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SubjectRe: swsusp_restore crap
Date
On Tuesday, 15 of March 2005 21:46, Pavel Machek wrote:
> Hi!
>
> > > > > x86-64 needs this, too.... Otherwise it looks okay.
> > > >
> > > > It breaks compilation on i386 either, because nr_copy_pages_check
> > > > is static in swsusp.c. May I propose the following patch instead (tested on
> > > > x86-64 and i386)?
> > >
> > >
> > > > +asmlinkage int __swsusp_flush_tlb(void)
> > > > +{
> > > > + swsusp_restore_check();
> > >
> > > Someone will certainly forget this one, and it is probably
> > > nicer/easier to just move BUG_ON into swsusp_suspend(), just after
> > > restore_processor_state() or something like that...
> >
> > ... in which case __swsusp_flush_tlb() would only contain a "call" to
> > __flush_tlb_global(), but this is a macro on both x86-64 and i386, so we can
> > drop the __swsusp_flush_tlb() altogether and do it in assembly (before the
> > GPRs are restored, perhaps). Patch follows.
> >
> > Greets,
> > Rafael
> >
> >
> > Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
>
> > diff -Nrup linux-2.6.11-bk10-a/arch/x86_64/kernel/suspend_asm.S linux-2.6.11-bk10-b/arch/x86_64/kernel/suspend_asm.S
> > --- linux-2.6.11-bk10-a/arch/x86_64/kernel/suspend_asm.S 2005-03-15 09:20:53.000000000 +0100
> > +++ linux-2.6.11-bk10-b/arch/x86_64/kernel/suspend_asm.S 2005-03-15 15:36:29.000000000 +0100
> > @@ -69,6 +69,14 @@ loop:
> > movq pbe_next(%rdx), %rdx
> > jmp loop
> > done:
> > + /* Flush TLB, including "global" things (vmalloc) */
> > + movq %rax, %rdx; # mmu_cr4_features(%rip)
>
> I somehow don't think %rax contains mmu_cr4_features at this
> point. Otherwise it seems to look ok.

Yes, it does, because on x86-64 the TLBs are flushed before the loop,
right after %cr3 is loaded with init_level4_pgt. %rax is not touched
afterwards, so it contains the right value. Here's the relevant code
from suspend_asm.S (with the patch applied):

ENTRY(swsusp_arch_resume)
/* set up cr3 */
leaq init_level4_pgt(%rip),%rax
subq $__START_KERNEL_map,%rax
movq %rax,%cr3

movq mmu_cr4_features(%rip), %rax
movq %rax, %rdx
andq $~(1<<7), %rdx # PGE
movq %rdx, %cr4; # turn off PGE
movq %cr3, %rcx; # flush TLB
movq %rcx, %cr3;
movq %rax, %cr4; # turn PGE back on

movq pagedir_nosave(%rip), %rdx
loop:
testq %rdx, %rdx
jz done

/* get addresses from the pbe and copy the page */
movq pbe_address(%rdx), %rsi
movq pbe_orig_address(%rdx), %rdi
movq $512, %rcx
rep
movsq

/* progress to the next pbe */
movq pbe_next(%rdx), %rdx
jmp loop
done:
/* Flush TLB, including "global" things (vmalloc) */
movq %rax, %rdx; # mmu_cr4_features(%rip)
andq $~(1<<7), %rdx; # PGE
movq %rdx, %cr4; # turn off PGE
movq %cr3, %rcx; # flush TLB
movq %rcx, %cr3
movq %rax, %cr4; # turn PGE back on


Greets,
Rafael


--
- Would you tell me, please, which way I ought to go from here?
- That depends a good deal on where you want to get to.
-- Lewis Carroll "Alice's Adventures in Wonderland"
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