Re: swsusp critical code rewritten to assembly

[Pavel Machek <pavel@suse.cz>]

Hi!

> > do_magic was really too fragile to be written in C. This patch
> > rewrites it into assembly, to make sure C compiler does not generate
> > stack access and corrupt memory that way. Plus it cleans up suspend.c
> > a bit, makes it really free memory it needs, an no longer calls
> > drivers from atomic context.
> 
> But this still has stuff in C:
> 
> > +	asm volatile ("movl %0, %%esp" :: "m" (saved_context_esp));
> > +	asm volatile ("movl %0, %%ebp" :: "m" (saved_context_ebp));
> > +	asm volatile ("movl %0, %%eax" :: "m" (saved_context_eax));
> > +	asm volatile ("movl %0, %%ebx" :: "m" (saved_context_ebx));
> > +	asm volatile ("movl %0, %%ecx" :: "m" (saved_context_ecx));
> > +	asm volatile ("movl %0, %%edx" :: "m" (saved_context_edx));
> > +	asm volatile ("movl %0, %%esi" :: "m" (saved_context_esi));
> > +	asm volatile ("movl %0, %%edi" :: "m" (saved_context_edi));
> >  
> > -	fix_processor_context();
> > +	restore_processor_state();
> 
> What's up with that? There's no way you can safely restore regular 
> registers and _especially_ %%esp from C code, since the compiler may be 
> using them for other things.

After applying that patch, this stuff is no longer used for
suspend-to-disk. Its still there for suspend-to-ram; I'll fix that.

								Pavel

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