Re: [patch 1/1] uml: fix lvalue for gcc4

From: Russell King
Date: Sat Jul 09 2005 - 06:08:53 EST


On Sat, Jul 09, 2005 at 01:01:33PM +0200, blaisorblade@xxxxxxxx wrote:
> diff -puN arch/um/sys-x86_64/signal.c~uml-fix-for-gcc4-lvalue arch/um/sys-x86_64/signal.c
> --- linux-2.6.git/arch/um/sys-x86_64/signal.c~uml-fix-for-gcc4-lvalue 2005-07-09 13:01:03.000000000 +0200
> +++ linux-2.6.git-paolo/arch/um/sys-x86_64/signal.c 2005-07-09 13:01:03.000000000 +0200
> @@ -168,7 +168,7 @@ int setup_signal_stack_si(unsigned long
>
> frame = (struct rt_sigframe __user *)
> round_down(stack_top - sizeof(struct rt_sigframe), 16) - 8;
> - ((unsigned char *) frame) -= 128;
> + frame -= 128 / sizeof(frame);

Are you sure these two are identical?

The above code fragment looks suspicious anyway, particularly:

frame = (struct rt_sigframe __user *)
round_down(stack_top - sizeof(struct rt_sigframe), 16) - 8;

which will put the frame at 8 * sizeof(struct rt_sigframe) below
the point which round_down() would return (which would be 1 struct
rt_sigframe below stack_top, rounded down).

--
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
maintainer of: 2.6 Serial core
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