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From:   Oscar Shiang <oscar0225@livemail.tw>
To:     Marcelo Tosatti <mtosatti@redhat.com>
Cc:     linux-kernel@vger.kernel.org, Nitesh Lal <nilal@redhat.com>,
        Nicolas Saenz Julienne <nsaenzju@redhat.com>,
        Frederic Weisbecker <frederic@kernel.org>,
        Christoph Lameter <cl@linux.com>,
        Juri Lelli <juri.lelli@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Alex Belits <abelits@belits.com>, Peter Xu <peterx@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Daniel Bristot de Oliveira <bristot@redhat.com>
Subject: Re: [patch v11 00/13] extensible prctl task isolation interface and vmstat sync
Date:   Tue,  8 Mar 2022 15:20:04 +0800
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Hi Marcelo,

I also tried to enable task isolation on arm64 with the following changes.

Maybe you can consider these in next version :)

diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
index 6623c99f0984..c1257bca1763 100644
--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h
@@ -72,6 +72,7 @@ int arch_dup_task_struct(struct task_struct *dst,
 #define TIF_SYSCALL_TRACEPOINT	10	/* syscall tracepoint for ftrace */
 #define TIF_SECCOMP		11	/* syscall secure computing */
 #define TIF_SYSCALL_EMU		12	/* syscall emulation active */
+#define TIF_TASK_ISOL		13      /* task isolation work pending */
 #define TIF_MEMDIE		18	/* is terminating due to OOM killer */
 #define TIF_FREEZE		19
 #define TIF_RESTORE_SIGMASK	20
@@ -85,6 +86,7 @@ int arch_dup_task_struct(struct task_struct *dst,
 #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)
 #define _TIF_NOTIFY_RESUME	(1 << TIF_NOTIFY_RESUME)
+#define _TIF_TASK_ISOL		(1 << TIF_TASK_ISOL)
 #define _TIF_FOREIGN_FPSTATE	(1 << TIF_FOREIGN_FPSTATE)
 #define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)
 #define _TIF_SYSCALL_AUDIT	(1 << TIF_SYSCALL_AUDIT)

diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
index c1257bca1763..c136850d623c 100644
--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h
@@ -103,7 +103,7 @@ int arch_dup_task_struct(struct task_struct *dst,
 #define _TIF_WORK_MASK		(_TIF_NEED_RESCHED | _TIF_SIGPENDING | \
 				 _TIF_NOTIFY_RESUME | _TIF_FOREIGN_FPSTATE | \
 				 _TIF_UPROBE | _TIF_MTE_ASYNC_FAULT | \
-				 _TIF_NOTIFY_SIGNAL)
+				 _TIF_NOTIFY_SIGNAL | _TIF_TASK_ISOL)
 
 #define _TIF_SYSCALL_WORK	(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
 				 _TIF_SYSCALL_TRACEPOINT | _TIF_SECCOMP | \
diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index c287b9407f28..8308f6dc5d4b 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -20,6 +20,7 @@
 #include <linux/tracehook.h>
 #include <linux/ratelimit.h>
 #include <linux/syscalls.h>
+#include <linux/task_isolation.h>
 
 #include <asm/daifflags.h>
 #include <asm/debug-monitors.h>
@@ -945,6 +946,9 @@ void do_notify_resume(struct pt_regs *regs, unsigned long thread_flags)
 
 			if (thread_flags & _TIF_FOREIGN_FPSTATE)
 				fpsimd_restore_current_state();
+
+			if (thread_flags & _TIF_TASK_ISOL)
+				task_isol_exit_to_user_mode();
 		}
 
 		local_daif_mask();

Thanks,
Oscar