[v4,3/6] Linux: Do not align the stack for __clone3
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dj/TryBot-apply_patch |
success
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Patch applied to master at the time it was sent
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Commit Message
All internal callers of __clone3 should provide an already aligned
stack. Removing the stack alignment in __clone3 is a net gain: it
simplifies the internal function contract (mask/unmask signals) along
with the arch-specific code.
Checked on x86_64-linux-gnu.
---
include/clone_internal.h | 3 +
.../sysv/linux/tst-misalign-clone-internal.c | 74 -------------------
sysdeps/unix/sysv/linux/x86_64/clone3.S | 3 -
3 files changed, 3 insertions(+), 77 deletions(-)
delete mode 100644 sysdeps/unix/sysv/linux/tst-misalign-clone-internal.c
Comments
On 1/12/23 08:58, Adhemerval Zanella wrote:
> All internal callers of __clone3 should provide an already aligned
> stack. Removing the stack alignment in __clone3 is a net gain: it
> simplifies the internal function contract (mask/unmask signals) along
> with the arch-specific code.
>
> Checked on x86_64-linux-gnu.
OK for 2.28.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
> ---
> include/clone_internal.h | 3 +
> .../sysv/linux/tst-misalign-clone-internal.c | 74 -------------------
> sysdeps/unix/sysv/linux/x86_64/clone3.S | 3 -
> 3 files changed, 3 insertions(+), 77 deletions(-)
> delete mode 100644 sysdeps/unix/sysv/linux/tst-misalign-clone-internal.c
>
> diff --git a/include/clone_internal.h b/include/clone_internal.h
> index 73b8114df4..f8198d8059 100644
> --- a/include/clone_internal.h
> +++ b/include/clone_internal.h
> @@ -11,6 +11,9 @@
> Different than kernel, the implementation also returns EINVAL for an
> invalid NULL __CL_ARGS or __FUNC (similar to __clone).
>
> + All callers are responsible for correctly aligning the stack. The stack is
> + not aligned prior to the syscall (this differs from the exported __clone).
> +
> This function is only implemented if the ABI defines HAVE_CLONE3_WRAPPER.
> */
> extern int __clone3 (struct clone_args *__cl_args, size_t __size,
> diff --git a/sysdeps/unix/sysv/linux/tst-misalign-clone-internal.c b/sysdeps/unix/sysv/linux/tst-misalign-clone-internal.c
> deleted file mode 100644
> index 8b94a74819..0000000000
> --- a/sysdeps/unix/sysv/linux/tst-misalign-clone-internal.c
> +++ /dev/null
> @@ -1,74 +0,0 @@
> -/* Verify that __clone_internal properly aligns the child stack.
> - Copyright (C) 2021-2023 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 <sched.h>
> -#include <stdbool.h>
> -#include <stdint.h>
> -#include <stdio.h>
> -#include <string.h>
> -#include <sys/wait.h>
> -#include <unistd.h>
> -#include <libc-pointer-arith.h>
> -#include <tst-stack-align.h>
> -#include <clone_internal.h>
> -#include <support/xunistd.h>
> -#include <support/check.h>
> -
> -static int
> -check_stack_alignment (void *arg)
> -{
> - puts ("in f");
> -
> - return TEST_STACK_ALIGN () ? 1 : 0;
> -}
> -
> -static int
> -do_test (void)
> -{
> - puts ("in do_test");
> -
> - if (TEST_STACK_ALIGN ())
> - FAIL_EXIT1 ("stack isn't aligned\n");
> -
> -#ifdef __ia64__
> -# define STACK_SIZE (256 * 1024)
> -#else
> -# define STACK_SIZE (128 * 1024)
> -#endif
> - char st[STACK_SIZE + 1];
> - /* NB: Align child stack to 1 byte. */
> - char *stack = PTR_ALIGN_UP (&st[0], 2) + 1;
> - struct clone_args clone_args =
> - {
> - .stack = (uintptr_t) stack,
> - .stack_size = STACK_SIZE,
> - };
> - pid_t p = __clone_internal (&clone_args, check_stack_alignment, 0);
> -
> - /* Clone must not fail. */
> - TEST_VERIFY_EXIT (p != -1);
> -
> - int e;
> - xwaitpid (p, &e, __WCLONE);
> - TEST_VERIFY (WIFEXITED (e));
> - TEST_COMPARE (WEXITSTATUS (e), 0);
> -
> - return 0;
> -}
> -
> -#include <support/test-driver.c>
> diff --git a/sysdeps/unix/sysv/linux/x86_64/clone3.S b/sysdeps/unix/sysv/linux/x86_64/clone3.S
> index bd4a834e46..802d56cbac 100644
> --- a/sysdeps/unix/sysv/linux/x86_64/clone3.S
> +++ b/sysdeps/unix/sysv/linux/x86_64/clone3.S
> @@ -73,9 +73,6 @@ L(thread_start):
> 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. */
@@ -11,6 +11,9 @@
Different than kernel, the implementation also returns EINVAL for an
invalid NULL __CL_ARGS or __FUNC (similar to __clone).
+ All callers are responsible for correctly aligning the stack. The stack is
+ not aligned prior to the syscall (this differs from the exported __clone).
+
This function is only implemented if the ABI defines HAVE_CLONE3_WRAPPER.
*/
extern int __clone3 (struct clone_args *__cl_args, size_t __size,
deleted file mode 100644
@@ -1,74 +0,0 @@
-/* Verify that __clone_internal properly aligns the child stack.
- Copyright (C) 2021-2023 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 <sched.h>
-#include <stdbool.h>
-#include <stdint.h>
-#include <stdio.h>
-#include <string.h>
-#include <sys/wait.h>
-#include <unistd.h>
-#include <libc-pointer-arith.h>
-#include <tst-stack-align.h>
-#include <clone_internal.h>
-#include <support/xunistd.h>
-#include <support/check.h>
-
-static int
-check_stack_alignment (void *arg)
-{
- puts ("in f");
-
- return TEST_STACK_ALIGN () ? 1 : 0;
-}
-
-static int
-do_test (void)
-{
- puts ("in do_test");
-
- if (TEST_STACK_ALIGN ())
- FAIL_EXIT1 ("stack isn't aligned\n");
-
-#ifdef __ia64__
-# define STACK_SIZE (256 * 1024)
-#else
-# define STACK_SIZE (128 * 1024)
-#endif
- char st[STACK_SIZE + 1];
- /* NB: Align child stack to 1 byte. */
- char *stack = PTR_ALIGN_UP (&st[0], 2) + 1;
- struct clone_args clone_args =
- {
- .stack = (uintptr_t) stack,
- .stack_size = STACK_SIZE,
- };
- pid_t p = __clone_internal (&clone_args, check_stack_alignment, 0);
-
- /* Clone must not fail. */
- TEST_VERIFY_EXIT (p != -1);
-
- int e;
- xwaitpid (p, &e, __WCLONE);
- TEST_VERIFY (WIFEXITED (e));
- TEST_COMPARE (WEXITSTATUS (e), 0);
-
- return 0;
-}
-
-#include <support/test-driver.c>
@@ -73,9 +73,6 @@ L(thread_start):
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. */