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
init_task.c
#include <linux/init_task.h>
#include <linux/export.h>
#include <linux/mqueue.h>
#include <linux/sched.h>
#include <linux/sched/sysctl.h>
#include <linux/sched/rt.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <asm/pgtable.h>
#include <asm/uaccess.h>
static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
/* Initial task structure */
struct task_struct init_task = INIT_TASK(init_task);
EXPORT_SYMBOL(init_task);
/*
* Initial thread structure. Alignment of this is handled by a special
* linker map entry.
*/
union thread_union init_thread_union __init_task_data =
{ INIT_THREAD_INFO(init_task) };
Computing file changes ...
