diff options
| author | Marc Zyngier <marc.zyngier@arm.com> | 2017-04-03 19:37:38 +0100 |
|---|---|---|
| committer | Christoffer Dall <cdall@linaro.org> | 2017-04-09 07:49:19 -0700 |
| commit | 810c86ee4ee70928952fe17bc593d569052d8198 (patch) | |
| tree | 637d71caa18c3d49ccc5b3df7127af4628cbce1d /arch/arm64/include/asm/virt.h | |
| parent | 4993fdcf399f59ed56a16ecfedf8a61066198816 (diff) | |
arm64: hyp-stub: Update documentation in asm/virt.h
Comments in asm/virt.h are slightly out of date, so let's align
them with the new behaviour of the code.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <cdall@linaro.org>
Diffstat (limited to 'arch/arm64/include/asm/virt.h')
| -rw-r--r-- | arch/arm64/include/asm/virt.h | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/arch/arm64/include/asm/virt.h b/arch/arm64/include/asm/virt.h index 1466d14c664d..1569c3a0d794 100644 --- a/arch/arm64/include/asm/virt.h +++ b/arch/arm64/include/asm/virt.h @@ -19,9 +19,14 @@ #define __ASM__VIRT_H /* - * The arm64 hcall implementation uses x0 to specify the hcall type. A value - * less than 0xfff indicates a special hcall, such as get/set vector. - * Any other value is used as a pointer to the function to call. + * The arm64 hcall implementation uses x0 to specify the hcall + * number. A value less than HVC_STUB_HCALL_NR indicates a special + * hcall, such as set vector. Any other value is handled in a + * hypervisor specific way. + * + * The hypercall is allowed to clobber any of the caller-saved + * registers (x0-x18), so it is advisable to use it through the + * indirection of a function call (as implemented in hyp-stub.S). */ /* HVC_GET_VECTORS - Return the value of the vbar_el2 register. */ |