Le 06/09/2024 à 14:23, Michael Ellerman a écrit :
Christophe Leroy <christophe.le...@csgroup.eu> writes:
When running in a non-root time namespace, the global VDSO data page
is replaced by a dedicated namespace data page and the global data
page is mapped next to it. Detailed explanations can be found at
commit 660fd04f9317 ("lib/vdso: Prepare for time namespace support").
When it happens, __kernel_get_syscall_map and __kernel_get_tbfreq
and __kernel_sync_dicache don't work anymore because they read 0
instead of the data they need.
To address that, clock_mode has to be read. When it is set to
VDSO_CLOCKMODE_TIMENS, it means it is a dedicated namespace data page
and the global data is located on the following page.
Add a macro called get_realdatapage which reads clock_mode and add
PAGE_SIZE to the pointer provided by get_datapage macro when
clock_mode is equal to VDSO_CLOCKMODE_TIMENS. Use this new macro
instead of get_datapage macro except for time functions as they handle
it internally.
Fixes: 74205b3fc2ef ("powerpc/vdso: Add support for time namespaces")
Signed-off-by: Christophe Leroy <christophe.le...@csgroup.eu>
Oops.
I guess it should also have:
Cc: sta...@vger.kernel.org # v5.13+
Reported-by: Jason A. Donenfeld <ja...@zx2c4.com>
Closes: https://lore.kernel.org/all/ztnyqzi-nrsns...@zx2c4.com/
Jason only reported a problem with getrandom, the other three are
"cherry on the cake".
The bug has been there for 3 years, I'm sure it can stay 3-4 more weeks,
I'm not sure there is a need to apply it in both trees.
As far as I understood Jason was about to squash the fix into his tree
so I was expecting him to apply patch 1 before "vDSO getrandom
implementation for powerpc" patches and then squash patch 2 in place.
Jason how do you want to handle this?
I can put patch 1 in a topic branch that we both merge? Then you can
apply patch 2 on top of that merge in your tree.
Or we could both apply patch 1 to our trees, it might lead to a conflict
but it wouldn't be anything drastic.
