Messages in this thread | | | Subject | Re: [PATCH v8 4/4] vsprintf: Add command line option debug_boot_weak_hash | From | Randy Dunlap <> | Date | Wed, 20 Jun 2018 09:09:49 -0700 |
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On 06/19/2018 09:20 PM, Tobin C. Harding wrote: > Currently printing [hashed] pointers requires enough entropy to be > available. Early in the boot sequence this may not be the case > resulting in a dummy string '(____ptrval____)' being printed. This > makes debugging the early boot sequence difficult. We can relax the > requirement to use cryptographically secure hashing during debugging. > This enables debugging while keeping development/production kernel > behaviour the same. > > If new command line option debug_boot_weak_hash is enabled use > cryptographically insecure hashing and hash pointer value immediately. > > Signed-off-by: Tobin C. Harding <me@tobin.cc> > Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> > --- > Documentation/admin-guide/kernel-parameters.txt | 9 +++++++++ > lib/vsprintf.c | 17 +++++++++++++++++ > 2 files changed, 26 insertions(+) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index 638342d0a095..a116fc0366b0 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -748,6 +748,15 @@ > > debug [KNL] Enable kernel debugging (events log level). > > + debug_boot_weak_hash > + [KNL] Enable printing pointers early in the boot > + sequence. If enabled, we use a weak hash instead of > + siphash to hash pointers. Use this option if you need > + to see pointer values during early boot (i.e you are
maybe: to see hashed pointer values i.e., not raw pointers.
> + seeing instances of '(___ptrval___)'). > + Cryptographically insecure, please do not use on > + production kernels. > + > debug_locks_verbose= > [KNL] verbose self-tests > Format=<0|1>
thanks, -- ~Randy
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