![Alexei Starovoitov](/assets/img/avatar_default.png)
generalize FETCH_FUNC_NAME(memory, string) into strncpy_from_unsafe() and fix sparse warnings that were present in original implementation. Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
135 lines
4.1 KiB
C
135 lines
4.1 KiB
C
#ifndef __LINUX_UACCESS_H__
|
|
#define __LINUX_UACCESS_H__
|
|
|
|
#include <linux/sched.h>
|
|
#include <asm/uaccess.h>
|
|
|
|
static __always_inline void pagefault_disabled_inc(void)
|
|
{
|
|
current->pagefault_disabled++;
|
|
}
|
|
|
|
static __always_inline void pagefault_disabled_dec(void)
|
|
{
|
|
current->pagefault_disabled--;
|
|
WARN_ON(current->pagefault_disabled < 0);
|
|
}
|
|
|
|
/*
|
|
* These routines enable/disable the pagefault handler. If disabled, it will
|
|
* not take any locks and go straight to the fixup table.
|
|
*
|
|
* User access methods will not sleep when called from a pagefault_disabled()
|
|
* environment.
|
|
*/
|
|
static inline void pagefault_disable(void)
|
|
{
|
|
pagefault_disabled_inc();
|
|
/*
|
|
* make sure to have issued the store before a pagefault
|
|
* can hit.
|
|
*/
|
|
barrier();
|
|
}
|
|
|
|
static inline void pagefault_enable(void)
|
|
{
|
|
/*
|
|
* make sure to issue those last loads/stores before enabling
|
|
* the pagefault handler again.
|
|
*/
|
|
barrier();
|
|
pagefault_disabled_dec();
|
|
}
|
|
|
|
/*
|
|
* Is the pagefault handler disabled? If so, user access methods will not sleep.
|
|
*/
|
|
#define pagefault_disabled() (current->pagefault_disabled != 0)
|
|
|
|
/*
|
|
* The pagefault handler is in general disabled by pagefault_disable() or
|
|
* when in irq context (via in_atomic()).
|
|
*
|
|
* This function should only be used by the fault handlers. Other users should
|
|
* stick to pagefault_disabled().
|
|
* Please NEVER use preempt_disable() to disable the fault handler. With
|
|
* !CONFIG_PREEMPT_COUNT, this is like a NOP. So the handler won't be disabled.
|
|
* in_atomic() will report different values based on !CONFIG_PREEMPT_COUNT.
|
|
*/
|
|
#define faulthandler_disabled() (pagefault_disabled() || in_atomic())
|
|
|
|
#ifndef ARCH_HAS_NOCACHE_UACCESS
|
|
|
|
static inline unsigned long __copy_from_user_inatomic_nocache(void *to,
|
|
const void __user *from, unsigned long n)
|
|
{
|
|
return __copy_from_user_inatomic(to, from, n);
|
|
}
|
|
|
|
static inline unsigned long __copy_from_user_nocache(void *to,
|
|
const void __user *from, unsigned long n)
|
|
{
|
|
return __copy_from_user(to, from, n);
|
|
}
|
|
|
|
#endif /* ARCH_HAS_NOCACHE_UACCESS */
|
|
|
|
/**
|
|
* probe_kernel_address(): safely attempt to read from a location
|
|
* @addr: address to read from - its type is type typeof(retval)*
|
|
* @retval: read into this variable
|
|
*
|
|
* Safely read from address @addr into variable @revtal. If a kernel fault
|
|
* happens, handle that and return -EFAULT.
|
|
* We ensure that the __get_user() is executed in atomic context so that
|
|
* do_page_fault() doesn't attempt to take mmap_sem. This makes
|
|
* probe_kernel_address() suitable for use within regions where the caller
|
|
* already holds mmap_sem, or other locks which nest inside mmap_sem.
|
|
* This must be a macro because __get_user() needs to know the types of the
|
|
* args.
|
|
*
|
|
* We don't include enough header files to be able to do the set_fs(). We
|
|
* require that the probe_kernel_address() caller will do that.
|
|
*/
|
|
#define probe_kernel_address(addr, retval) \
|
|
({ \
|
|
long ret; \
|
|
mm_segment_t old_fs = get_fs(); \
|
|
\
|
|
set_fs(KERNEL_DS); \
|
|
pagefault_disable(); \
|
|
ret = __copy_from_user_inatomic(&(retval), (__force typeof(retval) __user *)(addr), sizeof(retval)); \
|
|
pagefault_enable(); \
|
|
set_fs(old_fs); \
|
|
ret; \
|
|
})
|
|
|
|
/*
|
|
* probe_kernel_read(): safely attempt to read from a location
|
|
* @dst: pointer to the buffer that shall take the data
|
|
* @src: address to read from
|
|
* @size: size of the data chunk
|
|
*
|
|
* Safely read from address @src to the buffer at @dst. If a kernel fault
|
|
* happens, handle that and return -EFAULT.
|
|
*/
|
|
extern long probe_kernel_read(void *dst, const void *src, size_t size);
|
|
extern long __probe_kernel_read(void *dst, const void *src, size_t size);
|
|
|
|
/*
|
|
* probe_kernel_write(): safely attempt to write to a location
|
|
* @dst: address to write to
|
|
* @src: pointer to the data that shall be written
|
|
* @size: size of the data chunk
|
|
*
|
|
* Safely write to address @dst from the buffer at @src. If a kernel fault
|
|
* happens, handle that and return -EFAULT.
|
|
*/
|
|
extern long notrace probe_kernel_write(void *dst, const void *src, size_t size);
|
|
extern long notrace __probe_kernel_write(void *dst, const void *src, size_t size);
|
|
|
|
extern long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count);
|
|
|
|
#endif /* __LINUX_UACCESS_H__ */
|