diff options
| author | Arjan van de Ven <arjan@infradead.org> | 2006-01-06 00:12:04 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-01-06 08:33:36 -0800 |
| commit | 67df197b1a07944c2e0e40ded3d4fd07d108e110 (patch) | |
| tree | b29534a27b2c18e64c6b3d4cdc149de8978e38ba /arch | |
| parent | c728252c7a072628bd3932ff87943d1e12423359 (diff) | |
[PATCH] x86/x86_64: mark rodata section read-only: x86-64 support
x86-64 specific parts to make the .rodata section read only
Signed-off-by: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86_64/Kconfig.debug | 10 | ||||
| -rw-r--r-- | arch/x86_64/mm/init.c | 23 |
2 files changed, 33 insertions, 0 deletions
diff --git a/arch/x86_64/Kconfig.debug b/arch/x86_64/Kconfig.debug index e2c6e64a85ec..fcb06a50fdd2 100644 --- a/arch/x86_64/Kconfig.debug +++ b/arch/x86_64/Kconfig.debug @@ -9,6 +9,16 @@ config INIT_DEBUG Fill __init and __initdata at the end of boot. This helps debugging illegal uses of __init and __initdata after initialization. +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 2MB TLB anymore. + If in doubt, say "N". + config IOMMU_DEBUG depends on GART_IOMMU && DEBUG_KERNEL bool "Enable IOMMU debugging" diff --git a/arch/x86_64/mm/init.c b/arch/x86_64/mm/init.c index c016dfe84784..1faae5fc1c01 100644 --- a/arch/x86_64/mm/init.c +++ b/arch/x86_64/mm/init.c @@ -498,6 +498,29 @@ void free_initmem(void) printk ("Freeing unused kernel memory: %luk freed\n", (__init_end - __init_begin) >> 10); } +#ifdef CONFIG_DEBUG_RODATA + +extern char __start_rodata, __end_rodata; +void mark_rodata_ro(void) +{ + unsigned long addr = (unsigned long)&__start_rodata; + + for (; addr < (unsigned long)&__end_rodata; addr += PAGE_SIZE) + change_page_attr_addr(addr, 1, PAGE_KERNEL_RO); + + printk ("Write protecting the kernel read-only data: %luk\n", + (&__end_rodata - &__start_rodata) >> 10); + + /* + * change_page_attr_addr() requires a global_flush_tlb() call after it. + * We do this after the printk so that if something went wrong in the + * change, the printk gets out at least to give a better debug hint + * of who is the culprit. + */ + global_flush_tlb(); +} +#endif + #ifdef CONFIG_BLK_DEV_INITRD void free_initrd_mem(unsigned long start, unsigned long end) { |