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/*
* 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 copied 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
/*
* Calculate size of the kernel Image (same for original and copy).
*/
adrp x1, _text
add x1, x1, #:lo12:_text
adrp x2, _edata
add x2, x2, #:lo12:_edata
sub x1, x2, x1
/*
* Flush the copied Image to the PoC, and ensure it is not shadowed by
* stale icache entries from before relocation.
*/
bl __flush_dcache_area
ic ialluis
/*
* Ensure that the rest of this function (in the original Image) is
* visible when the caches are disabled. The I-cache can't have stale
* entries for the VA range of the current image, so no maintenance is
* necessary.
*/
adr x0, efi_stub_entry
adr x1, efi_stub_entry_end
sub x1, x1, x0
bl __flush_dcache_area
/* Turn off Dcache and MMU */
mrs x0, CurrentEL
cmp x0, #CurrentEL_EL2
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
efi_stub_entry_end:
ENDPROC(efi_stub_entry)
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