On Tue, Jun 19, 2018 at 04:45:41PM +0100, Catalin Marinas wrote:

On Mon, Jun 18, 2018 at 01:03:04PM +0100, Mark Rutland wrote:

quoted

diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 73810808cdf2..14312d334345 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h

@@ -80,6 +80,7 @@ union bpf_attr;
 #include <linux/unistd.h>
 #include <linux/quota.h>
 #include <linux/key.h>
+#include <linux/personality.h>
 #include <trace/syscall.h>
 
 #ifdef CONFIG_ARCH_HAS_SYSCALL_WRAPPER

@@ -1277,4 +1278,14 @@ static inline long ksys_truncate(const char __user *pathname, loff_t length)
 	return do_sys_truncate(pathname, length);
 }
 
+static inline unsigned int ksys_personality(unsigned int personality)
+{
+	unsigned int old = current->personality;
+
+	if (personality != 0xffffffff)
+		set_personality(personality);
+
+	return old;
+}
+
 #endif

It looks like this is identical to sys_personality() in
kernel/exec_domain.c. Should you call ksys_personality() from there
directly (a few lines saved)?

I had originally done so [1], but Christophe preferred that I open-code
the logic [2].

Thanks,
Mark.

[1] https://lkml.kernel.org/r/20180514094640.27569-13-mark.rutland at arm.com
[2] https://lkml.kernel.org/r/20180514120756.GA11638 at infradead.org