mirror of
https://github.com/torvalds/linux.git
synced 2024-12-28 05:41:55 +00:00
b1994304fc
The method used to work out whether we were booted by EFI firmware or via a boot loader is broken. Because efi_main() is always executed when booting from a boot loader we will dereference invalid pointers either on the stack (CONFIG_X86_32) or contained in %rdx (CONFIG_X86_64) when searching for an EFI System Table signature. Instead of dereferencing these invalid system table pointers, add a new entry point that is only used when booting from EFI firmware, when we know the pointer arguments will be valid. With this change legacy boot loaders will no longer execute efi_main(), but will instead skip EFI stub initialisation completely. [ hpa: Marking this for urgent/stable since it is a regression when the option is enabled; without the option the patch has no effect ] Signed-off-by: Matt Fleming <matt.hfleming@intel.com> Link: http://lkml.kernel.org/r/1334584744.26997.14.camel@mfleming-mobl1.ger.corp.intel.com Reported-by: Jordan Justen <jordan.l.justen@intel.com> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Cc: <stable@vger.kernel.org> v3.3
226 lines
4.4 KiB
ArmAsm
226 lines
4.4 KiB
ArmAsm
/*
|
|
* linux/boot/head.S
|
|
*
|
|
* Copyright (C) 1991, 1992, 1993 Linus Torvalds
|
|
*/
|
|
|
|
/*
|
|
* head.S contains the 32-bit startup code.
|
|
*
|
|
* NOTE!!! Startup happens at absolute address 0x00001000, which is also where
|
|
* the page directory will exist. The startup code will be overwritten by
|
|
* the page directory. [According to comments etc elsewhere on a compressed
|
|
* kernel it will end up at 0x1000 + 1Mb I hope so as I assume this. - AC]
|
|
*
|
|
* Page 0 is deliberately kept safe, since System Management Mode code in
|
|
* laptops may need to access the BIOS data stored there. This is also
|
|
* useful for future device drivers that either access the BIOS via VM86
|
|
* mode.
|
|
*/
|
|
|
|
/*
|
|
* High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996
|
|
*/
|
|
.text
|
|
|
|
#include <linux/init.h>
|
|
#include <linux/linkage.h>
|
|
#include <asm/segment.h>
|
|
#include <asm/page_types.h>
|
|
#include <asm/boot.h>
|
|
#include <asm/asm-offsets.h>
|
|
|
|
__HEAD
|
|
ENTRY(startup_32)
|
|
#ifdef CONFIG_EFI_STUB
|
|
jmp preferred_addr
|
|
|
|
.balign 0x10
|
|
/*
|
|
* We don't need the return address, so set up the stack so
|
|
* efi_main() can find its arugments.
|
|
*/
|
|
add $0x4, %esp
|
|
|
|
call efi_main
|
|
cmpl $0, %eax
|
|
movl %eax, %esi
|
|
jne 2f
|
|
1:
|
|
/* EFI init failed, so hang. */
|
|
hlt
|
|
jmp 1b
|
|
2:
|
|
call 3f
|
|
3:
|
|
popl %eax
|
|
subl $3b, %eax
|
|
subl BP_pref_address(%esi), %eax
|
|
add BP_code32_start(%esi), %eax
|
|
leal preferred_addr(%eax), %eax
|
|
jmp *%eax
|
|
|
|
preferred_addr:
|
|
#endif
|
|
cld
|
|
/*
|
|
* Test KEEP_SEGMENTS flag to see if the bootloader is asking
|
|
* us to not reload segments
|
|
*/
|
|
testb $(1<<6), BP_loadflags(%esi)
|
|
jnz 1f
|
|
|
|
cli
|
|
movl $__BOOT_DS, %eax
|
|
movl %eax, %ds
|
|
movl %eax, %es
|
|
movl %eax, %fs
|
|
movl %eax, %gs
|
|
movl %eax, %ss
|
|
1:
|
|
|
|
/*
|
|
* 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 0x1e4 (defined as a scratch field) are used as the stack
|
|
* for this calculation. Only 4 bytes are needed.
|
|
*/
|
|
leal (BP_scratch+4)(%esi), %esp
|
|
call 1f
|
|
1: popl %ebp
|
|
subl $1b, %ebp
|
|
|
|
/*
|
|
* %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
|
|
movl BP_kernel_alignment(%esi), %eax
|
|
decl %eax
|
|
addl %eax, %ebx
|
|
notl %eax
|
|
andl %eax, %ebx
|
|
#else
|
|
movl $LOAD_PHYSICAL_ADDR, %ebx
|
|
#endif
|
|
|
|
/* Target address to relocate to for decompression */
|
|
addl $z_extract_offset, %ebx
|
|
|
|
/* Set up the stack */
|
|
leal boot_stack_end(%ebx), %esp
|
|
|
|
/* Zero EFLAGS */
|
|
pushl $0
|
|
popfl
|
|
|
|
/*
|
|
* Copy the compressed kernel to the end of our buffer
|
|
* where decompression in place becomes safe.
|
|
*/
|
|
pushl %esi
|
|
leal (_bss-4)(%ebp), %esi
|
|
leal (_bss-4)(%ebx), %edi
|
|
movl $(_bss - startup_32), %ecx
|
|
shrl $2, %ecx
|
|
std
|
|
rep movsl
|
|
cld
|
|
popl %esi
|
|
|
|
/*
|
|
* Jump to the relocated address.
|
|
*/
|
|
leal relocated(%ebx), %eax
|
|
jmp *%eax
|
|
ENDPROC(startup_32)
|
|
|
|
.text
|
|
relocated:
|
|
|
|
/*
|
|
* Clear BSS (stack is currently empty)
|
|
*/
|
|
xorl %eax, %eax
|
|
leal _bss(%ebx), %edi
|
|
leal _ebss(%ebx), %ecx
|
|
subl %edi, %ecx
|
|
shrl $2, %ecx
|
|
rep stosl
|
|
|
|
/*
|
|
* Adjust our own GOT
|
|
*/
|
|
leal _got(%ebx), %edx
|
|
leal _egot(%ebx), %ecx
|
|
1:
|
|
cmpl %ecx, %edx
|
|
jae 2f
|
|
addl %ebx, (%edx)
|
|
addl $4, %edx
|
|
jmp 1b
|
|
2:
|
|
|
|
/*
|
|
* Do the decompression, and jump to the new kernel..
|
|
*/
|
|
leal z_extract_offset_negative(%ebx), %ebp
|
|
/* push arguments for decompress_kernel: */
|
|
pushl %ebp /* output address */
|
|
pushl $z_input_len /* input_len */
|
|
leal input_data(%ebx), %eax
|
|
pushl %eax /* input_data */
|
|
leal boot_heap(%ebx), %eax
|
|
pushl %eax /* heap area */
|
|
pushl %esi /* real mode pointer */
|
|
call decompress_kernel
|
|
addl $20, %esp
|
|
|
|
#if CONFIG_RELOCATABLE
|
|
/*
|
|
* Find the address of the relocations.
|
|
*/
|
|
leal z_output_len(%ebp), %edi
|
|
|
|
/*
|
|
* Calculate the delta between where vmlinux was compiled to run
|
|
* and where it was actually loaded.
|
|
*/
|
|
movl %ebp, %ebx
|
|
subl $LOAD_PHYSICAL_ADDR, %ebx
|
|
jz 2f /* Nothing to be done if loaded at compiled addr. */
|
|
/*
|
|
* Process relocations.
|
|
*/
|
|
|
|
1: subl $4, %edi
|
|
movl (%edi), %ecx
|
|
testl %ecx, %ecx
|
|
jz 2f
|
|
addl %ebx, -__PAGE_OFFSET(%ebx, %ecx)
|
|
jmp 1b
|
|
2:
|
|
#endif
|
|
|
|
/*
|
|
* Jump to the decompressed kernel.
|
|
*/
|
|
xorl %ebx, %ebx
|
|
jmp *%ebp
|
|
|
|
/*
|
|
* Stack and heap for uncompression
|
|
*/
|
|
.bss
|
|
.balign 4
|
|
boot_heap:
|
|
.fill BOOT_HEAP_SIZE, 1, 0
|
|
boot_stack:
|
|
.fill BOOT_STACK_SIZE, 1, 0
|
|
boot_stack_end:
|