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 v3 04/14] arm64: Kill 32-bit applications scheduled on 64-bit-only CPUs
Date: Fri, 13 Nov 2020 09:37:09 +0000 [thread overview]
Message-ID: <20201113093720.21106-5-will@kernel.org> (raw)
In-Reply-To: <20201113093720.21106-1-will@kernel.org>
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>
---
arch/arm64/kernel/process.c | 19 ++++++++++++++++++-
arch/arm64/kernel/signal.c | 26 ++++++++++++++++++++++++++
2 files changed, 44 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 4784011cecac..1540ab0fbf23 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -542,6 +542,15 @@ 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.
*/
@@ -558,6 +567,7 @@ __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
@@ -620,8 +630,15 @@ unsigned long arch_align_stack(unsigned long sp)
*/
void arch_setup_new_exec(void)
{
- current->mm->context.flags = is_compat_task() ? MMCF_AARCH32 : 0;
+ unsigned long mmflags = 0;
+
+ if (is_compat_task()) {
+ mmflags = MMCF_AARCH32;
+ if (static_branch_unlikely(&arm64_mismatched_32bit_el0))
+ set_tsk_thread_flag(current, TIF_NOTIFY_RESUME);
+ }
+ current->mm->context.flags = mmflags;
ptrauth_thread_init_user(current);
if (task_spec_ssb_noexec(current)) {
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;
+
+ /*
+ * 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)
{
@@ -948,6 +961,19 @@ 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)
--
2.29.2.299.gdc1121823c-goog
next prev parent reply other threads:[~2020-11-13 9:37 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-13 9:37 [PATCH v3 00/14] An alternative series for asymmetric AArch32 systems Will Deacon
2020-11-13 9:37 ` [PATCH v3 01/14] arm64: cpuinfo: Split AArch32 registers out into a separate struct Will Deacon
2020-11-13 9:37 ` [PATCH v3 02/14] arm64: Allow mismatched 32-bit EL0 support Will Deacon
2020-11-19 11:27 ` Valentin Schneider
2020-11-19 13:12 ` Will Deacon
2020-11-13 9:37 ` [PATCH v3 03/14] KVM: arm64: Kill 32-bit vCPUs on systems with mismatched " Will Deacon
2020-11-13 9:37 ` Will Deacon [this message]
2020-11-13 9:37 ` [PATCH v3 05/14] arm64: Advertise CPUs capable of running 32-bit applications in sysfs Will Deacon
2020-11-13 9:37 ` [PATCH v3 06/14] arm64: Hook up cmdline parameter to allow mismatched 32-bit EL0 Will Deacon
2020-11-13 9:37 ` [PATCH v3 07/14] sched: Introduce restrict_cpus_allowed_ptr() to limit task CPU affinity Will Deacon
2020-11-19 9:18 ` Quentin Perret
2020-11-19 11:03 ` Quentin Perret
2020-11-19 11:05 ` Will Deacon
2020-11-19 11:27 ` Valentin Schneider
2020-11-19 13:13 ` Will Deacon
2020-11-19 14:54 ` Valentin Schneider
2020-11-19 16:41 ` Will Deacon
2020-11-19 12:47 ` Valentin Schneider
2020-11-19 13:13 ` Will Deacon
2020-11-19 14:54 ` Valentin Schneider
2020-11-19 16:09 ` Peter Zijlstra
2020-11-19 16:57 ` Valentin Schneider
2020-11-19 19:25 ` Will Deacon
2020-11-13 9:37 ` [PATCH v3 08/14] arm64: exec: Adjust affinity for compat tasks with mismatched 32-bit EL0 Will Deacon
2020-11-19 9:24 ` Quentin Perret
2020-11-19 11:06 ` Will Deacon
2020-11-19 16:19 ` Peter Zijlstra
2020-11-19 16:30 ` Will Deacon
2020-11-19 16:44 ` Peter Zijlstra
2020-11-19 16:51 ` Will Deacon
2020-11-19 16:14 ` Peter Zijlstra
2020-11-19 16:28 ` Will Deacon
2020-11-19 16:42 ` Peter Zijlstra
2020-11-19 16:48 ` Will Deacon
2020-11-13 9:37 ` [PATCH v3 09/14] cpuset: Don't use the cpu_possible_mask as a last resort for cgroup v1 Will Deacon
2020-11-19 9:29 ` Quentin Perret
2020-11-19 11:06 ` Will Deacon
2020-11-13 9:37 ` [PATCH v3 10/14] sched: Introduce arch_cpu_allowed_mask() to limit fallback rq selection Will Deacon
2020-11-19 9:38 ` Quentin Perret
2020-11-19 11:07 ` Will Deacon
2020-11-19 20:39 ` Will Deacon
2020-11-23 14:48 ` Quentin Perret
2020-11-13 9:37 ` [PATCH v3 11/14] sched: Reject CPU affinity changes based on arch_cpu_allowed_mask() Will Deacon
2020-11-19 9:47 ` Quentin Perret
2020-11-19 11:07 ` Will Deacon
2020-11-19 14:30 ` Quentin Perret
2020-11-19 16:44 ` Will Deacon
2020-11-13 9:37 ` [PATCH v3 12/14] arm64: Prevent offlining first CPU with 32-bit EL0 on mismatched system Will Deacon
2020-11-13 9:37 ` [PATCH v3 13/14] arm64: Implement arch_cpu_allowed_mask() Will Deacon
2020-11-13 9:37 ` [PATCH v3 14/14] arm64: Remove logic to kill 32-bit tasks on 64-bit-only cores Will Deacon
2020-11-19 16:11 ` [PATCH v3 00/14] An alternative series for asymmetric AArch32 systems Peter Zijlstra
2020-11-19 16:39 ` 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=20201113093720.21106-5-will@kernel.org \
--to=will@kernel.org \
--cc=catalin.marinas@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=lizefan@huawei.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=surenb@google.com \
--cc=tj@kernel.org \
--cc=vincent.guittot@linaro.org \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).