Re: [PATCH RESEND^2] nios2: support clone3() syscall

[Dinh Nguyen]

On 8/2/23 10:43, Randy Dunlap wrote:
> On 8/2/23 01:16, Arnd Bergmann wrote:
> > On Wed, Aug 2, 2023, at 09:40, Christian Brauner wrote:
> > > On Tue, Aug 01, 2023 at 10:19:24PM -0700, Randy Dunlap wrote:
> > > > Add support for the clone3() syscall to prevent a warning from
> > > > checksyscalls.sh:
> > > >
> > > > <stdin>:1517:2: warning: #warning syscall clone3 not implemented [-Wcpp]
> > > >
> > > > Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
> > > > Cc: Dinh Nguyen <dinguyen@xxxxxxxxxx>
> > > > Cc: Christian Brauner <christian@xxxxxxxxxx>
> > > > ---
> > > > Is there some reason that NIOS2 should not (does not) support clone3()?
> > >
> > > Cc Arnd, in case he knows.
> >
> > As far as I remember, you left a few architectures without clone3
> > during the introduction when there was neither an obvious way to
> > handle the syscall entry nor a maintainer to have a look.
> >
> > Right now, it seems to be missing on alpha, hexagon, ia64,
> > microblaze, nios2, sh and sparc.
> >
> > There are a few architectures that implement a custom entry
> > point for both clone and clone3. The other architectures that
> > provide the generic sys_clone3 also use the generic sys_clone.
> > These are the wrappers I see:
> >
> > # ARC
> > ENTRY(sys_clone3_wrapper)
> >          SAVE_CALLEE_SAVED_USER
> >          bl  @sys_clone3
> >          DISCARD_CALLEE_SAVED_USER
> >
> >          GET_CURR_THR_INFO_FLAGS   r10
> >          and.f 0, r10, _TIF_SYSCALL_WORK
> >          bnz   tracesys_exit
> >
> >          b .Lret_from_system_call
> > END(sys_clone3_wrapper)
> >
> > # m68k
> > ENTRY(__sys_clone3)
> >          SAVE_SWITCH_STACK
> >          pea     %sp@(SWITCH_STACK_SIZE)
> >          jbsr    m68k_clone3
> >          lea     %sp@(28),%sp
> >          rts
> >
> >
> > # mips
> > save_static_function(sys_clone3);
> >
> > # openrisc
> > ENTRY(__sys_clone3)
> >          l.movhi r29,hi(sys_clone3)
> >          l.j     _fork_save_extra_regs_and_call
> >           l.ori  r29,r29,lo(sys_clone3)
> >
> > # parisc
> >          .macro  fork_like name
> > ENTRY_CFI(sys_\name\()_wrapper)
> >          mfctl   %cr30,%r1
> >          ldo     TASK_REGS(%r1),%r1
> >          reg_save %r1
> >          mfctl   %cr27, %r28
> >          ldil    L%sys_\name, %r31
> >          be      R%sys_\name(%sr4,%r31)
> >          STREG   %r28, PT_CR27(%r1)
> > ENDPROC_CFI(sys_\name\()_wrapper)
> >          .endm
> > fork_like clone
> > fork_like clone3
> >
> > Nios3 in turn has a wrapper for sys_clone:
> > ENTRY(sys_clone)
> >          SAVE_SWITCH_STACK
> >          subi    sp, sp, 4 /* make space for tls pointer */
> >          stw     r8, 0(sp) /* pass tls pointer (r8) via stack (5th argument) */
> >          call    nios2_clone
> >          addi    sp, sp, 4
> >          RESTORE_SWITCH_STACK
> >          ret
> >
> > so my guess would be that it needs the same thing
> > for clone3 as well. Same thing on alpha, ia64 and
> > sparc. On the other hand hexagon, microblaze and sh
> > use the generic sys_clone() and can probably just
> > enable sys_clone3() without extra work unless it's
> > already broken.
>
> OK, thanks for the help.

Applied!

Thank you,
Dinh