From: Ralf Baechle Date: Thu, 23 Jul 2015 09:10:59 +0000 (+0200) Subject: MIPS: Partially disable RIXI support. X-Git-Tag: drm-fsl-dcu-for-next~2741^2~9 X-Git-Url: http://git.agner.ch/gitweb/?p=linux-drm-fsl-dcu.git;a=commitdiff_plain;h=55fdcb2d56b6edc027657fde9da0c4f224d32303 MIPS: Partially disable RIXI support. Execution of break instruction, trap instructions, emulation of unaligned loads or floating point instructions - anything that tries to read the instruction's opcode from userspace - needs read access to a page. RIXI (Read Inhibit / Execute Inhibit) support however allows the creation of pags that are executable but not readable. On such a mapping the attempted load of the opcode by the kernel is going to cause an endless loop of page faults. The quick workaround for this is to disable the combinations that the kernel currently isn't able to handle which are executable mappings. Signed-off-by: Ralf Baechle --- diff --git a/arch/mips/mm/cache.c b/arch/mips/mm/cache.c index 77d96db8253c..aab218c36e0d 100644 --- a/arch/mips/mm/cache.c +++ b/arch/mips/mm/cache.c @@ -160,18 +160,18 @@ static inline void setup_protection_map(void) protection_map[1] = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_EXEC); protection_map[2] = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_NO_READ); protection_map[3] = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_EXEC); - protection_map[4] = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_READ); + protection_map[4] = __pgprot(_page_cachable_default | _PAGE_PRESENT); protection_map[5] = __pgprot(_page_cachable_default | _PAGE_PRESENT); - protection_map[6] = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_READ); + protection_map[6] = __pgprot(_page_cachable_default | _PAGE_PRESENT); protection_map[7] = __pgprot(_page_cachable_default | _PAGE_PRESENT); protection_map[8] = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_NO_READ); protection_map[9] = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_EXEC); protection_map[10] = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_WRITE | _PAGE_NO_READ); protection_map[11] = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_WRITE); - protection_map[12] = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_READ); + protection_map[12] = __pgprot(_page_cachable_default | _PAGE_PRESENT); protection_map[13] = __pgprot(_page_cachable_default | _PAGE_PRESENT); - protection_map[14] = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_WRITE | _PAGE_NO_READ); + protection_map[14] = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_WRITE); protection_map[15] = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_WRITE); } else {