From d7dd2ff11b7fcd425aca5a875983c862d19a67ae Mon Sep 17 00:00:00 2001 From: James Bottomley Date: Thu, 14 Apr 2011 18:25:21 -0500 Subject: [PARISC] only make executable areas executable Currently parisc has the whole kernel marked as RWX, meaning any kernel page at all is eligible to be executed. This can cause a theoretical problem on systems with combined I/D TLB because the act of referencing a page causes a TLB insertion with an executable bit. This TLB entry may be used by the CPU as the basis for speculating the page into the I-Cache. If this speculated page is subsequently used for a user process, there is the possibility we will get a stale I-cache line picked up as the binary executes. As a point of good practise, only mark actual kernel text pages as executable. The same has to be done for init_text pages, but they're converted to data pages (and the I-Cache flushed) when the init memory is released. Signed-off-by: James Bottomley --- arch/parisc/kernel/entry.S | 3 +++ 1 file changed, 3 insertions(+) (limited to 'arch/parisc/kernel/entry.S') diff --git a/arch/parisc/kernel/entry.S b/arch/parisc/kernel/entry.S index ead8d2a1034..6f059443914 100644 --- a/arch/parisc/kernel/entry.S +++ b/arch/parisc/kernel/entry.S @@ -692,6 +692,9 @@ ENTRY(fault_vector_11) END(fault_vector_11) #endif + /* Fault vector is separately protected and *must* be on its own page */ + .align PAGE_SIZE +ENTRY(end_fault_vector) .import handle_interruption,code .import do_cpu_irq_mask,code -- cgit v1.2.3