Hi Yury,

On 04/06/17 13:00, Yury Norov wrote:
> From: Andrew Pinski <apin...@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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