Re: [PATCH] nvme: Do not allocate 8kB buffer on stack

Pali Rohár
2022-01-14T10:41:01Z

Hello! Could you please review this patch?

On Thursday 09 December 2021 11:06:39 Pali Rohár wrote:
> Calling 'nvme scan' followed by 'nvme detail' crashes U-Boot on Turris
> Omnia with the following error:
>
> undefined instruction
> pc : [<0a000000>] lr : [<7ff80bfc>]
> reloc pc : [<8a8c0000>] lr : [<00840bfc>]
> sp : 7fb2b908 ip : 0000002a fp : 02000000
> r10: 04000000 r9 : 7fb2fed0 r8 : e1000000
> r7 : 0c000000 r6 : 03000000 r5 : 06000000 r4 : 01000000
> r3 : 7fb30928 r2 : 7fb30928 r1 : 00000000 r0 : 00000000
> Flags: nZCv IRQs off FIQs off Mode SVC_32
> Code: 0f0fb4f0 0f0fb4f0 0f0fb4f0 0f0fb4f0 (f0f04b0f)
> Resetting CPU ...
>
> This happens when nvme_print_info() tries to return to the caller. It
> looks like this error is caused by trying to allocate 8 KiB of memory
> on the stack by the two uses of ALLOC_CACHE_ALIGN_BUFFER().
>
> Use malloc_cache_aligned() to allocate this memory dynamically instead.
>
> This fixes 'nvme detail' on Turris Omnia.
>
> Note that similar change was applied to file drivers/nvme/nvme.c in past by
> commit 2f83481dff9c ("nvme: use page-aligned buffer for identify command").
>
> Signed-off-by: Pali Rohár <pali@kernel.org>
> Signed-off-by: Marek Behún <marek.behun@nic.cz>
> ---
> drivers/nvme/nvme_show.c | 35 ++++++++++++++++++++++++++---------
> 1 file changed, 26 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/nvme/nvme_show.c b/drivers/nvme/nvme_show.c
> index 15e459da1acd..72cbac82bcca 100644
> --- a/drivers/nvme/nvme_show.c
> +++ b/drivers/nvme/nvme_show.c
> @@ -106,24 +106,41 @@ int nvme_print_info(struct udevice *udev)
> {
> struct nvme_ns *ns = dev_get_priv(udev);
> struct nvme_dev *dev = ns->dev;
> - ALLOC_CACHE_ALIGN_BUFFER(char, buf_ns, sizeof(struct nvme_id_ns));
> - struct nvme_id_ns *id = (struct nvme_id_ns *)buf_ns;
> - ALLOC_CACHE_ALIGN_BUFFER(char, buf_ctrl, sizeof(struct nvme_id_ctrl));
> - struct nvme_id_ctrl *ctrl = (struct nvme_id_ctrl *)buf_ctrl;
> + struct nvme_id_ctrl *ctrl;
> + struct nvme_id_ns *id;
> + int ret = 0;
>
> - if (nvme_identify(dev, 0, 1, (dma_addr_t)(long)ctrl))
> - return -EIO;
> + ctrl = memalign(dev->page_size, sizeof(struct nvme_id_ctrl));
> + if (!ctrl)
> + return -ENOMEM;
> +
> + if (nvme_identify(dev, 0, 1, (dma_addr_t)(long)ctrl)) {
> + ret = -EIO;
> + goto free_ctrl;
> + }
>
> print_optional_admin_cmd(le16_to_cpu(ctrl->oacs), ns->devnum);
> print_optional_nvm_cmd(le16_to_cpu(ctrl->oncs), ns->devnum);
> print_format_nvme_attributes(ctrl->fna, ns->devnum);
>
> - if (nvme_identify(dev, ns->ns_id, 0, (dma_addr_t)(long)id))
> - return -EIO;
> + id = memalign(dev->page_size, sizeof(struct nvme_id_ns));
> + if (!id) {
> + ret = -ENOMEM;
> + goto free_ctrl;
> + }
> +
> + if (nvme_identify(dev, ns->ns_id, 0, (dma_addr_t)(long)id)) {
> + ret = -EIO;
> + goto free_id;
> + }
>
> print_formats(id, ns);
> print_data_protect_cap(id->dpc, ns->devnum);
> print_metadata_cap(id->mc, ns->devnum);
>
> - return 0;
> +free_id:
> + free(id);
> +free_ctrl:
> + free(ctrl);
> + return ret;
> }
> --
> 2.20.1
>