mm: add setup_initial_init_mm() helper

Patch series "init_mm: cleanup ARCH's text/data/brk setup code", v3.

Add setup_initial_init_mm() helper, then use it to cleanup the text, data
and brk setup code.

This patch (of 15):

Add setup_initial_init_mm() helper to setup kernel text, data and brk.

Link: https://lkml.kernel.org/r/20210608083418.137226-1-wangkefeng.wang@huawei.com
Link: https://lkml.kernel.org/r/20210608083418.137226-2-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Souptick Joarder <jrdr.linux@gmail.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Greg Ungerer <gerg@linux-m68k.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Ley Foon Tan <ley.foon.tan@intel.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nick Hu <nickhu@andestech.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Rich Felker <dalias@libc.org>
Cc: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/mm.h

@@ -238,6 +238,9 @@ int __add_to_page_cache_locked(struct page *page, struct address_space *mapping,
 
 #define lru_to_page(head) (list_entry((head)->prev, struct page, lru))
 
+void setup_initial_init_mm(void *start_code, void *end_code,
+			   void *end_data, void *brk);
+
 /*
  * Linux kernel virtual memory manager primitives.
  * The idea being to have a "virtual" mm in the same way

mm/init-mm.c

@@ -40,3 +40,12 @@ struct mm_struct init_mm = {
 	.cpu_bitmap	= CPU_BITS_NONE,
 	INIT_MM_CONTEXT(init_mm)
 };
+
+void setup_initial_init_mm(void *start_code, void *end_code,
+			   void *end_data, void *brk)
+{
+	init_mm.start_code = (unsigned long)start_code;
+	init_mm.end_code = (unsigned long)end_code;
+	init_mm.end_data = (unsigned long)end_data;
+	init_mm.brk = (unsigned long)brk;
+}