On Sat, Apr 3, 2010 at 2:43 AM, Suresh Siddha <suresh.b.siddha@xxxxxxxxx> wrote: > On Wed, 2010-03-31 at 18:59 -0700, Siarhei Liakh wrote: >> + /* >> + * .data and .bss should always be writable. >> + */ >> + if ((within(pfn, __pa((unsigned long)_sdata) >> PAGE_SHIFT, >> + __pa((unsigned long)_edata) >> PAGE_SHIFT)) || >> + (within(pfn, __pa((unsigned long)__bss_start) >> PAGE_SHIFT, >> + __pa((unsigned long)__bss_stop) >> PAGE_SHIFT))) { >> + pgprot_val(required) |= _PAGE_RW; >> + } > > I have reviewed this patch and the only comment I have is: > > On 64bit kernels, kernel text/data mapping and kernel identity mappings > are different virtual addresses mapping to same pfn ranges. For the > data/bss pages, does it help (in identifying certain data corruptions > more easily) in making the kernel identity mapping to be set to > read-only and enforce the need of RW only for the kernel data mappings. > > Or is there some obscure code that uses something like > __va(__pa(data_symbol)) and writes to it? > > If not, we can remove the __pa() constructs above and use the addr for > comparisons. Done. Patch V2 have been posted. -- To unsubscribe from this list: send the line "unsubscribe linux-next" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html