tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: 6b5f04b6cf8ebab9a65d9c0026c650bb2538fd0f
commit: a1b3695820aa490e58915d720a1438069813008b NTB: Add support for AMD PCI-Express Non-Transparent Bridge
date: 8 weeks ago
reproduce:
# apt-get install sparse
git checkout a1b3695820aa490e58915d720a1438069813008b
make ARCH=x86_64 allmodconfig
make C=1 CF=-D__CHECK_ENDIAN__
sparse warnings: (new ones prefixed by >>)
>> drivers/ntb/hw/amd/ntb_hw_amd.c:367:29: sparse: cast removes address space of expression
drivers/ntb/hw/amd/ntb_hw_amd.c:427:31: sparse: cast removes address space of expression
vim +367 drivers/ntb/hw/amd/ntb_hw_amd.c
351
352 spin_lock_irqsave(&ndev->db_mask_lock, flags);
353 ndev->db_mask &= ~db_bits;
354 writew((u16)ndev->db_mask, mmio + AMD_DBMASK_OFFSET);
355 spin_unlock_irqrestore(&ndev->db_mask_lock, flags);
356
357 return 0;
358 }
359
360 static int amd_ntb_peer_db_addr(struct ntb_dev *ntb,
361 phys_addr_t *db_addr,
362 resource_size_t *db_size)
363 {
364 struct amd_ntb_dev *ndev = ntb_ndev(ntb);
365
366 if (db_addr)
> 367 *db_addr = (phys_addr_t)(ndev->peer_mmio + AMD_DBREQ_OFFSET);
368 if (db_size)
369 *db_size = sizeof(u32);
370
371 return 0;
372 }
373
374 static int amd_ntb_peer_db_set(struct ntb_dev *ntb, u64 db_bits)
375 {
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
> >> drivers/ntb/hw/amd/ntb_hw_amd.c:367:29: sparse: cast removes address space of
> expression
> drivers/ntb/hw/amd/ntb_hw_amd.c:427:31: sparse: cast removes address space of
> expression
> 360 static int amd_ntb_peer_db_addr(struct ntb_dev *ntb,
> 361 phys_addr_t *db_addr,
> 362 resource_size_t *db_size)
> 363 {
> 364 struct amd_ntb_dev *ndev = ntb_ndev(ntb);
> 365
> 366 if (db_addr)
> > 367 *db_addr = (phys_addr_t)(ndev->peer_mmio + AMD_DBREQ_OFFSET);
This is a good warning. The code here does look wrong (both lines 367 and 427).
Instead of peer_mmio, the code here should use pci_resource_start(pcidev, 0) + AMD_PEER_OFFSET. For comparison, in ntb_hw_intel the offset is based on a physical address stored in peer_addr, not the virtual mapping of that address in peer_mmio.
Look at ntb_hw_amd around lines 1016 where self_mmio and peer_mmio are set up. The register physical address is never saved in the ndev object, only the virtual address is saved, therefore the physical address would need to be retrieved with pci_resoruce_start wherever it is used in the ntb_hw_amd driver.
Alternatively, the offending functions could be deleted until they are added later, after they have been tested. Note that the ntb_foo_addr functions are an optional part of the api for drivers to implement.
Allen