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/*
* Copyright (C) 2012,2013 - ARM Ltd
* Author: Marc Zyngier <marc.zyngier@arm.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.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <linux/linkage.h>
#include <asm/alternative.h>
#include <asm/assembler.h>
#include <asm/cpufeature.h>
/*
* u64 __kvm_call_hyp(void *hypfn, ...);
*
* This is not really a variadic function in the classic C-way and care must
* be taken when calling this to ensure parameters are passed in registers
* only, since the stack will change between the caller and the callee.
*
* Call the function with the first argument containing a pointer to the
* function you wish to call in Hyp mode, and subsequent arguments will be
* passed as x0, x1, and x2 (a maximum of 3 arguments in addition to the
* function pointer can be passed). The function being called must be mapped
* in Hyp mode (see init_hyp_mode in arch/arm/kvm/arm.c). Return values are
* passed in x0.
*
* A function pointer with a value less than 0xfff has a special meaning,
* and is used to implement __hyp_get_vectors in the same way as in
* arch/arm64/kernel/hyp_stub.S.
* HVC behaves as a 'bl' call and will clobber lr.
*/
ENTRY(__kvm_call_hyp)
alternative_if_not ARM64_HAS_VIRT_HOST_EXTN
str lr, [sp, #-16]!
hvc #0
ldr lr, [sp], #16
ret
alternative_else
b __vhe_hyp_call
nop
nop
nop
alternative_endif
ENDPROC(__kvm_call_hyp)
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