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@xxxxxxxxxx>
---
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);
+
+ if (copy_from_user(val, uaddr, regsize) != 0)
return -EFAULT;
+
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);
+
+ BUG_ON(regsize != 8);
+
+ if (copy_to_user(uaddr, val, regsize) != 0)
return -EFAULT;
return 0;
}
--
1.8.1.4
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