[v8,2/3] x86-64: Add the clone3 wrapper

Message ID 20210601145516.3553627-3-hjl.tools@gmail.com
State New
Headers show
Series
  • Add an internal wrapper for clone, clone2 and clone3
Related show

Commit Message

Szabolcs Nagy via Libc-alpha June 1, 2021, 2:55 p.m.
extern int clone3 (struct clone_args *__cl_args, size_t __size,
		   int (*__func) (void *__arg), void *__arg);
---
 sysdeps/unix/sysv/linux/x86_64/clone3.S | 92 +++++++++++++++++++++++++
 sysdeps/unix/sysv/linux/x86_64/sysdep.h |  2 +
 2 files changed, 94 insertions(+)
 create mode 100644 sysdeps/unix/sysv/linux/x86_64/clone3.S

-- 
2.31.1

Comments

Szabolcs Nagy via Libc-alpha July 13, 2021, 7:12 p.m. | #1
LGTM, thanks.

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


On 01/06/2021 11:55, H.J. Lu wrote:
> extern int clone3 (struct clone_args *__cl_args, size_t __size,

> 		   int (*__func) (void *__arg), void *__arg);

> ---

>  sysdeps/unix/sysv/linux/x86_64/clone3.S | 92 +++++++++++++++++++++++++

>  sysdeps/unix/sysv/linux/x86_64/sysdep.h |  2 +

>  2 files changed, 94 insertions(+)

>  create mode 100644 sysdeps/unix/sysv/linux/x86_64/clone3.S

> 

> diff --git a/sysdeps/unix/sysv/linux/x86_64/clone3.S b/sysdeps/unix/sysv/linux/x86_64/clone3.S

> new file mode 100644

> index 0000000000..71caaecc29

> --- /dev/null

> +++ b/sysdeps/unix/sysv/linux/x86_64/clone3.S

> @@ -0,0 +1,92 @@

> +/* The clone3 syscall wrapper.  Linux/x86-64 version.

> +   Copyright (C) 2021 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/>.  */

> +

> +/* clone3() is even more special than fork() as it mucks with stacks

> +   and invokes a function in the right context after its all over.  */

> +

> +#include <sysdep.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:

> +   rdi: cl_args

> +   rsi: size

> +   rdx: func

> +   rcx: arg

> +

> +   The kernel expects:

> +   rax: system call number

> +   rdi: cl_args

> +   rsi: size  */

> +

> +        .text

> +ENTRY (__clone3)

> +	/* Sanity check arguments.  */

> +	movl	$-EINVAL, %eax

> +	test	%RDI_LP, %RDI_LP	/* No NULL cl_args pointer.  */

> +	jz	SYSCALL_ERROR_LABEL

> +	test	%RDX_LP, %RDX_LP	/* No NULL function pointer.  */

> +	jz	SYSCALL_ERROR_LABEL

> +

> +	/* Save the cl_args pointer in R8 which is preserved by the

> +	   syscall.  */

> +	mov	%RCX_LP, %R8_LP

> +

> +	/* Do the system call.  */

> +	movl	$SYS_ify(clone3), %eax

> +

> +	/* End FDE now, because in the child the unwind info will be

> +	   wrong.  */

> +	cfi_endproc

> +	syscall

> +

> +	test	%RAX_LP, %RAX_LP

> +	jl	SYSCALL_ERROR_LABEL

> +	jz	L(thread_start)

> +

> +	ret

> +

> +L(thread_start):

> +	cfi_startproc

> +	/* Clearing frame pointer is insufficient, use CFI.  */

> +	cfi_undefined (rip)

> +	/* Clear the frame pointer.  The ABI suggests this be done, to mark

> +	   the outermost frame obviously.  */

> +	xorl	%ebp, %ebp

> +

> +	/* Align stack to 16 bytes per the x86-64 psABI.  */

> +	and	$-16, %RSP_LP

> +

> +	/* Set up arguments for the function call.  */

> +	mov	%R8_LP, %RDI_LP	/* Argument.  */

> +	call	*%rdx		/* Call function.  */

> +	/* Call exit with return value from function call. */

> +	movq	%rax, %rdi

> +	movl	$SYS_ify(exit), %eax

> +	syscall

> +	cfi_endproc

> +

> +	cfi_startproc

> +PSEUDO_END (__clone3)

> +

> +libc_hidden_def (__clone3)

> +weak_alias (__clone3, clone3)

> diff --git a/sysdeps/unix/sysv/linux/x86_64/sysdep.h b/sysdeps/unix/sysv/linux/x86_64/sysdep.h

> index dbad2c788a..f26ffc68ae 100644

> --- a/sysdeps/unix/sysv/linux/x86_64/sysdep.h

> +++ b/sysdeps/unix/sysv/linux/x86_64/sysdep.h

> @@ -377,6 +377,8 @@

>  # define HAVE_GETCPU_VSYSCALL		"__vdso_getcpu"

>  # define HAVE_CLOCK_GETRES64_VSYSCALL   "__vdso_clock_getres"

>  

> +# define HAVE_CLONE3_WAPPER			1

> +

>  # define SINGLE_THREAD_BY_GLOBAL		1

>  

>  #endif	/* __ASSEMBLER__ */

> 


Ok.

Patch

diff --git a/sysdeps/unix/sysv/linux/x86_64/clone3.S b/sysdeps/unix/sysv/linux/x86_64/clone3.S
new file mode 100644
index 0000000000..71caaecc29
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/x86_64/clone3.S
@@ -0,0 +1,92 @@ 
+/* The clone3 syscall wrapper.  Linux/x86-64 version.
+   Copyright (C) 2021 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/>.  */
+
+/* clone3() is even more special than fork() as it mucks with stacks
+   and invokes a function in the right context after its all over.  */
+
+#include <sysdep.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:
+   rdi: cl_args
+   rsi: size
+   rdx: func
+   rcx: arg
+
+   The kernel expects:
+   rax: system call number
+   rdi: cl_args
+   rsi: size  */
+
+        .text
+ENTRY (__clone3)
+	/* Sanity check arguments.  */
+	movl	$-EINVAL, %eax
+	test	%RDI_LP, %RDI_LP	/* No NULL cl_args pointer.  */
+	jz	SYSCALL_ERROR_LABEL
+	test	%RDX_LP, %RDX_LP	/* No NULL function pointer.  */
+	jz	SYSCALL_ERROR_LABEL
+
+	/* Save the cl_args pointer in R8 which is preserved by the
+	   syscall.  */
+	mov	%RCX_LP, %R8_LP
+
+	/* Do the system call.  */
+	movl	$SYS_ify(clone3), %eax
+
+	/* End FDE now, because in the child the unwind info will be
+	   wrong.  */
+	cfi_endproc
+	syscall
+
+	test	%RAX_LP, %RAX_LP
+	jl	SYSCALL_ERROR_LABEL
+	jz	L(thread_start)
+
+	ret
+
+L(thread_start):
+	cfi_startproc
+	/* Clearing frame pointer is insufficient, use CFI.  */
+	cfi_undefined (rip)
+	/* Clear the frame pointer.  The ABI suggests this be done, to mark
+	   the outermost frame obviously.  */
+	xorl	%ebp, %ebp
+
+	/* Align stack to 16 bytes per the x86-64 psABI.  */
+	and	$-16, %RSP_LP
+
+	/* Set up arguments for the function call.  */
+	mov	%R8_LP, %RDI_LP	/* Argument.  */
+	call	*%rdx		/* Call function.  */
+	/* Call exit with return value from function call. */
+	movq	%rax, %rdi
+	movl	$SYS_ify(exit), %eax
+	syscall
+	cfi_endproc
+
+	cfi_startproc
+PSEUDO_END (__clone3)
+
+libc_hidden_def (__clone3)
+weak_alias (__clone3, clone3)
diff --git a/sysdeps/unix/sysv/linux/x86_64/sysdep.h b/sysdeps/unix/sysv/linux/x86_64/sysdep.h
index dbad2c788a..f26ffc68ae 100644
--- a/sysdeps/unix/sysv/linux/x86_64/sysdep.h
+++ b/sysdeps/unix/sysv/linux/x86_64/sysdep.h
@@ -377,6 +377,8 @@ 
 # define HAVE_GETCPU_VSYSCALL		"__vdso_getcpu"
 # define HAVE_CLOCK_GETRES64_VSYSCALL   "__vdso_clock_getres"
 
+# define HAVE_CLONE3_WAPPER			1
+
 # define SINGLE_THREAD_BY_GLOBAL		1
 
 #endif	/* __ASSEMBLER__ */