On Tue, Feb 11, 2014 at 09:57:20PM -0800, Victor Kamensky wrote:
> This patch fixes issue of reading and writing V8 sys registers in
> BE case. It is similar to V7 "ARM: kvm one_reg coproc set and get
> BE fixes" patch.
>
> It changes reg_from_user and reg_to_user functions to have strong
> typed 'u64 *val' argument. And it uses endian angnostic way to
> pick up righ word from '*val' in case when register size is 4 bytes.
>
> Signed-off-by: Victor Kamensky <victor.kamensky@xxxxxxxxxx>
> ---
> arch/arm64/kvm/sys_regs.c | 39 +++++++++++++++++++++++++++++++++------
> 1 file changed, 33 insertions(+), 6 deletions(-)
>
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index 02e9d09..e7c3e24 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -701,18 +701,45 @@ 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);
> + 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;
This should never happen for arm64, right? IIRC, we expose all system
registers, even the aarch32 ones, as 64-bit versions with padded zeros,
just like in the ARM ARM...
> + case 8:
> + *val = tmp.dword;
> + break;
> + }
> return 0;
> }
>
> -static int reg_to_user(void __user *uaddr, const void *val, u64 id)
> +static int reg_to_user(void __user *uaddr, const u64 *val, u64 id)
> {
> - /* This Just Works because we are little endian. */
> - if (copy_to_user(uaddr, val, KVM_REG_SIZE(id)) != 0)
> + unsigned long regsize = KVM_REG_SIZE(id);
> + union {
> + u32 word;
> + u64 dword;
> + } tmp;
> +
> + switch (regsize) {
> + case 4:
> + tmp.word = *val;
> + break;
same
> + case 8:
> + tmp.dword = *val;
> + break;
> + }
> +
> + if (copy_to_user(uaddr, &tmp, regsize) != 0)
> return -EFAULT;
> return 0;
> }
> --
> 1.8.1.4
>
--
Christoffer
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