Blackfin: fix MPU handling of invalid memory accesses

The protect_page() function was incorrectly setting up the hardware tables
based on possible access capabilities rather than the actual requested
values.  This means we would grant more access to mmap-ed pages than we
should have.  Once we fix this, we need to tweak the signal generated by
such accesses to aline ourselves with other ports.  This allows the LTP
mmap0{5,6,7} cases to run properly.
Signed-off-by: Graf Yang <graf.yang@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

arch/blackfin/include/asm/mmu_context.h

@@ -127,17 +127,17 @@ static inline void protect_page(struct mm_struct *mm, unsigned long addr,
 	unsigned long idx = page >> 5;
 	unsigned long bit = 1 << (page & 31);
 
-	if (flags & VM_MAYREAD)
+	if (flags & VM_READ)
 		mask[idx] |= bit;
 	else
 		mask[idx] &= ~bit;
 	mask += page_mask_nelts;
-	if (flags & VM_MAYWRITE)
+	if (flags & VM_WRITE)
 		mask[idx] |= bit;
 	else
 		mask[idx] &= ~bit;
 	mask += page_mask_nelts;
-	if (flags & VM_MAYEXEC)
+	if (flags & VM_EXEC)
 		mask[idx] |= bit;
 	else
 		mask[idx] &= ~bit;

arch/blackfin/kernel/traps.c

@@ -411,7 +411,7 @@ asmlinkage void trap_c(struct pt_regs *fp)
 	/* 0x23 - Data CPLB protection violation, handled here */
 	case VEC_CPLB_VL:
 		info.si_code = ILL_CPLB_VI;
-		sig = SIGBUS;
+		sig = SIGSEGV;
 		strerror = KERN_NOTICE EXC_0x23(KERN_NOTICE);
 		CHK_DEBUGGER_TRAP_MAYBE();
 		break;