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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 v11 11/16] arm64: exec: Adjust affinity for compat tasks with mismatched 32-bit EL0
Date: Fri, 30 Jul 2021 12:24:38 +0100	[thread overview]
Message-ID: <20210730112443.23245-12-will@kernel.org> (raw)
In-Reply-To: <20210730112443.23245-1-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: Daniel Bristot de Oliveira <bristot@redhat.com>
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 c8989b999250..583ee58f8c9c 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -21,6 +21,7 @@
 #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>
@@ -579,6 +580,28 @@ 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) ||
+	       !dl_task_check_affinity(current, system_32bit_el0_cpumask());
+}
+#endif
+
 /*
  * Called from setup_new_exec() after (COMPAT_)SET_PERSONALITY.
  */
@@ -588,8 +611,22 @@ 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;
-- 
2.32.0.402.g57bb445576-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 v11 11/16] arm64: exec: Adjust affinity for compat tasks with mismatched 32-bit EL0
Date: Fri, 30 Jul 2021 12:24:38 +0100	[thread overview]
Message-ID: <20210730112443.23245-12-will@kernel.org> (raw)
In-Reply-To: <20210730112443.23245-1-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: Daniel Bristot de Oliveira <bristot@redhat.com>
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 c8989b999250..583ee58f8c9c 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -21,6 +21,7 @@
 #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>
@@ -579,6 +580,28 @@ 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) ||
+	       !dl_task_check_affinity(current, system_32bit_el0_cpumask());
+}
+#endif
+
 /*
  * Called from setup_new_exec() after (COMPAT_)SET_PERSONALITY.
  */
@@ -588,8 +611,22 @@ 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;
-- 
2.32.0.402.g57bb445576-goog


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  parent reply	other threads:[~2021-07-30 11:25 UTC|newest]

Thread overview: 67+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-30 11:24 [PATCH v11 00/16] Add support for 32-bit tasks on asymmetric AArch32 systems Will Deacon
2021-07-30 11:24 ` Will Deacon
2021-07-30 11:24 ` [PATCH v11 01/16] sched: Introduce task_cpu_possible_mask() to limit fallback rq selection Will Deacon
2021-07-30 11:24   ` Will Deacon
2021-08-23  9:26   ` [tip: sched/core] " tip-bot2 for Will Deacon
2021-07-30 11:24 ` [PATCH v11 02/16] cpuset: Don't use the cpu_possible_mask as a last resort for cgroup v1 Will Deacon
2021-07-30 11:24   ` Will Deacon
2021-08-23  9:26   ` [tip: sched/core] " tip-bot2 for Will Deacon
2021-07-30 11:24 ` [PATCH v11 03/16] cpuset: Honour task_cpu_possible_mask() in guarantee_online_cpus() Will Deacon
2021-07-30 11:24   ` Will Deacon
2021-08-23  9:26   ` [tip: sched/core] " tip-bot2 for Will Deacon
2021-07-30 11:24 ` [PATCH v11 04/16] cpuset: Cleanup cpuset_cpus_allowed_fallback() use in select_fallback_rq() Will Deacon
2021-07-30 11:24   ` Will Deacon
2021-08-23  9:26   ` [tip: sched/core] " tip-bot2 for Will Deacon
2021-07-30 11:24 ` [PATCH v11 05/16] sched: Reject CPU affinity changes based on task_cpu_possible_mask() Will Deacon
2021-07-30 11:24   ` Will Deacon
2021-08-23  9:26   ` [tip: sched/core] " tip-bot2 for Will Deacon
2021-07-30 11:24 ` [PATCH v11 06/16] sched: Introduce task_struct::user_cpus_ptr to track requested affinity Will Deacon
2021-07-30 11:24   ` Will Deacon
2021-08-23  9:26   ` [tip: sched/core] " tip-bot2 for Will Deacon
2021-07-30 11:24 ` [PATCH v11 07/16] sched: Split the guts of sched_setaffinity() into a helper function Will Deacon
2021-07-30 11:24   ` Will Deacon
2021-08-17 15:40   ` Peter Zijlstra
2021-08-17 15:40     ` Peter Zijlstra
2021-08-18 10:50     ` Will Deacon
2021-08-18 10:50       ` Will Deacon
2021-08-18 10:56       ` Peter Zijlstra
2021-08-18 10:56         ` Peter Zijlstra
2021-08-18 11:11         ` Will Deacon
2021-08-18 11:11           ` Will Deacon
2021-08-23  9:26   ` [tip: sched/core] " tip-bot2 for Will Deacon
2021-07-30 11:24 ` [PATCH v11 08/16] sched: Allow task CPU affinity to be restricted on asymmetric systems Will Deacon
2021-07-30 11:24   ` Will Deacon
2021-08-17 15:10   ` Peter Zijlstra
2021-08-17 15:10     ` Peter Zijlstra
2021-08-18 10:42     ` Will Deacon
2021-08-18 10:42       ` Will Deacon
2021-08-18 10:56       ` Peter Zijlstra
2021-08-18 10:56         ` Peter Zijlstra
2021-08-18 11:53         ` Peter Zijlstra
2021-08-18 11:53           ` Peter Zijlstra
2021-08-18 12:19           ` Will Deacon
2021-08-18 12:19             ` Will Deacon
2021-08-18 11:06       ` Peter Zijlstra
2021-08-18 11:06         ` Peter Zijlstra
2021-08-17 15:41   ` Peter Zijlstra
2021-08-17 15:41     ` Peter Zijlstra
2021-08-18 10:43     ` Will Deacon
2021-08-18 10:43       ` Will Deacon
2021-08-23  9:26   ` [tip: sched/core] " tip-bot2 for Will Deacon
2021-07-30 11:24 ` [PATCH v11 09/16] sched: Introduce dl_task_check_affinity() to check proposed affinity Will Deacon
2021-07-30 11:24   ` Will Deacon
2021-08-23  9:26   ` [tip: sched/core] " tip-bot2 for Will Deacon
2021-07-30 11:24 ` [PATCH v11 10/16] arm64: Implement task_cpu_possible_mask() Will Deacon
2021-07-30 11:24   ` Will Deacon
2021-07-30 11:24 ` Will Deacon [this message]
2021-07-30 11:24   ` [PATCH v11 11/16] arm64: exec: Adjust affinity for compat tasks with mismatched 32-bit EL0 Will Deacon
2021-07-30 11:24 ` [PATCH v11 12/16] arm64: Prevent offlining first CPU with 32-bit EL0 on mismatched system Will Deacon
2021-07-30 11:24   ` Will Deacon
2021-07-30 11:24 ` [PATCH v11 13/16] arm64: Advertise CPUs capable of running 32-bit applications in sysfs Will Deacon
2021-07-30 11:24   ` Will Deacon
2021-07-30 11:24 ` [PATCH v11 14/16] arm64: Hook up cmdline parameter to allow mismatched 32-bit EL0 Will Deacon
2021-07-30 11:24   ` Will Deacon
2021-07-30 11:24 ` [PATCH v11 15/16] arm64: Remove logic to kill 32-bit tasks on 64-bit-only cores Will Deacon
2021-07-30 11:24   ` Will Deacon
2021-07-30 11:24 ` [PATCH v11 16/16] Documentation: arm64: describe asymmetric 32-bit support Will Deacon
2021-07-30 11:24   ` Will Deacon

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