Messages in this thread | | | Date | Tue, 1 Jul 2014 16:05:39 +0100 | From | Catalin Marinas <> | Subject | Re: [PATCH 22/24] ARM64:ILP32: Use a seperate syscall table as a few syscalls need to be using the compat syscalls. |
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On Sat, May 24, 2014 at 12:02:17AM -0700, Andrew Pinski wrote: > diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S > index 1e1ebfc..8241ffe 100644 > --- a/arch/arm64/kernel/entry.S > +++ b/arch/arm64/kernel/entry.S > @@ -620,9 +620,14 @@ ENDPROC(ret_from_fork) > */ > .align 6 > el0_svc: > - adrp stbl, sys_call_table // load syscall table pointer > uxtw scno, w8 // syscall number in w8 > mov sc_nr, #__NR_syscalls > +#ifdef CONFIG_ARM64_ILP32 > + get_thread_info tsk > + ldr x16, [tsk, #TI_FLAGS] > + tbnz x16, #TIF_32BIT_AARCH64, el0_ilp32_svc // We are using ILP32 > +#endif > + adrp stbl, sys_call_table // load syscall table pointer
This adds a slight penalty on the AArch64 SVC entry path. I can't tell whether that's visible or not but I think the x86 guys decided to set an extra bit to the syscall number to distinguish it from native calls.
> diff --git a/arch/arm64/kernel/sys_ilp32.c b/arch/arm64/kernel/sys_ilp32.c > new file mode 100644 > index 0000000..1da1d11 > --- /dev/null > +++ b/arch/arm64/kernel/sys_ilp32.c [...] > +/* > + * Wrappers to pass the pt_regs argument. > + */ > +#define sys_rt_sigreturn sys_rt_sigreturn_wrapper > + > + > +/* Using Compat syscalls where necessary */ > +#define sys_ioctl compat_sys_ioctl > +/* iovec */ > +#define sys_readv compat_sys_readv > +#define sys_writev compat_sys_writev > +#define sys_preadv compat_sys_preadv64 > +#define sys_pwritev compat_sys_pwritev64 > +#define sys_vmsplice compat_sys_vmsplice
Do these actually work? compat_iovec has two members of 32-bit each while the ILP32 iovec has a void * (32-bit) and a __kernel_size_t which is 64-bit.
> +/* robust_list_head */ > +#define sys_set_robust_list compat_sys_set_robust_list > +#define sys_get_robust_list compat_sys_get_robust_list
Same here, we have a size_t * argument. The compat function would write back 32-bit but size_t is 64-bit for ILP32.
> +/* kexec_segment */ > +#define sys_kexec_load compat_sys_kexec_load
More size_t members in the kexec_segment structure (but we don't yet have kexec on arm64).
> +/* struct msghdr */ > +#define sys_recvfrom compat_sys_recvfrom
Why compat here? struct sockaddr seems to be the same as the native one.
> +#define sys_recvmmsg compat_sys_recvmmsg > +#define sys_sendmmsg compat_sys_sendmmsg > +#define sys_sendmsg compat_sys_sendmsg > +#define sys_recvmsg compat_sys_recvmsg
These get messier as well with a different size_t affecting struct msghdr.
> +#define sys_setsockopt compat_sys_setsockopt > +#define sys_getsockopt compat_sys_getsockopt
Looking at the sock_getsockopt() function, we have a union v copied to/from user. However, such a union contains a struct timeval which for ILP32 would be different than the compat one.
> +/* iovec */ > +#define sys_process_vm_readv compat_sys_process_vm_readv > +#define sys_process_vm_writev compat_sys_process_vm_writev
See above for iovec.
> +/* Pointer in struct */ > +#define sys_mount compat_sys_mount
Which structure is this?
> +/* Scheduler */ > +/* unsigned long bitmaps */ > +#define sys_sched_setaffinity compat_sys_sched_setaffinity > +#define sys_sched_getaffinity compat_sys_sched_getaffinity
Does the long bitmask matter here? I can see the length is passed in bytes.
> +/* iov usage */ > +#define sys_keyctl compat_sys_keyctl
Same problem as iovec above.
> +/* aio */ > +/* Pointer to Pointer */ > +#define sys_io_setup compat_sys_io_setup
sys_io_setup takes a pointer to aio_context_t which is defined as __kernel_ulong_t (same as LP64).
-- Catalin
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