The patch titled
kernel: constructor support
has been added to the -mm tree. Its filename is
kernel-constructor-support.patch
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out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: kernel: constructor support
From: Peter Oberparleiter <oberpar@xxxxxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxxxxx>
Acked-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Acked-by: WANG Cong <xiyou.wangcong@xxxxxxxxx>
Cc: Sam Ravnborg <sam@xxxxxxxxxxxx>
Cc: Jeff Dike <jdike@xxxxxxxxxxx>
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
Cc: Huang Ying <ying.huang@xxxxxxxxx>
Cc: Li Wei <W.Li@xxxxxxx>
Cc: Michael Ellerman <michaele@xxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Heiko Carstens <heicars2@xxxxxxxxxxxxxxxxxx>
Cc: Martin Schwidefsky <mschwid2@xxxxxxxxxxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/asm-generic/sections.h | 3 +++
include/asm-generic/vmlinux.lds.h | 9 +++++++++
include/linux/init.h | 3 +++
include/linux/module.h | 6 ++++++
init/Kconfig | 5 +++++
init/main.c | 12 ++++++++++++
kernel/module.c | 16 ++++++++++++++++
7 files changed, 54 insertions(+)
diff -puN include/asm-generic/sections.h~kernel-constructor-support include/asm-generic/sections.h
--- a/include/asm-generic/sections.h~kernel-constructor-support
+++ a/include/asm-generic/sections.h
@@ -14,6 +14,9 @@ extern char __kprobes_text_start[], __kp
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 -puN include/asm-generic/vmlinux.lds.h~kernel-constructor-support include/asm-generic/vmlinux.lds.h
--- a/include/asm-generic/vmlinux.lds.h~kernel-constructor-support
+++ a/include/asm-generic/vmlinux.lds.h
@@ -332,12 +332,21 @@
/* Section used for early init (in .S files) */
#define HEAD_TEXT *(HEAD_TEXT_SECTION)
+#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 -puN include/linux/init.h~kernel-constructor-support include/linux/init.h
--- a/include/linux/init.h~kernel-constructor-support
+++ a/include/linux/init.h
@@ -136,6 +136,9 @@ 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 -puN include/linux/module.h~kernel-constructor-support include/linux/module.h
--- a/include/linux/module.h~kernel-constructor-support
+++ a/include/linux/module.h
@@ -362,6 +362,12 @@ 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 -puN init/Kconfig~kernel-constructor-support init/Kconfig
--- a/init/Kconfig~kernel-constructor-support
+++ a/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 -puN init/main.c~kernel-constructor-support init/main.c
--- a/init/main.c~kernel-constructor-support
+++ a/init/main.c
@@ -701,6 +701,17 @@ 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);
@@ -782,6 +793,7 @@ static void __init do_basic_setup(void)
init_tmpfs();
driver_init();
init_irq_proc();
+ do_ctors();
do_initcalls();
}
diff -puN kernel/module.c~kernel-constructor-support kernel/module.c
--- a/kernel/module.c~kernel-constructor-support
+++ a/kernel/module.c
@@ -2216,6 +2216,10 @@ static noinline struct module *load_modu
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_modu
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
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);
_
Patches currently in -mm which might be from oberpar@xxxxxxxxxxxxxxxxxx are
kernel-constructor-support.patch
seq_file-add-function-to-write-binary-data.patch
gcov-add-gcov-profiling-infrastructure.patch
gcov-enable-gcov_profile_all-for-x86_64.patch
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