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The existing arm64 hcall implementations are limited in that they only
allow for two distinct hcalls; with the x0 register either zero or not
zero. Also, the API of the hyp-stub exception vector routines and the
KVM exception vector routines differ; hyp-stub uses a non-zero value in
x0 to implement __hyp_set_vectors, whereas KVM uses it to implement
kvm_call_hyp.
To allow for additional hcalls to be defined and to make the arm64 hcall
API more consistent across exception vector routines, change the hcall
implementations to reserve all x0 values below 0xfff for hcalls such
as {s,g}et_vectors().
Define two new preprocessor macros HVC_GET_VECTORS, and HVC_SET_VECTORS
to be used as hcall type specifiers and convert the existing
__hyp_get_vectors() and __hyp_set_vectors() routines to use these new
macros when executing an HVC call. Also, change the corresponding
hyp-stub and KVM el1_sync exception vector routines to use these new
macros.
Signed-off-by: Geoff Levand <geoff@infradead.org>
[Merged two hcall patches, moved immediate value from esr to x0, use lr
as a scratch register, changed limit to 0xfff]
Signed-off-by: James Morse <james.morse@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
56 lines
1.9 KiB
ArmAsm
56 lines
1.9 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
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b __vhe_hyp_call
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nop
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nop
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nop
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alternative_endif
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ENDPROC(__kvm_call_hyp)
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