[PATCH, RFC] fix UP futex code to not generate invalid streqt instruction
Russell King - ARM Linux
linux at arm.linux.org.uk
Fri Jul 22 14:22:42 EDT 2011
On Fri, Jul 22, 2011 at 07:12:30PM +0100, Dave Martin wrote:
> Do we have the same potential bug for the __put_user functions in
> arch/arm/include/asm/uaccess.h? Although cases where the two
> relevant arguments could be statically assigned to the same register
> by the compiler will be rare, those macros are used all over the place.
The only time it will happen is if the compiler sees that we're doing
In other words, you pass the same argument in for the value and pointer.
That should never happen for two reasons:
1. It will fail the type checking and issue compiler warnings about
2. This is silly code.
That goes for the futex case too - it can only happen if you pass in
the same pointer twice (or an alias of it.) And that's rubbish code.
The only other case it could happen is:
and I mean the constant 'NULL' not some NULL pointer. Again, this
has to be written explicitly, and writing to address 0 is... very
silly like this.
So, nothing to fix there either.
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