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[PATCHv5,15/21] kernel: add ksys_personality()

Message ID 20180711135656.20670-16-mark.rutland@arm.com
State Accepted
Commit bf1c77b4644f46d2986b7ca5e43e012f0fc8984b
Headers show
Series arm64: invoke syscalls with pt_regs | expand

Commit Message

Mark Rutland July 11, 2018, 1:56 p.m. UTC
Using this helper allows us to avoid the in-kernel call to the
sys_personality() syscall. The ksys_ prefix denotes that this function
is meant as a drop-in replacement for the syscall. In particular, it
uses the same calling convention as sys_personality().

Since ksys_personality is trivial, it is implemented directly in
<linux/syscalls.h>, as we do for ksys_close() and friends.

This helper is necessary to enable conversion of arm64's syscall
handling to use pt_regs wrappers.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>

Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dave Martin <dave.martin@arm.com>
 include/linux/syscalls.h | 11 +++++++++++
 1 file changed, 11 insertions(+)

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diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index a368a68cb667..abfe12d8a9c5 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>
@@ -1281,4 +1282,14 @@  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;