This is since the table is really a set of pointers, i.e. misplaced in
.text. There are no runtime writes to this table (and if an arch needs
to do boot time writes but the table is already r/o - on x86 it isn't -
it simply shouldn't make use of the new construct).
Quite likely other architectures would want to follow.
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
arch/x86/include/asm/sections.h | 2 +-
arch/x86/kernel/vmlinux.lds.S | 5 +++--
arch/x86/mm/init_64.c | 6 +++---
include/asm-generic/vmlinux.lds.h | 5 +++++
4 files changed, 12 insertions(+), 6 deletions(-)
--- 3.15-rc8/arch/x86/include/asm/sections.h
+++ 3.15-rc8-extable-in-rodata/arch/x86/include/asm/sections.h
@@ -5,7 +5,7 @@
#include <asm/uaccess.h>
extern char __brk_base[], __brk_limit[];
-extern struct exception_table_entry __stop___ex_table[];
+extern const void __stop_notes;
#if defined(CONFIG_X86_64) && defined(CONFIG_DEBUG_RODATA)
extern char __end_rodata_hpage_align[];
--- 3.15-rc8/arch/x86/kernel/vmlinux.lds.S
+++ 3.15-rc8-extable-in-rodata/arch/x86/kernel/vmlinux.lds.S
@@ -20,6 +20,8 @@
#define LOAD_OFFSET __START_KERNEL_map
#endif
+#define EXCEPTION_TABLE_RO EXCEPTION_TABLE(16)
+
#include <asm-generic/vmlinux.lds.h>
#include <asm/asm-offsets.h>
#include <asm/thread_info.h>
@@ -109,8 +111,7 @@ SECTIONS
} :text = 0x9090
NOTES :text :note
-
- EXCEPTION_TABLE(16) :text = 0x9090
+ text_continues : {} :text /* switch back to regular text... */
#if defined(CONFIG_DEBUG_RODATA)
/* .text should occupy whole number of pages */
--- 3.15-rc8/arch/x86/mm/init_64.c
+++ 3.15-rc8-extable-in-rodata/arch/x86/mm/init_64.c
@@ -1070,7 +1070,7 @@ int kernel_set_to_readonly;
void set_kernel_text_rw(void)
{
unsigned long start = PFN_ALIGN(_text);
- unsigned long end = PFN_ALIGN(__stop___ex_table);
+ unsigned long end = PFN_ALIGN(_etext);
if (!kernel_set_to_readonly)
return;
@@ -1089,7 +1089,7 @@ void set_kernel_text_rw(void)
void set_kernel_text_ro(void)
{
unsigned long start = PFN_ALIGN(_text);
- unsigned long end = PFN_ALIGN(__stop___ex_table);
+ unsigned long end = PFN_ALIGN(_etext);
if (!kernel_set_to_readonly)
return;
@@ -1108,7 +1108,7 @@ void mark_rodata_ro(void)
unsigned long start = PFN_ALIGN(_text);
unsigned long rodata_start = PFN_ALIGN(__start_rodata);
unsigned long end = (unsigned long) &__end_rodata_hpage_align;
- unsigned long text_end = PFN_ALIGN(&__stop___ex_table);
+ unsigned long text_end = PFN_ALIGN(&__stop_notes);
unsigned long rodata_end = PFN_ALIGN(&__end_rodata);
unsigned long all_end = PFN_ALIGN(&_end);
--- 3.15-rc8/include/asm-generic/vmlinux.lds.h
+++ 3.15-rc8-extable-in-rodata/include/asm-generic/vmlinux.lds.h
@@ -263,6 +263,7 @@
*(.rodata1) \
} \
\
+ EXCEPTION_TABLE_RO \
BUG_TABLE \
\
/* PCI quirks */ \
@@ -479,6 +480,10 @@
VMLINUX_SYMBOL(__stop___ex_table) = .; \
}
+#ifndef EXCEPTION_TABLE_RO
+#define EXCEPTION_TABLE_RO
+#endif
+
/*
* Init task
*/
--
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