diff options
| author | James Morris <jmorris@namei.org> | 2010-03-31 08:39:27 +1100 |
|---|---|---|
| committer | James Morris <jmorris@namei.org> | 2010-03-31 08:39:27 +1100 |
| commit | d25d6fa1a95f465ff1ec4458ca15e30b2c8dffec (patch) | |
| tree | 7362b182dedd825fc762ef7706830837e42943af /arch/x86/mm/pageattr.c | |
| parent | 225a9be24d799aa16d543c31fb09f0c9ed1d9caa (diff) | |
| parent | 2eaa9cfdf33b8d7fb7aff27792192e0019ae8fc6 (diff) | |
Merge branch 'master' into next
Diffstat (limited to 'arch/x86/mm/pageattr.c')
| -rw-r--r-- | arch/x86/mm/pageattr.c | 25 |
1 files changed, 23 insertions, 2 deletions
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 1d4eb93d333c..cf07c26d9a4a 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)); |