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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [xen master] x86: use 2M superpages for text/data/bss mappings
commit cf393624eec34e11275e83d2db01994b922e0673
Author: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Thu Feb 25 13:07:14 2016 +0100
Commit: Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Feb 25 13:07:14 2016 +0100
x86: use 2M superpages for text/data/bss mappings
This balloons the size of Xen in memory from 4.4MB to 8MB, because of the
required alignment adjustments.
However
* All mappings are 2M superpages.
* .text (and .init at boot) are the only sections marked executable.
* .text and .rodata are marked read-only.
Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
xen/arch/x86/setup.c | 38 +++++++++++++++++++++++++++++++++++---
xen/arch/x86/xen.lds.S | 27 +++++++++++++++++++++++++++
xen/include/asm-x86/setup.h | 5 +++++
3 files changed, 67 insertions(+), 3 deletions(-)
diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
index cddf954..806fa95 100644
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -920,14 +920,46 @@ void __init noreturn __start_xen(unsigned long mbi_p)
/* The only data mappings to be relocated are in the Xen area. */
pl2e = __va(__pa(l2_xenmap));
+ /*
+ * Undo the temporary-hooking of the l1_identmap. __2M_text_start
+ * is contained in this PTE.
+ */
*pl2e++ = l2e_from_pfn(xen_phys_start >> PAGE_SHIFT,
- PAGE_HYPERVISOR_RWX | _PAGE_PSE);
+ PAGE_HYPERVISOR_RX | _PAGE_PSE);
for ( i = 1; i < L2_PAGETABLE_ENTRIES; i++, pl2e++ )
{
+ unsigned int flags;
+
if ( !(l2e_get_flags(*pl2e) & _PAGE_PRESENT) )
continue;
- *pl2e = l2e_from_intpte(l2e_get_intpte(*pl2e) +
- xen_phys_start);
+
+ if ( i < l2_table_offset((unsigned long)&__2M_text_end) )
+ {
+ flags = PAGE_HYPERVISOR_RX | _PAGE_PSE;
+ }
+ else if ( i >= l2_table_offset((unsigned
long)&__2M_rodata_start) &&
+ i < l2_table_offset((unsigned
long)&__2M_rodata_end) )
+ {
+ flags = PAGE_HYPERVISOR_RO | _PAGE_PSE;
+ }
+ else if ( i >= l2_table_offset((unsigned
long)&__2M_init_start) &&
+ i < l2_table_offset((unsigned long)&__2M_init_end) )
+ {
+ flags = PAGE_HYPERVISOR_RWX | _PAGE_PSE;
+ }
+ else if ( (i >= l2_table_offset((unsigned
long)&__2M_rwdata_start) &&
+ i < l2_table_offset((unsigned
long)&__2M_rwdata_end)) )
+ {
+ flags = PAGE_HYPERVISOR_RW | _PAGE_PSE;
+ }
+ else
+ {
+ *pl2e = l2e_empty();
+ continue;
+ }
+
+ *pl2e = l2e_from_paddr(
+ l2e_get_paddr(*pl2e) + xen_phys_start, flags);
}
/* Re-sync the stack and then switch to relocated pagetables. */
diff --git a/xen/arch/x86/xen.lds.S b/xen/arch/x86/xen.lds.S
index 39cd513..905d908 100644
--- a/xen/arch/x86/xen.lds.S
+++ b/xen/arch/x86/xen.lds.S
@@ -38,6 +38,9 @@ SECTIONS
. = __XEN_VIRT_START;
__image_base__ = .;
#endif
+
+ __2M_text_start = .; /* Start of 2M superpages, mapped RX. */
+
. = __XEN_VIRT_START + MB(1);
_start = .;
.text : {
@@ -50,6 +53,10 @@ SECTIONS
_etext = .; /* End of text section */
} :text = 0x9090
+ . = ALIGN(MB(2));
+ __2M_text_end = .;
+
+ __2M_rodata_start = .; /* Start of 2M superpages, mapped RO. */
.rodata : {
/* Bug frames table */
. = ALIGN(4);
@@ -74,6 +81,10 @@ SECTIONS
#endif
} :text
+ . = ALIGN(MB(2));
+ __2M_rodata_end = .;
+
+ __2M_init_start = .; /* Start of 2M superpages, mapped RWX (boot
only). */
. = ALIGN(PAGE_SIZE); /* Init code and data */
__init_begin = .;
.init.text : {
@@ -137,6 +148,10 @@ SECTIONS
. = ALIGN(PAGE_SIZE);
__init_end = .;
+ . = ALIGN(MB(2));
+ __2M_init_end = .;
+
+ __2M_rwdata_start = .; /* Start of 2M superpages, mapped RW. */
. = ALIGN(SMP_CACHE_BYTES);
.data.read_mostly : {
/* Exception table */
@@ -185,6 +200,9 @@ SECTIONS
} :text
_end = . ;
+ . = ALIGN(MB(2));
+ __2M_rwdata_end = .;
+
#ifdef EFI
. = ALIGN(4);
.reloc : {
@@ -231,4 +249,13 @@ ASSERT(__image_base__ > XEN_VIRT_START ||
ASSERT(kexec_reloc_size - kexec_reloc <= PAGE_SIZE, "kexec_reloc is too large")
#endif
+ASSERT(IS_ALIGNED(__2M_text_start, MB(2)), "__2M_text_start misaligned")
+ASSERT(IS_ALIGNED(__2M_text_end, MB(2)), "__2M_text_end misaligned")
+ASSERT(IS_ALIGNED(__2M_rodata_start, MB(2)), "__2M_rodata_start misaligned")
+ASSERT(IS_ALIGNED(__2M_rodata_end, MB(2)), "__2M_rodata_end misaligned")
+ASSERT(IS_ALIGNED(__2M_init_start, MB(2)), "__2M_init_start misaligned")
+ASSERT(IS_ALIGNED(__2M_init_end, MB(2)), "__2M_init_end misaligned")
+ASSERT(IS_ALIGNED(__2M_rwdata_start, MB(2)), "__2M_rwdata_start misaligned")
+ASSERT(IS_ALIGNED(__2M_rwdata_end, MB(2)), "__2M_rwdata_end misaligned")
+
ASSERT(IS_ALIGNED(cpu0_stack, STACK_SIZE), "cpu0_stack misaligned")
diff --git a/xen/include/asm-x86/setup.h b/xen/include/asm-x86/setup.h
index 381d9f8..c65b79c 100644
--- a/xen/include/asm-x86/setup.h
+++ b/xen/include/asm-x86/setup.h
@@ -4,6 +4,11 @@
#include <xen/multiboot.h>
#include <asm/numa.h>
+extern const char __2M_text_start[], __2M_text_end[];
+extern const char __2M_rodata_start[], __2M_rodata_end[];
+extern char __2M_init_start[], __2M_init_end[];
+extern char __2M_rwdata_start[], __2M_rwdata_end[];
+
extern unsigned long xenheap_initial_phys_start;
void early_cpu_init(void);
--
generated by git-patchbot for /home/xen/git/xen.git#master
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