root/arch/arm64/kvm/hyp.S

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * Copyright (C) 2012,2013 - ARM Ltd
   4  * Author: Marc Zyngier <marc.zyngier@arm.com>
   5  */
   6 
   7 #include <linux/linkage.h>
   8 
   9 #include <asm/alternative.h>
  10 #include <asm/assembler.h>
  11 #include <asm/cpufeature.h>
  12 
  13 /*
  14  * u64 __kvm_call_hyp(void *hypfn, ...);
  15  *
  16  * This is not really a variadic function in the classic C-way and care must
  17  * be taken when calling this to ensure parameters are passed in registers
  18  * only, since the stack will change between the caller and the callee.
  19  *
  20  * Call the function with the first argument containing a pointer to the
  21  * function you wish to call in Hyp mode, and subsequent arguments will be
  22  * passed as x0, x1, and x2 (a maximum of 3 arguments in addition to the
  23  * function pointer can be passed).  The function being called must be mapped
  24  * in Hyp mode (see init_hyp_mode in arch/arm/kvm/arm.c).  Return values are
  25  * passed in x0.
  26  *
  27  * A function pointer with a value less than 0xfff has a special meaning,
  28  * and is used to implement hyp stubs in the same way as in
  29  * arch/arm64/kernel/hyp_stub.S.
  30  */
  31 ENTRY(__kvm_call_hyp)
  32         hvc     #0
  33         ret
  34 ENDPROC(__kvm_call_hyp)