[PARISC] Add CONFIG_DEBUG_RODATA to protect read-only data
Add the parisc version of the "mark rodata section read only" patches.
Based on code from and Signed-off-by Arjan van de Ven
<arjan@infradead.org>, Ingo Molnar <mingo@elte.hu>, Andi Kleen <ak@muc.de>,
Andrew Morton <akpm@osdl.org>, Linus Torvalds <torvalds@osdl.org>.
Signed-off-by: Helge Deller <deller@parisc-linux.org>
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
diff --git a/arch/parisc/Kconfig.debug b/arch/parisc/Kconfig.debug
index 8caaed1..9166bd1 100644
--- a/arch/parisc/Kconfig.debug
+++ b/arch/parisc/Kconfig.debug
@@ -11,4 +11,14 @@
too many attempts. If you suspect a rwlock problem or a kernel
hacker asks for this option then say Y. Otherwise say N.
+config DEBUG_RODATA
+ bool "Write protect kernel read-only data structures"
+ depends on DEBUG_KERNEL
+ help
+ Mark the kernel read-only data as write-protected in the pagetables,
+ in order to catch accidental (and incorrect) writes to such const
+ data. This option may have a slight performance impact because a
+ portion of the kernel code won't be covered by a TLB anymore.
+ If in doubt, say "N".
+
endmenu
diff --git a/arch/parisc/hpux/entry_hpux.S b/arch/parisc/hpux/entry_hpux.S
index fa9bf38..31c8ccc 100644
--- a/arch/parisc/hpux/entry_hpux.S
+++ b/arch/parisc/hpux/entry_hpux.S
@@ -22,10 +22,9 @@
#include <linux/linkage.h>
#include <asm/unistd.h>
- .text
-
#define ENTRY_NAME(_name_) .word _name_
+ .section .rodata,"a"
.align 4
.export hpux_call_table
.import hpux_unimplemented_wrapper
diff --git a/arch/parisc/kernel/syscall.S b/arch/parisc/kernel/syscall.S
index d661634..af88afe 100644
--- a/arch/parisc/kernel/syscall.S
+++ b/arch/parisc/kernel/syscall.S
@@ -650,6 +650,8 @@
#define LWS_ENTRY(_name_) .word (lws_##_name_ - linux_gateway_page)
#endif
+ .section .rodata,"a"
+
.align 4096
/* Light-weight-syscall table */
/* Start of lws table. */
diff --git a/arch/parisc/mm/init.c b/arch/parisc/mm/init.c
index 9999eb0..6f36d0b 100644
--- a/arch/parisc/mm/init.c
+++ b/arch/parisc/mm/init.c
@@ -417,6 +417,19 @@
#endif
}
+
+#ifdef CONFIG_DEBUG_RODATA
+void mark_rodata_ro(void)
+{
+ extern char __start_rodata, __end_rodata;
+ /* rodata memory was already mapped with KERNEL_RO access rights by
+ pagetable_init() and map_pages(). No need to do additional stuff here */
+ printk (KERN_INFO "Write protecting the kernel read-only data: %luk\n",
+ (unsigned long)(&__end_rodata - &__start_rodata) >> 10);
+}
+#endif
+
+
/*
* Just an arbitrary offset to serve as a "hole" between mapping areas
* (between top of physical memory and a potential pcxl dma mapping
@@ -685,7 +698,7 @@
#ifdef CONFIG_BLK_DEV_INITRD
if (initrd_end && initrd_end > mem_limit) {
- printk("initrd: mapping %08lx-%08lx\n", initrd_start, initrd_end);
+ printk(KERN_INFO "initrd: mapping %08lx-%08lx\n", initrd_start, initrd_end);
map_pages(initrd_start, __pa(initrd_start),
initrd_end - initrd_start, PAGE_KERNEL);
}
diff --git a/include/asm-parisc/cacheflush.h b/include/asm-parisc/cacheflush.h
index 1bc3c83..c53af9f 100644
--- a/include/asm-parisc/cacheflush.h
+++ b/include/asm-parisc/cacheflush.h
@@ -183,4 +183,10 @@
__flush_cache_page(vma, vmaddr);
}
+
+#ifdef CONFIG_DEBUG_RODATA
+void mark_rodata_ro(void);
#endif
+
+#endif /* _PARISC_CACHEFLUSH_H */
+
diff --git a/include/asm-parisc/pgtable.h b/include/asm-parisc/pgtable.h
index b455471..4e34c6b 100644
--- a/include/asm-parisc/pgtable.h
+++ b/include/asm-parisc/pgtable.h
@@ -213,7 +213,7 @@
#define PAGE_COPY PAGE_EXECREAD
#define PAGE_RWX __pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_READ | _PAGE_WRITE | _PAGE_EXEC |_PAGE_ACCESSED)
#define PAGE_KERNEL __pgprot(_PAGE_KERNEL)
-#define PAGE_KERNEL_RO __pgprot(_PAGE_PRESENT | _PAGE_EXEC | _PAGE_READ | _PAGE_DIRTY | _PAGE_ACCESSED)
+#define PAGE_KERNEL_RO __pgprot(_PAGE_KERNEL & ~_PAGE_WRITE)
#define PAGE_KERNEL_UNC __pgprot(_PAGE_KERNEL | _PAGE_NO_CACHE)
#define PAGE_GATEWAY __pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_ACCESSED | _PAGE_GATEWAY| _PAGE_READ)
#define PAGE_FLUSH __pgprot(_PAGE_FLUSH)
