pstore/pmsg: drop bounce buffer
Removing a bounce buffer copy operation in the pmsg driver path is
always better. We also gain in overall performance by not requesting
a vmalloc on every write as this can cause precious RT tasks, such
as user facing media operation, to stall while memory is being
reclaimed. Added a write_buf_user to the pstore functions, a backup
platform write_buf_user that uses the small buffer that is part of
the instance, and implemented a ramoops write_buf_user that only
supports PSTORE_TYPE_PMSG.
Signed-off-by: Mark Salyzyn <salyzyn@android.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index 76dd604..14984d9 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -623,6 +623,40 @@
size, psi);
}
+static int pstore_write_buf_user_compat(enum pstore_type_id type,
+ enum kmsg_dump_reason reason,
+ u64 *id, unsigned int part,
+ const char __user *buf,
+ bool compressed, size_t size,
+ struct pstore_info *psi)
+{
+ unsigned long flags = 0;
+ size_t i, bufsize = size;
+ long ret = 0;
+
+ if (unlikely(!access_ok(VERIFY_READ, buf, size)))
+ return -EFAULT;
+ if (bufsize > psinfo->bufsize)
+ bufsize = psinfo->bufsize;
+ spin_lock_irqsave(&psinfo->buf_lock, flags);
+ for (i = 0; i < size; ) {
+ size_t c = min(size - i, bufsize);
+
+ ret = __copy_from_user(psinfo->buf, buf + i, c);
+ if (unlikely(ret != 0)) {
+ ret = -EFAULT;
+ break;
+ }
+ ret = psi->write_buf(type, reason, id, part, psinfo->buf,
+ compressed, c, psi);
+ if (unlikely(ret < 0))
+ break;
+ i += c;
+ }
+ spin_unlock_irqrestore(&psinfo->buf_lock, flags);
+ return unlikely(ret < 0) ? ret : size;
+}
+
/*
* platform specific persistent storage driver registers with
* us here. If pstore is already mounted, call the platform
@@ -645,6 +679,8 @@
if (!psi->write)
psi->write = pstore_write_compat;
+ if (!psi->write_buf_user)
+ psi->write_buf_user = pstore_write_buf_user_compat;
psinfo = psi;
mutex_init(&psinfo->read_mutex);
spin_unlock(&pstore_lock);