| Message ID | 1582447993-7594-1-git-send-email-macpaul.lin@mediatek.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | usb: gadget: f_fs: try to fix AIO issue under ARM 64 bit TAGGED mode | expand |
diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c index ce1d023..b21541a 100644 --- a/drivers/usb/gadget/function/f_fs.c +++ b/drivers/usb/gadget/function/f_fs.c @@ -35,6 +35,7 @@ #include <linux/mmu_context.h> #include <linux/poll.h> #include <linux/eventfd.h> +#include <linux/thread_info.h> #include "u_fs.h" #include "u_f.h" @@ -826,6 +827,8 @@ static void ffs_user_copy_worker(struct work_struct *work) if (io_data->read && ret > 0) { mm_segment_t oldfs = get_fs(); + if (IS_ENABLED(CONFIG_ARM64_TAGGED_ADDR_ABI)) + set_thread_flag(TIF_TAGGED_ADDR); set_fs(USER_DS); use_mm(io_data->mm); ret = ffs_copy_to_iter(io_data->buf, ret, &io_data->data);
This issue was found when adbd trying to open functionfs with AIO mode. Usually, we need to set "setprop sys.usb.ffs.aio_compat 0" to enable adbd with AIO mode on Android. When adbd is opening functionfs, it will try to read 24 bytes at the fisrt read I/O control. If this reading has been failed, adbd will try to send FUNCTIONFS_CLEAR_HALT to functionfs. When adbd is in AIO mode, functionfs will be acted with asyncronized I/O path. After the successful read transfer has been completed by gadget hardware, the following series of functions will be called. ffs_epfile_async_io_complete() -> ffs_user_copy_worker() -> copy_to_iter() -> _copy_to_iter() -> copyout() -> iterate_and_advance() -> iterate_iovec() Adding debug trace to these functions, it has been found that in copyout(), access_ok() will check if the user space address is valid to write. However if CONFIG_ARM64_TAGGED_ADDR_ABI is enabled, adbd always passes user space address start with "0x3C" to gdaget's AIO blocks. This tagged address will cause access_ok() check always fail. Which causes later calculation in iterate_iovec() turn zero. Copyout() won't copy data to userspace since the length to be copied "v.iov_len" will be zero. Finally leads ffs_copy_to_iter() always return -EFAULT, causes adbd cannot open functionfs and send FUNCTIONFS_CLEAR_HALT. Signed-off-by: Macpaul Lin <macpaul.lin@mediatek.com> --- drivers/usb/gadget/function/f_fs.c | 3 +++ 1 file changed, 3 insertions(+)