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authorPeter Oberparleiter <oberpar@linux.vnet.ibm.com>2009-06-17 16:28:03 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-06-18 13:03:57 -0700
commitb99b87f70c7785ab1e253c6220f4b0b57ce3a7f7 (patch)
treeec5688052334448ec8edd3a1a9cb95cd68501ac7
parente24aca672ff06aff0e6a1045efab86043ea5f735 (diff)
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kernel: constructor support
Call constructors (gcc-generated initcall-like functions) during kernel start and module load. Constructors are e.g. used for gcov data initialization. Disable constructor support for usermode Linux to prevent conflicts with host glibc. Signed-off-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com> Acked-by: Rusty Russell <rusty@rustcorp.com.au> Acked-by: WANG Cong <xiyou.wangcong@gmail.com> Cc: Sam Ravnborg <sam@ravnborg.org> Cc: Jeff Dike <jdike@addtoit.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Huang Ying <ying.huang@intel.com> Cc: Li Wei <W.Li@Sun.COM> Cc: Michael Ellerman <michaele@au1.ibm.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Heiko Carstens <heicars2@linux.vnet.ibm.com> Cc: Martin Schwidefsky <mschwid2@linux.vnet.ibm.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/asm-generic/sections.h3
-rw-r--r--include/asm-generic/vmlinux.lds.h9
-rw-r--r--include/linux/init.h3
-rw-r--r--include/linux/module.h6
-rw-r--r--init/Kconfig5
-rw-r--r--init/main.c12
-rw-r--r--kernel/module.c16
7 files changed, 54 insertions, 0 deletions
diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h
index 4ce48e87853..d083561337f 100644
--- a/include/asm-generic/sections.h
+++ b/include/asm-generic/sections.h
@@ -14,6 +14,9 @@ extern char __kprobes_text_start[], __kprobes_text_end[];
extern char __initdata_begin[], __initdata_end[];
extern char __start_rodata[], __end_rodata[];
+/* Start and end of .ctors section - used for constructor calls. */
+extern char __ctors_start[], __ctors_end[];
+
/* function descriptor handling (if any). Override
* in asm/sections.h */
#ifndef dereference_function_descriptor
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 6bdba10fef4..55413e568f0 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -440,12 +440,21 @@
INIT_TASK \
}
+#ifdef CONFIG_CONSTRUCTORS
+#define KERNEL_CTORS() VMLINUX_SYMBOL(__ctors_start) = .; \
+ *(.ctors) \
+ VMLINUX_SYMBOL(__ctors_end) = .;
+#else
+#define KERNEL_CTORS()
+#endif
+
/* init and exit section handling */
#define INIT_DATA \
*(.init.data) \
DEV_DISCARD(init.data) \
CPU_DISCARD(init.data) \
MEM_DISCARD(init.data) \
+ KERNEL_CTORS() \
*(.init.rodata) \
DEV_DISCARD(init.rodata) \
CPU_DISCARD(init.rodata) \
diff --git a/include/linux/init.h b/include/linux/init.h
index 8c2c9989626..13b633ed695 100644
--- a/include/linux/init.h
+++ b/include/linux/init.h
@@ -134,6 +134,9 @@ typedef void (*exitcall_t)(void);
extern initcall_t __con_initcall_start[], __con_initcall_end[];
extern initcall_t __security_initcall_start[], __security_initcall_end[];
+/* Used for contructor calls. */
+typedef void (*ctor_fn_t)(void);
+
/* Defined in init/main.c */
extern int do_one_initcall(initcall_t fn);
extern char __initdata boot_command_line[];
diff --git a/include/linux/module.h b/include/linux/module.h
index 505f20dcc1c..098bdb7bfac 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -363,6 +363,12 @@ struct module
local_t ref;
#endif
#endif
+
+#ifdef CONFIG_CONSTRUCTORS
+ /* Constructor functions. */
+ ctor_fn_t *ctors;
+ unsigned int num_ctors;
+#endif
};
#ifndef MODULE_ARCH_INIT
#define MODULE_ARCH_INIT {}
diff --git a/init/Kconfig b/init/Kconfig
index c4b3c6d51a7..1ce05a4cb5f 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -16,6 +16,11 @@ config DEFCONFIG_LIST
default "$ARCH_DEFCONFIG"
default "arch/$ARCH/defconfig"
+config CONSTRUCTORS
+ bool
+ depends on !UML
+ default y
+
menu "General setup"
config EXPERIMENTAL
diff --git a/init/main.c b/init/main.c
index 0e7aedeaa05..1a65fdd0631 100644
--- a/init/main.c
+++ b/init/main.c
@@ -720,6 +720,17 @@ asmlinkage void __init start_kernel(void)
rest_init();
}
+/* Call all constructor functions linked into the kernel. */
+static void __init do_ctors(void)
+{
+#ifdef CONFIG_CONSTRUCTORS
+ ctor_fn_t *call = (ctor_fn_t *) __ctors_start;
+
+ for (; call < (ctor_fn_t *) __ctors_end; call++)
+ (*call)();
+#endif
+}
+
int initcall_debug;
core_param(initcall_debug, initcall_debug, bool, 0644);
@@ -800,6 +811,7 @@ static void __init do_basic_setup(void)
usermodehelper_init();
driver_init();
init_irq_proc();
+ do_ctors();
do_initcalls();
}
diff --git a/kernel/module.c b/kernel/module.c
index 215aaab09e9..38928fcaff2 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2216,6 +2216,10 @@ static noinline struct module *load_module(void __user *umod,
mod->unused_gpl_crcs = section_addr(hdr, sechdrs, secstrings,
"__kcrctab_unused_gpl");
#endif
+#ifdef CONFIG_CONSTRUCTORS
+ mod->ctors = section_objs(hdr, sechdrs, secstrings, ".ctors",
+ sizeof(*mod->ctors), &mod->num_ctors);
+#endif
#ifdef CONFIG_MARKERS
mod->markers = section_objs(hdr, sechdrs, secstrings, "__markers",
@@ -2389,6 +2393,17 @@ static noinline struct module *load_module(void __user *umod,
goto free_hdr;
}
+/* Call module constructors. */
+static void do_mod_ctors(struct module *mod)
+{
+#ifdef CONFIG_CONSTRUCTORS
+ unsigned long i;
+
+ for (i = 0; i < mod->num_ctors; i++)
+ mod->ctors[i]();
+#endif
+}
+
/* This is where the real work happens */
SYSCALL_DEFINE3(init_module, void __user *, umod,
unsigned long, len, const char __user *, uargs)
@@ -2417,6 +2432,7 @@ SYSCALL_DEFINE3(init_module, void __user *, umod,
blocking_notifier_call_chain(&module_notify_list,
MODULE_STATE_COMING, mod);
+ do_mod_ctors(mod);
/* Start the module */
if (mod->init != NULL)
ret = do_one_initcall(mod->init);