From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 1791) id 6FC463858401; Wed, 1 Feb 2023 12:20:07 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 6FC463858401 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1675254007; bh=TUdRn7YwP+MG3hm+X9mSZWdye+0RmLtJc4zw9WVNNvg=; h=From:To:Subject:Date:From; b=nGH8qP2wRS2+xTP1MSaRjNouI8VDT0p+u0rUs9cV4ZIPXQy85ICUNfdY9Su6pLZhm 4x7wbTnEiogFv0SnYDckB/T+/ru+qjglSExrqgPPbE+wgXuUiErqOsAQNXlIcMkOAQ 7umZkMFcTrp/t7WlPkZBv2HGPxEISIssq1rpRoxk= Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit From: Adhemerval Zanella To: glibc-cvs@sourceware.org Subject: [glibc] Linux: Do not align the stack for __clone3 X-Act-Checkin: glibc X-Git-Author: Adhemerval Zanella Netto X-Git-Refname: refs/heads/master X-Git-Oldrev: 2fe58919a0bfd1064c59120520116237ba818ed3 X-Git-Newrev: 2290cf73cce1292d9345a8183fd29ae3994a9481 Message-Id: <20230201122007.6FC463858401@sourceware.org> Date: Wed, 1 Feb 2023 12:20:07 +0000 (GMT) List-Id: https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=2290cf73cce1292d9345a8183fd29ae3994a9481 commit 2290cf73cce1292d9345a8183fd29ae3994a9481 Author: Adhemerval Zanella Netto Date: Thu Jan 12 10:58:50 2023 -0300 Linux: Do not align the stack for __clone3 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. Reviewed-by: Carlos O'Donell Diff: --- include/clone_internal.h | 3 + .../unix/sysv/linux/tst-misalign-clone-internal.c | 74 ---------------------- sysdeps/unix/sysv/linux/x86_64/clone3.S | 3 - 3 files changed, 3 insertions(+), 77 deletions(-) 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 - . */ - -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include - -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 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. */