From 53c99bd665a2649341ed6aed358ab56a3eedcd00 Mon Sep 17 00:00:00 2001
From: Martin Schwidefsky <schwidefsky@de.ibm.com>
Date: Fri, 31 Aug 2018 10:42:24 +0200
Subject: [PATCH] init: add arch_call_rest_init to allow stack switching
With CONFIG_VMAP_STACK=y the kernel stack of all tasks should be
allocated in the vmalloc space. The initial stack used for all
the early init code is in the init_thread_union. To be able to
switch from this early stack to a properly allocated stack
from vmalloc the architecture needs a switch-over point.
Introduce the arch_call_rest_init() function with a weak definition
in init/main.c with the only purpose to call rest_init() from the
end of start_kernel(). The architecture override can then do the
necessary magic to switch to the new vmalloc'ed stack.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---
include/linux/start_kernel.h | 2 ++
init/main.c | 9 +++++++--
2 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/include/linux/start_kernel.h b/include/linux/start_kernel.h
index 4b268d86a784c..8b369a41c03c0 100644
--- a/include/linux/start_kernel.h
+++ b/include/linux/start_kernel.h
@@ -9,5 +9,7 @@
up something else. */
extern asmlinkage void __init start_kernel(void);
+extern void __init arch_call_rest_init(void);
+extern void __ref rest_init(void);
#endif /* _LINUX_START_KERNEL_H */
diff --git a/init/main.c b/init/main.c
index 18f8f0140fa03..78b714a5fa94b 100644
--- a/init/main.c
+++ b/init/main.c
@@ -394,7 +394,7 @@ static void __init setup_command_line(char *command_line)
static __initdata DECLARE_COMPLETION(kthreadd_done);
-static noinline void __ref rest_init(void)
+noinline void __ref rest_init(void)
{
struct task_struct *tsk;
int pid;
@@ -528,6 +528,11 @@ static void __init mm_init(void)
pti_init();
}
+void __init __weak arch_call_rest_init(void)
+{
+ rest_init();
+}
+
asmlinkage __visible void __init start_kernel(void)
{
char *command_line;
@@ -736,7 +741,7 @@ asmlinkage __visible void __init start_kernel(void)
}
/* Do the rest non-__init'ed, we're now alive */
- rest_init();
+ arch_call_rest_init();
}
/* Call all constructor functions linked into the kernel. */
--
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