hi Kees Cook,
On 2020/5/8 PM 3:27, Kees Cook wrote:
> On Thu, May 07, 2020 at 11:39:52PM -0700, Kees Cook wrote:
>> So far, I've identified the following stuff left to do:
>> [...]
>> - implement ramoops-like probe feature for pstore/blk
>
> With the following hack, I'm able to start testing the series:
>
> diff --git a/fs/pstore/blk.c b/fs/pstore/blk.c
> index a736555e1ed3..7145da079267 100644
> --- a/fs/pstore/blk.c
> +++ b/fs/pstore/blk.c
> @@ -373,12 +373,14 @@ int psblk_register_blkdev(unsigned int major, unsigned
> int flags,
> if (IS_ERR(binfo))
> return PTR_ERR(binfo);
>
> +#if 0
> /* only allow driver matching the @blkdev */
> if (!binfo->devt || MAJOR(binfo->devt) != major) {
> pr_debug("invalid major %u (expect %u)\n",
> major, MAJOR(binfo->devt));
> return -ENODEV;
> }
> +#endif
>
> /* hold bdev exclusively */
> bdev = psblk_get_bdev(holder);
> @@ -423,7 +425,7 @@ void psblk_unregister_blkdev(unsigned int major)
> struct psblk_device dev = {.read = psblk_generic_blk_read};
> void *holder = blkdev;
>
> - if (psblk_bdev && MAJOR(psblk_bdev->bd_dev) == major) {
> + if (psblk_bdev/* && MAJOR(psblk_bdev->bd_dev) == major*/) {
> psblk_unregister_device(&dev);
> psblk_put_bdev(psblk_bdev, holder);
> blkdev_panic_write = NULL;
> @@ -476,6 +478,24 @@ int pstore_blk_usr_info(struct pstore_blk_info *info)
> }
> EXPORT_SYMBOL_GPL(pstore_blk_usr_info);
>
> +static int __init pstore_blk_init(void)
> +{
> + int ret = 0;
> +
> + if (blkdev[0])
> + ret = psblk_register_blkdev(0, 0, NULL);
> +
> + return ret;
> +}
> +postcore_initcall(pstore_blk_init);
> +
> +static void __exit pstore_blk_exit(void)
> +{
> + psblk_unregister_blkdev(0);
> +}
> +module_exit(pstore_blk_exit);
> +
> +
> MODULE_LICENSE("GPL");
> MODULE_AUTHOR("WeiXiong Liao <[email protected]>");
> MODULE_DESCRIPTION("pstore backend for block devices");
>
>
> Then I can get things up and running with:
>
> # insmod pstore.ko compress=off
> # insmod pstore_zone.ko
> # truncate pstore-blk.raw --size 100M
> # losetup -f --show pstore-blk.raw
> /dev/loop0
> # insmod pstore_blk.ko blkdev=/dev/loop0 kmsg_size=16 console_size=64
>
> So far, I've hit a few bugs. The most obvious is that "rmmod" causes a
> fault, so I think locking and other things need to be fixed up further.
> After that, it looked like all the compressed files were failing to
> decompress, which implies some kind of buffer offset problem. When I
> loaded with pstore.compress=off I got readable logs, but there is a span
> of garbage between the header and the body in
> /sys/fs/pstore/dmesg-pstore-zone-1 etc.
>
Both of the above two bugs have been fix on series v6.
The following diff is to fix "rmmod" bug.
@@ -1273,8 +1273,8 @@ static void psz_free_zones(struct pstore_zone
***pszones, unsigned int *cnt)
return;
while (*cnt > 0) {
- psz_free_zone(&zones[*cnt]);
(*cnt)--;
+ psz_free_zone(&zones[*cnt]);
}
kfree(zones);
*pszones = NULL;
> Cool so far! It just needs a bit more testing a polish. :)
>
--
WeiXiong Liao
