• Dimitry Andric's avatar
    [ARM] 3529/1: s3c24xx: fix restoring control register with undefined instruction · c3fb0416
    Dimitry Andric authored
    Patch from Dimitry Andric
    
    In arch/arm/mach-s3c2410/sleep.S, the coprocessor registers are saved at
    suspend time, and restored at resume time. However, an undefined
    instruction is used when attempting to restore a non-existent "auxiliary
    control register".  This leads to a crash on S3C2412, which has an ARM926
    core instead of an ARM920.
    
    At suspend time, the following fragment runs:
    
    	mrc	p15, 0, r7, c2, c0, 0	@ translation table base address
    	mrc	p15, 0, r8, c2, c0, 0	@ auxiliary control register
    	mrc	p15, 0, r9, c1, c0, 0	@ control register
    
    and at resume time, the following fragment runs:
    
    	mcr	p15, 0, r7, c2, c0, 0		@ translation table base
    	mcr	p15, 0, r8, c1, c1, 0		@ auxilliary control
    	...
    	mcr	p15, 0, r9, c1, c0, 0		@ turn on MMU, etc
    
    There are several problems with these fragments:
    1. The ARM920 and ARM926 cores don't have any "auxiliary control
       register", at least not according to the ARM920 and ARM926 TRM's.
    2. The 2nd line of suspend erroneously saves the c2 register again.
    3. This saved c2 value is restored using an undefined instruction.  For
       some reason this does not crash on ARM920, but does crash on ARM926.
    
    The following patch fixes all these problems.
    Signed-off-by: default avatarDimitry Andric <dimitry@andric.com>
    Yes, this looks sensible
    Signed-off-by: default avatarBen Dooks <ben-linux@fluff.org>
    Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
    c3fb0416
sleep.S 4.79 KB