slab: Decouple slab_debug and no_hash_pointers

Some system owners use slab_debug=FPZ (or similar) as a hardening option,
but do not want to be forced into having kernel addresses exposed due
to the implicit "no_hash_pointers" boot param setting.[1]

Introduce the "hash_pointers" boot param, which defaults to "auto"
(the current behavior), but also includes "always" (forcing on hashing
even when "slab_debug=..." is defined), and "never". The existing
"no_hash_pointers" boot param becomes an alias for "hash_pointers=never".

This makes it possible to boot with "slab_debug=FPZ hash_pointers=always".

Link: https://github.com/KSPP/linux/issues/368 [1]
Fixes: 792702911f58 ("slub: force on no_hash_pointers when slub_debug is enabled")
Co-developed-by: Sergio Perez Gonzalez <[email protected]>
Signed-off-by: Sergio Perez Gonzalez <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Acked-by: David Rientjes <[email protected]>
Reviewed-by: Bagas Sanjaya <[email protected]>
Signed-off-by: Kees Cook <[email protected]>
Reviewed-by: Harry Yoo <[email protected]>
Acked-by: Rafael Aquini <[email protected]>
Tested-by: Petr Mladek <[email protected]>
Reviewed-by: Petr Mladek <[email protected]>
Link: https://patch.msgid.link/[email protected]
[[email protected]: Add note about hash_pointers into slab_debug kernel parameter documentation.]
Signed-off-by: Petr Mladek <[email protected]>

0 files changed, 0 insertions, 0 deletions