Re: [PATCH v9 8/9] arch, mm: wire up memfd_secret system call were relevant

Catalin Marinas
2020-11-17T17:16:06Z

On Tue, Nov 17, 2020 at 06:29:31PM +0200, Mike Rapoport wrote:
> From: Mike Rapoport <rppt@linux.ibm.com>
>
> Wire up memfd_secret system call on architectures that define
> ARCH_HAS_SET_DIRECT_MAP, namely arm64, risc-v and x86.
>
> Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
> Acked-by: Palmer Dabbelt <palmerdabbelt@google.com>
> Acked-by: Arnd Bergmann <arnd@arndb.de>
> ---
> arch/arm64/include/asm/unistd.h | 2 +-
> arch/arm64/include/asm/unistd32.h | 2 ++
> arch/arm64/include/uapi/asm/unistd.h | 1 +
> arch/riscv/include/asm/unistd.h | 1 +
> arch/x86/entry/syscalls/syscall_32.tbl | 1 +
> arch/x86/entry/syscalls/syscall_64.tbl | 1 +
> include/linux/syscalls.h | 1 +
> include/uapi/asm-generic/unistd.h | 6 +++++-
> scripts/checksyscalls.sh | 4 ++++
> 9 files changed, 17 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/include/asm/unistd.h b/arch/arm64/include/asm/unistd.h
> index 86a9d7b3eabe..949788f5ba40 100644
> --- a/arch/arm64/include/asm/unistd.h
> +++ b/arch/arm64/include/asm/unistd.h
> @@ -38,7 +38,7 @@
> #define __ARM_NR_compat_set_tls (__ARM_NR_COMPAT_BASE + 5)
> #define __ARM_NR_COMPAT_END (__ARM_NR_COMPAT_BASE + 0x800)
>
> -#define __NR_compat_syscalls 442
> +#define __NR_compat_syscalls 443
> #endif
>
> #define __ARCH_WANT_SYS_CLONE
> diff --git a/arch/arm64/include/asm/unistd32.h b/arch/arm64/include/asm/unistd32.h
> index 6c1dcca067e0..5279481ec95b 100644
> --- a/arch/arm64/include/asm/unistd32.h
> +++ b/arch/arm64/include/asm/unistd32.h
> @@ -891,6 +891,8 @@ __SYSCALL(__NR_faccessat2, sys_faccessat2)
> __SYSCALL(__NR_process_madvise, sys_process_madvise)
> #define __NR_watch_mount 441
> __SYSCALL(__NR_watch_mount, sys_watch_mount)
> +/* 442 is memfd_secret, it is not implemented for 32-bit */
> +__SYSCALL(442, sys_ni_syscall)

It now behaves correctly for compat but I don't think we need to
increment __NR_compat_syscalls. The compat syscall handler already calls
sys_ni_syscall() if out of range.

So the only arm64 change needed is defining __ARCH_WANT_MEMFD_SECRET
(well, we don't have a use for it yet ;)).

--
Catalin