Messages in this thread |  | | Date | Fri, 27 Nov 2020 13:12:17 +0000 | From | Qais Yousef <> | Subject | Re: [PATCH v4 04/14] arm64: Kill 32-bit applications scheduled on 64-bit-only CPUs |
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On 11/24/20 15:50, Will Deacon wrote: > Scheduling a 32-bit application on a 64-bit-only CPU is a bad idea. > > Ensure that 32-bit applications always take the slow-path when returning > to userspace on a system with mismatched support at EL0, so that we can > avoid trying to run on a 64-bit-only CPU and force a SIGKILL instead. > > Signed-off-by: Will Deacon <will@kernel.org> > ---
nit: We drop this patch at the end. Can't we avoid it altogether instead?
[...]
> diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c > index a8184cad8890..bcb6ca2d9a7c 100644 > --- a/arch/arm64/kernel/signal.c > +++ b/arch/arm64/kernel/signal.c > @@ -911,6 +911,19 @@ static void do_signal(struct pt_regs *regs) > restore_saved_sigmask(); > } > > +static bool cpu_affinity_invalid(struct pt_regs *regs) > +{ > + if (!compat_user_mode(regs)) > + return false;
Silly question. Is there an advantage of using compat_user_mode() vs is_compat_task()? I see the latter used in the file although struct pt_regs *regs is passed to the functions calling it.
Nothing's wrong with it, just curious.
Thanks
-- Qais Yousef
> + > + /* > + * We're preemptible, but a reschedule will cause us to check the > + * affinity again. > + */ > + return !cpumask_test_cpu(raw_smp_processor_id(), > + system_32bit_el0_cpumask()); > +}
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