[PATCH 22/24] ARM64:ILP32: Use a seperate syscall table as a few syscalls need to be using the compat syscalls.
From: catalin.marinas@arm.com (Catalin Marinas)
Date: 2014-07-01 15:06:06
Also in:
lkml
On Sat, May 24, 2014 at 12:02:17AM -0700, Andrew Pinski wrote:
quoted hunk ↗ jump to hunk
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.
quoted hunk ↗ jump to hunk
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