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  1. Jul 06, 2015
  2. Jul 04, 2015
    • Ingo Molnar's avatar
      x86/fpu: Fix boot crash in the early FPU code · b96fecbf
      Ingo Molnar authored
      
      
      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:
      
         91a8c2a5 ("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: default avatarJan Kara <jack@suse.cz>
      Reported-bisected-and-tested-by: default avatarThomas 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: default avatarIngo Molnar <mingo@kernel.org>
      b96fecbf
  3. Jul 03, 2015
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