diff mbox series

[v2] riscv: fix incorrect use of __user pointer

Message ID 20231124113803.165431-1-cleger@rivosinc.com
State New
Headers
Series [v2] riscv: fix incorrect use of __user pointer |

Commit Message

Clément Léger Nov. 24, 2023, 11:38 a.m. UTC 
  These warnings were reported by sparse and were due to lack of __user
annotation as well as dereferencing such pointer:

arch/riscv/kernel/traps_misaligned.c:361:21: warning: dereference of noderef expression
arch/riscv/kernel/traps_misaligned.c:373:21: warning: dereference of noderef expression
arch/riscv/kernel/traps_misaligned.c:381:21: warning: dereference of noderef expression
arch/riscv/kernel/traps_misaligned.c:322:24: warning: incorrect type in initializer (different address spaces)
arch/riscv/kernel/traps_misaligned.c:322:24:    expected unsigned char const [noderef] __user *__gu_ptr
arch/riscv/kernel/traps_misaligned.c:322:24:    got unsigned char const [usertype] *addr
arch/riscv/kernel/traps_misaligned.c:361:21: warning: dereference of noderef expression
arch/riscv/kernel/traps_misaligned.c:373:21: warning: dereference of noderef expression
arch/riscv/kernel/traps_misaligned.c:381:21: warning: dereference of noderef expression
arch/riscv/kernel/traps_misaligned.c:332:24: warning: incorrect type in initializer (different address spaces)
arch/riscv/kernel/traps_misaligned.c:332:24:    expected unsigned char [noderef] __user *__gu_ptr
arch/riscv/kernel/traps_misaligned.c:332:24:    got unsigned char [usertype] *addr

As suggested by Christoph Hellwig, casting pointers from an address
space to another is not a good idea and we should rather cast the
untyped unsigned long to their final address space. Fix the ones in
load_u8()/store_u8()/__read_insn() by passing a unsigned long and then
casting it to the appropriate type (__user of not) depending if used in
kernel/ user mode. Also remove unneeded else construct in store_u8()/
load_u8().

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202311160606.obGOOwB3-lkp@intel.com/
Signed-off-by: Clément Léger <cleger@rivosinc.com>
---
 arch/riscv/kernel/traps_misaligned.c | 55 +++++++++++++---------------
 1 file changed, 25 insertions(+), 30 deletions(-)

Comments

Christoph Hellwig Nov. 25, 2023, 6:22 a.m. UTC | #1 
On Fri, Nov 24, 2023 at 12:38:03PM +0100, Clément Léger wrote:
>  
>  #ifdef CONFIG_RISCV_M_MODE
> -static inline int load_u8(struct pt_regs *regs, const u8 *addr, u8 *r_val)
> +static inline int load_u8(struct pt_regs *regs, const unsigned long addr, u8 *r_val)

Please avoid the overly long line here.  Or just drop the const as that
is rather pointless for a scalaer (unlike the pointer).

Otherwise looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>
David Laight Nov. 25, 2023, 3:37 p.m. UTC | #2 
...
> @@ -491,7 +486,7 @@ int handle_misaligned_load(struct pt_regs *regs)
> 
>  	val.data_u64 = 0;
>  	for (i = 0; i < len; i++) {
> -		if (load_u8(regs, (void *)(addr + i), &val.data_bytes[i]))
> +		if (load_u8(regs, addr + i, &val.data_bytes[i]))
>  			return -1;
>  	}

I'd really have thought that you'd want to pull the kernel/user
check way outside the loop?
In any case, for a misaligned read why not just read (addr & ~7)[0]
and (if needed) (addr & ~7)[1] and then ahift and or together?

clang will do it for misaligned structure members with known
misalignment, but it is almost certainly also better for reads
with unknown misalignment.

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
Clément Léger Nov. 27, 2023, 10:24 a.m. UTC | #3 
On 25/11/2023 16:37, David Laight wrote:
> ...
>> @@ -491,7 +486,7 @@ int handle_misaligned_load(struct pt_regs *regs)
>>
>>  	val.data_u64 = 0;
>>  	for (i = 0; i < len; i++) {
>> -		if (load_u8(regs, (void *)(addr + i), &val.data_bytes[i]))
>> +		if (load_u8(regs, addr + i, &val.data_bytes[i]))
>>  			return -1;
>>  	}
> 
> I'd really have thought that you'd want to pull the kernel/user
> check way outside the loop?

Hi David,

I hope the compiler is able to extract that 'if' out of the loop since
regs isn't modified in the loop. Nevertheless, that could be more
"clear" if put outside indeed.

> In any case, for a misaligned read why not just read (addr & ~7)[0]
> and (if needed) (addr & ~7)[1] and then ahift and or together?

Makes sense, the original code was like that but probably copy/pasted
from openSBI I guess. (?)

Let's keep that for the moment (this patch is about fixing wrong __user
address space). I will try to submit another series using what you proposed.

Regards,

Clément

> 
> clang will do it for misaligned structure members with known
> misalignment, but it is almost certainly also better for reads
> with unknown misalignment.
> 
> 	David
> 
> -
> Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
> Registration No: 1397386 (Wales)
David Laight Nov. 27, 2023, 10:35 a.m. UTC | #4 
From: Clément Léger
> Sent: 27 November 2023 10:24
> 
> On 25/11/2023 16:37, David Laight wrote:
> > ...
> >> @@ -491,7 +486,7 @@ int handle_misaligned_load(struct pt_regs *regs)
> >>
> >>  	val.data_u64 = 0;
> >>  	for (i = 0; i < len; i++) {
> >> -		if (load_u8(regs, (void *)(addr + i), &val.data_bytes[i]))
> >> +		if (load_u8(regs, addr + i, &val.data_bytes[i]))
> >>  			return -1;
> >>  	}
> >
> > I'd really have thought that you'd want to pull the kernel/user
> > check way outside the loop?
> 
> Hi David,
> 
> I hope the compiler is able to extract that 'if' out of the loop since
> regs isn't modified in the loop. Nevertheless, that could be more
> "clear" if put outside indeed.

If has access regs->xxx then the compiler can't do so because it
will must assume that the assignment might alias into 'regs'.
That is even true for byte writes if 'strict-aliasing' is enabled
- which it isn't for linux kernel builds.

It might do so if 'regs' were 'const'; it tends to assume that if
it can't change  something nothing can - although that isn't true.

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
Clément Léger Nov. 27, 2023, 10:37 a.m. UTC | #5 
On 27/11/2023 11:35, David Laight wrote:
> From: Clément Léger
>> Sent: 27 November 2023 10:24
>>
>> On 25/11/2023 16:37, David Laight wrote:
>>> ...
>>>> @@ -491,7 +486,7 @@ int handle_misaligned_load(struct pt_regs *regs)
>>>>
>>>>  	val.data_u64 = 0;
>>>>  	for (i = 0; i < len; i++) {
>>>> -		if (load_u8(regs, (void *)(addr + i), &val.data_bytes[i]))
>>>> +		if (load_u8(regs, addr + i, &val.data_bytes[i]))
>>>>  			return -1;
>>>>  	}
>>>
>>> I'd really have thought that you'd want to pull the kernel/user
>>> check way outside the loop?
>>
>> Hi David,
>>
>> I hope the compiler is able to extract that 'if' out of the loop since
>> regs isn't modified in the loop. Nevertheless, that could be more
>> "clear" if put outside indeed.
> 
> If has access regs->xxx then the compiler can't do so because it
> will must assume that the assignment might alias into 'regs'.
> That is even true for byte writes if 'strict-aliasing' is enabled
> - which it isn't for linux kernel builds.
> 
> It might do so if 'regs' were 'const'; it tends to assume that if
> it can't change  something nothing can - although that isn't true.

Ok, good to know ! As I said, I'll modify that in a subsequent patch.

Thanks,

Clément

> 
> 	David
> 
> -
> Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
> Registration No: 1397386 (Wales)
David Laight Nov. 27, 2023, 10:51 a.m. UTC | #6 
From: Clément Léger
> Sent: 27 November 2023 10:37
> 
> On 27/11/2023 11:35, David Laight wrote:
> > From: Clément Léger
> >> Sent: 27 November 2023 10:24
> >>
> >> On 25/11/2023 16:37, David Laight wrote:
> >>> ...
> >>>> @@ -491,7 +486,7 @@ int handle_misaligned_load(struct pt_regs *regs)
> >>>>
> >>>>  	val.data_u64 = 0;
> >>>>  	for (i = 0; i < len; i++) {
> >>>> -		if (load_u8(regs, (void *)(addr + i), &val.data_bytes[i]))
> >>>> +		if (load_u8(regs, addr + i, &val.data_bytes[i]))
> >>>>  			return -1;
> >>>>  	}
> >>>
> >>> I'd really have thought that you'd want to pull the kernel/user
> >>> check way outside the loop?
> >>
> >> Hi David,
> >>
> >> I hope the compiler is able to extract that 'if' out of the loop since
> >> regs isn't modified in the loop. Nevertheless, that could be more
> >> "clear" if put outside indeed.
> >
> > If has access regs->xxx then the compiler can't do so because it
> > will must assume that the assignment might alias into 'regs'.
> > That is even true for byte writes if 'strict-aliasing' is enabled
> > - which it isn't for linux kernel builds.
> >
> > It might do so if 'regs' were 'const'; it tends to assume that if
> > it can't change  something nothing can - although that isn't true.
> 
> Ok, good to know ! As I said, I'll modify that in a subsequent patch.

Actually the following loops will (probably) generate much better code:
	// Read kernel
	val = 0;
	for (i = 0; i < len; i++)
		val |= addr[i] << (i * 8);
	// write kernel
	for (i = 0; i < len; i++, val >>= 8)
		addr[i] = val;
For user using __get/put_user() as appropriate.
I think there is a 'goto' variant of the user access functions
that probably make the code clearer.

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
Clément Léger Nov. 27, 2023, 12:46 p.m. UTC | #7 
On 27/11/2023 13:02, Ben Dooks wrote:
> On 24/11/2023 11:38, Clément Léger wrote:
>> These warnings were reported by sparse and were due to lack of __user
>> annotation as well as dereferencing such pointer:
>>
>> arch/riscv/kernel/traps_misaligned.c:361:21: warning: dereference of
>> noderef expression
>> arch/riscv/kernel/traps_misaligned.c:373:21: warning: dereference of
>> noderef expression
>> arch/riscv/kernel/traps_misaligned.c:381:21: warning: dereference of
>> noderef expression
>> arch/riscv/kernel/traps_misaligned.c:322:24: warning: incorrect type
>> in initializer (different address spaces)
>> arch/riscv/kernel/traps_misaligned.c:322:24:    expected unsigned char
>> const [noderef] __user *__gu_ptr
>> arch/riscv/kernel/traps_misaligned.c:322:24:    got unsigned char
>> const [usertype] *addr
>> arch/riscv/kernel/traps_misaligned.c:361:21: warning: dereference of
>> noderef expression
>> arch/riscv/kernel/traps_misaligned.c:373:21: warning: dereference of
>> noderef expression
>> arch/riscv/kernel/traps_misaligned.c:381:21: warning: dereference of
>> noderef expression
>> arch/riscv/kernel/traps_misaligned.c:332:24: warning: incorrect type
>> in initializer (different address spaces)
>> arch/riscv/kernel/traps_misaligned.c:332:24:    expected unsigned char
>> [noderef] __user *__gu_ptr
>> arch/riscv/kernel/traps_misaligned.c:332:24:    got unsigned char
>> [usertype] *addr
>>
>> As suggested by Christoph Hellwig, casting pointers from an address
>> space to another is not a good idea and we should rather cast the
>> untyped unsigned long to their final address space. Fix the ones in
>> load_u8()/store_u8()/__read_insn() by passing a unsigned long and then
>> casting it to the appropriate type (__user of not) depending if used in
>> kernel/ user mode. Also remove unneeded else construct in store_u8()/
>> load_u8().
>>
>> Reported-by: kernel test robot <lkp@intel.com>
>> Closes:
>> https://lore.kernel.org/oe-kbuild-all/202311160606.obGOOwB3-lkp@intel.com/
>> Signed-off-by: Clément Léger <cleger@rivosinc.com>
>> ---
>>   arch/riscv/kernel/traps_misaligned.c | 55 +++++++++++++---------------
>>   1 file changed, 25 insertions(+), 30 deletions(-)
>>
>> diff --git a/arch/riscv/kernel/traps_misaligned.c
>> b/arch/riscv/kernel/traps_misaligned.c
>> index 5eba37147caa..a92b88af855a 100644
>> --- a/arch/riscv/kernel/traps_misaligned.c
>> +++ b/arch/riscv/kernel/traps_misaligned.c
>> @@ -265,19 +265,19 @@ static unsigned long get_f32_rs(unsigned long
>> insn, u8 fp_reg_offset,
>>   #define GET_F32_RS2S(insn, regs) (get_f32_rs(RVC_RS2S(insn), 0, regs))
>>     #ifdef CONFIG_RISCV_M_MODE
>> -static inline int load_u8(struct pt_regs *regs, const u8 *addr, u8
>> *r_val)
>> +static inline int load_u8(struct pt_regs *regs, const unsigned long
>> addr, u8 *r_val)
>>   {
>>       u8 val;
>>   -    asm volatile("lbu %0, %1" : "=&r" (val) : "m" (*addr));
>> +    asm volatile("lbu %0, %1" : "=&r" (val) : "m" (*(const u8 *)addr));
>>       *r_val = val;
>>         return 0;
>>   }
>>   -static inline int store_u8(struct pt_regs *regs, u8 *addr, u8 val)
>> +static inline int store_u8(struct pt_regs *regs, unsigned long addr,
>> u8 val)
>>   {
>> -    asm volatile ("sb %0, %1\n" : : "r" (val), "m" (*addr));
>> +    asm volatile ("sb %0, %1\n" : : "r" (val), "m" (*(u8 *)addr));
>>         return 0;
>>   }
>> @@ -316,34 +316,32 @@ static inline int get_insn(struct pt_regs *regs,
>> ulong mepc, ulong *r_insn)
>>       return 0;
>>   }
>>   #else
>> -static inline int load_u8(struct pt_regs *regs, const u8 *addr, u8
>> *r_val)
>> +static inline int load_u8(struct pt_regs *regs, const unsigned long
>> addr, u8 *r_val)
>>   {
>> -    if (user_mode(regs)) {
>> -        return __get_user(*r_val, addr);
>> -    } else {
>> -        *r_val = *addr;
>> -        return 0;
>> -    }
>> +    if (user_mode(regs))
>> +        return __get_user(*r_val, (u8 __user *)addr);
>> +
>> +    *r_val = *(const u8 *)addr;
>> +    return 0;
>>   }
>>   -static inline int store_u8(struct pt_regs *regs, u8 *addr, u8 val)
>> +static inline int store_u8(struct pt_regs *regs, unsigned long addr,
>> u8 val)
>>   {
>> -    if (user_mode(regs)) {
>> -        return __put_user(val, addr);
>> -    } else {
>> -        *addr = val;
>> -        return 0;
>> -    }
>> +    if (user_mode(regs))
>> +        return __put_user(val, (u8 __user *)addr);
>> +
>> +    *(u8 *)addr = val;
>> +    return 0;
>>   }
>>   -#define __read_insn(regs, insn, insn_addr)        \
>> +#define __read_insn(regs, insn, insn_addr, type)    \
>>   ({                            \
>>       int __ret;                    \
>>                               \
>>       if (user_mode(regs)) {                \
>> -        __ret = __get_user(insn, insn_addr);    \
>> +        __ret = __get_user(insn, (type __user *) insn_addr); \
>>       } else {                    \
>> -        insn = *insn_addr;            \
>> +        insn = *(type *)insn_addr;        \
>>           __ret = 0;                \
>>       }                        \
>>                               \
>> @@ -356,9 +354,8 @@ static inline int get_insn(struct pt_regs *regs,
>> ulong epc, ulong *r_insn)
>>         if (epc & 0x2) {
>>           ulong tmp = 0;
>> -        u16 __user *insn_addr = (u16 __user *)epc;
>>   -        if (__read_insn(regs, insn, insn_addr))
>> +        if (__read_insn(regs, insn, epc, u16))
>>               return -EFAULT;
>>           /* __get_user() uses regular "lw" which sign extend the loaded
>>            * value make sure to clear higher order bits in case we
>> "or" it
>> @@ -369,16 +366,14 @@ static inline int get_insn(struct pt_regs *regs,
>> ulong epc, ulong *r_insn)
>>               *r_insn = insn;
>>               return 0;
>>           }
>> -        insn_addr++;
>> -        if (__read_insn(regs, tmp, insn_addr))
>> +        epc += sizeof(u16);
>> +        if (__read_insn(regs, tmp, epc, u16))
>>               return -EFAULT;
>>           *r_insn = (tmp << 16) | insn;
>>             return 0;
>>       } else {
>> -        u32 __user *insn_addr = (u32 __user *)epc;
>> -
>> -        if (__read_insn(regs, insn, insn_addr))
>> +        if (__read_insn(regs, insn, epc, u32))
>>               return -EFAULT;
>>           if ((insn & __INSN_LENGTH_MASK) == __INSN_LENGTH_32) {
>>               *r_insn = insn;
>> @@ -491,7 +486,7 @@ int handle_misaligned_load(struct pt_regs *regs)
>>         val.data_u64 = 0;
>>       for (i = 0; i < len; i++) {
>> -        if (load_u8(regs, (void *)(addr + i), &val.data_bytes[i]))
>> +        if (load_u8(regs, addr + i, &val.data_bytes[i]))
>>               return -1;
>>       }
>>   @@ -589,7 +584,7 @@ int handle_misaligned_store(struct pt_regs *regs)
>>           return -EOPNOTSUPP;
>>         for (i = 0; i < len; i++) {
>> -        if (store_u8(regs, (void *)(addr + i), val.data_bytes[i]))
>> +        if (store_u8(regs, addr + i, val.data_bytes[i]))
>>
> 
> Would it not be easier to have a switch here for memcpy or copy_to_user?

Most probably yes. I'll update the V3 with these modifications. We'll
get rid of store_u8()/load_u8() entirely.

Thanks,

Clément

> 
>                return -1;
>>       }
>>   
>
Clément Léger Nov. 27, 2023, 12:57 p.m. UTC | #8 
On 27/11/2023 13:46, Clément Léger wrote:
> 
> 
>>> @@ -369,16 +366,14 @@ static inline int get_insn(struct pt_regs *regs,
>>> ulong epc, ulong *r_insn)
>>>               *r_insn = insn;
>>>               return 0;
>>>           }
>>> -        insn_addr++;
>>> -        if (__read_insn(regs, tmp, insn_addr))
>>> +        epc += sizeof(u16);
>>> +        if (__read_insn(regs, tmp, epc, u16))
>>>               return -EFAULT;
>>>           *r_insn = (tmp << 16) | insn;
>>>             return 0;
>>>       } else {
>>> -        u32 __user *insn_addr = (u32 __user *)epc;
>>> -
>>> -        if (__read_insn(regs, insn, insn_addr))
>>> +        if (__read_insn(regs, insn, epc, u32))
>>>               return -EFAULT;
>>>           if ((insn & __INSN_LENGTH_MASK) == __INSN_LENGTH_32) {
>>>               *r_insn = insn;
>>> @@ -491,7 +486,7 @@ int handle_misaligned_load(struct pt_regs *regs)
>>>         val.data_u64 = 0;
>>>       for (i = 0; i < len; i++) {
>>> -        if (load_u8(regs, (void *)(addr + i), &val.data_bytes[i]))
>>> +        if (load_u8(regs, addr + i, &val.data_bytes[i]))
>>>               return -1;
>>>       }
>>>   @@ -589,7 +584,7 @@ int handle_misaligned_store(struct pt_regs *regs)
>>>           return -EOPNOTSUPP;
>>>         for (i = 0; i < len; i++) {
>>> -        if (store_u8(regs, (void *)(addr + i), val.data_bytes[i]))
>>> +        if (store_u8(regs, addr + i, val.data_bytes[i]))
>>>
>>
>> Would it not be easier to have a switch here for memcpy or copy_to_user?
> 
> Most probably yes. I'll update the V3 with these modifications. We'll
> get rid of store_u8()/load_u8() entirely.

While memcpy/copy_from_user will be slower than David Laight proposed
solution (read two 4/8 bytes long once and shifting the content) it is
more maintainable and this path of code will not suffer a few lost cycle
(emulating misaligned access is already horribly slow...).

BTW, need to check but maybe we can get rid of all the specific M_MODE
code entirely (__read_insn) also.

Clément

> 
> Thanks,
> 
> Clément
> 
>>
>>                return -1;
>>>       }
>>>   
>>
diff mbox series

Patch

diff --git a/arch/riscv/kernel/traps_misaligned.c b/arch/riscv/kernel/traps_misaligned.c
index 5eba37147caa..a92b88af855a 100644
--- a/arch/riscv/kernel/traps_misaligned.c
+++ b/arch/riscv/kernel/traps_misaligned.c
@@ -265,19 +265,19 @@  static unsigned long get_f32_rs(unsigned long insn, u8 fp_reg_offset,
 #define GET_F32_RS2S(insn, regs) (get_f32_rs(RVC_RS2S(insn), 0, regs))
 
 #ifdef CONFIG_RISCV_M_MODE
-static inline int load_u8(struct pt_regs *regs, const u8 *addr, u8 *r_val)
+static inline int load_u8(struct pt_regs *regs, const unsigned long addr, u8 *r_val)
 {
 	u8 val;
 
-	asm volatile("lbu %0, %1" : "=&r" (val) : "m" (*addr));
+	asm volatile("lbu %0, %1" : "=&r" (val) : "m" (*(const u8 *)addr));
 	*r_val = val;
 
 	return 0;
 }
 
-static inline int store_u8(struct pt_regs *regs, u8 *addr, u8 val)
+static inline int store_u8(struct pt_regs *regs, unsigned long addr, u8 val)
 {
-	asm volatile ("sb %0, %1\n" : : "r" (val), "m" (*addr));
+	asm volatile ("sb %0, %1\n" : : "r" (val), "m" (*(u8 *)addr));
 
 	return 0;
 }
@@ -316,34 +316,32 @@  static inline int get_insn(struct pt_regs *regs, ulong mepc, ulong *r_insn)
 	return 0;
 }
 #else
-static inline int load_u8(struct pt_regs *regs, const u8 *addr, u8 *r_val)
+static inline int load_u8(struct pt_regs *regs, const unsigned long addr, u8 *r_val)
 {
-	if (user_mode(regs)) {
-		return __get_user(*r_val, addr);
-	} else {
-		*r_val = *addr;
-		return 0;
-	}
+	if (user_mode(regs))
+		return __get_user(*r_val, (u8 __user *)addr);
+
+	*r_val = *(const u8 *)addr;
+	return 0;
 }
 
-static inline int store_u8(struct pt_regs *regs, u8 *addr, u8 val)
+static inline int store_u8(struct pt_regs *regs, unsigned long addr, u8 val)
 {
-	if (user_mode(regs)) {
-		return __put_user(val, addr);
-	} else {
-		*addr = val;
-		return 0;
-	}
+	if (user_mode(regs))
+		return __put_user(val, (u8 __user *)addr);
+
+	*(u8 *)addr = val;
+	return 0;
 }
 
-#define __read_insn(regs, insn, insn_addr)		\
+#define __read_insn(regs, insn, insn_addr, type)	\
 ({							\
 	int __ret;					\
 							\
 	if (user_mode(regs)) {				\
-		__ret = __get_user(insn, insn_addr);	\
+		__ret = __get_user(insn, (type __user *) insn_addr); \
 	} else {					\
-		insn = *insn_addr;			\
+		insn = *(type *)insn_addr;		\
 		__ret = 0;				\
 	}						\
 							\
@@ -356,9 +354,8 @@  static inline int get_insn(struct pt_regs *regs, ulong epc, ulong *r_insn)
 
 	if (epc & 0x2) {
 		ulong tmp = 0;
-		u16 __user *insn_addr = (u16 __user *)epc;
 
-		if (__read_insn(regs, insn, insn_addr))
+		if (__read_insn(regs, insn, epc, u16))
 			return -EFAULT;
 		/* __get_user() uses regular "lw" which sign extend the loaded
 		 * value make sure to clear higher order bits in case we "or" it
@@ -369,16 +366,14 @@  static inline int get_insn(struct pt_regs *regs, ulong epc, ulong *r_insn)
 			*r_insn = insn;
 			return 0;
 		}
-		insn_addr++;
-		if (__read_insn(regs, tmp, insn_addr))
+		epc += sizeof(u16);
+		if (__read_insn(regs, tmp, epc, u16))
 			return -EFAULT;
 		*r_insn = (tmp << 16) | insn;
 
 		return 0;
 	} else {
-		u32 __user *insn_addr = (u32 __user *)epc;
-
-		if (__read_insn(regs, insn, insn_addr))
+		if (__read_insn(regs, insn, epc, u32))
 			return -EFAULT;
 		if ((insn & __INSN_LENGTH_MASK) == __INSN_LENGTH_32) {
 			*r_insn = insn;
@@ -491,7 +486,7 @@  int handle_misaligned_load(struct pt_regs *regs)
 
 	val.data_u64 = 0;
 	for (i = 0; i < len; i++) {
-		if (load_u8(regs, (void *)(addr + i), &val.data_bytes[i]))
+		if (load_u8(regs, addr + i, &val.data_bytes[i]))
 			return -1;
 	}
 
@@ -589,7 +584,7 @@  int handle_misaligned_store(struct pt_regs *regs)
 		return -EOPNOTSUPP;
 
 	for (i = 0; i < len; i++) {
-		if (store_u8(regs, (void *)(addr + i), val.data_bytes[i]))
+		if (store_u8(regs, addr + i, val.data_bytes[i]))
 			return -1;
 	}