYSICAL_START + pushq %rsi # Save the real mode argument + movq %rsi, %rdi # real mode address + leaq _heap(%rip), %rsi # _heap + leaq input_data(%rip), %rdx # input_data + movl input_len(%rip), %eax + movq %rax, %rcx # input_len + movq %rbp, %r8 # output + call decompress_kernel + popq %rsi -/* - * We come here, if we were loaded high. - * We need to move the move-in-place routine down to 0x1000 - * and then start it with the buffer addresses in registers, - * which we got from the stack. - */ -3: - movl %esi,%ebx - movl $move_routine_start,%esi - movl $0x1000,%edi - movl $move_routine_end,%ecx - subl %esi,%ecx - addl $3,%ecx - shrl $2,%ecx - cld - rep - movsl - - popl %esi # discard the address - addl $4,%esp # real mode pointer - popl %esi # low_buffer_start - popl %ecx # lcount - popl %edx # high_buffer_start - popl %eax # hcount - movl $__PHYSICAL_START,%edi - cli # make sure we don't get interrupted - ljmp $(__KERNEL_CS), $0x1000 # and jump to the move routine /* - * Routine (template) for moving the decompressed kernel in place, - * if we were high loaded. This _must_ PIC-code ! + * Jump to the decompressed kernel. */ -move_routine_start: - movl %ecx,%ebp - shrl $2,%ecx - rep - movsl - movl %ebp,%ecx - andl $3,%ecx - rep - movsb - movl %edx,%esi - movl %eax,%ecx # NOTE: rep movsb won't move if %ecx == 0 - addl $3,%ecx - shrl $2,%ecx - rep - movsl - movl %ebx,%esi # Restore setup pointer - xorl %ebx,%ebx - ljmp $(__KERNEL_CS), $__PHYSICAL_START -move_routine_end: + jmp *%rbp - -/* Stack for uncompression */ - .align 32 -user_stack: + .data +gdt: + .word gdt_end - gdt + .long gdt + .word 0 + .quad 0x0000000000000000 /* NULL descriptor */ + .quad 0x00af9a000000ffff /* __KERNEL_CS */ + .quad 0x00cf92000000ffff /* __KERNEL_DS */ +gdt_end: + .bss +/* Stack for uncompression */ + .balign 4 +user_stack: .fill 4096,4,0 -stack_start: - .long user_stack+4096 - .word __KERNEL_DS - +user_stack_end: |