lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Thu, 19 Nov 2020 09:24:07 +0000 From: Quentin Perret <qperret@...gle.com> To: Will Deacon <will@...nel.org> Cc: linux-arm-kernel@...ts.infradead.org, linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org, Catalin Marinas <catalin.marinas@....com>, Marc Zyngier <maz@...nel.org>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Peter Zijlstra <peterz@...radead.org>, Morten Rasmussen <morten.rasmussen@....com>, Qais Yousef <qais.yousef@....com>, Suren Baghdasaryan <surenb@...gle.com>, Tejun Heo <tj@...nel.org>, Li Zefan <lizefan@...wei.com>, Johannes Weiner <hannes@...xchg.org>, Ingo Molnar <mingo@...hat.com>, Juri Lelli <juri.lelli@...hat.com>, Vincent Guittot <vincent.guittot@...aro.org>, kernel-team@...roid.com Subject: Re: [PATCH v3 08/14] arm64: exec: Adjust affinity for compat tasks with mismatched 32-bit EL0 On Friday 13 Nov 2020 at 09:37:13 (+0000), Will Deacon wrote: > When exec'ing a 32-bit task on a system with mismatched support for > 32-bit EL0, try to ensure that it starts life on a CPU that can actually > run it. > > Signed-off-by: Will Deacon <will@...nel.org> > --- > arch/arm64/kernel/process.c | 12 +++++++++++- > 1 file changed, 11 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c > index 1540ab0fbf23..17b94007fed4 100644 > --- a/arch/arm64/kernel/process.c > +++ b/arch/arm64/kernel/process.c > @@ -625,6 +625,16 @@ unsigned long arch_align_stack(unsigned long sp) > return sp & ~0xf; > } > > +static void adjust_compat_task_affinity(struct task_struct *p) > +{ > + const struct cpumask *mask = system_32bit_el0_cpumask(); > + > + if (restrict_cpus_allowed_ptr(p, mask)) > + set_cpus_allowed_ptr(p, mask); My understanding of this call to set_cpus_allowed_ptr() is that you're mimicking the hotplug vs affinity case behaviour in some ways. That is, if a task is pinned to a CPU and userspace hotplugs that CPU, then the kernel will reset the affinity of the task to the remaining online CPUs. I guess that is a sensible fallback path when userspace gives contradictory commands to the kernel, but that most certainly deserves a comment :) > + > + set_tsk_thread_flag(current, TIF_NOTIFY_RESUME); > +} > > /* > * Called from setup_new_exec() after (COMPAT_)SET_PERSONALITY. > */ > @@ -635,7 +645,7 @@ void arch_setup_new_exec(void) > if (is_compat_task()) { > mmflags = MMCF_AARCH32; > if (static_branch_unlikely(&arm64_mismatched_32bit_el0)) > - set_tsk_thread_flag(current, TIF_NOTIFY_RESUME); > + adjust_compat_task_affinity(current); > } > > current->mm->context.flags = mmflags; > -- > 2.29.2.299.gdc1121823c-goog >
Powered by blists - more mailing lists