From 130031906fbd143068aa9575338174a061f89b85 Mon Sep 17 00:00:00 2001
From: Hajime Tazaki <thehajime@gmail.com>
Date: Thu, 23 Jul 2026 11:35:43 +0200
Subject: [PATCH] um: decouple MMU specific code from the common part

This splits the memory, process related code with common and MMU
specific parts in order to avoid ifdefs in .c file and duplication
between MMU and !MMU.

Signed-off-by: Hajime Tazaki <thehajime@gmail.com>
[drop many unnecessary changes]
Link: https://patch.msgid.link/20260723113633.af7d6a109c22.Ie82119143778b91fa5585ea3493cf4014113da47@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---
 arch/um/kernel/Makefile      |  3 +-
 arch/um/kernel/mem-pgtable.c | 55 ++++++++++++++++++++++++++++++++++++
 arch/um/kernel/mem.c         | 35 -----------------------
 3 files changed, 57 insertions(+), 36 deletions(-)
 create mode 100644 arch/um/kernel/mem-pgtable.c

diff --git a/arch/um/kernel/Makefile b/arch/um/kernel/Makefile
index be60bc451b3f..d56fe6d829cc 100644
--- a/arch/um/kernel/Makefile
+++ b/arch/um/kernel/Makefile
@@ -16,9 +16,10 @@ always-$(KBUILD_BUILTIN) := vmlinux.lds
 
 obj-y = config.o exec.o exitcode.o irq.o ksyms.o mem.o \
 	physmem.o process.o ptrace.o reboot.o sigio.o \
-	signal.o sysrq.o time.o tlb.o trap.o \
+	signal.o sysrq.o time.o trap.o \
 	um_arch.o umid.o kmsg_dump.o capflags.o skas/
 obj-y += load_file.o
+obj-$(CONFIG_MMU) += mem-pgtable.o tlb.o
 
 obj-$(CONFIG_BLK_DEV_INITRD) += initrd.o
 obj-$(CONFIG_GPROF)	+= gprof_syms.o
diff --git a/arch/um/kernel/mem-pgtable.c b/arch/um/kernel/mem-pgtable.c
new file mode 100644
index 000000000000..549da1d3bff0
--- /dev/null
+++ b/arch/um/kernel/mem-pgtable.c
@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ */
+
+#include <linux/stddef.h>
+#include <linux/module.h>
+#include <linux/memblock.h>
+#include <linux/swap.h>
+#include <linux/slab.h>
+#include <asm/page.h>
+#include <asm/pgalloc.h>
+#include <as-layout.h>
+#include <init.h>
+#include <kern.h>
+#include <kern_util.h>
+#include <mem_user.h>
+#include <os.h>
+#include <um_malloc.h>
+
+
+/* Allocate and free page tables. */
+
+pgd_t *pgd_alloc(struct mm_struct *mm)
+{
+	pgd_t *pgd = (pgd_t *)__get_free_page(GFP_KERNEL);
+
+	if (pgd) {
+		memset(pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
+		memcpy(pgd + USER_PTRS_PER_PGD,
+		       swapper_pg_dir + USER_PTRS_PER_PGD,
+		       (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
+	}
+	return pgd;
+}
+
+static const pgprot_t protection_map[16] = {
+	[VM_NONE]					= PAGE_NONE,
+	[VM_READ]					= PAGE_READONLY,
+	[VM_WRITE]					= PAGE_COPY,
+	[VM_WRITE | VM_READ]				= PAGE_COPY,
+	[VM_EXEC]					= PAGE_READONLY,
+	[VM_EXEC | VM_READ]				= PAGE_READONLY,
+	[VM_EXEC | VM_WRITE]				= PAGE_COPY,
+	[VM_EXEC | VM_WRITE | VM_READ]			= PAGE_COPY,
+	[VM_SHARED]					= PAGE_NONE,
+	[VM_SHARED | VM_READ]				= PAGE_READONLY,
+	[VM_SHARED | VM_WRITE]				= PAGE_SHARED,
+	[VM_SHARED | VM_WRITE | VM_READ]		= PAGE_SHARED,
+	[VM_SHARED | VM_EXEC]				= PAGE_READONLY,
+	[VM_SHARED | VM_EXEC | VM_READ]			= PAGE_READONLY,
+	[VM_SHARED | VM_EXEC | VM_WRITE]		= PAGE_SHARED,
+	[VM_SHARED | VM_EXEC | VM_WRITE | VM_READ]	= PAGE_SHARED
+};
+DECLARE_VM_GET_PAGE_PROT
diff --git a/arch/um/kernel/mem.c b/arch/um/kernel/mem.c
index 1eef0e42ef5d..4b84760b5e55 100644
--- a/arch/um/kernel/mem.c
+++ b/arch/um/kernel/mem.c
@@ -6,7 +6,6 @@
 #include <linux/stddef.h>
 #include <linux/module.h>
 #include <linux/memblock.h>
-#include <linux/mm.h>
 #include <linux/swap.h>
 #include <linux/slab.h>
 #include <linux/init.h>
@@ -91,45 +90,11 @@ void free_initmem(void)
 {
 }
 
-/* Allocate and free page tables. */
-
-pgd_t *pgd_alloc(struct mm_struct *mm)
-{
-	pgd_t *pgd = __pgd_alloc(mm, 0);
-
-	if (pgd)
-		memcpy(pgd + USER_PTRS_PER_PGD,
-		       swapper_pg_dir + USER_PTRS_PER_PGD,
-		       (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
-
-	return pgd;
-}
-
 void *uml_kmalloc(int size, int flags)
 {
 	return kmalloc(size, flags);
 }
 
-static const pgprot_t protection_map[16] = {
-	[VM_NONE]					= PAGE_NONE,
-	[VM_READ]					= PAGE_READONLY,
-	[VM_WRITE]					= PAGE_COPY,
-	[VM_WRITE | VM_READ]				= PAGE_COPY,
-	[VM_EXEC]					= PAGE_READONLY,
-	[VM_EXEC | VM_READ]				= PAGE_READONLY,
-	[VM_EXEC | VM_WRITE]				= PAGE_COPY,
-	[VM_EXEC | VM_WRITE | VM_READ]			= PAGE_COPY,
-	[VM_SHARED]					= PAGE_NONE,
-	[VM_SHARED | VM_READ]				= PAGE_READONLY,
-	[VM_SHARED | VM_WRITE]				= PAGE_SHARED,
-	[VM_SHARED | VM_WRITE | VM_READ]		= PAGE_SHARED,
-	[VM_SHARED | VM_EXEC]				= PAGE_READONLY,
-	[VM_SHARED | VM_EXEC | VM_READ]			= PAGE_READONLY,
-	[VM_SHARED | VM_EXEC | VM_WRITE]		= PAGE_SHARED,
-	[VM_SHARED | VM_EXEC | VM_WRITE | VM_READ]	= PAGE_SHARED
-};
-DECLARE_VM_GET_PAGE_PROT
-
 void mark_rodata_ro(void)
 {
 	unsigned long rodata_start = PFN_ALIGN(__start_rodata);