[PATCH v2 03/14] powerpc: Remove direct call to mmap2 syscall handlers

[Christophe Leroy]

Le 25/07/2022 à 08:25, Rohan McLure a écrit :
> 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 <rmclure at linux.ibm.com>
> ---
> V1 -> V2: Move mmap2 compat implementation to asm/kernel/syscalls.c.
> ---
>   arch/powerpc/kernel/sys_ppc32.c                    | 10 ----------
>   arch/powerpc/kernel/syscalls.c                     | 11 +++++++++++
>   arch/powerpc/kernel/syscalls/syscall.tbl           |  2 +-
>   tools/perf/arch/powerpc/entry/syscalls/syscall.tbl |  4 ++--
>   4 files changed, 14 insertions(+), 13 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/sys_ppc32.c b/arch/powerpc/kernel/sys_ppc32.c
> index c3490adcb158..89e8c478fd6a 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>
> @@ -48,15 +47,6 @@
>   #include <asm/syscalls.h>
>   #include <asm/switch_to.h>
>   
> -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 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 22755502afc0..9f339bcb433d 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)
> diff --git a/arch/powerpc/kernel/syscalls/syscall.tbl b/arch/powerpc/kernel/syscalls/syscall.tbl
> index 54bb5834785f..59d9259dfbb5 100644
> --- a/arch/powerpc/kernel/syscalls/syscall.tbl
> +++ b/arch/powerpc/kernel/syscalls/syscall.tbl
> @@ -243,7 +243,7 @@
>   189	nospu	vfork				sys_vfork
>   190	common	ugetrlimit			sys_getrlimit			compat_sys_getrlimit
>   191	common	readahead			sys_readahead			compat_sys_ppc_readahead
> -192	32	mmap2				sys_mmap2			compat_sys_ppc_mmap2
> +192	32	mmap2				sys_mmap2			compat_sys_mmap2

Why a name change here when the function is just move from one C file to 
another without any name change ?

This look like the reverse of what was done in patch 1. Could that 
change go up front so that patch 1 doesn't need a change at all in the 
table ?

>   193	32	truncate64			sys_truncate64			compat_sys_ppc_truncate64
>   194	32	ftruncate64			sys_ftruncate64			compat_sys_ppc_ftruncate64
>   195	32	stat64				sys_stat64
> diff --git a/tools/perf/arch/powerpc/entry/syscalls/syscall.tbl b/tools/perf/arch/powerpc/entry/syscalls/syscall.tbl
> index 54bb5834785f..437066f5c4b2 100644
> --- a/tools/perf/arch/powerpc/entry/syscalls/syscall.tbl
> +++ b/tools/perf/arch/powerpc/entry/syscalls/syscall.tbl
> @@ -243,7 +243,7 @@
>   189	nospu	vfork				sys_vfork
>   190	common	ugetrlimit			sys_getrlimit			compat_sys_getrlimit
>   191	common	readahead			sys_readahead			compat_sys_ppc_readahead
> -192	32	mmap2				sys_mmap2			compat_sys_ppc_mmap2
> +192	32	mmap2				sys_mmap2			compat_sys_mmap2
>   193	32	truncate64			sys_truncate64			compat_sys_ppc_truncate64
>   194	32	ftruncate64			sys_ftruncate64			compat_sys_ppc_ftruncate64
>   195	32	stat64				sys_stat64
> @@ -391,7 +391,7 @@
>   306	common	timerfd_create			sys_timerfd_create
>   307	common	eventfd				sys_eventfd
>   308	common	sync_file_range2		sys_sync_file_range2		compat_sys_ppc_sync_file_range2
> -309	nospu	fallocate			sys_fallocate			compat_sys_ppc_fallocate
> +309	nospu	fallocate			sys_fallocate			compat_sys_fallocate

Why this name change ?


>   310	nospu	subpage_prot			sys_subpage_prot
>   311	32	timerfd_settime			sys_timerfd_settime32
>   311	64	timerfd_settime			sys_timerfd_settime