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authorLinus Torvalds <torvalds@linux-foundation.org>2010-03-13 14:45:49 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2010-03-13 14:45:49 -0800
commit15c989d4d14b82f43cae7efc6a7794cdd556f274 (patch)
tree3f1a22991aacf42acaf56467cbe79897146d3e32 /arch/x86/mm
parent4e3eaddd142e2142c048c5052a0a9d2604fccfc6 (diff)
parent0e152cd7c16832bd5cadee0c2e41d9959bc9b6f9 (diff)
Merge branch 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: x86, k8 nb: Fix boot crash: enable k8_northbridges unconditionally on AMD systems x86, UV: Fix target_cpus() in x2apic_uv_x.c x86: Reduce per cpu warning boot up messages x86: Reduce per cpu MCA boot up messages x86_64, cpa: Don't work hard in preserving kernel 2M mappings when using 4K already
Diffstat (limited to 'arch/x86/mm')
-rw-r--r--arch/x86/mm/pageattr.c25
1 files changed, 23 insertions, 2 deletions
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 1d4eb93d333..cf07c26d9a4 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -291,8 +291,29 @@ static inline pgprot_t static_protections(pgprot_t prot, unsigned long address,
*/
if (kernel_set_to_readonly &&
within(address, (unsigned long)_text,
- (unsigned long)__end_rodata_hpage_align))
- pgprot_val(forbidden) |= _PAGE_RW;
+ (unsigned long)__end_rodata_hpage_align)) {
+ unsigned int level;
+
+ /*
+ * Don't enforce the !RW mapping for the kernel text mapping,
+ * if the current mapping is already using small page mapping.
+ * No need to work hard to preserve large page mappings in this
+ * case.
+ *
+ * This also fixes the Linux Xen paravirt guest boot failure
+ * (because of unexpected read-only mappings for kernel identity
+ * mappings). In this paravirt guest case, the kernel text
+ * mapping and the kernel identity mapping share the same
+ * page-table pages. Thus we can't really use different
+ * protections for the kernel text and identity mappings. Also,
+ * these shared mappings are made of small page mappings.
+ * Thus this don't enforce !RW mapping for small page kernel
+ * text mapping logic will help Linux Xen parvirt guest boot
+ * aswell.
+ */
+ if (lookup_address(address, &level) && (level != PG_LEVEL_4K))
+ pgprot_val(forbidden) |= _PAGE_RW;
+ }
#endif
prot = __pgprot(pgprot_val(prot) & ~pgprot_val(forbidden));