All of lore.kernel.org
 help / color / mirror / Atom feed
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 v9 19/20] arm64: Remove logic to kill 32-bit tasks on 64-bit-only cores
Date: Tue,  8 Jun 2021 19:03:12 +0100	[thread overview]
Message-ID: <20210608180313.11502-20-will@kernel.org> (raw)
In-Reply-To: <20210608180313.11502-1-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.rc1.229.g3e70b5a671-goog


WARNING: multiple messages have this Message-ID
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 v9 19/20] arm64: Remove logic to kill 32-bit tasks on 64-bit-only cores
Date: Tue,  8 Jun 2021 19:03:12 +0100	[thread overview]
Message-ID: <20210608180313.11502-20-will@kernel.org> (raw)
In-Reply-To: <20210608180313.11502-1-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.rc1.229.g3e70b5a671-goog


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2021-06-08 18:05 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-08 18:02 [PATCH v9 00/20] Add support for 32-bit tasks on asymmetric AArch32 systems Will Deacon
2021-06-08 18:02 ` Will Deacon
2021-06-08 18:02 ` [PATCH v9 01/20] arm64: cpuinfo: Split AArch32 registers out into a separate struct Will Deacon
2021-06-08 18:02   ` Will Deacon
2021-06-08 18:02 ` [PATCH v9 02/20] arm64: Allow mismatched 32-bit EL0 support Will Deacon
2021-06-08 18:02   ` Will Deacon
2021-06-08 18:02 ` [PATCH v9 03/20] KVM: arm64: Kill 32-bit vCPUs on systems with mismatched " Will Deacon
2021-06-08 18:02   ` Will Deacon
2021-06-08 18:02 ` [PATCH v9 04/20] arm64: Kill 32-bit applications scheduled on 64-bit-only CPUs Will Deacon
2021-06-08 18:02   ` Will Deacon
2021-06-08 18:02 ` [PATCH v9 05/20] sched: Introduce task_cpu_possible_mask() to limit fallback rq selection Will Deacon
2021-06-08 18:02   ` Will Deacon
2021-06-08 18:02 ` [PATCH v9 06/20] cpuset: Don't use the cpu_possible_mask as a last resort for cgroup v1 Will Deacon
2021-06-08 18:02   ` Will Deacon
2021-06-10 12:59   ` Valentin Schneider
2021-06-10 12:59     ` Valentin Schneider
2021-06-08 18:03 ` [PATCH v9 07/20] cpuset: Honour task_cpu_possible_mask() in guarantee_online_cpus() Will Deacon
2021-06-08 18:03   ` Will Deacon
2021-06-08 18:03 ` [PATCH v9 08/20] cpuset: Cleanup cpuset_cpus_allowed_fallback() use in select_fallback_rq() Will Deacon
2021-06-08 18:03   ` Will Deacon
2021-06-10 12:59   ` Valentin Schneider
2021-06-10 12:59     ` Valentin Schneider
2021-06-08 18:03 ` [PATCH v9 09/20] sched: Reject CPU affinity changes based on task_cpu_possible_mask() Will Deacon
2021-06-08 18:03   ` Will Deacon
2021-06-08 18:03 ` [PATCH v9 10/20] sched: Introduce task_struct::user_cpus_ptr to track requested affinity Will Deacon
2021-06-08 18:03   ` Will Deacon
2021-06-08 18:03 ` [PATCH v9 11/20] sched: Split the guts of sched_setaffinity() into a helper function Will Deacon
2021-06-08 18:03   ` Will Deacon
2021-06-08 18:03 ` [PATCH v9 12/20] sched: Allow task CPU affinity to be restricted on asymmetric systems Will Deacon
2021-06-08 18:03   ` Will Deacon
2021-06-10 13:00   ` Valentin Schneider
2021-06-10 13:00     ` Valentin Schneider
2021-06-08 18:03 ` [PATCH v9 13/20] sched: Introduce dl_task_check_affinity() to check proposed affinity Will Deacon
2021-06-08 18:03   ` Will Deacon
2021-06-08 18:03 ` [PATCH v9 14/20] arm64: Implement task_cpu_possible_mask() Will Deacon
2021-06-08 18:03   ` Will Deacon
2021-06-08 18:03 ` [PATCH v9 15/20] arm64: exec: Adjust affinity for compat tasks with mismatched 32-bit EL0 Will Deacon
2021-06-08 18:03   ` Will Deacon
2021-06-08 18:03 ` [PATCH v9 16/20] arm64: Prevent offlining first CPU with 32-bit EL0 on mismatched system Will Deacon
2021-06-08 18:03   ` Will Deacon
2021-06-08 18:03 ` [PATCH v9 17/20] arm64: Advertise CPUs capable of running 32-bit applications in sysfs Will Deacon
2021-06-08 18:03   ` Will Deacon
2021-06-08 18:03 ` [PATCH v9 18/20] arm64: Hook up cmdline parameter to allow mismatched 32-bit EL0 Will Deacon
2021-06-08 18:03   ` Will Deacon
2021-06-08 18:03 ` Will Deacon [this message]
2021-06-08 18:03   ` [PATCH v9 19/20] arm64: Remove logic to kill 32-bit tasks on 64-bit-only cores Will Deacon
2021-06-08 18:03 ` [PATCH v9 20/20] Documentation: arm64: describe asymmetric 32-bit support Will Deacon
2021-06-08 18:03   ` Will Deacon
2021-06-11 16:15 ` [PATCH v9 00/20] Add support for 32-bit tasks on asymmetric AArch32 systems Will Deacon
2021-06-11 16:15   ` Will Deacon

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210608180313.11502-20-will@kernel.org \
    --to=will@kernel.org \
    --cc=bristot@redhat.com \
    --cc=catalin.marinas@arm.com \
    --cc=dietmar.eggemann@arm.com \
    --cc=gregkh@linuxfoundation.org \
    --cc=hannes@cmpxchg.org \
    --cc=juri.lelli@redhat.com \
    --cc=kernel-team@android.com \
    --cc=linux-arch@vger.kernel.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mark.rutland@arm.com \
    --cc=maz@kernel.org \
    --cc=mingo@redhat.com \
    --cc=morten.rasmussen@arm.com \
    --cc=peterz@infradead.org \
    --cc=qais.yousef@arm.com \
    --cc=qperret@google.com \
    --cc=rjw@rjwysocki.net \
    --cc=surenb@google.com \
    --cc=tj@kernel.org \
    --cc=valentin.schneider@arm.com \
    --cc=vincent.guittot@linaro.org \
    --subject='Re: [PATCH v9 19/20] arm64: Remove logic to kill 32-bit tasks on 64-bit-only cores' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.