Re: [PATCH] m68k: use conventional function parameters for do_sigreturn

[Andreas Schwab <schwab@linux-m68k.org>]

Greg Ungerer <gerg@uclinux.org> writes:

> The motivation for this change is a problem with non-MMU targets that
> have broken signal return paths on newer versions of gcc. It appears as
> though aliasing of the regs and switch stack pointers, caused by their
> construction from pointers derived from the dummy long function parameter,
> is resulting in the gcc optimizer removing what it thinks is useless
> updates to the regs fields.

I wonder why gcc is doing that.  The kernel is explicitly built without
strict aliasing, so this looks like something to investigate.

> -asmlinkage int do_sigreturn(unsigned long __unused)
> +asmlinkage int do_sigreturn(struct pt_regs *regs, struct switch_stack *sw)

Does it work to use this signature:

asmlinkage int do_sigreturn(struct switch_stack sw, struct pt_regs regs)

without changing the caller?

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
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