Messages in this thread | | | Date | Thu, 08 Jun 2017 16:05:36 +0100 | From | James Morse <> | Subject | Re: [PATCH 14/20] arm64: ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it |
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Hi Yury,
On 04/06/17 13:00, Yury Norov wrote: > From: Andrew Pinski <apinski@cavium.com> > > Add a separate syscall-table for ILP32, which dispatches either to native > LP64 system call implementation or to compat-syscalls, as appropriate.
(I'm still reading through this series trying to understand it, but spotted this: )
> diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S > index 279bc2ab10c3..7d52fe1ec6bd 100644 > --- a/arch/arm64/kernel/entry.S > +++ b/arch/arm64/kernel/entry.S > @@ -577,6 +594,7 @@ el0_svc_compat: > * AArch32 syscall handling > */ > adrp stbl, compat_sys_call_table // load compat syscall table pointer > + ldr x16, [tsk, #TSK_TI_FLAGS] > uxtw scno, w7 // syscall number in w7 (r7) > mov sc_nr, #__NR_compat_syscalls > b el0_svc_naked > @@ -798,15 +816,21 @@ ENDPROC(ret_from_fork) > .align 6 > el0_svc: > adrp stbl, sys_call_table // load syscall table pointer > + ldr x16, [tsk, #TSK_TI_FLAGS] > uxtw scno, w8 // syscall number in w8 > mov sc_nr, #__NR_syscalls > +#ifdef CONFIG_ARM64_ILP32 > + tst x16, #_TIF_32BIT_AARCH64 > + b.eq el0_svc_naked // We are using LP64 syscall table > + adrp stbl, sys_call_ilp32_table // load ilp32 syscall table pointer > + delouse_input_regs > +#endif > el0_svc_naked: // compat entry point > stp x0, scno, [sp, #S_ORIG_X0] // save the original x0 and syscall number > enable_dbg_and_irq > ct_user_exit 1 >
> - ldr x16, [tsk, #TSK_TI_FLAGS] // check for syscall hooks
If built with CONFIG_CONTEXT_TRACKING, ct_user_exit will call context_tracking_user_exit(), this will clobber x16 which you depend on not changing below:
> - tst x16, #_TIF_SYSCALL_WORK > + tst x16, #_TIF_SYSCALL_WORK // check for syscall hooks
> b.ne __sys_trace > cmp scno, sc_nr // check upper syscall limit > b.hs ni_sys
Thanks,
James
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