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>, Li Zefan <lizefan@huawei.com>, Johannes Weiner <hannes@cmpxchg.org>, Ingo Molnar <mingo@redhat.com>, Juri Lelli <juri.lelli@redhat.com>, Vincent Guittot <vincent.guittot@linaro.org>, kernel-team@android.com Subject: [PATCH v4 14/14] arm64: Remove logic to kill 32-bit tasks on 64-bit-only cores Date: Tue, 24 Nov 2020 15:50:39 +0000 [thread overview] Message-ID: <20201124155039.13804-15-will@kernel.org> (raw) In-Reply-To: <20201124155039.13804-1-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. 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 72116b0c7c73..e21c631c8b17 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -543,15 +543,6 @@ 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); -} - /* * Thread switching. */ @@ -568,7 +559,6 @@ __notrace_funcgraph struct task_struct *__switch_to(struct task_struct *prev, uao_thread_switch(next); ssbs_thread_switch(next); erratum_1418040_thread_switch(prev, next); - compat_thread_switch(next); /* * Complete any pending TLB or cache maintenance on this CPU in case @@ -644,7 +634,7 @@ static void adjust_compat_task_affinity(struct task_struct *p) * execve(). */ if (!restrict_cpus_allowed_ptr(p, possible_mask)) - goto out; + return; if (alloc_cpumask_var(&cpuset_mask, GFP_KERNEL)) { cpuset_cpus_allowed(p, cpuset_mask); @@ -661,8 +651,6 @@ static void adjust_compat_task_affinity(struct task_struct *p) out_set_mask: set_cpus_allowed_ptr(p, newmask); free_cpumask_var(cpuset_mask); -out: - set_tsk_thread_flag(current, TIF_NOTIFY_RESUME); } /* diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c index bcb6ca2d9a7c..a8184cad8890 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) { @@ -961,19 +948,6 @@ 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) -- 2.29.2.454.gaff20da3a2-goog
WARNING: multiple messages have this Message-ID (diff)
From: Will Deacon <will@kernel.org> To: linux-arm-kernel@lists.infradead.org Cc: linux-arch@vger.kernel.org, Marc Zyngier <maz@kernel.org>, kernel-team@android.com, Vincent Guittot <vincent.guittot@linaro.org>, Juri Lelli <juri.lelli@redhat.com>, Quentin Perret <qperret@google.com>, Peter Zijlstra <peterz@infradead.org>, Catalin Marinas <catalin.marinas@arm.com>, Johannes Weiner <hannes@cmpxchg.org>, linux-kernel@vger.kernel.org, Qais Yousef <qais.yousef@arm.com>, Suren Baghdasaryan <surenb@google.com>, Ingo Molnar <mingo@redhat.com>, Li Zefan <lizefan@huawei.com>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Tejun Heo <tj@kernel.org>, Will Deacon <will@kernel.org>, Morten Rasmussen <morten.rasmussen@arm.com> Subject: [PATCH v4 14/14] arm64: Remove logic to kill 32-bit tasks on 64-bit-only cores Date: Tue, 24 Nov 2020 15:50:39 +0000 [thread overview] Message-ID: <20201124155039.13804-15-will@kernel.org> (raw) In-Reply-To: <20201124155039.13804-1-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. 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 72116b0c7c73..e21c631c8b17 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -543,15 +543,6 @@ 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); -} - /* * Thread switching. */ @@ -568,7 +559,6 @@ __notrace_funcgraph struct task_struct *__switch_to(struct task_struct *prev, uao_thread_switch(next); ssbs_thread_switch(next); erratum_1418040_thread_switch(prev, next); - compat_thread_switch(next); /* * Complete any pending TLB or cache maintenance on this CPU in case @@ -644,7 +634,7 @@ static void adjust_compat_task_affinity(struct task_struct *p) * execve(). */ if (!restrict_cpus_allowed_ptr(p, possible_mask)) - goto out; + return; if (alloc_cpumask_var(&cpuset_mask, GFP_KERNEL)) { cpuset_cpus_allowed(p, cpuset_mask); @@ -661,8 +651,6 @@ static void adjust_compat_task_affinity(struct task_struct *p) out_set_mask: set_cpus_allowed_ptr(p, newmask); free_cpumask_var(cpuset_mask); -out: - set_tsk_thread_flag(current, TIF_NOTIFY_RESUME); } /* diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c index bcb6ca2d9a7c..a8184cad8890 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) { @@ -961,19 +948,6 @@ 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) -- 2.29.2.454.gaff20da3a2-goog _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-11-24 15:52 UTC|newest] Thread overview: 122+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-11-24 15:50 [PATCH v4 00/14] An alternative series for asymmetric AArch32 systems Will Deacon 2020-11-24 15:50 ` Will Deacon 2020-11-24 15:50 ` [PATCH v4 01/14] arm64: cpuinfo: Split AArch32 registers out into a separate struct Will Deacon 2020-11-24 15:50 ` Will Deacon 2020-11-24 15:50 ` [PATCH v4 02/14] arm64: Allow mismatched 32-bit EL0 support Will Deacon 2020-11-24 15:50 ` Will Deacon 2020-11-27 10:25 ` Marc Zyngier 2020-11-27 10:25 ` Marc Zyngier 2020-11-27 11:50 ` Will Deacon 2020-11-27 11:50 ` Will Deacon 2020-11-27 13:09 ` Qais Yousef 2020-11-27 13:09 ` Qais Yousef 2020-12-01 16:56 ` Will Deacon 2020-12-01 16:56 ` Will Deacon 2020-12-02 13:16 ` Qais Yousef 2020-12-02 13:16 ` Qais Yousef 2020-11-24 15:50 ` [PATCH v4 03/14] KVM: arm64: Kill 32-bit vCPUs on systems with mismatched " Will Deacon 2020-11-24 15:50 ` Will Deacon 2020-11-27 10:26 ` Marc Zyngier 2020-11-27 10:26 ` Marc Zyngier 2020-11-27 11:53 ` Will Deacon 2020-11-27 11:53 ` Will Deacon 2020-11-27 17:14 ` Marc Zyngier 2020-11-27 17:14 ` Marc Zyngier 2020-11-27 17:24 ` Quentin Perret 2020-11-27 17:24 ` Quentin Perret 2020-11-27 18:16 ` Marc Zyngier 2020-11-27 18:16 ` Marc Zyngier 2020-12-01 16:57 ` Will Deacon 2020-12-01 16:57 ` Will Deacon 2020-12-02 8:18 ` Marc Zyngier 2020-12-02 8:18 ` Marc Zyngier 2020-12-02 17:27 ` Will Deacon 2020-12-02 17:27 ` Will Deacon 2020-11-24 15:50 ` [PATCH v4 04/14] arm64: Kill 32-bit applications scheduled on 64-bit-only CPUs Will Deacon 2020-11-24 15:50 ` Will Deacon 2020-11-27 13:12 ` Qais Yousef 2020-11-27 13:12 ` Qais Yousef 2020-12-01 16:56 ` Will Deacon 2020-12-01 16:56 ` Will Deacon 2020-12-02 13:52 ` Qais Yousef 2020-12-02 13:52 ` Qais Yousef 2020-12-02 17:42 ` Will Deacon 2020-12-02 17:42 ` Will Deacon 2020-11-24 15:50 ` [PATCH v4 05/14] arm64: Advertise CPUs capable of running 32-bit applications in sysfs Will Deacon 2020-11-24 15:50 ` Will Deacon 2020-11-24 15:50 ` [PATCH v4 06/14] arm64: Hook up cmdline parameter to allow mismatched 32-bit EL0 Will Deacon 2020-11-24 15:50 ` Will Deacon 2020-11-27 13:17 ` Qais Yousef 2020-11-27 13:17 ` Qais Yousef 2020-12-01 16:56 ` Will Deacon 2020-12-01 16:56 ` Will Deacon 2020-11-24 15:50 ` [PATCH v4 07/14] sched: Introduce restrict_cpus_allowed_ptr() to limit task CPU affinity Will Deacon 2020-11-24 15:50 ` Will Deacon 2020-11-27 9:49 ` Quentin Perret 2020-11-27 9:49 ` Quentin Perret 2020-11-27 13:19 ` Qais Yousef 2020-11-27 13:19 ` Qais Yousef 2020-12-01 16:56 ` Will Deacon 2020-12-01 16:56 ` Will Deacon 2020-12-02 13:06 ` Qais Yousef 2020-12-02 13:06 ` Qais Yousef 2020-11-24 15:50 ` [PATCH v4 08/14] arm64: exec: Adjust affinity for compat tasks with mismatched 32-bit EL0 Will Deacon 2020-11-24 15:50 ` Will Deacon 2020-11-27 10:01 ` Quentin Perret 2020-11-27 10:01 ` Quentin Perret 2020-11-27 13:23 ` Qais Yousef 2020-11-27 13:23 ` Qais Yousef 2020-12-01 16:55 ` Will Deacon 2020-12-01 16:55 ` Will Deacon 2020-12-02 14:07 ` Qais Yousef 2020-12-02 14:07 ` Qais Yousef 2020-11-24 15:50 ` [PATCH v4 09/14] cpuset: Don't use the cpu_possible_mask as a last resort for cgroup v1 Will Deacon 2020-11-24 15:50 ` Will Deacon 2020-11-27 13:32 ` Qais Yousef 2020-11-27 13:32 ` Qais Yousef 2020-11-30 17:05 ` Qais Yousef 2020-11-30 17:05 ` Qais Yousef 2020-11-30 17:36 ` Quentin Perret 2020-11-30 17:36 ` Quentin Perret 2020-12-01 11:58 ` Qais Yousef 2020-12-01 11:58 ` Qais Yousef 2020-12-01 12:37 ` Quentin Perret 2020-12-01 12:37 ` Quentin Perret 2020-12-01 14:11 ` Qais Yousef 2020-12-01 14:11 ` Qais Yousef 2020-12-01 15:56 ` Quentin Perret 2020-12-01 15:56 ` Quentin Perret 2020-12-01 22:30 ` Will Deacon 2020-12-01 22:30 ` Will Deacon 2020-12-02 11:34 ` Qais Yousef 2020-12-02 11:34 ` Qais Yousef 2020-12-02 11:33 ` Qais Yousef 2020-12-02 11:33 ` Qais Yousef 2020-11-24 15:50 ` [PATCH v4 10/14] sched: Introduce arch_task_cpu_possible_mask() to limit fallback rq selection Will Deacon 2020-11-24 15:50 ` Will Deacon 2020-11-24 15:50 ` [PATCH v4 11/14] sched: Reject CPU affinity changes based on arch_task_cpu_possible_mask() Will Deacon 2020-11-24 15:50 ` Will Deacon 2020-11-27 9:54 ` Quentin Perret 2020-11-27 9:54 ` Quentin Perret 2020-11-24 15:50 ` [PATCH v4 12/14] arm64: Prevent offlining first CPU with 32-bit EL0 on mismatched system Will Deacon 2020-11-24 15:50 ` Will Deacon 2020-11-27 13:41 ` Qais Yousef 2020-11-27 13:41 ` Qais Yousef 2020-12-01 22:13 ` Will Deacon 2020-12-01 22:13 ` Will Deacon 2020-12-02 12:59 ` Qais Yousef 2020-12-02 12:59 ` Qais Yousef 2020-12-02 17:42 ` Will Deacon 2020-12-02 17:42 ` Will Deacon 2020-12-02 18:08 ` Qais Yousef 2020-12-02 18:08 ` Qais Yousef 2020-11-24 15:50 ` [PATCH v4 13/14] arm64: Implement arch_task_cpu_possible_mask() Will Deacon 2020-11-24 15:50 ` Will Deacon 2020-11-27 13:41 ` Qais Yousef 2020-11-27 13:41 ` Qais Yousef 2020-11-24 15:50 ` Will Deacon [this message] 2020-11-24 15:50 ` [PATCH v4 14/14] arm64: Remove logic to kill 32-bit tasks on 64-bit-only cores Will Deacon 2020-11-27 13:58 ` [PATCH v4 00/14] An alternative series for asymmetric AArch32 systems Qais Yousef 2020-11-27 13:58 ` Qais Yousef 2020-12-05 20:43 ` Pavel Machek 2020-12-05 20:43 ` Pavel Machek
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