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Message-Id: <200708222249.51616.rjw@sisk.pl>
Date: Wed, 22 Aug 2007 22:49:51 +0200
From: "Rafael J. Wysocki" <rjw@...k.pl>
To: Pavel Machek <pavel@....cz>
Cc: linux-pm@...ts.linux-foundation.org, Andi Kleen <ak@...e.de>,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [linux-pm] Re: [RFC][PATCH -mm 3/4] Hibernation: Pass CR3 in the image header on x86_64
On Wednesday, 22 August 2007 18:17, Rafael J. Wysocki wrote:
> On Wednesday, 22 August 2007 10:28, Pavel Machek wrote:
> > Hi!
> >
> > > From: Rafael J. Wysocki <rjw@...k.pl>
> > >
> > > Since we already pass the address of restore_registers() in the image header,
> > > we can also pass the value of the CR3 register from before the hibernation in
> > > the same way. This will allow us to avoid using init_level4_pgt page tables
> > > during the restore.
> > >
> > > Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
> >
> > > @@ -253,10 +262,13 @@ int arch_hibernation_header_save(void *a
> > > {
> > > struct restore_data_record *rdr = addr;
> > >
> > > - if (max_size < sizeof(struct restore_data_record))
> > > + if (max_size < sizeof(*rdr))
> > > return -EOVERFLOW;
> > > rdr->jump_address = restore_jump_address;
> > > - rdr->control = (restore_jump_address ^ RESTORE_MAGIC);
> > > + rdr->cr3 = restore_cr3;
> > > + rdr->magic = RESTORE_MAGIC;
> > > + rdr->crc = 0;
> > > + rdr->crc = crc32_le(0, addr, sizeof(*rdr));
> > > return 0;
> > > }
> >
> > No, I do not think I like that. I believe both -> control and -> crc
> > is just useless paranoia. Bitflip in this area is not going to be any
> > worse than bitflip anywhere else, we should not pretend this is
> > somehow "more important".
> >
> > -> control should really be "protocol version"... probably should
> > contain some field that is easy to increment.
>
> OK
>
> Perhaps I'll just remove the crc field.
Like in the patch below.
---
From: Rafael J. Wysocki <rjw@...k.pl>
Since we already pass the address of restore_registers() in the image header,
we can also pass the value of the CR3 register from before the hibernation in
the same way. This will allow us to avoid using init_level4_pgt page tables
during the restore.
Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
---
arch/x86_64/kernel/suspend.c | 17 +++++++++++++----
arch/x86_64/kernel/suspend_asm.S | 8 +++++---
2 files changed, 18 insertions(+), 7 deletions(-)
Index: linux-2.6.23-rc3/arch/x86_64/kernel/suspend.c
===================================================================
--- linux-2.6.23-rc3.orig/arch/x86_64/kernel/suspend.c
+++ linux-2.6.23-rc3/arch/x86_64/kernel/suspend.c
@@ -9,6 +9,7 @@
#include <linux/smp.h>
#include <linux/suspend.h>
+#include <linux/crc32.h>
#include <asm/proto.h>
#include <asm/page.h>
#include <asm/pgtable.h>
@@ -150,6 +151,12 @@ extern int restore_image(void);
*/
unsigned long restore_jump_address;
+/*
+ * Value of the cr3 register from before the hibernation (this value is passed
+ * in the image header).
+ */
+unsigned long restore_cr3;
+
pgd_t *temp_level4_pgt;
static int res_phys_pud_init(pud_t *pud, unsigned long address, unsigned long end)
@@ -239,7 +246,8 @@ int pfn_is_nosave(unsigned long pfn)
struct restore_data_record {
unsigned long jump_address;
- unsigned long control;
+ unsigned long cr3;
+ unsigned long magic;
};
#define RESTORE_MAGIC 0x0123456789ABCDEFUL
@@ -256,7 +264,8 @@ int arch_hibernation_header_save(void *a
if (max_size < sizeof(struct restore_data_record))
return -EOVERFLOW;
rdr->jump_address = restore_jump_address;
- rdr->control = (restore_jump_address ^ RESTORE_MAGIC);
+ rdr->cr3 = restore_cr3;
+ rdr->magic = RESTORE_MAGIC;
return 0;
}
@@ -270,7 +279,7 @@ int arch_hibernation_header_restore(void
struct restore_data_record *rdr = addr;
restore_jump_address = rdr->jump_address;
- return (rdr->control == (restore_jump_address ^ RESTORE_MAGIC)) ?
- 0 : -EINVAL;
+ restore_cr3 = rdr->cr3;
+ return (rdr->magic == RESTORE_MAGIC) ? 0 : -EINVAL;
}
#endif /* CONFIG_HIBERNATION */
Index: linux-2.6.23-rc3/arch/x86_64/kernel/suspend_asm.S
===================================================================
--- linux-2.6.23-rc3.orig/arch/x86_64/kernel/suspend_asm.S
+++ linux-2.6.23-rc3/arch/x86_64/kernel/suspend_asm.S
@@ -39,6 +39,9 @@ ENTRY(swsusp_arch_suspend)
/* save the address of restore_registers */
movq $restore_registers, %rax
movq %rax, restore_jump_address(%rip)
+ /* save cr3 */
+ movq %cr3, %rax
+ movq %rax, restore_cr3(%rip)
call swsusp_save
ret
@@ -66,6 +69,7 @@ ENTRY(restore_image)
/* prepare to jump to the image kernel */
movq restore_jump_address(%rip), %rax
+ movq restore_cr3(%rip), %rbx
/* copy image data to their original locations */
xorq %r10, %r10
@@ -116,9 +120,7 @@ ENTRY(restore_registers)
movsq
/* go back to the original page tables */
-1: movq $(init_level4_pgt - __START_KERNEL_map), %rax
- addq phys_base(%rip), %rax
- movq %rax, %cr3
+1: movq %rbx, %cr3
/* Flush TLB, including "global" things (vmalloc) */
movq mmu_cr4_features(%rip), %rax
-
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