init: allow initcall tables to be emitted using relative references

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.

Link: http://lkml.kernel.org/r/20180704083651.24360-5-ard.biesheuvel@linaro.org
Acked-by: James Morris <james.morris@microsoft.com>
Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: Petr Mladek <pmladek@suse.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morris <jmorris@namei.org>
Cc: Jessica Yu <jeyu@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Nicolas Pitre <nico@linaro.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Garnier <thgarnie@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/init.h b/include/linux/init.h
index bc27cf0..2538d17 100644 (file)
--- a/include/linux/init.h
+++ b/include/linux/init.h
@@ -116,8 +116,24 @@
 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 int initcall_entry_t;
+
+static inline initcall_t initcall_from_entry(initcall_entry_t *entry)
+{
+       return offset_to_ptr(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);
@@ -167,9 +183,20 @@ 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      " #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.
@@ -208,13 +235,8 @@ 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 b729e1f..3a6ce89 100644 (file)
--- a/init/main.c
+++ b/init/main.c
@@ -902,18 +902,18 @@ 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,
@@ -939,7 +939,7 @@ 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],
@@ -950,7 +950,7 @@ static void __init do_initcall_level(int level)
 
        trace_initcall_level(initcall_level_names[level]);
        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)
@@ -981,11 +981,11 @@ static void __init do_basic_setup(void)
 
 static void __init do_pre_smp_initcalls(void)
 {
-       initcall_t *fn;
+       initcall_entry_t *fn;
 
        trace_initcall_level("early");
        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 90b6ab0..918f386 100644 (file)
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2788,7 +2788,8 @@ EXPORT_SYMBOL(unregister_console);
 void __init console_init(void)
 {
        int ret;
-       initcall_t *call;
+       initcall_t call;
+       initcall_entry_t *ce;
 
        /* Setup the default TTY line discipline. */
        n_tty_init();
@@ -2797,13 +2798,14 @@ void __init console_init(void)
         * set up the console device so that later boot sequences can
         * inform about problems etc..
         */
-       call = __con_initcall_start;
+       ce = __con_initcall_start;
        trace_initcall_level("console");
-       while (call < __con_initcall_end) {
-               trace_initcall_start((*call));
-               ret = (*call)();
-               trace_initcall_finish((*call), ret);
-               call++;
+       while (ce < __con_initcall_end) {
+               call = initcall_from_entry(ce);
+               trace_initcall_start(call);
+               ret = call();
+               trace_initcall_finish(call, ret);
+               ce++;
        }
 }
 

diff --git a/security/security.c b/security/security.c
index 47cfff0..736e78d 100644 (file)
--- a/security/security.c
+++ b/security/security.c
@@ -48,14 +48,17 @@ static __initdata char chosen_lsm[SECURITY_NAME_MAX + 1] =
 static void __init do_security_initcalls(void)
 {
        int ret;
-       initcall_t *call;
-       call = __security_initcall_start;
+       initcall_t call;
+       initcall_entry_t *ce;
+
+       ce = __security_initcall_start;
        trace_initcall_level("security");
-       while (call < __security_initcall_end) {
-               trace_initcall_start((*call));
-               ret = (*call) ();
-               trace_initcall_finish((*call), ret);
-               call++;
+       while (ce < __security_initcall_end) {
+               call = initcall_from_entry(ce);
+               trace_initcall_start(call);
+               ret = call();
+               trace_initcall_finish(call, ret);
+               ce++;
        }
 }