Re: [PATCH 09/13] purgatory: Core purgatory functionality

Vivek Goyal
2014-06-06T19:51:49Z

On Thu, Jun 05, 2014 at 10:05:23PM +0200, Borislav Petkov wrote:

[..]
> > @@ -249,6 +254,7 @@ archclean:
> > $(Q)rm -rf $(objtree)/arch/x86_64
> > $(Q)$(MAKE) $(clean)=$(boot)
> > $(Q)$(MAKE) $(clean)=arch/x86/tools
>
> ifeq ($(CONFIG_KEXEC),y)
> $(Q)$(MAKE) $(clean)=arch/x86/purgatory
> endif

Hmm.., is it strictly required? I am wondering what happens if I build
a kernel with CONFIG_KEXEC=y, then set CONFIG_KEXEC=n and do "make clean".
I think I will still like any files in arch/x86/purgatory to be cleaned
despite the fact that CONFIG_KEXEC=n. Isn't it?

[..]
> > +ifeq ($(CONFIG_X86_64),y)
> > +KBUILD_CFLAGS := -fno-strict-aliasing -Wall -Wstrict-prototypes -fno-zero-initialized-in-bss -mcmodel=large -Os -fno-builtin -ffreestanding -c -MD
> > +else
> > +KBUILD_CFLAGS := -fno-strict-aliasing -Wall -Wstrict-prototypes -fno-zero-initialized-in-bss -Os -fno-builtin -ffreestanding -c -MD -m32
> > +endif
>
> Those variable assignments have a lot of duplication, let's simplify
> (diff ontop):

Thanks. This looks cleaner and also highlights the difference between
x86_64 and x86. Will change.

[..]
> > + .section ".rodata"
> > + .balign 4
> > +entry64_regs:
> > +rax: .quad 0x00000000
>
> Simply 0x0? Or am I missing something?

I think .quad 0x0 should work. Will use it.

[..]
> > + sha256_final(&sctx, digest);
> > +
> > + if (memcmp(digest, sha256_digest, sizeof(digest)) != 0)
>
> if (memcmp(...))
> return 1;
>
> should be a bit cleaner.
>

Ok. Will do.

[..]
> > +void purgatory(void)
> > +{
> > + int ret;
> > +
> > + ret = verify_sha256_digest();
> > + if (ret) {
> > + /* loop forever */
> > + for (;;);
>
> checkpatch bitches about this:
>
> ERROR: trailing statements should be on next line
> #303: FILE: arch/x86/purgatory/purgatory.c:68:
> + for (;;);

Ok, will move semicolon to next line.

Thanks
Vivek