0b61f2c0f3
When Xen is copying data to/from the guest it will check if the kernel
has the right to do the access. If not, the hypercall will return an
error.
After the commit a5e090acbf "ARM:
software-based privileged-no-access support", the kernel can't access
any longer the user space by default. This will result to fail on every
hypercall made by the userspace (i.e via privcmd).
We have to enable the userspace access and then restore the correct
permission every time the privcmd is used to made an hypercall.
I didn't find generic helpers to do a these operations, so the change
is only arm32 specific.
Reported-by: Riku Voipio <riku.voipio@linaro.org>
Signed-off-by: Julien Grall <julien.grall@citrix.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
121 lines
3.7 KiB
ArmAsm
121 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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HYPERCALL2(multicall);
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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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