Re: [PATCH 20/25] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it

[Yury Norov]

On Mon, Apr 25, 2016 at 09:19:13PM +0300, Yury Norov wrote:
> On Mon, Apr 25, 2016 at 06:26:56PM +0100, Catalin Marinas wrote:
> > On Wed, Apr 06, 2016 at 01:08:42AM +0300, Yury Norov wrote:
> > > --- a/arch/arm64/kernel/entry.S
> > > +++ b/arch/arm64/kernel/entry.S
> > > @@ -715,9 +715,13 @@ 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
> > > + ldr     x16, [tsk, #TI_FLAGS]
> > > + tbnz    x16, #TIF_32BIT_AARCH64, el0_ilp32_svc // We are using ILP32
> > > +#endif
> > 
> > There is another ldr x16, [tsk, #TI_FLAGS] load further down in the
> > el0_svc_naked block. We should rework these a bit to avoid loading the
> > same location twice unnecessarily. E.g. move the ldr x16 just before
> > el0_svc_naked and branch one line after in case of the ILP32 syscall.
> > 
> 
> Yes, I thiks we can refactor it. Thanks for a catch.

Now it's better, I think


diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index cf4d1ae..21312bb 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -715,16 +715,22 @@ 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
+       ldr     x16, [tsk, #TI_FLAGS]
+#ifdef CONFIG_ARM64_ILP32
+       tbz     x16, #TIF_32BIT_AARCH64, el0_lp64_svc // We are using ILP32
+       adrp    stbl, sys_call_ilp32_table      // load ilp32 syscall table 
pointer
+       b el0_svc_naked
+el0_lp64_svc:
+#endif
+       adrp    stbl, sys_call_table            // load syscall table pointer
 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, #TI_FLAGS]           // check for syscall hooks
-       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
--
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