Re: [PATCH] Fix i486 suspend to disk CR4 oops

[Ingo Molnar]

* David Fries <david@xxxxxxxxx> wrote:

> arch/x86/power/cpu_32.c __save_processor_state calls read_cr4() only a 
> i486 CPU doesn't have the CR4 register.  Trying to read it produces an 
> invalid opcode oops during suspend to disk.
> 
> Added the check (boot_cpu_data.x86 >= 5) before reading the register.  
> If the value to be written is zero the write is skipped.
> 
> arch/x86/power/hibernate_asm_32.S
> done: swapped the use of %eax and %ecx to use jecxz for
> the zero test and jump over store to %cr4.
> restore_image: s/%ecx/%eax/ to be consistent with done:
> 
> In addition to __save_processor_state, acpi_save_state_mem, 
> efi_call_phys_prelog, and efi_call_phys_epilog had checks added (acpi 
> restore was in assembly and already had a check for non-zero).  There 
> were other reads and writes of CR4, but MCE and virtualization 
> shouldn't be executed on a i486 anyway.
> 
> Signed-off-by: David Fries <david@xxxxxxxxx>

applied to tip/x86/urgent, thanks David. I've changed the conditions to 
read_cr4_safe() instead - that's cleaner. Could you please check whether 
the patch below works fine too on your box?

Rafael, Pavel - does the commit below look good to you too?

	Ingo

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