On Fri, Dec 23, 2022 at 10:27:02AM +0100, Christoph Hellwig wrote:
> This reverts commit fc156629b23a21181e473e60341e3a78af25a1d4.
>
> This commit manages to do three API violations at once:
>
> - dereference the return value of dma_alloc_attrs with the
> DMA_ATTR_NO_KERNEL_MAPPING mapping, which is clearly forbidden and
> will do the wrong thing on various dma mapping implementations. The
> fact that dma-direct uses a struct page as a cookie is an undocumented
> implementation detail
> - include dma-map-ops.h and use pgprot_dmacoherent despite a clear
> comment documenting that this is not acceptable
> - use of the VM_DMA_COHERENT for something that is not the dma-mapping
> code
> - use of VM_FLUSH_RESET_PERMS for vmap, while it is only supported for
> vmalloc
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Acked-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
Thanks,
Mani
> ---
> drivers/remoteproc/qcom_q6v5_mss.c | 38 +++++-------------------------
> 1 file changed, 6 insertions(+), 32 deletions(-)
>
> diff --git a/drivers/remoteproc/qcom_q6v5_mss.c b/drivers/remoteproc/qcom_q6v5_mss.c
> index fddb63cffee078..a8b141db4de63f 100644
> --- a/drivers/remoteproc/qcom_q6v5_mss.c
> +++ b/drivers/remoteproc/qcom_q6v5_mss.c
> @@ -10,7 +10,6 @@
> #include <linux/clk.h>
> #include <linux/delay.h>
> #include <linux/devcoredump.h>
> -#include <linux/dma-map-ops.h>
> #include <linux/dma-mapping.h>
> #include <linux/interrupt.h>
> #include <linux/kernel.h>
> @@ -933,52 +932,27 @@ static void q6v5proc_halt_axi_port(struct q6v5 *qproc,
> static int q6v5_mpss_init_image(struct q6v5 *qproc, const struct firmware *fw,
> const char *fw_name)
> {
> - unsigned long dma_attrs = DMA_ATTR_FORCE_CONTIGUOUS | DMA_ATTR_NO_KERNEL_MAPPING;
> - unsigned long flags = VM_DMA_COHERENT | VM_FLUSH_RESET_PERMS;
> - struct page **pages;
> - struct page *page;
> + unsigned long dma_attrs = DMA_ATTR_FORCE_CONTIGUOUS;
> dma_addr_t phys;
> void *metadata;
> int mdata_perm;
> int xferop_ret;
> size_t size;
> - void *vaddr;
> - int count;
> + void *ptr;
> int ret;
> - int i;
>
> metadata = qcom_mdt_read_metadata(fw, &size, fw_name, qproc->dev);
> if (IS_ERR(metadata))
> return PTR_ERR(metadata);
>
> - page = dma_alloc_attrs(qproc->dev, size, &phys, GFP_KERNEL, dma_attrs);
> - if (!page) {
> + ptr = dma_alloc_attrs(qproc->dev, size, &phys, GFP_KERNEL, dma_attrs);
> + if (!ptr) {
> kfree(metadata);
> dev_err(qproc->dev, "failed to allocate mdt buffer\n");
> return -ENOMEM;
> }
>
> - count = PAGE_ALIGN(size) >> PAGE_SHIFT;
> - pages = kmalloc_array(count, sizeof(struct page *), GFP_KERNEL);
> - if (!pages) {
> - ret = -ENOMEM;
> - goto free_dma_attrs;
> - }
> -
> - for (i = 0; i < count; i++)
> - pages[i] = nth_page(page, i);
> -
> - vaddr = vmap(pages, count, flags, pgprot_dmacoherent(PAGE_KERNEL));
> - kfree(pages);
> - if (!vaddr) {
> - dev_err(qproc->dev, "unable to map memory region: %pa+%zx\n", &phys, size);
> - ret = -EBUSY;
> - goto free_dma_attrs;
> - }
> -
> - memcpy(vaddr, metadata, size);
> -
> - vunmap(vaddr);
> + memcpy(ptr, metadata, size);
>
> /* Hypervisor mapping to access metadata by modem */
> mdata_perm = BIT(QCOM_SCM_VMID_HLOS);
> @@ -1008,7 +982,7 @@ static int q6v5_mpss_init_image(struct q6v5 *qproc, const struct firmware *fw,
> "mdt buffer not reclaimed system may become unstable\n");
>
> free_dma_attrs:
> - dma_free_attrs(qproc->dev, size, page, phys, dma_attrs);
> + dma_free_attrs(qproc->dev, size, ptr, phys, dma_attrs);
> kfree(metadata);
>
> return ret < 0 ? ret : 0;
> --
> 2.35.1
>
--
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