arm64: efi: add EFI stub (f70e084a) · Commits · e / devices / android_kernel_sony_msm8994

arch/arm64/Kconfig

+3 −2

Original line number	Diff line number	Diff line
		@@ -505,8 +505,9 @@ config EFI
		help
		This option provides support for runtime services provided
		by UEFI firmware (such as non-volatile variables, realtime
		clock, and platform reset). This is only useful on systems
		that have UEFI firmware.
		clock, and platform reset). A UEFI stub is also provided to
		allow the kernel to be booted as an EFI application. This
		is only useful on systems that have UEFI firmware.

		endmenu

arch/arm64/kernel/Makefile

+3 −1

Original line number	Diff line number	Diff line
		@@ -4,6 +4,8 @@

		CPPFLAGS_vmlinux.lds := -DTEXT_OFFSET=$(TEXT_OFFSET)
		AFLAGS_head.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
		CFLAGS_efi-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET) \
		-I$(src)/../../../scripts/dtc/libfdt

		CFLAGS_REMOVE_ftrace.o = -pg
		CFLAGS_REMOVE_insn.o = -pg
		@@ -29,7 +31,7 @@ arm64-obj-$(CONFIG_EARLY_PRINTK) += early_printk.o
		arm64-obj-$(CONFIG_ARM64_CPU_SUSPEND) += sleep.o suspend.o
		arm64-obj-$(CONFIG_JUMP_LABEL) += jump_label.o
		arm64-obj-$(CONFIG_KGDB) += kgdb.o
		arm64-obj-$(CONFIG_EFI) += efi.o
		arm64-obj-$(CONFIG_EFI) += efi.o efi-stub.o efi-entry.o

		obj-$(CONFIG_SWP_EMULATE) += swp_emulate.o

arch/arm64/kernel/efi-entry.S

0 → 100644

+109 −0

Original line number	Diff line number	Diff line
		/*
		* EFI entry point.
		*
		* Copyright (C) 2013, 2014 Red Hat, Inc.
		* Author: Mark Salter <msalter@redhat.com>
		*
		* This program is free software; you can redistribute it and/or modify
		* it under the terms of the GNU General Public License version 2 as
		* published by the Free Software Foundation.
		*
		*/
		#include <linux/linkage.h>
		#include <linux/init.h>

		#include <asm/assembler.h>

		#define EFI_LOAD_ERROR 0x8000000000000001

		__INIT

		/*
		* We arrive here from the EFI boot manager with:
		*
		* * CPU in little-endian mode
		* * MMU on with identity-mapped RAM
		* * Icache and Dcache on
		*
		* We will most likely be running from some place other than where
		* we want to be. The kernel image wants to be placed at TEXT_OFFSET
		* from start of RAM.
		*/
		ENTRY(efi_stub_entry)
		/*
		* Create a stack frame to save FP/LR with extra space
		* for image_addr variable passed to efi_entry().
		*/
		stp x29, x30, [sp, #-32]!

		/*
		* Call efi_entry to do the real work.
		* x0 and x1 are already set up by firmware. Current runtime
		* address of image is calculated and passed via *image_addr.
		*
		* unsigned long efi_entry(void *handle,
		* efi_system_table_t *sys_table,
		* unsigned long *image_addr) ;
		*/
		adrp x8, _text
		add x8, x8, #:lo12:_text
		add x2, sp, 16
		str x8, [x2]
		bl efi_entry
		cmn x0, #1
		b.eq efi_load_fail

		/*
		* efi_entry() will have relocated the kernel image if necessary
		* and we return here with device tree address in x0 and the kernel
		* entry point stored at *image_addr. Save those values in registers
		* which are callee preserved.
		*/
		mov x20, x0 // DTB address
		ldr x0, [sp, #16] // relocated _text address
		mov x21, x0

		/*
		* Flush dcache covering current runtime addresses
		* of kernel text/data. Then flush all of icache.
		*/
		adrp x1, _text
		add x1, x1, #:lo12:_text
		adrp x2, _edata
		add x2, x2, #:lo12:_edata
		sub x1, x2, x1

		bl __flush_dcache_area
		ic ialluis

		/* Turn off Dcache and MMU */
		mrs x0, CurrentEL
		cmp x0, #PSR_MODE_EL2t
		ccmp x0, #PSR_MODE_EL2h, #0x4, ne
		b.ne 1f
		mrs x0, sctlr_el2
		bic x0, x0, #1 << 0 // clear SCTLR.M
		bic x0, x0, #1 << 2 // clear SCTLR.C
		msr sctlr_el2, x0
		isb
		b 2f
		1:
		mrs x0, sctlr_el1
		bic x0, x0, #1 << 0 // clear SCTLR.M
		bic x0, x0, #1 << 2 // clear SCTLR.C
		msr sctlr_el1, x0
		isb
		2:
		/* Jump to kernel entry point */
		mov x0, x20
		mov x1, xzr
		mov x2, xzr
		mov x3, xzr
		br x21

		efi_load_fail:
		mov x0, #EFI_LOAD_ERROR
		ldp x29, x30, [sp], #32
		ret

		ENDPROC(efi_stub_entry)

arch/arm64/kernel/efi-stub.c

0 → 100644

+81 −0

Original line number	Diff line number	Diff line
		/*
		* Copyright (C) 2013, 2014 Linaro Ltd; <roy.franz@linaro.org>
		*
		* This file implements the EFI boot stub for the arm64 kernel.
		* Adapted from ARM version by Mark Salter <msalter@redhat.com>
		*
		* This program is free software; you can redistribute it and/or modify
		* it under the terms of the GNU General Public License version 2 as
		* published by the Free Software Foundation.
		*
		*/
		#include <linux/efi.h>
		#include <linux/libfdt.h>
		#include <asm/sections.h>
		#include <generated/compile.h>
		#include <generated/utsrelease.h>

		/*
		* AArch64 requires the DTB to be 8-byte aligned in the first 512MiB from
		* start of kernel and may not cross a 2MiB boundary. We set alignment to
		* 2MiB so we know it won't cross a 2MiB boundary.
		*/
		#define EFI_FDT_ALIGN SZ_2M /* used by allocate_new_fdt_and_exit_boot() */
		#define MAX_FDT_OFFSET SZ_512M

		#define efi_call_early(f, ...) sys_table_arg->boottime->f(__VA_ARGS__)

		static void efi_char16_printk(efi_system_table_t *sys_table_arg,
		efi_char16_t *str);

		static efi_status_t efi_open_volume(efi_system_table_t *sys_table,
		void __image, void *__fh);
		static efi_status_t efi_file_close(void *handle);

		static efi_status_t
		efi_file_read(void handle, unsigned long size, void *addr);

		static efi_status_t
		efi_file_size(efi_system_table_t sys_table, void __fh,
		efi_char16_t filename_16, void handle, u64 file_sz);

		/* Include shared EFI stub code */
		#include "../../../drivers/firmware/efi/efi-stub-helper.c"
		#include "../../../drivers/firmware/efi/fdt.c"
		#include "../../../drivers/firmware/efi/arm-stub.c"


		static efi_status_t handle_kernel_image(efi_system_table_t *sys_table,
		unsigned long *image_addr,
		unsigned long *image_size,
		unsigned long *reserve_addr,
		unsigned long *reserve_size,
		unsigned long dram_base,
		efi_loaded_image_t *image)
		{
		efi_status_t status;
		unsigned long kernel_size, kernel_memsize = 0;

		/* Relocate the image, if required. */
		kernel_size = _edata - _text;
		if (*image_addr != (dram_base + TEXT_OFFSET)) {
		kernel_memsize = kernel_size + (_end - _edata);
		status = efi_relocate_kernel(sys_table, image_addr,
		kernel_size, kernel_memsize,
		dram_base + TEXT_OFFSET,
		PAGE_SIZE);
		if (status != EFI_SUCCESS) {
		pr_efi_err(sys_table, "Failed to relocate kernel\n");
		return status;
		}
		if (*image_addr != (dram_base + TEXT_OFFSET)) {
		pr_efi_err(sys_table, "Failed to alloc kernel memory\n");
		efi_free(sys_table, kernel_memsize, *image_addr);
		return EFI_ERROR;
		}
		*image_size = kernel_memsize;
		}


		return EFI_SUCCESS;
		}

arch/arm64/kernel/head.S

+112 −0

Original line number	Diff line number	Diff line
		@@ -108,8 +108,18 @@
		/*
		* DO NOT MODIFY. Image header expected by Linux boot-loaders.
		*/
		#ifdef CONFIG_EFI
		efi_head:
		/*
		* This add instruction has no meaningful effect except that
		* its opcode forms the magic "MZ" signature required by UEFI.
		*/
		add x13, x18, #0x16
		b stext
		#else
		b stext // branch to kernel start, magic
		.long 0 // reserved
		#endif
		.quad TEXT_OFFSET // Image load offset from start of RAM
		.quad 0 // reserved
		.quad 0 // reserved
		@@ -120,7 +130,109 @@
		.byte 0x52
		.byte 0x4d
		.byte 0x64
		#ifdef CONFIG_EFI
		.long pe_header - efi_head // Offset to the PE header.
		#else
		.word 0 // reserved
		#endif

		#ifdef CONFIG_EFI
		.align 3
		pe_header:
		.ascii "PE"
		.short 0
		coff_header:
		.short 0xaa64 // AArch64
		.short 2 // nr_sections
		.long 0 // TimeDateStamp
		.long 0 // PointerToSymbolTable
		.long 1 // NumberOfSymbols
		.short section_table - optional_header // SizeOfOptionalHeader
		.short 0x206 // Characteristics.
		// IMAGE_FILE_DEBUG_STRIPPED \|
		// IMAGE_FILE_EXECUTABLE_IMAGE \|
		// IMAGE_FILE_LINE_NUMS_STRIPPED
		optional_header:
		.short 0x20b // PE32+ format
		.byte 0x02 // MajorLinkerVersion
		.byte 0x14 // MinorLinkerVersion
		.long _edata - stext // SizeOfCode
		.long 0 // SizeOfInitializedData
		.long 0 // SizeOfUninitializedData
		.long efi_stub_entry - efi_head // AddressOfEntryPoint
		.long stext - efi_head // BaseOfCode

		extra_header_fields:
		.quad 0 // ImageBase
		.long 0x20 // SectionAlignment
		.long 0x8 // FileAlignment
		.short 0 // MajorOperatingSystemVersion
		.short 0 // MinorOperatingSystemVersion
		.short 0 // MajorImageVersion
		.short 0 // MinorImageVersion
		.short 0 // MajorSubsystemVersion
		.short 0 // MinorSubsystemVersion
		.long 0 // Win32VersionValue

		.long _edata - efi_head // SizeOfImage

		// Everything before the kernel image is considered part of the header
		.long stext - efi_head // SizeOfHeaders
		.long 0 // CheckSum
		.short 0xa // Subsystem (EFI application)
		.short 0 // DllCharacteristics
		.quad 0 // SizeOfStackReserve
		.quad 0 // SizeOfStackCommit
		.quad 0 // SizeOfHeapReserve
		.quad 0 // SizeOfHeapCommit
		.long 0 // LoaderFlags
		.long 0x6 // NumberOfRvaAndSizes

		.quad 0 // ExportTable
		.quad 0 // ImportTable
		.quad 0 // ResourceTable
		.quad 0 // ExceptionTable
		.quad 0 // CertificationTable
		.quad 0 // BaseRelocationTable

		// Section table
		section_table:

		/*
		* The EFI application loader requires a relocation section
		* because EFI applications must be relocatable. This is a
		* dummy section as far as we are concerned.
		*/
		.ascii ".reloc"
		.byte 0
		.byte 0 // end of 0 padding of section name
		.long 0
		.long 0
		.long 0 // SizeOfRawData
		.long 0 // PointerToRawData
		.long 0 // PointerToRelocations
		.long 0 // PointerToLineNumbers
		.short 0 // NumberOfRelocations
		.short 0 // NumberOfLineNumbers
		.long 0x42100040 // Characteristics (section flags)


		.ascii ".text"
		.byte 0
		.byte 0
		.byte 0 // end of 0 padding of section name
		.long _edata - stext // VirtualSize
		.long stext - efi_head // VirtualAddress
		.long _edata - stext // SizeOfRawData
		.long stext - efi_head // PointerToRawData

		.long 0 // PointerToRelocations (0 for executables)
		.long 0 // PointerToLineNumbers (0 for executables)
		.short 0 // NumberOfRelocations (0 for executables)
		.short 0 // NumberOfLineNumbers (0 for executables)
		.long 0xe0500020 // Characteristics (section flags)
		.align 5
		#endif

		ENTRY(stext)
		mov x21, x0 // x21=FDT