arm64: Change elfcore for_each_mte_vma() to use VMA iterator

Rework for_each_mte_vma() to use a VMA iterator instead of an explicit
linked-list. This will allow easy integration with the maple tree work
which removes the VMA list altogether.
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20220218023650.672072-1-Liam.Howlett@oracle.com
[will: Folded in fix from Catalin]
Link: https://lore.kernel.org/r/YhUcywqIhmHvX6dG@arm.comSigned-off--by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>

arch/arm64/kernel/elfcore.c

@@ -8,9 +8,16 @@
 #include <asm/cpufeature.h>
 #include <asm/mte.h>
 
-#define for_each_mte_vma(tsk, vma)					\
+#ifndef VMA_ITERATOR
+#define VMA_ITERATOR(name, mm, addr)	\
+	struct mm_struct *name = mm
+#define for_each_vma(vmi, vma)		\
+	for (vma = vmi->mmap; vma; vma = vma->vm_next)
+#endif
+
+#define for_each_mte_vma(vmi, vma)					\
 	if (system_supports_mte())					\
-		for (vma = tsk->mm->mmap; vma; vma = vma->vm_next)	\
+		for_each_vma(vmi, vma)					\
 			if (vma->vm_flags & VM_MTE)
 
 static unsigned long mte_vma_tag_dump_size(struct vm_area_struct *vma)
@@ -65,8 +72,9 @@ Elf_Half elf_core_extra_phdrs(void)
 {
 	struct vm_area_struct *vma;
 	int vma_count = 0;
+	VMA_ITERATOR(vmi, current->mm, 0);
 
-	for_each_mte_vma(current, vma)
+	for_each_mte_vma(vmi, vma)
 		vma_count++;
 
 	return vma_count;
@@ -75,8 +83,9 @@ Elf_Half elf_core_extra_phdrs(void)
 int elf_core_write_extra_phdrs(struct coredump_params *cprm, loff_t offset)
 {
 	struct vm_area_struct *vma;
+	VMA_ITERATOR(vmi, current->mm, 0);
 
-	for_each_mte_vma(current, vma) {
+	for_each_mte_vma(vmi, vma) {
 		struct elf_phdr phdr;
 
 		phdr.p_type = PT_ARM_MEMTAG_MTE;
@@ -100,8 +109,9 @@ size_t elf_core_extra_data_size(void)
 {
 	struct vm_area_struct *vma;
 	size_t data_size = 0;
+	VMA_ITERATOR(vmi, current->mm, 0);
 
-	for_each_mte_vma(current, vma)
+	for_each_mte_vma(vmi, vma)
 		data_size += mte_vma_tag_dump_size(vma);
 
 	return data_size;
@@ -110,8 +120,9 @@ size_t elf_core_extra_data_size(void)
 int elf_core_write_extra_data(struct coredump_params *cprm)
 {
 	struct vm_area_struct *vma;
+	VMA_ITERATOR(vmi, current->mm, 0);
 
-	for_each_mte_vma(current, vma) {
+	for_each_mte_vma(vmi, vma) {
 		if (vma->vm_flags & VM_DONTDUMP)
 			continue;