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

Arnd Bergmann
2024-03-22T13:01:31Z

From: Arnd Bergmann <arnd@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@imgtec.com>
Link: https://lore.kernel.org/lkml/9df9e4f87727399928c068dbbf614c9895ae15f9.camel@imgtec.com/
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
I sent this one last year when the warning appeared, it looks like it
got lost in the meantime, resending it unchanged.
---
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);

--
2.39.2