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Subject[PATCH v3 08/14] arm64: exec: Adjust affinity for compat tasks with mismatched 32-bit EL0
Date
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.

Signed-off-by: Will Deacon <will@kernel.org>
---
arch/arm64/kernel/process.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 1540ab0fbf23..17b94007fed4 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -625,6 +625,16 @@ unsigned long arch_align_stack(unsigned long sp)
return sp & ~0xf;
}

+static void adjust_compat_task_affinity(struct task_struct *p)
+{
+ const struct cpumask *mask = system_32bit_el0_cpumask();
+
+ if (restrict_cpus_allowed_ptr(p, mask))
+ set_cpus_allowed_ptr(p, mask);
+
+ set_tsk_thread_flag(current, TIF_NOTIFY_RESUME);
+}
+
/*
* Called from setup_new_exec() after (COMPAT_)SET_PERSONALITY.
*/
@@ -635,7 +645,7 @@ void arch_setup_new_exec(void)
if (is_compat_task()) {
mmflags = MMCF_AARCH32;
if (static_branch_unlikely(&arm64_mismatched_32bit_el0))
- set_tsk_thread_flag(current, TIF_NOTIFY_RESUME);
+ adjust_compat_task_affinity(current);
}

current->mm->context.flags = mmflags;
--
2.29.2.299.gdc1121823c-goog
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