[PATCH] [RESEND] drm/imagination: avoid -Woverflow warning

[Matt Coster]

On 22/03/2024 13:01, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd at arndb.de>
> 
> The array size calculation in pvr_vm_mips_fini() appears to be incorrect based on
> taking the size of the pointer rather than the size of the array, which manifests
> as a warning about signed integer overflow:
> 
> In file included from include/linux/kernel.h:16,
>                  from drivers/gpu/drm/imagination/pvr_rogue_fwif.h:10,
>                  from drivers/gpu/drm/imagination/pvr_ccb.h:7,
>                  from drivers/gpu/drm/imagination/pvr_device.h:7,
>                  from drivers/gpu/drm/imagination/pvr_vm_mips.c:4:
> drivers/gpu/drm/imagination/pvr_vm_mips.c: In function 'pvr_vm_mips_fini':
> include/linux/array_size.h:11:25: error: overflow in conversion from 'long unsigned int' to 'int' changes value from '18446744073709551615' to '-1' [-Werror=overflow]
>    11 | #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr))
>       |                         ^
> drivers/gpu/drm/imagination/pvr_vm_mips.c:106:24: note: in expansion of macro 'ARRAY_SIZE'
>   106 |         for (page_nr = ARRAY_SIZE(mips_data->pt_pages) - 1; page_nr >= 0; page_nr--) {
>       |                        ^~~~~~~~~~
> 
> Just use the number of array elements directly here, and in the corresponding
> init function for consistency.
> 
> Fixes: 927f3e0253c1 ("drm/imagination: Implement MIPS firmware processor and MMU support")
> Reviewed-by: Donald Robson <donald.robson at imgtec.com>
> Link: https://lore.kernel.org/lkml/9df9e4f87727399928c068dbbf614c9895ae15f9.camel@imgtec.com/
> Signed-off-by: Arnd Bergmann <arnd at arndb.de>
> ---
> I sent this one last year when the warning appeared, it looks like it
> got lost in the meantime, resending it unchanged.

Apologies for letting this slip through the cracks last year - applied
to drm-misc-next.

Thanks for resending!

Cheers,
Matt

> ---
>  drivers/gpu/drm/imagination/pvr_vm_mips.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/imagination/pvr_vm_mips.c b/drivers/gpu/drm/imagination/pvr_vm_mips.c
> index b7fef3c797e6..4f99b4af871c 100644
> --- a/drivers/gpu/drm/imagination/pvr_vm_mips.c
> +++ b/drivers/gpu/drm/imagination/pvr_vm_mips.c
> @@ -46,7 +46,7 @@ pvr_vm_mips_init(struct pvr_device *pvr_dev)
>  	if (!mips_data)
>  		return -ENOMEM;
>  
> -	for (page_nr = 0; page_nr < ARRAY_SIZE(mips_data->pt_pages); page_nr++) {
> +	for (page_nr = 0; page_nr < PVR_MIPS_PT_PAGE_COUNT; page_nr++) {
>  		mips_data->pt_pages[page_nr] = alloc_page(GFP_KERNEL | __GFP_ZERO);
>  		if (!mips_data->pt_pages[page_nr]) {
>  			err = -ENOMEM;
> @@ -102,7 +102,7 @@ pvr_vm_mips_fini(struct pvr_device *pvr_dev)
>  	int page_nr;
>  
>  	vunmap(mips_data->pt);
> -	for (page_nr = ARRAY_SIZE(mips_data->pt_pages) - 1; page_nr >= 0; page_nr--) {
> +	for (page_nr = PVR_MIPS_PT_PAGE_COUNT - 1; page_nr >= 0; page_nr--) {
>  		dma_unmap_page(from_pvr_device(pvr_dev)->dev,
>  			       mips_data->pt_dma_addr[page_nr], PAGE_SIZE, DMA_TO_DEVICE);
>  
-------------- next part --------------
A non-text attachment was scrubbed...
Name: OpenPGP_signature.asc
Type: application/pgp-signature
Size: 236 bytes
Desc: OpenPGP digital signature
URL: <https://lists.freedesktop.org/archives/dri-devel/attachments/20240325/d7a9d04b/attachment-0001.sig>