From: Will Deacon <will@kernel.org>
To: linux-arm-kernel@lists.infradead.org
Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
Will Deacon <will@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Marc Zyngier <maz@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Peter Zijlstra <peterz@infradead.org>,
Morten Rasmussen <morten.rasmussen@arm.com>,
Qais Yousef <qais.yousef@arm.com>,
Suren Baghdasaryan <surenb@google.com>,
Quentin Perret <qperret@google.com>, Tejun Heo <tj@kernel.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Ingo Molnar <mingo@redhat.com>,
Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Daniel Bristot de Oliveira <bristot@redhat.com>,
Valentin Schneider <valentin.schneider@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
kernel-team@android.com
Subject: [PATCH v10 15/16] arm64: Remove logic to kill 32-bit tasks on 64-bit-only cores
Date: Wed, 23 Jun 2021 18:38:47 +0100 [thread overview]
Message-ID: <20210623173848.318-16-will@kernel.org> (raw)
In-Reply-To: <20210623173848.318-1-will@kernel.org>
The scheduler now knows enough about these braindead systems to place
32-bit tasks accordingly, so throw out the safety checks and allow the
ret-to-user path to avoid do_notify_resume() if there is nothing to do.
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
---
arch/arm64/kernel/process.c | 14 +-------------
arch/arm64/kernel/signal.c | 26 --------------------------
2 files changed, 1 insertion(+), 39 deletions(-)
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 220134888d7e..1de4d934db7f 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -528,15 +528,6 @@ static void erratum_1418040_thread_switch(struct task_struct *prev,
write_sysreg(val, cntkctl_el1);
}
-static void compat_thread_switch(struct task_struct *next)
-{
- if (!is_compat_thread(task_thread_info(next)))
- return;
-
- if (static_branch_unlikely(&arm64_mismatched_32bit_el0))
- set_tsk_thread_flag(next, TIF_NOTIFY_RESUME);
-}
-
static void update_sctlr_el1(u64 sctlr)
{
/*
@@ -578,7 +569,6 @@ __notrace_funcgraph struct task_struct *__switch_to(struct task_struct *prev,
ssbs_thread_switch(next);
erratum_1418040_thread_switch(prev, next);
ptrauth_thread_switch_user(next);
- compat_thread_switch(next);
/*
* Complete any pending TLB or cache maintenance on this CPU in case
@@ -680,10 +670,8 @@ void arch_setup_new_exec(void)
* at the point of execve(), although we try a bit harder to
* honour the cpuset hierarchy.
*/
- if (static_branch_unlikely(&arm64_mismatched_32bit_el0)) {
+ if (static_branch_unlikely(&arm64_mismatched_32bit_el0))
force_compatible_cpus_allowed_ptr(current);
- set_tsk_thread_flag(current, TIF_NOTIFY_RESUME);
- }
} else if (static_branch_unlikely(&arm64_mismatched_32bit_el0)) {
relax_compatible_cpus_allowed_ptr(current);
}
diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index f8192f4ae0b8..6237486ff6bb 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -911,19 +911,6 @@ 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;
-
- /*
- * 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());
-}
-
asmlinkage void do_notify_resume(struct pt_regs *regs,
unsigned long thread_flags)
{
@@ -951,19 +938,6 @@ asmlinkage void do_notify_resume(struct pt_regs *regs,
if (thread_flags & _TIF_NOTIFY_RESUME) {
tracehook_notify_resume(regs);
rseq_handle_notify_resume(NULL, regs);
-
- /*
- * If we reschedule after checking the affinity
- * then we must ensure that TIF_NOTIFY_RESUME
- * is set so that we check the affinity again.
- * Since tracehook_notify_resume() clears the
- * flag, ensure that the compiler doesn't move
- * it after the affinity check.
- */
- barrier();
-
- if (cpu_affinity_invalid(regs))
- force_sig(SIGKILL);
}
if (thread_flags & _TIF_FOREIGN_FPSTATE)
--
2.32.0.93.g670b81a890-goog
next prev parent reply other threads:[~2021-06-23 17:40 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-23 17:38 [PATCH v10 00/16] Add support for 32-bit tasks on asymmetric AArch32 systems Will Deacon
2021-06-23 17:38 ` [PATCH v10 01/16] sched: Introduce task_cpu_possible_mask() to limit fallback rq selection Will Deacon
2021-06-23 17:38 ` [PATCH v10 02/16] cpuset: Don't use the cpu_possible_mask as a last resort for cgroup v1 Will Deacon
2021-06-23 17:38 ` [PATCH v10 03/16] cpuset: Honour task_cpu_possible_mask() in guarantee_online_cpus() Will Deacon
2021-06-23 17:38 ` [PATCH v10 04/16] cpuset: Cleanup cpuset_cpus_allowed_fallback() use in select_fallback_rq() Will Deacon
2021-06-23 17:38 ` [PATCH v10 05/16] sched: Reject CPU affinity changes based on task_cpu_possible_mask() Will Deacon
2021-06-23 17:38 ` [PATCH v10 06/16] sched: Introduce task_struct::user_cpus_ptr to track requested affinity Will Deacon
2021-06-23 17:38 ` [PATCH v10 07/16] sched: Split the guts of sched_setaffinity() into a helper function Will Deacon
2021-06-23 17:38 ` [PATCH v10 08/16] sched: Allow task CPU affinity to be restricted on asymmetric systems Will Deacon
2021-06-23 17:38 ` [PATCH v10 09/16] sched: Introduce dl_task_check_affinity() to check proposed affinity Will Deacon
2021-06-23 17:38 ` [PATCH v10 10/16] arm64: Implement task_cpu_possible_mask() Will Deacon
2021-06-23 17:38 ` [PATCH v10 11/16] arm64: exec: Adjust affinity for compat tasks with mismatched 32-bit EL0 Will Deacon
2021-06-23 17:38 ` [PATCH v10 12/16] arm64: Prevent offlining first CPU with 32-bit EL0 on mismatched system Will Deacon
2021-06-23 17:38 ` [PATCH v10 13/16] arm64: Advertise CPUs capable of running 32-bit applications in sysfs Will Deacon
2021-06-25 8:46 ` Greg Kroah-Hartman
2021-06-25 9:36 ` Will Deacon
2021-06-25 9:49 ` Greg Kroah-Hartman
2021-06-23 17:38 ` [PATCH v10 14/16] arm64: Hook up cmdline parameter to allow mismatched 32-bit EL0 Will Deacon
2021-06-23 17:38 ` Will Deacon [this message]
2021-06-23 17:38 ` [PATCH v10 16/16] Documentation: arm64: describe asymmetric 32-bit support Will Deacon
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