diff options
| author | Ian Abbott <abbotti@mev.co.uk> | 2017-04-20 19:05:14 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-04-25 20:43:42 +0200 |
| commit | 255364f7b8a0fee3fb642b3e1521e943dd67bfb3 (patch) | |
| tree | 9b67464441cc98d69eece7d42852637ee3dd89ca /drivers/staging/comedi/comedi_buf.c | |
| parent | e44adf05b85e5a9d1d224f5ecde1c1c5e5371e36 (diff) | |
staging: comedi: support vm_access_process for mmap'd buffer
If a process that has mmap'd a COMEDI buffer is being run under a
debugger such as GDB, the buffer contents are inaccessible from the
debugger. Support the `access()` VM operation to allow the buffer
contents to be accessed by another process.
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/staging/comedi/comedi_buf.c')
| -rw-r--r-- | drivers/staging/comedi/comedi_buf.c | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/drivers/staging/comedi/comedi_buf.c b/drivers/staging/comedi/comedi_buf.c index 1e1df89b5018..8e9b30b26810 100644 --- a/drivers/staging/comedi/comedi_buf.c +++ b/drivers/staging/comedi/comedi_buf.c @@ -161,6 +161,30 @@ int comedi_buf_map_put(struct comedi_buf_map *bm) return 1; } +/* helper for "access" vm operation */ +int comedi_buf_map_access(struct comedi_buf_map *bm, unsigned long offset, + void *buf, int len, int write) +{ + unsigned int pgoff = offset & ~PAGE_MASK; + unsigned long pg = offset >> PAGE_SHIFT; + int done = 0; + + while (done < len && pg < bm->n_pages) { + int l = min_t(int, len - done, PAGE_SIZE - pgoff); + void *b = bm->page_list[pg].virt_addr + pgoff; + + if (write) + memcpy(b, buf, l); + else + memcpy(buf, b, l); + buf += l; + done += l; + pg++; + pgoff = 0; + } + return done; +} + /* returns s->async->buf_map and increments its kref refcount */ struct comedi_buf_map * comedi_buf_map_from_subdev_get(struct comedi_subdevice *s) |