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Subject[PATCH 3/5] init: allow initcall tables to be emitted using relative references
Date
Allow the initcall tables to be emitted using relative references that
are only half the size on 64-bit architectures and don't require fixups
at runtime on relocatable kernels.

Cc: Petr Mladek <pmladek@suse.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: James Morris <james.l.morris@oracle.com>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
include/linux/init.h | 44 +++++++++++++++-----
init/main.c | 32 +++++++-------
kernel/printk/printk.c | 4 +-
security/security.c | 4 +-
4 files changed, 53 insertions(+), 31 deletions(-)

diff --git a/include/linux/init.h b/include/linux/init.h
index 94769d687cf0..a65628998ce3 100644
--- a/include/linux/init.h
+++ b/include/linux/init.h
@@ -110,8 +110,24 @@
typedef int (*initcall_t)(void);
typedef void (*exitcall_t)(void);

-extern initcall_t __con_initcall_start[], __con_initcall_end[];
-extern initcall_t __security_initcall_start[], __security_initcall_end[];
+#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
+typedef signed int initcall_entry_t;
+
+static inline initcall_t initcall_from_entry(initcall_entry_t *entry)
+{
+ return (initcall_t)((unsigned long)entry + *entry);
+}
+#else
+typedef initcall_t initcall_entry_t;
+
+static inline initcall_t initcall_from_entry(initcall_entry_t *entry)
+{
+ return *entry;
+}
+#endif
+
+extern initcall_entry_t __con_initcall_start[], __con_initcall_end[];
+extern initcall_entry_t __security_initcall_start[], __security_initcall_end[];

/* Used for contructor calls. */
typedef void (*ctor_fn_t)(void);
@@ -161,9 +177,20 @@ extern bool initcall_debug;
* as KEEP() in the linker script.
*/

-#define __define_initcall(fn, id) \
+#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
+#define ___define_initcall(fn, id, __sec) \
+ __ADDRESSABLE(fn) \
+ asm(".section \"" #__sec ".init\", \"a\" \n" \
+ "__initcall_" #fn #id ": \n" \
+ ".long " VMLINUX_SYMBOL_STR(fn) " - . \n" \
+ ".previous \n");
+#else
+#define ___define_initcall(fn, id, __sec) \
static initcall_t __initcall_##fn##id __used \
- __attribute__((__section__(".initcall" #id ".init"))) = fn;
+ __attribute__((__section__(#__sec ".init"))) = fn;
+#endif
+
+#define __define_initcall(fn, id) ___define_initcall(fn, id, .initcall##id)

/*
* Early initcalls run before initializing SMP.
@@ -202,13 +229,8 @@ extern bool initcall_debug;
#define __exitcall(fn) \
static exitcall_t __exitcall_##fn __exit_call = fn

-#define console_initcall(fn) \
- static initcall_t __initcall_##fn \
- __used __section(.con_initcall.init) = fn
-
-#define security_initcall(fn) \
- static initcall_t __initcall_##fn \
- __used __section(.security_initcall.init) = fn
+#define console_initcall(fn) ___define_initcall(fn,, .con_initcall)
+#define security_initcall(fn) ___define_initcall(fn,, .security_initcall)

struct obs_kernel_param {
const char *str;
diff --git a/init/main.c b/init/main.c
index 052481fbe363..ac2a91f71107 100644
--- a/init/main.c
+++ b/init/main.c
@@ -833,18 +833,18 @@ int __init_or_module do_one_initcall(initcall_t fn)
}


-extern initcall_t __initcall_start[];
-extern initcall_t __initcall0_start[];
-extern initcall_t __initcall1_start[];
-extern initcall_t __initcall2_start[];
-extern initcall_t __initcall3_start[];
-extern initcall_t __initcall4_start[];
-extern initcall_t __initcall5_start[];
-extern initcall_t __initcall6_start[];
-extern initcall_t __initcall7_start[];
-extern initcall_t __initcall_end[];
-
-static initcall_t *initcall_levels[] __initdata = {
+extern initcall_entry_t __initcall_start[];
+extern initcall_entry_t __initcall0_start[];
+extern initcall_entry_t __initcall1_start[];
+extern initcall_entry_t __initcall2_start[];
+extern initcall_entry_t __initcall3_start[];
+extern initcall_entry_t __initcall4_start[];
+extern initcall_entry_t __initcall5_start[];
+extern initcall_entry_t __initcall6_start[];
+extern initcall_entry_t __initcall7_start[];
+extern initcall_entry_t __initcall_end[];
+
+static initcall_entry_t *initcall_levels[] __initdata = {
__initcall0_start,
__initcall1_start,
__initcall2_start,
@@ -870,7 +870,7 @@ static char *initcall_level_names[] __initdata = {

static void __init do_initcall_level(int level)
{
- initcall_t *fn;
+ initcall_entry_t *fn;

strcpy(initcall_command_line, saved_command_line);
parse_args(initcall_level_names[level],
@@ -880,7 +880,7 @@ static void __init do_initcall_level(int level)
NULL, &repair_env_string);

for (fn = initcall_levels[level]; fn < initcall_levels[level+1]; fn++)
- do_one_initcall(*fn);
+ do_one_initcall(initcall_from_entry(fn));
}

static void __init do_initcalls(void)
@@ -911,10 +911,10 @@ static void __init do_basic_setup(void)

static void __init do_pre_smp_initcalls(void)
{
- initcall_t *fn;
+ initcall_entry_t *fn;

for (fn = __initcall_start; fn < __initcall0_start; fn++)
- do_one_initcall(*fn);
+ do_one_initcall(initcall_from_entry(fn));
}

/*
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index fc47863f629c..39d343c1c4b2 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2623,7 +2623,7 @@ EXPORT_SYMBOL(unregister_console);
*/
void __init console_init(void)
{
- initcall_t *call;
+ initcall_entry_t *call;

/* Setup the default TTY line discipline. */
n_tty_init();
@@ -2634,7 +2634,7 @@ void __init console_init(void)
*/
call = __con_initcall_start;
while (call < __con_initcall_end) {
- (*call)();
+ initcall_from_entry(call)();
call++;
}
}
diff --git a/security/security.c b/security/security.c
index 30132378d103..63b5f52bb098 100644
--- a/security/security.c
+++ b/security/security.c
@@ -44,10 +44,10 @@ static __initdata char chosen_lsm[SECURITY_NAME_MAX + 1] =

static void __init do_security_initcalls(void)
{
- initcall_t *call;
+ initcall_entry_t *call;
call = __security_initcall_start;
while (call < __security_initcall_end) {
- (*call) ();
+ initcall_from_entry(call)();
call++;
}
}
--
2.11.0
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