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linux-next/arch/arm64/kernel/efi-entry.S
Ard Biesheuvel cd1b76bb73 arm64: efi: add missing frame pointer assignment
The prologue of the EFI entry point pushes x29 and x30 onto the stack but
fails to create the stack frame correctly by omitting the assignment of x29
to the new value of the stack pointer. So fix that.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-03-04 18:12:23 +00:00

126 lines
2.9 KiB
ArmAsm

/*
* 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(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]!
mov x29, sp
/*
* 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
movz x21, #:abs_g0:stext_offset
add x21, x0, x21
/*
* 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, entry
adr x1, 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
entry_end:
ENDPROC(entry)