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>,
kernel-team@android.com
Subject: [PATCH v7 18/22] arm64: exec: Adjust affinity for compat tasks with mismatched 32-bit EL0
Date: Tue, 25 May 2021 16:14:28 +0100 [thread overview]
Message-ID: <20210525151432.16875-19-will@kernel.org> (raw)
In-Reply-To: <20210525151432.16875-1-will@kernel.org>
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.
Similarly, when exec'ing a 64-bit task on such a system, try to restore
the old affinity mask if it was previously restricted.
Reviewed-by: Quentin Perret <qperret@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
---
arch/arm64/include/asm/elf.h | 6 ++----
arch/arm64/kernel/process.c | 39 +++++++++++++++++++++++++++++++++++-
2 files changed, 40 insertions(+), 5 deletions(-)
diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h
index 8d1c8dcb87fd..97932fbf973d 100644
--- a/arch/arm64/include/asm/elf.h
+++ b/arch/arm64/include/asm/elf.h
@@ -213,10 +213,8 @@ typedef compat_elf_greg_t compat_elf_gregset_t[COMPAT_ELF_NGREG];
/* AArch32 EABI. */
#define EF_ARM_EABI_MASK 0xff000000
-#define compat_elf_check_arch(x) (system_supports_32bit_el0() && \
- ((x)->e_machine == EM_ARM) && \
- ((x)->e_flags & EF_ARM_EABI_MASK))
-
+int compat_elf_check_arch(const struct elf32_hdr *);
+#define compat_elf_check_arch compat_elf_check_arch
#define compat_start_thread compat_start_thread
/*
* Unlike the native SET_PERSONALITY macro, the compat version maintains
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index f4a91bf1ce0c..3aea06fdd1f9 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -22,6 +22,7 @@
#include <linux/mman.h>
#include <linux/mm.h>
#include <linux/nospec.h>
+#include <linux/sched.h>
#include <linux/stddef.h>
#include <linux/sysctl.h>
#include <linux/unistd.h>
@@ -638,6 +639,28 @@ unsigned long arch_align_stack(unsigned long sp)
return sp & ~0xf;
}
+#ifdef CONFIG_COMPAT
+int compat_elf_check_arch(const struct elf32_hdr *hdr)
+{
+ if (!system_supports_32bit_el0())
+ return false;
+
+ if ((hdr)->e_machine != EM_ARM)
+ return false;
+
+ if (!((hdr)->e_flags & EF_ARM_EABI_MASK))
+ return false;
+
+ /*
+ * Prevent execve() of a 32-bit program from a deadline task
+ * if the restricted affinity mask would be inadmissible on an
+ * asymmetric system.
+ */
+ return !static_branch_unlikely(&arm64_mismatched_32bit_el0) ||
+ task_cpus_dl_admissible(current, system_32bit_el0_cpumask());
+}
+#endif
+
/*
* Called from setup_new_exec() after (COMPAT_)SET_PERSONALITY.
*/
@@ -647,8 +670,22 @@ void arch_setup_new_exec(void)
if (is_compat_task()) {
mmflags = MMCF_AARCH32;
- if (static_branch_unlikely(&arm64_mismatched_32bit_el0))
+
+ /*
+ * Restrict the CPU affinity mask for a 32-bit task so that
+ * it contains only 32-bit-capable CPUs.
+ *
+ * From the perspective of the task, this looks similar to
+ * what would happen if the 64-bit-only CPUs were hot-unplugged
+ * at the point of execve(), although we try a bit harder to
+ * honour the cpuset hierarchy.
+ */
+ 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);
}
current->mm->context.flags = mmflags;
--
2.31.1.818.g46aad6cb9e-goog
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next prev parent reply other threads:[~2021-05-25 15:34 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-25 15:14 [PATCH v7 00/22] Add support for 32-bit tasks on asymmetric AArch32 systems Will Deacon
2021-05-25 15:14 ` [PATCH v7 01/22] sched: Favour predetermined active CPU as migration destination Will Deacon
2021-05-26 11:14 ` Valentin Schneider
2021-05-26 12:32 ` Peter Zijlstra
2021-05-26 12:36 ` Valentin Schneider
2021-05-26 16:03 ` Will Deacon
2021-05-26 17:46 ` Valentin Schneider
2021-05-25 15:14 ` [PATCH v7 02/22] arm64: cpuinfo: Split AArch32 registers out into a separate struct Will Deacon
2021-05-25 15:14 ` [PATCH v7 03/22] arm64: Allow mismatched 32-bit EL0 support Will Deacon
2021-05-25 15:14 ` [PATCH v7 04/22] KVM: arm64: Kill 32-bit vCPUs on systems with mismatched " Will Deacon
2021-05-25 15:14 ` [PATCH v7 05/22] arm64: Kill 32-bit applications scheduled on 64-bit-only CPUs Will Deacon
2021-05-25 15:14 ` [PATCH v7 06/22] arm64: Advertise CPUs capable of running 32-bit applications in sysfs Will Deacon
2021-05-25 15:14 ` [PATCH v7 07/22] sched: Introduce task_cpu_possible_mask() to limit fallback rq selection Will Deacon
2021-05-25 15:14 ` [PATCH v7 08/22] cpuset: Don't use the cpu_possible_mask as a last resort for cgroup v1 Will Deacon
2021-05-26 15:02 ` Peter Zijlstra
2021-05-26 16:07 ` Will Deacon
2021-05-25 15:14 ` [PATCH v7 09/22] cpuset: Honour task_cpu_possible_mask() in guarantee_online_cpus() Will Deacon
2021-05-25 15:14 ` [PATCH v7 10/22] sched: Reject CPU affinity changes based on task_cpu_possible_mask() Will Deacon
2021-05-26 15:15 ` Peter Zijlstra
2021-05-26 16:12 ` Will Deacon
2021-05-26 17:56 ` Peter Zijlstra
2021-05-26 18:59 ` Will Deacon
2021-05-25 15:14 ` [PATCH v7 11/22] sched: Introduce task_struct::user_cpus_ptr to track requested affinity Will Deacon
2021-05-25 15:14 ` [PATCH v7 12/22] sched: Split the guts of sched_setaffinity() into a helper function Will Deacon
2021-05-25 15:14 ` [PATCH v7 13/22] sched: Allow task CPU affinity to be restricted on asymmetric systems Will Deacon
2021-05-26 16:20 ` Peter Zijlstra
2021-05-26 16:35 ` Will Deacon
2021-05-26 16:30 ` Peter Zijlstra
2021-05-26 17:02 ` Will Deacon
2021-05-27 7:56 ` Peter Zijlstra
2021-05-25 15:14 ` [PATCH v7 14/22] sched: Introduce task_cpus_dl_admissible() to check proposed affinity Will Deacon
2021-05-25 15:14 ` [PATCH v7 15/22] freezer: Add frozen_or_skipped() helper function Will Deacon
2021-05-25 15:14 ` [PATCH v7 16/22] sched: Defer wakeup in ttwu() for unschedulable frozen tasks Will Deacon
2021-05-27 14:10 ` Peter Zijlstra
2021-05-27 14:31 ` Peter Zijlstra
2021-05-27 14:44 ` Will Deacon
2021-05-27 14:55 ` Peter Zijlstra
2021-05-27 14:50 ` Peter Zijlstra
2021-05-28 10:49 ` Peter Zijlstra
2021-05-27 14:36 ` Will Deacon
2021-06-01 8:21 ` [RFC][PATCH] freezer,sched: Rewrite core freezer logic Peter Zijlstra
2021-06-01 11:27 ` Peter Zijlstra
2021-06-02 12:54 ` Will Deacon
2021-06-03 10:35 ` Peter Zijlstra
2021-06-03 10:58 ` Will Deacon
2021-06-03 11:26 ` Peter Zijlstra
2021-06-03 11:36 ` Will Deacon
2021-05-25 15:14 ` [PATCH v7 17/22] arm64: Implement task_cpu_possible_mask() Will Deacon
2021-05-25 15:14 ` Will Deacon [this message]
2021-05-25 15:14 ` [PATCH v7 19/22] arm64: Prevent offlining first CPU with 32-bit EL0 on mismatched system Will Deacon
2021-05-25 15:14 ` [PATCH v7 20/22] arm64: Hook up cmdline parameter to allow mismatched 32-bit EL0 Will Deacon
2021-05-25 15:14 ` [PATCH v7 21/22] arm64: Remove logic to kill 32-bit tasks on 64-bit-only cores Will Deacon
2021-05-25 15:14 ` [PATCH v7 22/22] Documentation: arm64: describe asymmetric 32-bit support Will Deacon
2021-05-25 17:13 ` Marc Zyngier
2021-05-25 17:27 ` Will Deacon
2021-05-25 18:11 ` Marc Zyngier
2021-05-26 16:00 ` Will Deacon
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