[...]
Let's fix the remaining issues and prepare for reverting the workarounds
by setting the HW writable bit only if both, the SW dirty bit and the SW
writable bit are set.
We have to move pte_dirty() and pte_dirty() up. The code patching
One of the pte_dirty() should be replaced with pte_write().
Indeed, thanks. I assume Andrew can change the latter to pte_write().
[unless I have to resend, of course]
It would have been nice to separate moving and changes in two patches,
but keeping it together works too.
I prefer to not have "move code within the same file around" in separate
patches as long as it doesn't add too much noise. Here, I think it's
acceptable.
mechanism and handling constants > 22bit is a bit special on sparc64.
The ASM logic in pte_mkdirty() and pte_mkwrite() match the logic in
pte_mkold() to create the mask depending on the machine type. The ASM
logic in __pte_mkhwwrite() matches the logic in pte_present(), just
using an "or" instead of an "and" instruction.
With this commit (sun4u in QEMU):
root@debian:~/linux/tools/testing/selftests/mm# ./mkdirty
# [INFO] detected THP size: 8192 KiB
TAP version 13
1..6
# [INFO] PTRACE write access
ok 1 SIGSEGV generated, page not modified
# [INFO] PTRACE write access to THP
ok 2 SIGSEGV generated, page not modified
# [INFO] Page migration
ok 3 SIGSEGV generated, page not modified
# [INFO] Page migration of THP
ok 4 SIGSEGV generated, page not modified
# [INFO] PTE-mapping a THP
ok 5 SIGSEGV generated, page not modified
# [INFO] UFFDIO_COPY
ok 6 SIGSEGV generated, page not modified
# Totals: pass:6 fail:0 xfail:0 xpass:0 skip:0 error:0
Nice!
This handling seems to have been in place forever.
[1] https://lkml.kernel.org/r/533a7c3d-3a48-b16b-b421-6e8386e0b142@xxxxxxxxxx
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
I tried to follow your changes, but my knowledge of gcc assembler failed
me. But based on the nice and detailed change log and the code I managed
to understand:
Acked-by: Sam Ravnborg <sam@xxxxxxxxxxxx>
Thanks Sam!
--
Thanks,
David / dhildenb
