arm64/mm: Identify user instruction aborts

We don't currently set the FAULT_FLAG_INSTRUCTION mm flag for EL0
instruction aborts. This has no functional impact, as we don't override
arch_vma_access_permitted(), and the default implementation always returns
true. However, it would be helpful to provide the flag so that it can be
consumed by tracepoints such as dax_pmd_fault.

This patch sets the FAULT_FLAG_INSTRUCTION flag for EL0 instruction aborts.
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/mm/fault.c

@@ -464,6 +464,7 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
 
 	if (is_el0_instruction_abort(esr)) {
 		vm_flags = VM_EXEC;
+		mm_flags |= FAULT_FLAG_INSTRUCTION;
 	} else if ((esr & ESR_ELx_WNR) && !(esr & ESR_ELx_CM)) {
 		vm_flags = VM_WRITE;
 		mm_flags |= FAULT_FLAG_WRITE;