From: marc.zyngier@arm•com (Marc Zyngier)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v3 13/14] ARM64: KVM: set and get of sys registers in BE case
Date: Wed, 14 May 2014 09:45:37 +0100 [thread overview]
Message-ID: <87lhu4hhou.fsf@approximate.cambridge.arm.com> (raw)
In-Reply-To: <1399997646-4716-14-git-send-email-victor.kamensky@linaro.org> (Victor Kamensky's message of "Tue, 13 May 2014 17:14:05 +0100")
Hi Victor,
On Tue, May 13 2014 at 5:14:05 pm BST, Victor Kamensky <victor.kamensky@linaro•org> wrote:
> This patch addresses issue of reading and writing V8 sys registers in
> BE case. Since only register size function deals with is 8 bytes,
> existing code works in both little and big endian cases.
> Removed comment about little endian. Added BUG_ON that register
> size should be always 8 bytes.
>
> If these functions would ever need to support both 8 bytes and 4 bytes
> register sizes to deals with them in endian agnostic way code should
> do something along these lines:
>
> unsigned long regsize = KVM_REG_SIZE(id);
> union {
> u32 word;
> u64 dword;
> } tmp = {0};
>
> if (copy_from_user(&tmp, uaddr, regsize) != 0)
> return -EFAULT;
> switch (regsize) {
> case 4:
> *val = tmp.word;
> break;
> case 8:
> *val = tmp.dword;
> break;
> }
>
> Signed-off-by: Victor Kamensky <victor.kamensky@linaro•org>
> ---
> arch/arm64/kvm/sys_regs.c | 19 +++++++++++++------
> 1 file changed, 13 insertions(+), 6 deletions(-)
>
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index 0324458..060c3a9 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -776,18 +776,25 @@ static struct sys_reg_desc invariant_sys_regs[] = {
> NULL, get_ctr_el0 },
> };
>
> -static int reg_from_user(void *val, const void __user *uaddr, u64 id)
> +static int reg_from_user(u64 *val, const void __user *uaddr, u64 id)
> {
> - /* This Just Works because we are little endian. */
> - if (copy_from_user(val, uaddr, KVM_REG_SIZE(id)) != 0)
> + unsigned long regsize = KVM_REG_SIZE(id);
> +
> + BUG_ON(regsize != 8);
I haven't had time to review this series just yet, but this bit just
sends chivers down my spine.
regsize is derived from id, which comes from a struct one_reg, which is
directly provided by userspace. Here, you're trusting the luser to give
you 8 as a size, and panic the kernel if not.
As much as I'd like to qualify this as only being a slightly undesirable
effect, I think it deserves a NAK.
Thanks,
M.
--
Jazz is not dead. It just smells funny.
next prev parent reply other threads:[~2014-05-14 8:45 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-13 16:13 [PATCH v3 00/14] ARM/ARM64: KVM: big endian host support Victor Kamensky
2014-05-13 16:13 ` [PATCH v3 01/14] ARM: KVM: switch hypervisor into BE mode in case of BE host Victor Kamensky
2014-05-27 14:23 ` Marc Zyngier
2014-05-13 16:13 ` [PATCH v3 02/14] ARM: KVM: fix vgic V7 assembler code to work in BE image Victor Kamensky
2014-05-27 14:24 ` Marc Zyngier
2014-05-13 16:13 ` [PATCH v3 03/14] ARM: KVM: handle 64bit values passed to mrcc or from mcrr instructions in BE case Victor Kamensky
2014-05-26 15:28 ` Christoffer Dall
2014-05-28 6:09 ` Victor Kamensky
2014-05-27 14:30 ` Marc Zyngier
2014-05-13 16:13 ` [PATCH v3 04/14] ARM: KVM: __kvm_vcpu_run function return result fix " Victor Kamensky
2014-05-27 15:02 ` Marc Zyngier
2014-05-28 6:10 ` Victor Kamensky
2014-05-13 16:13 ` [PATCH v3 05/14] ARM: KVM: vgic mmio should hold data as LE bytes array " Victor Kamensky
2014-05-27 15:07 ` Marc Zyngier
2014-05-13 16:13 ` [PATCH v3 06/14] ARM: KVM: MMIO support BE host running LE code Victor Kamensky
2014-05-27 15:49 ` Marc Zyngier
2014-05-13 16:13 ` [PATCH v3 07/14] ARM: KVM: one_reg coproc set and get BE fixes Victor Kamensky
2014-05-25 19:14 ` Christoffer Dall
2014-05-28 6:19 ` Victor Kamensky
2014-05-28 8:03 ` Christoffer Dall
2014-05-27 18:22 ` Marc Zyngier
2014-05-28 6:23 ` Victor Kamensky
2014-05-13 16:14 ` [PATCH v3 08/14] ARM: KVM: enable KVM in Kconfig on big-endian systems Victor Kamensky
2014-05-13 16:14 ` [PATCH v3 09/14] ARM64: KVM: MMIO support BE host running LE code Victor Kamensky
2014-05-27 18:25 ` Marc Zyngier
2014-05-13 16:14 ` [PATCH v3 10/14] ARM64: KVM: store kvm_vcpu_fault_info est_el2 as word Victor Kamensky
2014-05-27 18:34 ` Marc Zyngier
2014-05-13 16:14 ` [PATCH v3 11/14] ARM64: KVM: fix vgic_bitmap_get_reg function for BE 64bit case Victor Kamensky
2014-05-26 15:49 ` Christoffer Dall
2014-05-13 16:14 ` [PATCH v3 12/14] ARM64: KVM: vgic_elrsr and vgic_eisr need to be byteswapped in BE case Victor Kamensky
2014-05-26 17:35 ` Christoffer Dall
2014-05-27 19:11 ` Marc Zyngier
2014-05-13 16:14 ` [PATCH v3 13/14] ARM64: KVM: set and get of sys registers " Victor Kamensky
2014-05-14 8:45 ` Marc Zyngier [this message]
2014-05-14 14:18 ` Victor Kamensky
2014-05-25 18:26 ` Christoffer Dall
2014-05-13 16:14 ` [PATCH v3 14/14] ARM64: KVM: fix big endian issue in access_vm_reg for 32bit guest Victor Kamensky
2014-05-26 17:52 ` Christoffer Dall
2014-05-28 6:11 ` Victor Kamensky
2014-05-28 9:14 ` Christoffer Dall
2014-05-28 13:56 ` Victor Kamensky
2014-05-28 14:09 ` Christoffer Dall
2014-05-28 14:20 ` Marc Zyngier
2014-05-26 15:49 ` [PATCH v3 00/14] ARM/ARM64: KVM: big endian host support Christoffer Dall
2014-05-28 6:31 ` Victor Kamensky
2014-05-28 8:12 ` Christoffer Dall
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