[PATCH 1/2] ARC: Add the clone3 wrapper

[PATCH 1/2] ARC: Add the clone3 wrapper

[Pavel.Kozlov]

From: Pavel Kozlov <pavel.kozlov@synopsys.com>

Use the clone3 wrapper on ARC. It doesn't care about stack alignment.
All callers should provide an aligned stack.
It follows the internal signature:

extern int clone3 (struct clone_args *__cl_args, size_t __size,
 int (*__func) (void *__arg), void *__arg);
---
Checked on arc-linux-gnu. Previously observed tst-misaling-clone-internal
test fail was because I used outdated master branch.
Full testsuite runs without regressions.
But I also see fail of the new tst-spawn7, as already repoted at [1].

[1]
https://sourceware.org/pipermail/libc-alpha/2023-February/145937.html

 sysdeps/unix/sysv/linux/arc/clone3.S | 90 ++++++++++++++++++++++++++++
 sysdeps/unix/sysv/linux/arc/sysdep.h |  2 +
 2 files changed, 92 insertions(+)
 create mode 100644 sysdeps/unix/sysv/linux/arc/clone3.S

diff --git a/sysdeps/unix/sysv/linux/arc/clone3.S b/sysdeps/unix/sysv/linux/arc/clone3.S
new file mode 100644
index 000000000000..87a8272a3977
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/arc/clone3.S
@@ -0,0 +1,90 @@
+/* The clone3 syscall wrapper.  Linux/arc version.
+   Copyright (C) 2023 Free Software Foundation, Inc.
+
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <sysdep.h>
+#define _ERRNO_H	1
+#include <bits/errno.h>
+
+/* The userland implementation is:
+   int clone3 (struct clone_args *cl_args, size_t size,
+               int (*func)(void *arg), void *arg);
+
+   the kernel entry is:
+   int clone3 (struct clone_args *cl_args, size_t size);
+
+   The parameters are passed in registers from userland:
+   r0: cl_args
+   r1: size
+   r2: func
+   r3: arg  */
+
+ENTRY(__clone3)
+
+	/* Save args for the child.  */
+	mov	r10, r0		/* cl_args  */
+	mov	r11, r2		/* func	 */
+	mov	r12, r3		/* args  */
+
+	/* Sanity check args.  */
+	breq	r10, 0, L (__sys_err)	/* No NULL cl_args pointer.  */
+	breq	r11, 0, L (__sys_err)	/* No NULL function pointer.  */
+
+	/* Do the system call, the kernel expects:
+	   r8: system call number
+	   r0: cl_args
+	   r1: size  */
+	mov	r0, r10
+	mov	r8, __NR_clone3
+	ARC_TRAP_INSN
+
+	cmp	r0, 0
+	beq	thread_start_clone3	/* Child returns.  */
+	blt	L (__sys_err2)
+	j	[blink]			/* Parent returns.  */
+
+L (__sys_err):
+	mov	r0, -EINVAL
+L (__sys_err2):
+	b	__syscall_error
+PSEUDO_END (__clone3)
+
+
+	.align 4
+	.type thread_start_clone3, %function
+thread_start_clone3:
+	cfi_startproc
+	/* Terminate call stack by noting ra is undefined.  */
+	cfi_undefined (blink)
+
+	/* Child jumps off to @fn with @arg as argument.  */
+	jl.d	[r11]
+	mov	r0, r12
+
+	/* exit() with result from @fn (already in r0).  */
+	mov	r8, __NR_exit
+	ARC_TRAP_INSN
+
+	/* In case it ever came back.  */
+	flag	1
+
+	cfi_endproc
+	.size thread_start_clone3, .-thread_start_clone3
+
+libc_hidden_def (__clone3)
+weak_alias (__clone3, clone3)
diff --git a/sysdeps/unix/sysv/linux/arc/sysdep.h b/sysdeps/unix/sysv/linux/arc/sysdep.h
index dd6fe73445f9..88dc1dff017f 100644
--- a/sysdeps/unix/sysv/linux/arc/sysdep.h
+++ b/sysdeps/unix/sysv/linux/arc/sysdep.h
@@ -141,6 +141,8 @@ hidden_proto (__syscall_error)
 
 # define ARC_TRAP_INSN	"trap_s 0	\n\t"
 
+# define HAVE_CLONE3_WRAPPER	1
+
 # undef INTERNAL_SYSCALL_NCS
 # define INTERNAL_SYSCALL_NCS(number, nr_args, args...)	\
   ({								\
-- 
2.25.1


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[PATCH 2/2] ARC: run child from the separate start block in __clone

[Pavel.Kozlov]

From: Pavel Kozlov <pavel.kozlov@synopsys.com>

For better debug experience use separate code block with extra
cfi_* directives to run child (same as in __clone3).
---
 sysdeps/unix/sysv/linux/arc/clone.S | 40 ++++++++++++++++++-----------
 1 file changed, 25 insertions(+), 15 deletions(-)

diff --git a/sysdeps/unix/sysv/linux/arc/clone.S b/sysdeps/unix/sysv/linux/arc/clone.S
index 766649625658..0029aaeb8170 100644
--- a/sysdeps/unix/sysv/linux/arc/clone.S
+++ b/sysdeps/unix/sysv/linux/arc/clone.S
@@ -20,9 +20,6 @@
 #include <sysdep.h>
 #define _ERRNO_H	1
 #include <bits/errno.h>
-#include <tcb-offsets.h>
-
-#define CLONE_SETTLS		0x00080000
 
 /* int clone(int (*fn)(void *), void *child_stack,
            int flags, void *arg, ...
@@ -63,19 +60,9 @@ ENTRY (__clone)
 	ARC_TRAP_INSN
 
 	cmp	r0, 0		/* return code : 0 new process, !0 parent.  */
+	beq	thread_start_clone
 	blt	L (__sys_err2)	/* < 0 (signed) error.  */
-	jnz	[blink]		/* Parent returns.  */
-
-	/* child jumps off to @fn with @arg as argument
-           TP register already set by kernel.  */
-	jl.d	[r10]
-	mov	r0, r11
-
-	/* exit() with result from @fn (already in r0).  */
-	mov	r8, __NR_exit
-	ARC_TRAP_INSN
-	/* In case it ever came back.  */
-	flag	1
+	j	[blink]		/* Parent returns.  */
 
 L (__sys_err):
 	mov	r0, -EINVAL
@@ -89,5 +76,28 @@ L (__sys_err2):
 	       position independent.  */
 	b   __syscall_error
 PSEUDO_END (__clone)
+
+
+	.align 4
+	.type thread_start_clone, %function
+thread_start_clone:
+	cfi_startproc
+	/* Terminate call stack by noting ra is undefined.  */
+	cfi_undefined (blink)
+
+	/* Child jumps off to @fn with @arg as argument.  */
+	jl.d	[r10]
+	mov	r0, r11
+
+	/* exit() with result from @fn (already in r0).  */
+	mov	r8, __NR_exit
+	ARC_TRAP_INSN
+
+	/* In case it ever came back.  */
+	flag	1
+
+	cfi_endproc
+	.size thread_start_clone, .-thread_start_clone
+
 libc_hidden_def (__clone)
 weak_alias (__clone, clone)
-- 
2.25.1


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Re: [PATCH 1/2] ARC: Add the clone3 wrapper

[Adhemerval Zanella Netto]

On 02/03/23 13:10, Pavel Kozlov via Libc-alpha wrote:
> From: Pavel Kozlov <pavel.kozlov@synopsys.com>
> 
> Use the clone3 wrapper on ARC. It doesn't care about stack alignment.
> All callers should provide an aligned stack.
> It follows the internal signature:
> 
> extern int clone3 (struct clone_args *__cl_args, size_t __size,
>  int (*__func) (void *__arg), void *__arg);

LGTM, thanks.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

> ---
> Checked on arc-linux-gnu. Previously observed tst-misaling-clone-internal
> test fail was because I used outdated master branch.
> Full testsuite runs without regressions.
> But I also see fail of the new tst-spawn7, as already repoted at [1].
> 
> [1]
> https://sourceware.org/pipermail/libc-alpha/2023-February/145937.html
> 
>  sysdeps/unix/sysv/linux/arc/clone3.S | 90 ++++++++++++++++++++++++++++
>  sysdeps/unix/sysv/linux/arc/sysdep.h |  2 +
>  2 files changed, 92 insertions(+)
>  create mode 100644 sysdeps/unix/sysv/linux/arc/clone3.S
> 
> diff --git a/sysdeps/unix/sysv/linux/arc/clone3.S b/sysdeps/unix/sysv/linux/arc/clone3.S
> new file mode 100644
> index 000000000000..87a8272a3977
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/arc/clone3.S
> @@ -0,0 +1,90 @@
> +/* The clone3 syscall wrapper.  Linux/arc version.
> +   Copyright (C) 2023 Free Software Foundation, Inc.
> +
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#include <sysdep.h>
> +#define _ERRNO_H	1
> +#include <bits/errno.h>
> +
> +/* The userland implementation is:
> +   int clone3 (struct clone_args *cl_args, size_t size,
> +               int (*func)(void *arg), void *arg);
> +
> +   the kernel entry is:
> +   int clone3 (struct clone_args *cl_args, size_t size);
> +
> +   The parameters are passed in registers from userland:
> +   r0: cl_args
> +   r1: size
> +   r2: func
> +   r3: arg  */
> +
> +ENTRY(__clone3)
> +
> +	/* Save args for the child.  */
> +	mov	r10, r0		/* cl_args  */
> +	mov	r11, r2		/* func	 */
> +	mov	r12, r3		/* args  */
> +
> +	/* Sanity check args.  */
> +	breq	r10, 0, L (__sys_err)	/* No NULL cl_args pointer.  */
> +	breq	r11, 0, L (__sys_err)	/* No NULL function pointer.  */
> +
> +	/* Do the system call, the kernel expects:
> +	   r8: system call number
> +	   r0: cl_args
> +	   r1: size  */
> +	mov	r0, r10
> +	mov	r8, __NR_clone3
> +	ARC_TRAP_INSN
> +
> +	cmp	r0, 0
> +	beq	thread_start_clone3	/* Child returns.  */
> +	blt	L (__sys_err2)
> +	j	[blink]			/* Parent returns.  */
> +
> +L (__sys_err):
> +	mov	r0, -EINVAL
> +L (__sys_err2):
> +	b	__syscall_error
> +PSEUDO_END (__clone3)
> +
> +
> +	.align 4
> +	.type thread_start_clone3, %function
> +thread_start_clone3:
> +	cfi_startproc
> +	/* Terminate call stack by noting ra is undefined.  */
> +	cfi_undefined (blink)
> +
> +	/* Child jumps off to @fn with @arg as argument.  */
> +	jl.d	[r11]
> +	mov	r0, r12
> +
> +	/* exit() with result from @fn (already in r0).  */
> +	mov	r8, __NR_exit
> +	ARC_TRAP_INSN
> +
> +	/* In case it ever came back.  */
> +	flag	1
> +
> +	cfi_endproc
> +	.size thread_start_clone3, .-thread_start_clone3
> +
> +libc_hidden_def (__clone3)
> +weak_alias (__clone3, clone3)
> diff --git a/sysdeps/unix/sysv/linux/arc/sysdep.h b/sysdeps/unix/sysv/linux/arc/sysdep.h
> index dd6fe73445f9..88dc1dff017f 100644
> --- a/sysdeps/unix/sysv/linux/arc/sysdep.h
> +++ b/sysdeps/unix/sysv/linux/arc/sysdep.h
> @@ -141,6 +141,8 @@ hidden_proto (__syscall_error)
>  
>  # define ARC_TRAP_INSN	"trap_s 0	\n\t"
>  
> +# define HAVE_CLONE3_WRAPPER	1
> +
>  # undef INTERNAL_SYSCALL_NCS
>  # define INTERNAL_SYSCALL_NCS(number, nr_args, args...)	\
>    ({								\

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Re: [PATCH 2/2] ARC: run child from the separate start block in __clone

[Adhemerval Zanella Netto]

On 02/03/23 13:10, Pavel Kozlov via Libc-alpha wrote:
> From: Pavel Kozlov <pavel.kozlov@synopsys.com>
> 
> For better debug experience use separate code block with extra
> cfi_* directives to run child (same as in __clone3).

LGTM, thanks.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

> ---
>  sysdeps/unix/sysv/linux/arc/clone.S | 40 ++++++++++++++++++-----------
>  1 file changed, 25 insertions(+), 15 deletions(-)
> 
> diff --git a/sysdeps/unix/sysv/linux/arc/clone.S b/sysdeps/unix/sysv/linux/arc/clone.S
> index 766649625658..0029aaeb8170 100644
> --- a/sysdeps/unix/sysv/linux/arc/clone.S
> +++ b/sysdeps/unix/sysv/linux/arc/clone.S
> @@ -20,9 +20,6 @@
>  #include <sysdep.h>
>  #define _ERRNO_H	1
>  #include <bits/errno.h>
> -#include <tcb-offsets.h>
> -
> -#define CLONE_SETTLS		0x00080000
>  
>  /* int clone(int (*fn)(void *), void *child_stack,
>             int flags, void *arg, ...
> @@ -63,19 +60,9 @@ ENTRY (__clone)
>  	ARC_TRAP_INSN
>  
>  	cmp	r0, 0		/* return code : 0 new process, !0 parent.  */
> +	beq	thread_start_clone
>  	blt	L (__sys_err2)	/* < 0 (signed) error.  */
> -	jnz	[blink]		/* Parent returns.  */
> -
> -	/* child jumps off to @fn with @arg as argument
> -           TP register already set by kernel.  */
> -	jl.d	[r10]
> -	mov	r0, r11
> -
> -	/* exit() with result from @fn (already in r0).  */
> -	mov	r8, __NR_exit
> -	ARC_TRAP_INSN
> -	/* In case it ever came back.  */
> -	flag	1
> +	j	[blink]		/* Parent returns.  */
>  
>  L (__sys_err):
>  	mov	r0, -EINVAL
> @@ -89,5 +76,28 @@ L (__sys_err2):
>  	       position independent.  */
>  	b   __syscall_error
>  PSEUDO_END (__clone)
> +
> +
> +	.align 4
> +	.type thread_start_clone, %function
> +thread_start_clone:
> +	cfi_startproc
> +	/* Terminate call stack by noting ra is undefined.  */
> +	cfi_undefined (blink)
> +
> +	/* Child jumps off to @fn with @arg as argument.  */
> +	jl.d	[r10]
> +	mov	r0, r11
> +
> +	/* exit() with result from @fn (already in r0).  */
> +	mov	r8, __NR_exit
> +	ARC_TRAP_INSN
> +
> +	/* In case it ever came back.  */
> +	flag	1
> +
> +	cfi_endproc
> +	.size thread_start_clone, .-thread_start_clone
> +
>  libc_hidden_def (__clone)
>  weak_alias (__clone, clone)

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