* Xen hypercall wrappers
* Stefano Stabellini <email@example.com>, Citrix, 2012
* This program is free software; you can redistribute it and/or
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* The Xen hypercall calling convention is very similar to the procedure
* call standard for the ARM 64-bit architecture: the first parameter is
* passed in x0, the second in x1, the third in x2, the fourth in x3 and
* the fifth in x4.
* The hypercall number is passed in x16.
* The return value is in x0.
* The hvc ISS is required to be 0xEA1, that is the Xen specific ARM
* hypercall tag.
* Parameter structs passed to hypercalls are laid out according to
* the ARM 64-bit EABI standard.
#define XEN_IMM 0xEA1
#define HYPERCALL_SIMPLE(hypercall) \
mov x16, #__HYPERVISOR_##hypercall; \
hvc XEN_IMM; \
#define HYPERCALL0 HYPERCALL_SIMPLE
#define HYPERCALL1 HYPERCALL_SIMPLE
#define HYPERCALL2 HYPERCALL_SIMPLE
#define HYPERCALL3 HYPERCALL_SIMPLE
#define HYPERCALL4 HYPERCALL_SIMPLE
#define HYPERCALL5 HYPERCALL_SIMPLE
mov x16, x0
mov x0, x1
mov x1, x2
mov x2, x3
mov x3, x4
mov x4, x5
* Privcmd calls are issued by the userspace. The kernel needs to
* enable access to TTBR0_EL1 as the hypervisor would issue stage 1
* translations to user memory via AT instructions. Since AT
* instructions are not affected by the PAN bit (ARMv8.1), we only
* need the explicit uaccess_enable/disable if the TTBR0 PAN emulation
* is enabled (it implies that hardware UAO and PAN disabled).
uaccess_ttbr0_enable x6, x7
* Disable userspace access from kernel once the hyp call completed.