Subject: Re: [PATCH v4 06/20] powerpc: Remove direct call to mmap2 syscall handlers

From: "Nicholas Piggin" <[email-masked]>
Date: Mon, 12 Sep 2022 19:47:17 +1000

On Wed Aug 24, 2022 at 12:05 PM AEST, Rohan McLure wrote:
> Syscall handlers should not be invoked internally by their symbol names,
> as these symbols defined by the architecture-defined SYSCALL_DEFINE
> macro. Move the compatibility syscall definition for mmap2 to
> syscalls.c, so that all mmap implementations can share an inline helper
> function, as is done with the personality handlers.
>
> Signed-off-by: Rohan McLure <[email-masked]>

Is there any point to keping sys_ppc32.c at all? Might as well move them
all to syscall.c IMO.

Reviewed-by: Nicholas Piggin <[email-masked]>

> ---
> V1 -> V2: Move mmap2 compat implementation to asm/kernel/syscalls.c.
> V3 -> V4: Move to be applied before syscall wrapper introduced.
> ---
>  arch/powerpc/kernel/sys_ppc32.c |  9 ---------
>  arch/powerpc/kernel/syscalls.c  | 11 +++++++++++
>  2 files changed, 11 insertions(+), 9 deletions(-)
>
> diff --git a/arch/powerpc/kernel/sys_ppc32.c b/arch/powerpc/kernel/sys_ppc32.c
> index f4edcc9489fb..bc6491ed6454 100644
> --- a/arch/powerpc/kernel/sys_ppc32.c
> +++ b/arch/powerpc/kernel/sys_ppc32.c
> @@ -25,7 +25,6 @@
>  #include <linux/poll.h>
>  #include <linux/personality.h>
>  #include <linux/stat.h>
> -#include <linux/mman.h>
>  #include <linux/in.h>
>  #include <linux/syscalls.h>
>  #include <linux/unistd.h>
> @@ -48,14 +47,6 @@
>  #include <asm/syscalls.h>
>  #include <asm/switch_to.h>
>  
> -unsigned long compat_sys_mmap2(unsigned long addr, size_t len,
> -			  unsigned long prot, unsigned long flags,
> -			  unsigned long fd, unsigned long pgoff)
> -{
> -	/* This should remain 12 even if PAGE_SIZE changes */
> -	return sys_mmap(addr, len, prot, flags, fd, pgoff << 12);
> -}
> -
>  /* 
>   * long long munging:
>   * The 32 bit ABI passes long longs in an odd even register pair.
> diff --git a/arch/powerpc/kernel/syscalls.c b/arch/powerpc/kernel/syscalls.c
> index b8461128c8f7..32fadf3c2cd3 100644
> --- a/arch/powerpc/kernel/syscalls.c
> +++ b/arch/powerpc/kernel/syscalls.c
> @@ -56,6 +56,17 @@ SYSCALL_DEFINE6(mmap2, unsigned long, addr, size_t, len,
>  	return do_mmap2(addr, len, prot, flags, fd, pgoff, PAGE_SHIFT-12);
>  }
>  
> +#ifdef CONFIG_COMPAT
> +COMPAT_SYSCALL_DEFINE6(mmap2,
> +		       unsigned long, addr, size_t, len,
> +		       unsigned long, prot, unsigned long, flags,
> +		       unsigned long, fd, unsigned long, pgoff)
> +{
> +	/* This should remain 12 even if PAGE_SIZE changes */
> +	return do_mmap2(addr, len, prot, flags, fd, pgoff << 12, PAGE_SHIFT-12);
> +}
> +#endif
> +
>  SYSCALL_DEFINE6(mmap, unsigned long, addr, size_t, len,
>  		unsigned long, prot, unsigned long, flags,
>  		unsigned long, fd, off_t, offset)
> -- 
> 2.34.1