Messages in this thread | | | Subject | Re: [PATCH v4 04/26] arm64: alternative: Apply alternatives early in boot process | From | Suzuki K Poulose <> | Date | Fri, 25 May 2018 11:00:58 +0100 |
| |
On 25/05/18 10:49, Julien Thierry wrote: > From: Daniel Thompson <daniel.thompson@linaro.org> > > Currently alternatives are applied very late in the boot process (and > a long time after we enable scheduling). Some alternative sequences, > such as those that alter the way CPU context is stored, must be applied > much earlier in the boot sequence. > > Introduce apply_boot_alternatives() to allow some alternatives to be > applied immediately after we detect the CPU features of the boot CPU. > > Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> > [julien.thierry@arm.com: rename to fit new cpufeature framework better, > apply BOOT_SCOPE feature early in boot] > Signed-off-by: Julien Thierry <julien.thierry@arm.com> > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Will Deacon <will.deacon@arm.com> > Cc: Christoffer Dall <christoffer.dall@linaro.org> > Cc: Suzuki K Poulose <suzuki.poulose@arm.com> > --- > arch/arm64/include/asm/alternative.h | 3 +-- > arch/arm64/include/asm/cpufeature.h | 2 ++ > arch/arm64/kernel/alternative.c | 30 +++++++++++++++++++++++++++--- > arch/arm64/kernel/cpufeature.c | 5 +++++ > arch/arm64/kernel/smp.c | 7 +++++++ > 5 files changed, 42 insertions(+), 5 deletions(-) >
...
> > +unsigned long boot_capabilities; > + > /* > * Flag to indicate if we have computed the system wide > * capabilities based on the boot time active CPUs. This > @@ -1370,6 +1372,9 @@ static void __update_cpu_capabilities(const struct arm64_cpu_capabilities *caps, > if (!cpus_have_cap(caps->capability) && caps->desc) > pr_info("%s %s\n", info, caps->desc); > cpus_set_cap(caps->capability); > + > + if (scope_mask & SCOPE_BOOT_CPU) > + __set_bit(caps->capability, &boot_capabilities);
Julien
I think this check is problematic. The scope_mask passed on by the boot CPU is (SCOPE_BOOT_CPU | SCOPE_LOCAL_CPU) to cover both BOOT CPU capabilities *and* CPU local capabilites on the boot CPU. So, you might apply the alternatives for a "local" CPU erratum, which is not intended. You may change the above check to :
if (caps->type & SCOPE_BOOT_CPU)
to make sure you check the "capability" has the SCOPE_BOOT_CPU set.
Suzuki
| |