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Subject[PATCH 3/3] x86, hibernate: Backport several fixes from 64bits to 32bits hibernation
Date
From: Zhimin Gu <kookoo.gu@intel.com>

Currently there are mainly three bugs in 32bits system when doing
hibernation:
1. The page copy code is not running in safe page, which might
cause hang during resume.
2. There's no text mapping for the final jump address
of the original kernel, which might cause the system jumping
into illegal address and causes system hang during resume.
3. The restore kernel switches to its own kernel page table(swapper_pg_dir)
rather than the original kernel page table after all the pages
been copied back, which might cause invalid virtual-physical
mapping issue during resume.

To solve these problems:

1. Copy the code core_restore_code to a safe page, to avoid the instruction
code be overwritten when image kernel pages are being copied.
2. Set up temporary text mapping for the image kernel's jump address, so that
after all the pages have been copied back, the system could jump to this address.
3. Switch to the original kernel page table during resume.

Furthermore, MD5 hash check for e820 map is also backported from 64bits
system.

Acked-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Zhimin Gu <kookoo.gu@intel.com>
---
arch/x86/Kconfig | 2 +-
arch/x86/include/asm/suspend_32.h | 4 +++
arch/x86/power/hibernate.c | 2 --
arch/x86/power/hibernate_32.c | 54 ++++++++++++++++++++++++++++++++++++---
arch/x86/power/hibernate_asm_32.S | 49 ++++++++++++++++++++++++++++-------
5 files changed, 95 insertions(+), 16 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index c5ff296..d1c3c9d 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2422,7 +2422,7 @@ menu "Power management and ACPI options"

config ARCH_HIBERNATION_HEADER
def_bool y
- depends on X86_64 && HIBERNATION
+ depends on HIBERNATION

source "kernel/power/Kconfig"

diff --git a/arch/x86/include/asm/suspend_32.h b/arch/x86/include/asm/suspend_32.h
index 8be6afb..fdbd9d7 100644
--- a/arch/x86/include/asm/suspend_32.h
+++ b/arch/x86/include/asm/suspend_32.h
@@ -32,4 +32,8 @@ struct saved_context {
unsigned long return_address;
} __attribute__((packed));

+/* routines for saving/restoring kernel state */
+extern char core_restore_code[];
+extern char restore_registers[];
+
#endif /* _ASM_X86_SUSPEND_32_H */
diff --git a/arch/x86/power/hibernate.c b/arch/x86/power/hibernate.c
index 6f91f7b..d3ef08d 100644
--- a/arch/x86/power/hibernate.c
+++ b/arch/x86/power/hibernate.c
@@ -63,7 +63,6 @@ int pfn_is_nosave(unsigned long pfn)
return (pfn >= nosave_begin_pfn) && (pfn < nosave_end_pfn);
}

-#ifdef CONFIG_X86_64
static int relocate_restore_code(void)
{
pgd_t *pgd;
@@ -252,4 +251,3 @@ int arch_hibernation_header_restore(void *addr)

return 0;
}
-#endif
diff --git a/arch/x86/power/hibernate_32.c b/arch/x86/power/hibernate_32.c
index 7922e11..d0a41ed 100644
--- a/arch/x86/power/hibernate_32.c
+++ b/arch/x86/power/hibernate_32.c
@@ -8,9 +8,6 @@

#include "hibernate.c"

-/* Pointer to the temporary resume page tables */
-pgd_t *resume_pg_dir;
-
/* The following three functions are based on the analogous code in
* arch/x86/mm/init_32.c
*/
@@ -135,20 +132,69 @@ static inline void resume_init_first_level_page_table(pgd_t *pg_dir)
#endif
}

-asmlinkage int swsusp_arch_resume(void)
+static int set_up_temporary_text_mapping(pgd_t *pgd_base)
+{
+ pgd_t *pgd;
+ pmd_t *pmd;
+ pte_t *pte;
+
+ pgd = pgd_base + pgd_index(restore_jump_address);
+
+ pmd = resume_one_md_table_init(pgd);
+ if (!pmd)
+ return -ENOMEM;
+
+ if (boot_cpu_has(X86_FEATURE_PSE)) {
+ set_pmd(pmd + pmd_index(restore_jump_address),
+ __pmd((jump_address_phys & PMD_MASK) | pgprot_val(PAGE_KERNEL_LARGE_EXEC)));
+ } else {
+ pte = resume_one_page_table_init(pmd);
+ if (!pte)
+ return -ENOMEM;
+ set_pte(pte + pte_index(restore_jump_address),
+ __pte((jump_address_phys & PAGE_MASK) | pgprot_val(PAGE_KERNEL_EXEC)));
+ }
+
+ return 0;
+}
+
+/* Set up the temporary kernel text and direct mapping. */
+static int set_up_temporary_mappings(void)
{
int error;
+ pgd_t *resume_pg_dir;

resume_pg_dir = (pgd_t *)get_safe_page(GFP_ATOMIC);
if (!resume_pg_dir)
return -ENOMEM;

resume_init_first_level_page_table(resume_pg_dir);
+ error = set_up_temporary_text_mapping(resume_pg_dir);
+ if (error)
+ return error;
+
error = resume_physical_mapping_init(resume_pg_dir);
if (error)
return error;

+ temp_pgt = __pa(resume_pg_dir);
+
+ return 0;
+}
+
+asmlinkage int swsusp_arch_resume(void)
+{
+ int error;
+
/* We have got enough memory and from now on we cannot recover */
+ error = set_up_temporary_mappings();
+ if (error)
+ return error;
+
+ error = relocate_restore_code();
+ if (error)
+ return error;
+
restore_image();
return 0;
}
diff --git a/arch/x86/power/hibernate_asm_32.S b/arch/x86/power/hibernate_asm_32.S
index 6e56815..a53b4a4 100644
--- a/arch/x86/power/hibernate_asm_32.S
+++ b/arch/x86/power/hibernate_asm_32.S
@@ -24,21 +24,40 @@ ENTRY(swsusp_arch_suspend)
pushfl
popl saved_context_eflags

+ /* save cr3 */
+ movl %cr3, %eax
+ movl %eax, restore_cr3
+
call swsusp_save
ret
+ENDPROC(swsusp_arch_suspend)

ENTRY(restore_image)
- movl mmu_cr4_features, %ecx
- movl resume_pg_dir, %eax
- subl $__PAGE_OFFSET, %eax
+ /* prepare to jump to the image kernel */
+ movl restore_jump_address, %ebx
+ movl restore_cr3, %ebp
+
+ movl mmu_cr4_features, %edx
+
+ /* jump to relocated restore code */
+ movl relocated_restore_code, %eax
+ jmpl *%eax
+
+ /* code below has been relocated to a safe page */
+ENTRY(core_restore_code)
+ movl temp_pgt, %eax
movl %eax, %cr3

+ /* flush TLB */
+ movl %edx, %ecx
jecxz 1f # cr4 Pentium and higher, skip if zero
andl $~(X86_CR4_PGE), %ecx
movl %ecx, %cr4; # turn off PGE
movl %cr3, %eax; # flush TLB
movl %eax, %cr3
+ movl %edx, %cr4; # turn PGE back on
1:
+ /* prepare to copy image data to their original locations */
movl restore_pblist, %edx
.p2align 4,,7

@@ -49,7 +68,7 @@ copy_loop:
movl pbe_address(%edx), %esi
movl pbe_orig_address(%edx), %edi

- movl $1024, %ecx
+ movl $(PAGE_SIZE >> 2), %ecx
rep
movsl

@@ -58,13 +77,22 @@ copy_loop:
.p2align 4,,7

done:
+ jmpl *%ebx
+ .align PAGE_SIZE
+
+ENTRY(restore_registers)
/* go back to the original page tables */
- movl $swapper_pg_dir, %eax
- subl $__PAGE_OFFSET, %eax
- movl %eax, %cr3
- movl mmu_cr4_features, %ecx
+ movl %ebp, %cr3
+
+ /* flush TLB */
+ movl mmu_cr4_features, %edx
+ movl %edx, %ecx
jecxz 1f # cr4 Pentium and higher, skip if zero
- movl %ecx, %cr4; # turn PGE back on
+ andl $~(X86_CR4_PGE), %ecx
+ movl %ecx, %cr4; # turn off PGE
+ movl %cr3, %ecx; # flush TLB
+ movl %ecx, %cr3;
+ movl %edx, %cr4; # turn PGE back on
1:

movl saved_context_esp, %esp
@@ -82,4 +110,7 @@ done:

xorl %eax, %eax

+ movl %eax, in_suspend
+
ret
+ENDPROC(restore_registers)
--
2.7.4
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