diff options
| -rw-r--r-- | arch/x86/mm/pageattr.c | 47 |
1 files changed, 37 insertions, 10 deletions
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index cbe8e9223be..00f6f341e29 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -24,22 +24,49 @@ void clflush_cache_range(void *addr, int size) #include <asm/pgalloc.h> /* - * We allow the BIOS range to be executable: + * We must allow the BIOS range to be executable: */ #define BIOS_BEGIN 0x000a0000 #define BIOS_END 0x00100000 -static inline pgprot_t check_exec(pgprot_t prot, unsigned long address) +static inline int +within(unsigned long addr, unsigned long start, unsigned long end) { - if (__pa(address) >= BIOS_BEGIN && __pa(address) < BIOS_END) - pgprot_val(prot) &= ~_PAGE_NX; + return addr >= start && addr < end; +} + +/* + * Certain areas of memory on x86 require very specific protection flags, + * for example the BIOS area or kernel text. Callers don't always get this + * right (again, ioremap() on BIOS memory is not uncommon) so this function + * checks and fixes these known static required protection bits. + */ +static inline pgprot_t static_protections(pgprot_t prot, unsigned long address) +{ + pgprot_t forbidden = __pgprot(0); + /* - * Better fail early if someone sets the kernel text to NX. - * Does not cover __inittext + * The BIOS area between 640k and 1Mb needs to be executable for + * PCI BIOS based config access (CONFIG_PCI_GOBIOS) support. */ - BUG_ON(address >= (unsigned long)&_text && - address < (unsigned long)&_etext && - (pgprot_val(prot) & _PAGE_NX)); + if (within(__pa(address), BIOS_BEGIN, BIOS_END)) + pgprot_val(forbidden) |= _PAGE_NX; + + /* + * The kernel text needs to be executable for obvious reasons + * Does not cover __inittext since that is gone later on + */ + if (within(address, (unsigned long)_text, (unsigned long)_etext)) + pgprot_val(forbidden) |= _PAGE_NX; + +#ifdef CONFIG_DEBUG_RODATA + /* The .rodata section needs to be read-only */ + if (within(address, (unsigned long)__start_rodata, + (unsigned long)__end_rodata)) + pgprot_val(forbidden) |= _PAGE_RW; +#endif + + prot = __pgprot(pgprot_val(prot) & ~pgprot_val(forbidden)); return prot; } @@ -169,7 +196,7 @@ repeat: BUG_ON(PageLRU(kpte_page)); BUG_ON(PageCompound(kpte_page)); - prot = check_exec(prot, address); + prot = static_protections(prot, address); if (level == PG_LEVEL_4K) { set_pte_atomic(kpte, pfn_pte(pfn, canon_pgprot(prot))); |