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Subject[PATCHv5 15/21] kernel: add ksys_personality()
Date
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(+)

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>

#ifdef CONFIG_ARCH_HAS_SYSCALL_WRAPPER
@@ -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;
+}
+
#endif
--
2.11.0
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