x86/power/64: Do not refer to __PAGE_OFFSET from assembly code

When CONFIG_RANDOMIZE_MEMORY is set on x86-64, __PAGE_OFFSET becomes
a variable and using it as a symbol in the image memory restoration
assembly code under core_restore_code is not correct any more.

To avoid that problem, modify set_up_temporary_mappings() to compute
the physical address of the temporary page tables and store it in
temp_level4_pgt, so that the value of that variable is ready to be
written into CR3.  Then, the assembly code doesn't have to worry
about converting that value into a physical address and things work
regardless of whether or not CONFIG_RANDOMIZE_MEMORY is set.

Reported-and-tested-by: Thomas Garnier <thgarnie@google.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/arch/x86/power/hibernate_64.c b/arch/x86/power/hibernate_64.c
index f2b5e6a..f0b5f2d 100644 (file)
--- a/arch/x86/power/hibernate_64.c
+++ b/arch/x86/power/hibernate_64.c
@@ -37,11 +37,11 @@ unsigned long jump_address_phys;
  */
 unsigned long restore_cr3 __visible;
 
-pgd_t *temp_level4_pgt __visible;
+unsigned long temp_level4_pgt __visible;
 
 unsigned long relocated_restore_code __visible;
 
-static int set_up_temporary_text_mapping(void)
+static int set_up_temporary_text_mapping(pgd_t *pgd)
 {
        pmd_t *pmd;
        pud_t *pud;
@@ -71,7 +71,7 @@ static int set_up_temporary_text_mapping(void)
                __pmd((jump_address_phys & PMD_MASK) | __PAGE_KERNEL_LARGE_EXEC));
        set_pud(pud + pud_index(restore_jump_address),
                __pud(__pa(pmd) | _KERNPG_TABLE));
-       set_pgd(temp_level4_pgt + pgd_index(restore_jump_address),
+       set_pgd(pgd + pgd_index(restore_jump_address),
                __pgd(__pa(pud) | _KERNPG_TABLE));
 
        return 0;
@@ -90,15 +90,16 @@ static int set_up_temporary_mappings(void)
                .kernel_mapping = true,
        };
        unsigned long mstart, mend;
+       pgd_t *pgd;
        int result;
        int i;
 
-       temp_level4_pgt = (pgd_t *)get_safe_page(GFP_ATOMIC);
-       if (!temp_level4_pgt)
+       pgd = (pgd_t *)get_safe_page(GFP_ATOMIC);
+       if (!pgd)
                return -ENOMEM;
 
        /* Prepare a temporary mapping for the kernel text */
-       result = set_up_temporary_text_mapping();
+       result = set_up_temporary_text_mapping(pgd);
        if (result)
                return result;
 
@@ -107,13 +108,12 @@ static int set_up_temporary_mappings(void)
                mstart = pfn_mapped[i].start << PAGE_SHIFT;
                mend   = pfn_mapped[i].end << PAGE_SHIFT;
 
-               result = kernel_ident_mapping_init(&info, temp_level4_pgt,
-                                                  mstart, mend);
-
+               result = kernel_ident_mapping_init(&info, pgd, mstart, mend);
                if (result)
                        return result;
        }
 
+       temp_level4_pgt = (unsigned long)pgd - __PAGE_OFFSET;
        return 0;
 }
 

diff --git a/arch/x86/power/hibernate_asm_64.S b/arch/x86/power/hibernate_asm_64.S
index 8eee0e9..ce8da3a 100644 (file)
--- a/arch/x86/power/hibernate_asm_64.S
+++ b/arch/x86/power/hibernate_asm_64.S
@@ -72,8 +72,6 @@ ENTRY(restore_image)
        /* code below has been relocated to a safe page */
 ENTRY(core_restore_code)
        /* switch to temporary page tables */
-       movq    $__PAGE_OFFSET, %rcx
-       subq    %rcx, %rax
        movq    %rax, %cr3
        /* flush TLB */
        movq    %rbx, %rcx