mirror of
https://github.com/torvalds/linux
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546c8c44f0
Apart from the arm64/linux and EFI header data structures, there is nothing in the .head.text section that must reside at the beginning of the Image. So let's move it to the .init section where it belongs. Note that this involves some minor tweaking of the EFI header, primarily because the address of 'stext' no longer coincides with the start of the .text section. It also requires a couple of relocated symbol references to be slightly rewritten or their definition moved to the linker script. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
126 lines
2.9 KiB
ArmAsm
126 lines
2.9 KiB
ArmAsm
/*
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* EFI entry point.
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*
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* Copyright (C) 2013, 2014 Red Hat, Inc.
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* Author: Mark Salter <msalter@redhat.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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*/
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#include <linux/linkage.h>
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#include <linux/init.h>
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#include <asm/assembler.h>
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#define EFI_LOAD_ERROR 0x8000000000000001
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__INIT
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/*
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* We arrive here from the EFI boot manager with:
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*
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* * CPU in little-endian mode
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* * MMU on with identity-mapped RAM
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* * Icache and Dcache on
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*
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* We will most likely be running from some place other than where
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* we want to be. The kernel image wants to be placed at TEXT_OFFSET
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* from start of RAM.
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*/
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ENTRY(entry)
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/*
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* Create a stack frame to save FP/LR with extra space
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* for image_addr variable passed to efi_entry().
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*/
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stp x29, x30, [sp, #-32]!
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mov x29, sp
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/*
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* Call efi_entry to do the real work.
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* x0 and x1 are already set up by firmware. Current runtime
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* address of image is calculated and passed via *image_addr.
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*
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* unsigned long efi_entry(void *handle,
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* efi_system_table_t *sys_table,
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* unsigned long *image_addr) ;
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*/
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adrp x8, _text
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add x8, x8, #:lo12:_text
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add x2, sp, 16
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str x8, [x2]
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bl efi_entry
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cmn x0, #1
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b.eq efi_load_fail
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/*
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* efi_entry() will have copied the kernel image if necessary and we
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* return here with device tree address in x0 and the kernel entry
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* point stored at *image_addr. Save those values in registers which
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* are callee preserved.
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*/
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mov x20, x0 // DTB address
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ldr x0, [sp, #16] // relocated _text address
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ldr w21, =stext_offset
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add x21, x0, x21
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/*
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* Calculate size of the kernel Image (same for original and copy).
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*/
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adrp x1, _text
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add x1, x1, #:lo12:_text
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adrp x2, _edata
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add x2, x2, #:lo12:_edata
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sub x1, x2, x1
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/*
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* Flush the copied Image to the PoC, and ensure it is not shadowed by
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* stale icache entries from before relocation.
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*/
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bl __flush_dcache_area
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ic ialluis
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/*
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* Ensure that the rest of this function (in the original Image) is
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* visible when the caches are disabled. The I-cache can't have stale
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* entries for the VA range of the current image, so no maintenance is
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* necessary.
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*/
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adr x0, entry
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adr x1, entry_end
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sub x1, x1, x0
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bl __flush_dcache_area
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/* Turn off Dcache and MMU */
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mrs x0, CurrentEL
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cmp x0, #CurrentEL_EL2
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b.ne 1f
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mrs x0, sctlr_el2
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bic x0, x0, #1 << 0 // clear SCTLR.M
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bic x0, x0, #1 << 2 // clear SCTLR.C
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msr sctlr_el2, x0
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isb
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b 2f
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1:
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mrs x0, sctlr_el1
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bic x0, x0, #1 << 0 // clear SCTLR.M
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bic x0, x0, #1 << 2 // clear SCTLR.C
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msr sctlr_el1, x0
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isb
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2:
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/* Jump to kernel entry point */
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mov x0, x20
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mov x1, xzr
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mov x2, xzr
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mov x3, xzr
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br x21
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efi_load_fail:
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mov x0, #EFI_LOAD_ERROR
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ldp x29, x30, [sp], #32
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ret
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entry_end:
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ENDPROC(entry)
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