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ab520be8cd
Recently a new dm_op[1] hypercall was added to Xen to provide a mechanism
for restricting device emulators (such as QEMU) to a limited set of
hypervisor operations, and being able to audit those operations in the
kernel of the domain in which they run.
This patch adds IOCTL_PRIVCMD_DM_OP as gateway for __HYPERVISOR_dm_op.
NOTE: There is no requirement for user-space code to bounce data through
locked memory buffers (as with IOCTL_PRIVCMD_HYPERCALL) since
privcmd has enough information to lock the original buffers
directly.
[1] http://xenbits.xen.org/gitweb/?p=xen.git;a=commit;h=524a98c2
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
123 lines
3.7 KiB
ArmAsm
123 lines
3.7 KiB
ArmAsm
/******************************************************************************
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* hypercall.S
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*
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* Xen hypercall wrappers
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*
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* Stefano Stabellini <stefano.stabellini@eu.citrix.com>, Citrix, 2012
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License version 2
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* as published by the Free Software Foundation; or, when distributed
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* separately from the Linux kernel or incorporated into other
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* software packages, subject to the following license:
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this source file (the "Software"), to deal in the Software without
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* restriction, including without limitation the rights to use, copy, modify,
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* merge, publish, distribute, sublicense, and/or sell copies of the Software,
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* and to permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*/
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/*
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* The Xen hypercall calling convention is very similar to the ARM
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* procedure calling convention: the first paramter is passed in r0, the
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* second in r1, the third in r2 and the fourth in r3. Considering that
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* Xen hypercalls have 5 arguments at most, the fifth paramter is passed
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* in r4, differently from the procedure calling convention of using the
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* stack for that case.
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*
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* The hypercall number is passed in r12.
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*
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* The return value is in r0.
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*
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* The hvc ISS is required to be 0xEA1, that is the Xen specific ARM
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* hypercall tag.
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*/
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#include <linux/linkage.h>
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#include <asm/assembler.h>
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#include <asm/opcodes-virt.h>
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#include <xen/interface/xen.h>
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#define XEN_IMM 0xEA1
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#define HYPERCALL_SIMPLE(hypercall) \
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ENTRY(HYPERVISOR_##hypercall) \
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mov r12, #__HYPERVISOR_##hypercall; \
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__HVC(XEN_IMM); \
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ret lr; \
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ENDPROC(HYPERVISOR_##hypercall)
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#define HYPERCALL0 HYPERCALL_SIMPLE
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#define HYPERCALL1 HYPERCALL_SIMPLE
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#define HYPERCALL2 HYPERCALL_SIMPLE
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#define HYPERCALL3 HYPERCALL_SIMPLE
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#define HYPERCALL4 HYPERCALL_SIMPLE
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#define HYPERCALL5(hypercall) \
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ENTRY(HYPERVISOR_##hypercall) \
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stmdb sp!, {r4} \
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ldr r4, [sp, #4] \
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mov r12, #__HYPERVISOR_##hypercall; \
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__HVC(XEN_IMM); \
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ldm sp!, {r4} \
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ret lr \
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ENDPROC(HYPERVISOR_##hypercall)
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.text
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HYPERCALL2(xen_version);
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HYPERCALL3(console_io);
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HYPERCALL3(grant_table_op);
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HYPERCALL2(sched_op);
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HYPERCALL2(event_channel_op);
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HYPERCALL2(hvm_op);
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HYPERCALL2(memory_op);
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HYPERCALL2(physdev_op);
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HYPERCALL3(vcpu_op);
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HYPERCALL1(tmem_op);
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HYPERCALL1(platform_op_raw);
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HYPERCALL2(multicall);
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HYPERCALL2(vm_assist);
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HYPERCALL3(dm_op);
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ENTRY(privcmd_call)
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stmdb sp!, {r4}
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mov r12, r0
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mov r0, r1
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mov r1, r2
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mov r2, r3
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ldr r3, [sp, #8]
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/*
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* Privcmd calls are issued by the userspace. We need to allow the
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* kernel to access the userspace memory before issuing the hypercall.
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*/
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uaccess_enable r4
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/* r4 is loaded now as we use it as scratch register before */
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ldr r4, [sp, #4]
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__HVC(XEN_IMM)
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/*
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* Disable userspace access from kernel. This is fine to do it
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* unconditionally as no set_fs(KERNEL_DS)/set_fs(get_ds()) is
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* called before.
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*/
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uaccess_disable r4
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ldm sp!, {r4}
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ret lr
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ENDPROC(privcmd_call);
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