uaccess: Add non-pagefault user-space read functions
Add probe_user_read(), strncpy_from_unsafe_user() and strnlen_unsafe_user() which allows caller to access user-space in IRQ context. Current probe_kernel_read() and strncpy_from_unsafe() are not available for user-space memory, because it sets KERNEL_DS while accessing data. On some arch, user address space and kernel address space can be co-exist, but others can not. In that case, setting KERNEL_DS means given address is treated as a kernel address space. Also strnlen_user() is only available from user context since it can sleep if pagefault is enabled. To access user-space memory without pagefault, we need these new functions which sets USER_DS while accessing the data. Link: http://lkml.kernel.org/r/155789869802.26965.4940338412595759063.stgit@devnote2Acked-by: NIngo Molnar <mingo@kernel.org> Signed-off-by: NMasami Hiramatsu <mhiramat@kernel.org> Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
Showing
想要评论请 注册 或 登录