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Message-ID: <2464745.UmGP58NeXC@vostro.rjw.lan>
Date: Wed, 03 Aug 2016 01:19:26 +0200
From: "Rafael J. Wysocki" <rjw@...ysocki.net>
To: the arch/x86 maintainers <x86@...nel.org>, Linux PM list <linux-pm@...r.kernel.org>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>, Thomas Garnier <thgarnie@...gle.com>, Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, "H . Peter Anvin" <hpa@...or.com>, Kees Cook <keescook@...omium.org>, Yinghai Lu <yinghai@...nel.org>, Pavel Machek <pavel@....cz>, LKML <linux-kernel@...r.kernel.org>, kernel-hardening@...ts.openwall.com
Subject: [PATCH] x86/power/64: Do not refer to __PAGE_OFFSET from assembly code
From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
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@...gle.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
I'm going to queue this up, so if there are any objections/concerns about it,
please let me know ASAP.
Thanks,
Rafael
---
arch/x86/power/hibernate_64.c | 18 +++++++++---------
arch/x86/power/hibernate_asm_64.S | 2 --
2 files changed, 9 insertions(+), 11 deletions(-)
Index: linux-pm/arch/x86/power/hibernate_asm_64.S
===================================================================
--- linux-pm.orig/arch/x86/power/hibernate_asm_64.S
+++ linux-pm/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
Index: linux-pm/arch/x86/power/hibernate_64.c
===================================================================
--- linux-pm.orig/arch/x86/power/hibernate_64.c
+++ linux-pm/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
__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(voi
.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(voi
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;
}
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