add patch_process_vm(). (in progress)

This function patches specified range of specified user space even if
the range is not writable.

refs #401

arch/x86/kernel/include/registers.h

@@ -219,6 +219,7 @@ enum x86_pf_error_code {
 	PF_RSVD		=		1 << 3,
 	PF_INSTR	=		1 << 4,
 
+	PF_PATCH	=		1 << 29,
 	PF_POPULATE	=		1 << 30,
 };
 

arch/x86/kernel/memory.c

@@ -1870,7 +1870,8 @@ enum ihk_mc_pt_attribute arch_vrflag_to_ptattr(unsigned long flag, uint64_t faul
 	attr = common_vrflag_to_ptattr(flag, fault, ptep);
 
 	if ((fault & PF_PROT)
-			|| ((fault & PF_POPULATE) && (flag & VR_PRIVATE))) {
+			|| ((fault & (PF_POPULATE | PF_PATCH))
+				&& (flag & VR_PRIVATE))) {
 		attr |= PTATTR_DIRTY;
 	}
 
@@ -2282,3 +2283,61 @@ int write_process_vm(struct process_vm *vm, void *udst, const void *ksrc, size_t
 
 	return 0;
 } /* write_process_vm() */
+
+int patch_process_vm(struct process_vm *vm, void *udst, const void *ksrc, size_t siz)
+{
+	const uintptr_t ustart = (uintptr_t)udst;
+	const uintptr_t uend = ustart + siz;
+	uint64_t reason;
+	uintptr_t addr;
+	int error;
+	const void *from;
+	void *to;
+	size_t remain;
+	size_t cpsize;
+	unsigned long pa;
+	void *va;
+
+	kprintf("patch_process_vm(%p,%p,%p,%lx)\n", vm, udst, ksrc, siz);
+	if ((ustart < vm->region.user_start)
+			|| (vm->region.user_end <= ustart)
+			|| ((vm->region.user_end - ustart) < siz)) {
+		kprintf("patch_process_vm(%p,%p,%p,%lx):not in user\n", vm, udst, ksrc, siz);
+		return -EFAULT;
+	}
+
+	reason = PF_PATCH | PF_WRITE | PF_USER;
+	for (addr = ustart & PAGE_MASK; addr < uend; addr += PAGE_SIZE) {
+		error = page_fault_process_vm(vm, (void *)addr, reason);
+		if (error) {
+			kprintf("patch_process_vm(%p,%p,%p,%lx):pf(%lx):%d\n", vm, udst, ksrc, siz, addr, error);
+			return error;
+		}
+	}
+
+	from = ksrc;
+	to = udst;
+	remain = siz;
+	while (remain > 0) {
+		cpsize = PAGE_SIZE - ((uintptr_t)to & (PAGE_SIZE - 1));
+		if (cpsize > remain) {
+			cpsize = remain;
+		}
+
+		error = ihk_mc_pt_virt_to_phys(vm->page_table, to, &pa);
+		if (error) {
+			kprintf("patch_process_vm(%p,%p,%p,%lx):v2p(%p):%d\n", vm, udst, ksrc, siz, to, error);
+			return error;
+		}
+
+		va = phys_to_virt(pa);
+		memcpy(va, from, cpsize);
+
+		from += cpsize;
+		to += cpsize;
+		remain -= cpsize;
+	}
+
+	kprintf("patch_process_vm(%p,%p,%p,%lx):%d\n", vm, udst, ksrc, siz, 0);
+	return 0;
+} /* patch_process_vm() */

kernel/process.c

@@ -1378,7 +1378,7 @@ static int page_fault_process_memory_range(struct process_vm *vm, struct vm_rang
 	ihk_mc_spinlock_lock_noirq(&vm->page_table_lock);
 	/*****/
 	ptep = ihk_mc_pt_lookup_pte(vm->page_table, (void *)fault_addr, &pgaddr, &pgsize, &p2align);
-	if (!(reason & PF_PROT) && ptep && !pte_is_null(ptep)
+	if (!(reason & (PF_PROT | PF_PATCH)) && ptep && !pte_is_null(ptep)
 			&& !pte_is_fileoff(ptep, pgsize)) {
 		if (!pte_is_present(ptep)) {
 			error = -EFAULT;
@@ -1439,7 +1439,10 @@ static int page_fault_process_memory_range(struct process_vm *vm, struct vm_rang
 	}
 	page = phys_to_page(phys);
 	/*****/
-	if ((range->flag & VR_PRIVATE) && (!page || page_is_in_memobj(page) || page_is_multi_mapped(page))) {
+	if (((range->flag & VR_PRIVATE)
+				|| ((reason & PF_PATCH)
+					&& !(range->flag & VR_PROT_WRITE)))
+			&& (!page || page_is_in_memobj(page) || page_is_multi_mapped(page))) {
 		if (!(attr & PTATTR_DIRTY)) {
 			attr &= ~PTATTR_WRITABLE;
 		}
@@ -1513,7 +1516,7 @@ static int do_page_fault_process_vm(struct process_vm *vm, void *fault_addr0, ui
 	}
 
 	if (((range->flag & VR_PROT_MASK) == VR_PROT_NONE)
-			|| ((reason & PF_WRITE)
+			|| (((reason & PF_WRITE) && !(reason & PF_PATCH))
 				&& !(range->flag & VR_PROT_WRITE))
 			|| ((reason & PF_INSTR)
 				&& !(range->flag & VR_PROT_EXEC))) {