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Subject[PATCH] allow placing exception table in .rodata (and do so on x86)
This is since the table is really a set of pointers, i.e. misplaced in
.text.

Quite likely other architectures would want to follow.

Signed-off-by: Jan Beulich <jbeulich@novell.com>

---
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(-)
--- 2.6.39-rc5/arch/x86/include/asm/sections.h
+++ 2.6.39-rc5-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 char __stop_notes[];

#if defined(CONFIG_X86_64) && defined(CONFIG_DEBUG_RODATA)
extern char __end_rodata_hpage_align[];
--- 2.6.39-rc5/arch/x86/kernel/vmlinux.lds.S
+++ 2.6.39-rc5-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>
@@ -114,8 +116,7 @@ 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 */
--- 2.6.39-rc5/arch/x86/mm/init_64.c
+++ 2.6.39-rc5-extable-in-rodata/arch/x86/mm/init_64.c
@@ -741,7 +741,7 @@ 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;
@@ -760,7 +760,7 @@ 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;
@@ -780,7 +780,7 @@ void mark_rodata_ro(void)
unsigned long rodata_start =
((unsigned long)__start_rodata + PAGE_SIZE - 1) & PAGE_MASK;
unsigned long end = (unsigned long) &__end_rodata_hpage_align;
- unsigned long text_end = PAGE_ALIGN((unsigned long) &__stop___ex_table);
+ unsigned long text_end = PAGE_ALIGN((unsigned long) &__stop_notes);
unsigned long rodata_end = PAGE_ALIGN((unsigned long) &__end_rodata);
unsigned long data_start = (unsigned long) &_sdata;

--- 2.6.39-rc5/include/asm-generic/vmlinux.lds.h
+++ 2.6.39-rc5-extable-in-rodata/include/asm-generic/vmlinux.lds.h
@@ -226,6 +226,7 @@
*(.rodata1) \
} \
\
+ EXCEPTION_TABLE_RO \
BUG_TABLE \
\
JUMP_TABLE \
@@ -459,6 +460,10 @@
VMLINUX_SYMBOL(__stop___ex_table) = .; \
}

+#ifndef EXCEPTION_TABLE_RO
+#define EXCEPTION_TABLE_RO
+#endif
+
/*
* Init task
*/




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