https://github.com/torvalds/linux
Revision b96fecbfa8c88b057e2bbf10021521c232bb3650 authored by Ingo Molnar on 04 July 2015, 07:58:19 UTC, committed by Ingo Molnar on 04 July 2015, 08:05:56 UTC
Jan Kara and Thomas Gleixner reported boot crashes in the FPU code: general protection fault: 0000 [#1] SMP RIP: 0010:[<ffffffff81048a6c>] [<ffffffff81048a6c>] mxcsr_feature_mask_init+0x1c/0x40 2b:* 0f ae 85 00 fe ff ff fxsave -0x200(%rbp) and bisected it down to the following FPU commit: 91a8c2a5b43f ("x86/fpu: Clean up and fix MXCSR handling") The reason is that the on-stack FPU registers state variable, used by the FXSAVE instruction, did not have the required minimum alignment of 16 bytes, causing the general protection fault. This is most likely a GCC bug in older GCC versions, but the offending commit also added a bogus extra 32-byte alignment (which GCC ignored too). So fix this bug by making the variable static again, but also mark it __initdata this time, because fpu__init_system_mxcsr() is now an __init function. Reported-and-bisected-by: Jan Kara <jack@suse.cz> Reported-bisected-and-tested-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Jan Kara <jack@suse.cz> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20150704075819.GA9201@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
1 parent 864d5bb
Tip revision: b96fecbfa8c88b057e2bbf10021521c232bb3650 authored by Ingo Molnar on 04 July 2015, 07:58:19 UTC
x86/fpu: Fix boot crash in the early FPU code
x86/fpu: Fix boot crash in the early FPU code
Tip revision: b96fecb
noinitramfs.c
/*
* init/noinitramfs.c
*
* Copyright (C) 2006, NXP Semiconductors, All Rights Reserved
* Author: Jean-Paul Saman <jean-paul.saman@nxp.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2 of the License.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/init.h>
#include <linux/stat.h>
#include <linux/kdev_t.h>
#include <linux/syscalls.h>
/*
* Create a simple rootfs that is similar to the default initramfs
*/
static int __init default_rootfs(void)
{
int err;
err = sys_mkdir((const char __user __force *) "/dev", 0755);
if (err < 0)
goto out;
err = sys_mknod((const char __user __force *) "/dev/console",
S_IFCHR | S_IRUSR | S_IWUSR,
new_encode_dev(MKDEV(5, 1)));
if (err < 0)
goto out;
err = sys_mkdir((const char __user __force *) "/root", 0700);
if (err < 0)
goto out;
return 0;
out:
printk(KERN_WARNING "Failed to create a rootfs\n");
return err;
}
rootfs_initcall(default_rootfs);
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