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e506236a7b
Make use of the new alternative_if and alternative_else_nop_endif and get rid of our open-coded NOP sleds, making the code simpler to read. Note that for __kvm_call_hyp the branch to __vhe_hyp_call has been moved out of the alternative sequence, and in the default case there will be four additional NOPs executed. Cc: Marc Zyngier <marc.zyngier@arm.com> Cc: kvmarm@lists.cs.columbia.edu Acked-by: Christoffer Dall <christoffer.dall@linaro.org> Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
52 lines
1.8 KiB
ArmAsm
52 lines
1.8 KiB
ArmAsm
/*
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* Copyright (C) 2012,2013 - ARM Ltd
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* Author: Marc Zyngier <marc.zyngier@arm.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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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <linux/linkage.h>
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#include <asm/alternative.h>
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#include <asm/assembler.h>
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#include <asm/cpufeature.h>
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/*
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* u64 __kvm_call_hyp(void *hypfn, ...);
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*
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* This is not really a variadic function in the classic C-way and care must
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* be taken when calling this to ensure parameters are passed in registers
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* only, since the stack will change between the caller and the callee.
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*
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* Call the function with the first argument containing a pointer to the
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* function you wish to call in Hyp mode, and subsequent arguments will be
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* passed as x0, x1, and x2 (a maximum of 3 arguments in addition to the
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* function pointer can be passed). The function being called must be mapped
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* in Hyp mode (see init_hyp_mode in arch/arm/kvm/arm.c). Return values are
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* passed in x0.
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*
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* A function pointer with a value less than 0xfff has a special meaning,
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* and is used to implement __hyp_get_vectors in the same way as in
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* arch/arm64/kernel/hyp_stub.S.
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* HVC behaves as a 'bl' call and will clobber lr.
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*/
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ENTRY(__kvm_call_hyp)
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alternative_if_not ARM64_HAS_VIRT_HOST_EXTN
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str lr, [sp, #-16]!
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hvc #0
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ldr lr, [sp], #16
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ret
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alternative_else_nop_endif
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b __vhe_hyp_call
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ENDPROC(__kvm_call_hyp)
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