[PATCH 12/18] kernel: add ksys_personality()

[Dave Martin]

On Mon, May 14, 2018 at 10:46:34AM +0100, Mark Rutland wrote:
> 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().
> 
> This is necessary to enable conversion of arm64's syscall handling to
> use pt_regs wrappers.
> 
> Signed-off-by: Mark Rutland <mark.rutland at arm.com>
> Cc: Al Viro <viro at zeniv.linux.org.uk>
> Cc: Dominik Brodowski <linux at dominikbrodowski.net>

Reviewed-by: Dave Martin <Dave.Martin at arm.com>

> ---
>  include/linux/syscalls.h | 1 +
>  kernel/exec_domain.c     | 7 ++++++-
>  2 files changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
> index 70fcda1a9049..6723ea51ec99 100644
> --- a/include/linux/syscalls.h
> +++ b/include/linux/syscalls.h
> @@ -1148,6 +1148,7 @@ unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len,
>  			      unsigned long prot, unsigned long flags,
>  			      unsigned long fd, unsigned long pgoff);
>  ssize_t ksys_readahead(int fd, loff_t offset, size_t count);
> +unsigned int ksys_personality(unsigned int personality);
>  
>  /*
>   * The following kernel syscall equivalents are just wrappers to fs-internal
> diff --git a/kernel/exec_domain.c b/kernel/exec_domain.c
> index a5697119290e..4ba2b404cba2 100644
> --- a/kernel/exec_domain.c
> +++ b/kernel/exec_domain.c
> @@ -47,7 +47,7 @@ static int __init proc_execdomains_init(void)
>  module_init(proc_execdomains_init);
>  #endif
>  
> -SYSCALL_DEFINE1(personality, unsigned int, personality)
> +unsigned int ksys_personality(unsigned int personality)
>  {
>  	unsigned int old = current->personality;
>  
> @@ -56,3 +56,8 @@ SYSCALL_DEFINE1(personality, unsigned int, personality)
>  
>  	return old;
>  }
> +
> +SYSCALL_DEFINE1(personality, unsigned int, personality)
> +{
> +	return ksys_personality(personality);
> +}
> -- 
> 2.11.0
> 
> 
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