On 2022/4/28 18:46, Will Deacon wrote:
On Wed, Apr 27, 2022 at 08:14:09PM +0800, Kefeng Wang wrote:
Let's arm64 use GENERIC_IOREMAP to cleanup code, and
support ioremap_prot()/HAVE_IOREMAP_PROT, which could
enable generic_access_phys().
Kefeng Wang (4):
mm: ioremap: Setup phys_addr of struct vm_struct
mm: ioremap: Add arch_ioremap/iounmap_check()
arm64: mm: Convert to GENERIC_IOREMAP
arm64: Add HAVE_IOREMAP_PROT support
.../features/vm/ioremap_prot/arch-support.txt | 2 +-
arch/arm64/Kconfig | 2 +
arch/arm64/include/asm/io.h | 14 +--
arch/arm64/include/asm/pgtable.h | 10 +++
arch/arm64/kernel/acpi.c | 2 +-
arch/arm64/mm/hugetlbpage.c | 10 ---
arch/arm64/mm/ioremap.c | 86 +++----------------
include/asm-generic/io.h | 3 +
mm/ioremap.c | 21 ++++-
9 files changed, 56 insertions(+), 94 deletions(-)
That's not a massively compelling diffstat for a cleanup, in all honesty.
I looked at generic_access_phys() to try to figure out why we would want
that on arm64, but it seems like it's related to mmap() of devices in
userspace. Bearing in mind that CONFIG_STRICT_DEVMEM=y by default, please
can you justify why this is something worth doing?
The geneirc_access_phys was introduced by
7ae8ed5053a3 use generic_access_phys for /dev/mem mappings
28b2ee20c7cb access_process_vm device memory infrastructure
and add into uio.c by
7294151d0592 "uio: provide vm access to UIO_MEM_PHYS maps"
It could let user to debug(eg, gdb or ptrace) app via access_process_vm().
also some upstream drivers and out-of-tree modules could use it too
drivers/fpga/dfl-afu-main.c: .access = generic_access_phys,
drivers/pci/mmap.c: .access = generic_access_phys,
When see the ioremap_prot from generic ioremap, for better debug, I think
we could enabled it on arm64 too.
Will
.
