ARM: Add support for checking access permissions on prefetch aborts
ARMv6 introduces non-executable mappings, which can cause prefetch aborts
when an attempt is made to execute from such a mapping. Currently, this
causes us to loop in the page fault handler since we don't correctly
check for proper permissions.
Fix this by checking that VMAs have VM_EXEC set for prefetch aborts.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index b7ce07d..379f785 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -26,8 +26,9 @@
#include "fault.h"
/*
- * Fault status register encodings
+ * Fault status register encodings. We steal bit 31 for our own purposes.
*/
+#define FSR_LNX_PF (1 << 31)
#define FSR_WRITE (1 << 11)
#define FSR_FS4 (1 << 10)
#define FSR_FS3_0 (15)
@@ -205,6 +206,8 @@
if (fsr & FSR_WRITE)
mask = VM_WRITE;
+ if (fsr & FSR_LNX_PF)
+ mask = VM_EXEC;
return vma->vm_flags & mask ? false : true;
}
@@ -503,7 +506,7 @@
const struct fsr_info *inf = fsr_info + fsr_fs(fsr);
struct siginfo info;
- if (!inf->fn(addr, fsr, regs))
+ if (!inf->fn(addr, fsr & ~FSR_LNX_PF, regs))
return;
printk(KERN_ALERT "Unhandled fault: %s (0x%03x) at 0x%08lx\n",
@@ -519,6 +522,6 @@
asmlinkage void __exception
do_PrefetchAbort(unsigned long addr, struct pt_regs *regs)
{
- do_translation_fault(addr, 0, regs);
+ do_translation_fault(addr, FSR_LNX_PF, regs);
}