diff options
Diffstat (limited to 'arch/x86/lib/usercopy.c')
| -rw-r--r-- | arch/x86/lib/usercopy.c | 34 |
1 files changed, 28 insertions, 6 deletions
diff --git a/arch/x86/lib/usercopy.c b/arch/x86/lib/usercopy.c index c8c6ad0d58b8..24b48af27417 100644 --- a/arch/x86/lib/usercopy.c +++ b/arch/x86/lib/usercopy.c @@ -6,26 +6,48 @@ #include <linux/uaccess.h> #include <linux/export.h> +#include <linux/instrumented.h> -/* - * We rely on the nested NMI work to allow atomic faults from the NMI path; the - * nested NMI paths are careful to preserve CR2. +#include <asm/tlbflush.h> + +/** + * copy_from_user_nmi - NMI safe copy from user + * @to: Pointer to the destination buffer + * @from: Pointer to a user space address of the current task + * @n: Number of bytes to copy + * + * Returns: The number of not copied bytes. 0 is success, i.e. all bytes copied + * + * Contrary to other copy_from_user() variants this function can be called + * from NMI context. Despite the name it is not restricted to be called + * from NMI context. It is safe to be called from any other context as + * well. It disables pagefaults across the copy which means a fault will + * abort the copy. + * + * For NMI context invocations this relies on the nested NMI work to allow + * atomic faults from the NMI path; the nested NMI paths are careful to + * preserve CR2. */ unsigned long copy_from_user_nmi(void *to, const void __user *from, unsigned long n) { unsigned long ret; - if (__range_not_ok(from, n, TASK_SIZE)) + if (!__access_ok(from, n)) + return n; + + if (!nmi_uaccess_okay()) return n; /* * Even though this function is typically called from NMI/IRQ context * disable pagefaults so that its behaviour is consistent even when - * called form other contexts. + * called from other contexts. */ pagefault_disable(); - ret = __copy_from_user_inatomic(to, from, n); + instrument_copy_from_user_before(to, from, n); + ret = raw_copy_from_user(to, from, n); + instrument_copy_from_user_after(to, from, n, ret); pagefault_enable(); return ret; |