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SubjectRe: [PATCH] powerpc: Wire up clone3 syscall
On Mon, Jul 22, 2019 at 11:22:31PM +1000, Michael Ellerman wrote:
> Wire up the new clone3 syscall added in commit 7f192e3cd316 ("fork:
> add clone3").
>
> This requires a ppc_clone3 wrapper, in order to save the non-volatile
> GPRs before calling into the generic syscall code. Otherwise we hit
> the BUG_ON in CHECK_FULL_REGS in copy_thread().
>
> Lightly tested using Christian's test code on a Power8 LE VM.
>
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Thank you, Michael!

One comment below, otherwise:

Acked-by: Christian Brauner <christian@brauner.io>

> ---
> arch/powerpc/include/asm/unistd.h | 1 +
> arch/powerpc/kernel/entry_64.S | 5 +++++
> arch/powerpc/kernel/syscalls/syscall.tbl | 1 +
> 3 files changed, 7 insertions(+)
>
> diff --git a/arch/powerpc/include/asm/unistd.h b/arch/powerpc/include/asm/unistd.h
> index 68473c3c471c..b0720c7c3fcf 100644
> --- a/arch/powerpc/include/asm/unistd.h
> +++ b/arch/powerpc/include/asm/unistd.h
> @@ -49,6 +49,7 @@
> #define __ARCH_WANT_SYS_FORK
> #define __ARCH_WANT_SYS_VFORK
> #define __ARCH_WANT_SYS_CLONE
> +#define __ARCH_WANT_SYS_CLONE3
>
> #endif /* __ASSEMBLY__ */
> #endif /* _ASM_POWERPC_UNISTD_H_ */
> diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
> index d9105fcf4021..0a0b5310f54a 100644
> --- a/arch/powerpc/kernel/entry_64.S
> +++ b/arch/powerpc/kernel/entry_64.S
> @@ -487,6 +487,11 @@ _GLOBAL(ppc_clone)
> bl sys_clone
> b .Lsyscall_exit
>
> +_GLOBAL(ppc_clone3)
> + bl save_nvgprs
> + bl sys_clone3
> + b .Lsyscall_exit
> +
> _GLOBAL(ppc32_swapcontext)
> bl save_nvgprs
> bl compat_sys_swapcontext
> diff --git a/arch/powerpc/kernel/syscalls/syscall.tbl b/arch/powerpc/kernel/syscalls/syscall.tbl
> index f2c3bda2d39f..6886ecb590d5 100644
> --- a/arch/powerpc/kernel/syscalls/syscall.tbl
> +++ b/arch/powerpc/kernel/syscalls/syscall.tbl
> @@ -516,3 +516,4 @@
> 432 common fsmount sys_fsmount
> 433 common fspick sys_fspick
> 434 common pidfd_open sys_pidfd_open
> +435 common clone3 ppc_clone3

Note that in v5.3-rc1 there's now a comment that 435 is reserved in
there. So this will likely cause a merge conflict. You might want to
base your change off of v5.3-rc1 instead to avoid that. :)

So basically:

From 10b2e4176d712e45c7cb22af4aed4ce09818785c Mon Sep 17 00:00:00 2001
From: Michael Ellerman <mpe@ellerman.id.au>
Date: Mon, 22 Jul 2019 23:22:31 +1000
Subject: [PATCH] powerpc: Wire up clone3 syscall

Wire up the new clone3 syscall added in commit 7f192e3cd316 ("fork:
add clone3").

This requires a ppc_clone3 wrapper, in order to save the non-volatile
GPRs before calling into the generic syscall code. Otherwise we hit
the BUG_ON in CHECK_FULL_REGS in copy_thread().

Lightly tested using Christian's test code on a Power8 LE VM.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Christian Brauner <christian@brauner.io>
Link: https://lore.kernel.org/r/20190722132231.10169-1-mpe@ellerman.id.au
---
arch/powerpc/include/asm/unistd.h | 1 +
arch/powerpc/kernel/entry_64.S | 5 +++++
arch/powerpc/kernel/syscalls/syscall.tbl | 2 +-
3 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/unistd.h b/arch/powerpc/include/asm/unistd.h
index 68473c3c471c..b0720c7c3fcf 100644
--- a/arch/powerpc/include/asm/unistd.h
+++ b/arch/powerpc/include/asm/unistd.h
@@ -49,6 +49,7 @@
#define __ARCH_WANT_SYS_FORK
#define __ARCH_WANT_SYS_VFORK
#define __ARCH_WANT_SYS_CLONE
+#define __ARCH_WANT_SYS_CLONE3

#endif /* __ASSEMBLY__ */
#endif /* _ASM_POWERPC_UNISTD_H_ */
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index d9105fcf4021..0a0b5310f54a 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -487,6 +487,11 @@ _GLOBAL(ppc_clone)
bl sys_clone
b .Lsyscall_exit

+_GLOBAL(ppc_clone3)
+ bl save_nvgprs
+ bl sys_clone3
+ b .Lsyscall_exit
+
_GLOBAL(ppc32_swapcontext)
bl save_nvgprs
bl compat_sys_swapcontext
diff --git a/arch/powerpc/kernel/syscalls/syscall.tbl b/arch/powerpc/kernel/syscalls/syscall.tbl
index 3331749aab20..6886ecb590d5 100644
--- a/arch/powerpc/kernel/syscalls/syscall.tbl
+++ b/arch/powerpc/kernel/syscalls/syscall.tbl
@@ -516,4 +516,4 @@
432 common fsmount sys_fsmount
433 common fspick sys_fspick
434 common pidfd_open sys_pidfd_open
-# 435 reserved for clone3
+435 common clone3 ppc_clone3
--
2.22.0
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