Message ID | 20230112135853.3786675-4-adhemerval.zanella@linaro.org |
---|---|
State | New |
Headers | show |
Series | Optimize posix_spawn signal setup with clone3 | expand |
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. */
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. */