On Sat, Sep 15, 2018 at 07:28:03PM +0200, Thomas Gleixner wrote:
> On Sun, 16 Sep 2018, Feng Tang wrote:
> > I have tried to change some header files incluing fixmap.h/apicdef.h/
> > vsyscall.h, and most of the .c files compile fine now, but I can not
> > use the "__end_of_permanent_fixed_addresses" in head_64.S as it is a
> > enum type, and could not be recognized by assembly code.
>
> Hrmm. I did not think about the enum. So we have two possibilities:
>
> 1) Have some preprocessing which provides the info for the assembler
>
> 2) Use a constant for the number of PMDs which is defined in a header and
> then compile time checked against the size of the fixmap in a C-file.
As there is no fixmap.c, I put the chck into __native_set_fixmap temply,
please review, thanks
- Feng
diff --git a/arch/x86/include/asm/fixmap.h b/arch/x86/include/asm/fixmap.h
index e203169931c7..ffaa0fa31044 100644
--- a/arch/x86/include/asm/fixmap.h
+++ b/arch/x86/include/asm/fixmap.h
@@ -14,6 +14,9 @@
#ifndef _ASM_X86_FIXMAP_H
#define _ASM_X86_FIXMAP_H
+/* Put here to be accessble for assembly code like head_64.S */
+#define FIXMAP_PMD_NUM 2
+
#ifndef __ASSEMBLY__
#include <linux/kernel.h>
#include <asm/acpi.h>
diff --git a/arch/x86/include/asm/pgtable_64.h
b/arch/x86/include/asm/pgtable_64.h
index f773d5e6c8cc..d6820d4c6e47 100644
--- a/arch/x86/include/asm/pgtable_64.h
+++ b/arch/x86/include/asm/pgtable_64.h
@@ -14,6 +14,7 @@
#include <asm/processor.h>
#include <linux/bitops.h>
#include <linux/threads.h>
+#include <asm/fixmap.h>
extern p4d_t level4_kernel_pgt[512];
extern p4d_t level4_ident_pgt[512];
@@ -22,7 +23,7 @@ extern pud_t level3_ident_pgt[512];
extern pmd_t level2_kernel_pgt[512];
extern pmd_t level2_fixmap_pgt[512];
extern pmd_t level2_ident_pgt[512];
-extern pte_t level1_fixmap_pgt[512];
+extern pte_t level1_fixmap_pgt[512 * FIXMAP_PMD_NUM];
extern pgd_t init_top_pgt[];
#define swapper_pg_dir init_top_pgt
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index 15ebc2fc166e..985eaff70792 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -24,6 +24,7 @@
#include "../entry/calling.h"
#include <asm/export.h>
#include <asm/nospec-branch.h>
+#include <asm/fixmap.h>
#ifdef CONFIG_PARAVIRT
#include <asm/asm-offsets.h>
@@ -445,13 +446,19 @@ NEXT_PAGE(level2_kernel_pgt)
KERNEL_IMAGE_SIZE/PMD_SIZE)
NEXT_PAGE(level2_fixmap_pgt)
- .fill 506,8,0
- .quad level1_fixmap_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC
- /* 8MB reserved for vsyscalls + a 2MB hole = 4 + 1 entries */
- .fill 5,8,0
+ .fill (512 - 4 - FIXMAP_PMD_NUM),8,0
+ pgtno = 0
+ .rept (FIXMAP_PMD_NUM)
+ .quad level1_fixmap_pgt + (pgtno << PAGE_SHIFT) - __START_KERNEL_map +
_PAGE_TABLE_NOENC
+ pgtno = pgtno + 1
+ .endr
+ /* 6 MB reserved space + a 2MB hole */
+ .fill 4,8,0
NEXT_PAGE(level1_fixmap_pgt)
+ .rept (FIXMAP_PMD_NUM)
.fill 512,8,0
+ .endr
#undef PMDS
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index e848a4811785..a927f5f39bee 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -637,6 +637,16 @@ void __native_set_fixmap(enum fixed_addresses idx, pte_t
pte)
{
unsigned long address = __fix_to_virt(idx);
+#ifdef CONFIG_X86_64
+ /*
+ * In arch/x86/kernel/head_64.S, the static page table has
+ * been setup for fixmap. Add a sanity compiling check
+ * whether fixmap space has exceeded the capacity.
+ */
+ BUILD_BUG_ON((__end_of_permanent_fixed_addresses + 511)/512
+ > FIXMAP_PMD_NUM);
+#endif
+
if (idx >= __end_of_fixed_addresses) {
BUG();
return;
diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c
index 45b700ac5fe7..b0aa2364a3c6 100644
--- a/arch/x86/xen/mmu_pv.c
+++ b/arch/x86/xen/mmu_pv.c
@@ -1953,7 +1953,10 @@ void __init xen_setup_kernel_pagetable(pgd_t *pgd,
unsigned long max_pfn)
set_page_prot(level2_ident_pgt, PAGE_KERNEL_RO);
set_page_prot(level2_kernel_pgt, PAGE_KERNEL_RO);
set_page_prot(level2_fixmap_pgt, PAGE_KERNEL_RO);
- set_page_prot(level1_fixmap_pgt, PAGE_KERNEL_RO);
+
+ for (i = 0; i < FIXMAP_PMD_NUM; i++)
+ set_page_prot(level1_fixmap_pgt + i * 512,
+ PAGE_KERNEL_RO);
/* Pin down new L4 */
pin_pagetable_pfn(MMUEXT_PIN_L4_TABLE,
>
> #1 would be preferred, but for a quick fix #2 is okay as well.
>
> Thanks,
>
> tglx
>
