Messages in this thread | | | Subject | Re: [PATCH 3/3] riscv: fix __user annotation for __copy_user() | From | Atish Patra <> | Date | Mon, 4 Jun 2018 11:46:50 -0700 |
| |
On 6/1/18 8:22 AM, Luc Van Oostenryck wrote: > __copy_user() is a function, written in assembly, used to copy > memory between kernel & user space. As such its to & from args > may both take a user pointer or a kernel pointer. > > However the prototype for this function declare these two args > as 'void __user *', which is no more & no less correct than > declaring them as 'void *'. In fact theer is no possible correct
/s/theer/there
> annotation for such a function. > > The problem is worked around here by declaring these args as > unsigned long and casting them to the right type in each of > two callers raw_copy_{to,from}_user() as some kind of cast would > be needed anyway. > > Note: another solution, maybe cleaner but slightly more complex, > would be to declare two version of __copy_user, > either in the asm file or via an alias, each having already > the correct typing for raw_copy_{to,from}_user(). >
I feel that would be a better solution as it is implemented similarly in ARM as well.
I am unable to understand how "unsigned long" is better than "void*". x86 implementation has both arguments as void*. Can you please clarify ?
Regards, Atish > Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com> > --- > arch/riscv/include/asm/uaccess.h | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/arch/riscv/include/asm/uaccess.h b/arch/riscv/include/asm/uaccess.h > index 14b0b22fb..c7a6a4a4a 100644 > --- a/arch/riscv/include/asm/uaccess.h > +++ b/arch/riscv/include/asm/uaccess.h > @@ -392,19 +392,19 @@ do { \ > }) > > > -extern unsigned long __must_check __copy_user(void __user *to, > - const void __user *from, unsigned long n); > +extern unsigned long __must_check __copy_user(unsigned long to, > + const unsigned long from, unsigned long n); > > static inline unsigned long > raw_copy_from_user(void *to, const void __user *from, unsigned long n) > { > - return __copy_user(to, from, n); > + return __copy_user((unsigned long)to, (unsigned long)from, n); > } > > static inline unsigned long > raw_copy_to_user(void __user *to, const void *from, unsigned long n) > { > - return __copy_user(to, from, n); > + return __copy_user((unsigned long)to, (unsigned long)from, n); > } > > extern long strncpy_from_user(char *dest, const char __user *src, long count); >
| |