linux/arch/x86/boot/compressed/efi_stub_64.S

#include <asm/segment.h>
#include <asm/msr.h>
#include <asm/processor-flags.h>

#include "../../platform/efi/efi_stub_64.S"

#ifdef CONFIG_EFI_MIXED
	.code64
	.text
ENTRY(efi64_thunk)
	push	%rbp
	push	%rbx

	subq	$16, %rsp
	leaq	efi_exit32(%rip), %rax
	movl	%eax, 8(%rsp)
	leaq	efi_gdt64(%rip), %rax
	movl	%eax, 4(%rsp)
	movl	%eax, 2(%rax)		/* Fixup the gdt base address */
	leaq	efi32_boot_gdt(%rip), %rax
	movl	%eax, (%rsp)

	call	__efi64_thunk

	addq	$16, %rsp
	pop	%rbx
	pop	%rbp
	ret
ENDPROC(efi64_thunk)
#endif /* CONFIG_EFI_MIXED */
x86/efi: Add early thunk code to go from 64-bit to 32-bit Implement the transition code to go from IA32e mode to protected mode in the EFI boot stub. This is required to use 32-bit EFI services from a 64-bit kernel. Since EFI boot stub is executed in an identity-mapped region, there's not much we need to do before invoking the 32-bit EFI boot services. However, we do reload the firmware's global descriptor table (efi32_boot_gdt) in case things like timer events are still running in the firmware. Signed-off-by: Matt Fleming <matt.fleming@intel.com> 2014-01-10 15:37:17 +00:00			`#include <asm/segment.h>`
			`#include <asm/msr.h>`
			`#include <asm/processor-flags.h>`

x86, efi: EFI boot stub support There is currently a large divide between kernel development and the development of EFI boot loaders. The idea behind this patch is to give the kernel developers full control over the EFI boot process. As H. Peter Anvin put it, "The 'kernel carries its own stub' approach been very successful in dealing with BIOS, and would make a lot of sense to me for EFI as well." This patch introduces an EFI boot stub that allows an x86 bzImage to be loaded and executed by EFI firmware. The bzImage appears to the firmware as an EFI application. Luckily there are enough free bits within the bzImage header so that it can masquerade as an EFI application, thereby coercing the EFI firmware into loading it and jumping to its entry point. The beauty of this masquerading approach is that both BIOS and EFI boot loaders can still load and run the same bzImage, thereby allowing a single kernel image to work in any boot environment. The EFI boot stub supports multiple initrds, but they must exist on the same partition as the bzImage. Command-line arguments for the kernel can be appended after the bzImage name when run from the EFI shell, e.g. Shell> bzImage console=ttyS0 root=/dev/sdb initrd=initrd.img v7: - Fix checkpatch warnings. v6: - Try to allocate initrd memory just below hdr->inird_addr_max. v5: - load_options_size is UTF-16, which needs dividing by 2 to convert to the corresponding ASCII size. v4: - Don't read more than image->load_options_size v3: - Fix following warnings when compiling CONFIG_EFI_STUB=n arch/x86/boot/tools/build.c: In function ‘main’: arch/x86/boot/tools/build.c:138:24: warning: unused variable ‘pe_header’ arch/x86/boot/tools/build.c:138:15: warning: unused variable ‘file_sz’ - As reported by Matthew Garrett, some Apple machines have GOPs that don't have hardware attached. We need to weed these out by searching for ones that handle the PCIIO protocol. - Don't allocate memory if no initrds are on cmdline - Don't trust image->load_options_size Maarten Lankhorst noted: - Don't strip first argument when booted from efibootmgr - Don't allocate too much memory for cmdline - Don't update cmdline_size, the kernel considers it read-only - Don't accept '\n' for initrd names v2: - File alignment was too large, was 8192 should be 512. Reported by Maarten Lankhorst on LKML. - Added UGA support for graphics - Use VIDEO_TYPE_EFI instead of hard-coded number. - Move linelength assignment until after we've assigned depth - Dynamically fill out AddressOfEntryPoint in tools/build.c - Don't use magic number for GDT/TSS stuff. Requested by Andi Kleen - The bzImage may need to be relocated as it may have been loaded at a high address address by the firmware. This was required to get my macbook booting because the firmware loaded it at 0x7cxxxxxx, which triggers this error in decompress_kernel(), if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff)) error("Destination address too large"); Cc: Mike Waychison <mikew@google.com> Cc: Matthew Garrett <mjg@redhat.com> Tested-by: Henrik Rydberg <rydberg@euromail.se> Signed-off-by: Matt Fleming <matt.fleming@intel.com> Link: http://lkml.kernel.org/r/1321383097.2657.9.camel@mfleming-mobl1.ger.corp.intel.com Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> 2011-12-12 21:27:52 +00:00			`#include "../../platform/efi/efi_stub_64.S"`
x86/efi: Add early thunk code to go from 64-bit to 32-bit Implement the transition code to go from IA32e mode to protected mode in the EFI boot stub. This is required to use 32-bit EFI services from a 64-bit kernel. Since EFI boot stub is executed in an identity-mapped region, there's not much we need to do before invoking the 32-bit EFI boot services. However, we do reload the firmware's global descriptor table (efi32_boot_gdt) in case things like timer events are still running in the firmware. Signed-off-by: Matt Fleming <matt.fleming@intel.com> 2014-01-10 15:37:17 +00:00
			`#ifdef CONFIG_EFI_MIXED`
			`.code64`
			`.text`
			`ENTRY(efi64_thunk)`
			`push %rbp`
			`push %rbx`

			`subq $16, %rsp`
			`leaq efi_exit32(%rip), %rax`
			`movl %eax, 8(%rsp)`
			`leaq efi_gdt64(%rip), %rax`
			`movl %eax, 4(%rsp)`
			`movl %eax, 2(%rax) /* Fixup the gdt base address */`
			`leaq efi32_boot_gdt(%rip), %rax`
			`movl %eax, (%rsp)`

			`call __efi64_thunk`

			`addq $16, %rsp`
			`pop %rbx`
			`pop %rbp`
			`ret`
			`ENDPROC(efi64_thunk)`
			`#endif /* CONFIG_EFI_MIXED */`