forked from Minki/linux
974c8e450b
The CurrentEL system register reports the Current Exception Level of the CPU. It doesn't say anything about the stack handling, and yet we compare it to PSR_MODE_EL2t and PSR_MODE_EL2h. It works by chance because PSR_MODE_EL2t happens to match the right bits, but that's otherwise a very bad idea. Just check for the EL value instead. Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> [catalin.marinas@arm.com: fixed arch/arm64/kernel/efi-entry.S] Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
109 lines
2.4 KiB
ArmAsm
109 lines
2.4 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(efi_stub_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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/*
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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 relocated the kernel image if necessary
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* and we return here with device tree address in x0 and the kernel
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* entry point stored at *image_addr. Save those values in registers
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* which 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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mov x21, x0
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/*
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* Flush dcache covering current runtime addresses
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* of kernel text/data. Then flush all of icache.
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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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bl __flush_dcache_area
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ic ialluis
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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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ENDPROC(efi_stub_entry)
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