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Message-ID: <874ngiwije.fsf@rustcorp.com.au>
Date: Mon, 11 Mar 2013 17:05:17 +1030
From: Rusty Russell <rusty@...tcorp.com.au>
To: James Hogan <james.hogan@...tec.com>
Cc: Al Viro <viro@...iv.linux.org.uk>, Michal Marek <mmarek@...e.cz>,
Andrew Morton <akpm@...ux-foundation.org>,
Guenter Roeck <linux@...ck-us.net>,
Jean Delvare <khali@...ux-fr.org>,
linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org,
Mike Frysinger <vapier@...too.org>,
uclinux-dist-devel@...ckfin.uclinux.org, linux-next@...r.kernel.org
Subject: Re: [RFC -next] linux/linkage.h: fix symbol prefix handling
James Hogan <james.hogan@...tec.com> writes:
> Hi Rusty,
>
> On 08/03/13 00:03, Rusty Russell wrote:
>> James Hogan <james.hogan@...tec.com> writes:
>>> Also the definition of SYMBOL_PREFIX in <linux/kernel.h> is removed as
>>> it conflicts, isn't used anywhere, and is defined as a string so differs
>>> from the assembly definition.
>>
>> So now, if CONFIG_SYMBOL_PREFIX, SYMBOL_PREFIX is defined on the cmdline
>> as a string. Otherwise it's empty (not the empty string?):
>
> No, SYMBOL_PREFIX is now defined as a non-string, same as asm files
Ah, I misread this. It's stripping the quotes, not adding them:
_sym_flags = -DSYMBOL_PREFIX=$(patsubst "%",%,$(CONFIG_SYMBOL_PREFIX))
> Does that make sense? It's all a bit messy unfortunately (hence RFC).
Yes, let's clear it up once and for all. Does this work?
CONFIG_SYMBOL_PREFIX: cleanup.
We have CONFIG_SYMBOL_PREFIX, which three archs define to the string
"_". But Al Viro broke this in "consolidate cond_syscall and
SYSCALL_ALIAS declarations", and he's not the first to do so.
Using CONFIG_SYMBOL_PREFIX is awkward, since we usually just want to
prefix it so something. So various places define helpers which are
defined to nothing if CONFIG_SYMBOL_PREFIX isn't set:
1) include/asm-generic/unistd.h defines __SYMBOL_PREFIX.
2) include/asm-generic/vmlinux.lds.h defines VMLINUX_SYMBOL(sym)
3) include/linux/export.h defines MODULE_SYMBOL_PREFIX.
4) include/linux/kernel.h defines SYMBOL_PREFIX (which differs from #7)
5) kernel/modsign_certificate.S defines ASM_SYMBOL(sym)
6) scripts/modpost.c defines MODULE_SYMBOL_PREFIX
7) scripts/Makefile.lib defines SYMBOL_PREFIX on the commandline if
CONFIG_SYMBOL_PREFIX is set, so that we have a non-string version
for pasting.
(arch/h8300/include/asm/linkage.h defines SYMBOL_NAME(), too).
Let's solve this properly:
1) No more generic prefix, just CONFIG_SYMBOL_PREFIX_UNDERSCORE.
2) Make linux/export.h usable from asm.
3) Define VMLINUX_SYMBOL, VMLINUX_SYMBOL_NAME and VMLINUX_SYMBOL_PREFIX_STR.
4) Make everyone use them.
Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
diff --git a/Makefile b/Makefile
index 5bd9f77..b2e3e1b 100644
--- a/Makefile
+++ b/Makefile
@@ -1398,7 +1398,7 @@ quiet_cmd_rmfiles = $(if $(wildcard $(rm-files)),CLEAN $(wildcard $(rm-files))
# Run depmod only if we have System.map and depmod is executable
quiet_cmd_depmod = DEPMOD $(KERNELRELEASE)
cmd_depmod = $(CONFIG_SHELL) $(srctree)/scripts/depmod.sh $(DEPMOD) \
- $(KERNELRELEASE) "$(patsubst "%",%,$(CONFIG_SYMBOL_PREFIX))"
+ $(KERNELRELEASE) "$(patsubst y,_,$(CONFIG_SYMBOL_PREFIX_UNDERSCORE))"
# Create temporary dir for module support files
# clean it up only when building all modules
diff --git a/arch/blackfin/Kconfig b/arch/blackfin/Kconfig
index 600494c..cd0f7c7 100644
--- a/arch/blackfin/Kconfig
+++ b/arch/blackfin/Kconfig
@@ -1,6 +1,5 @@
-config SYMBOL_PREFIX
- string
- default "_"
+config SYMBOL_PREFIX_UNDERSCORE
+ def_bool y
config MMU
def_bool n
diff --git a/arch/h8300/Kconfig b/arch/h8300/Kconfig
index ae8551e..ec9924d 100644
--- a/arch/h8300/Kconfig
+++ b/arch/h8300/Kconfig
@@ -13,9 +13,8 @@ config H8300
select OLD_SIGSUSPEND3
select OLD_SIGACTION
-config SYMBOL_PREFIX
- string
- default "_"
+config SYMBOL_PREFIX_UNDERSCORE
+ def_bool y
config MMU
bool
diff --git a/arch/metag/Kconfig b/arch/metag/Kconfig
index afc8973..e8719b4 100644
--- a/arch/metag/Kconfig
+++ b/arch/metag/Kconfig
@@ -1,6 +1,5 @@
-config SYMBOL_PREFIX
- string
- default "_"
+config SYMBOL_PREFIX_UNDERSCORE
+ def_bool y
config METAG
def_bool y
diff --git a/drivers/mtd/chips/gen_probe.c b/drivers/mtd/chips/gen_probe.c
index 3b9a284..00d20ad 100644
--- a/drivers/mtd/chips/gen_probe.c
+++ b/drivers/mtd/chips/gen_probe.c
@@ -204,14 +204,14 @@ static inline struct mtd_info *cfi_cmdset_unknown(struct map_info *map,
struct cfi_private *cfi = map->fldrv_priv;
__u16 type = primary?cfi->cfiq->P_ID:cfi->cfiq->A_ID;
#ifdef CONFIG_MODULES
- char probename[16+sizeof(MODULE_SYMBOL_PREFIX)];
+ char probename[16+sizeof(VMLINUX_SYMBOL_PREFIX_STR)];
cfi_cmdset_fn_t *probe_function;
- sprintf(probename, MODULE_SYMBOL_PREFIX "cfi_cmdset_%4.4X", type);
+ sprintf(probename, VMLINUX_SYMBOL_PREFIX_STR "cfi_cmdset_%4.4X", type);
probe_function = __symbol_get(probename);
if (!probe_function) {
- request_module(probename + sizeof(MODULE_SYMBOL_PREFIX) - 1);
+ request_module(probename + sizeof(VMLINUX_SYMBOL_PREFIX_STR)-1);
probe_function = __symbol_get(probename);
}
diff --git a/include/asm-generic/unistd.h b/include/asm-generic/unistd.h
index 4077b5d..80122d4 100644
--- a/include/asm-generic/unistd.h
+++ b/include/asm-generic/unistd.h
@@ -1,4 +1,5 @@
#include <uapi/asm-generic/unistd.h>
+#include <linux/export.h>
/*
* These are required system calls, we should
@@ -17,12 +18,7 @@
* but it doesn't work on all toolchains, so we just do it by hand
*/
#ifndef cond_syscall
-#ifdef CONFIG_SYMBOL_PREFIX
-#define __SYMBOL_PREFIX CONFIG_SYMBOL_PREFIX
-#else
-#define __SYMBOL_PREFIX
-#endif
-#define cond_syscall(x) asm(".weak\t" __SYMBOL_PREFIX #x "\n\t" \
- ".set\t" __SYMBOL_PREFIX #x "," \
- __SYMBOL_PREFIX "sys_ni_syscall")
+#define cond_syscall(x) asm(".weak\t" SYMBOL_NAME_STR(x) "\n\t" \
+ ".set\t" SYMBOL_NAME_STR(x) "," \
+ SYMBOL_NAME_STR(sys_ni_syscall))
#endif
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index afa12c7..eb58d2d 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -52,13 +52,7 @@
#define LOAD_OFFSET 0
#endif
-#ifndef SYMBOL_PREFIX
-#define VMLINUX_SYMBOL(sym) sym
-#else
-#define PASTE2(x,y) x##y
-#define PASTE(x,y) PASTE2(x,y)
-#define VMLINUX_SYMBOL(sym) PASTE(SYMBOL_PREFIX, sym)
-#endif
+#include <linux/export.h>
/* Align . to a 8 byte boundary equals to maximum function alignment. */
#define ALIGN_FUNCTION() . = ALIGN(8)
diff --git a/include/linux/export.h b/include/linux/export.h
index 696c0f4..c3c1cfc 100644
--- a/include/linux/export.h
+++ b/include/linux/export.h
@@ -7,15 +7,27 @@
*
* If you feel the need to add #include <linux/foo.h> to this file
* then you are doing something wrong and should go away silently.
+ *
+ * If you think the above arrogance just encourages more people to add
+ * random crap to this file, you're not alone.
*/
/* Some toolchains use a `_' prefix for all user symbols. */
-#ifdef CONFIG_SYMBOL_PREFIX
-#define MODULE_SYMBOL_PREFIX CONFIG_SYMBOL_PREFIX
+#ifdef CONFIG_SYMBOL_PREFIX_UNDERSCORE
+#define __VMLINUX_SYMBOL(x) _##x
+#define __VMLINUX_SYMBOL_STR(x) "_" #x
+#define VMLINUX_SYMBOL_PREFIX_STR "_"
#else
-#define MODULE_SYMBOL_PREFIX ""
+#define __VMLINUX_SYMBOL(x) x
+#define __VMLINUX_SYMBOL_STR(x) #x
+#define VMLINUX_SYMBOL_PREFIX_STR ""
#endif
+/* Indirect, so macros are expanded before pasting. */
+#define VMLINUX_SYMBOL(x) __VMLINUX_SYMBOL(x)
+#define VMLINUX_SYMBOL_STR(x) __VMLINUX_SYMBOL_STR(x)
+
+#ifndef __ASSEMBLY__
struct kernel_symbol
{
unsigned long value;
@@ -51,7 +63,7 @@ extern struct module __this_module;
__CRC_SYMBOL(sym, sec) \
static const char __kstrtab_##sym[] \
__attribute__((section("__ksymtab_strings"), aligned(1))) \
- = MODULE_SYMBOL_PREFIX #sym; \
+ = VMLINUX_SYMBOL_STR(sym); \
static const struct kernel_symbol __ksymtab_##sym \
__used \
__attribute__((section("___ksymtab" sec "+" #sym), unused)) \
@@ -85,5 +97,6 @@ extern struct module __this_module;
#define EXPORT_UNUSED_SYMBOL_GPL(sym)
#endif /* CONFIG_MODULES */
+#endif /* !__ASSEMBLY__ */
#endif /* _LINUX_EXPORT_H */
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 80d3687..e13e992 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -723,13 +723,6 @@ static inline void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) { }
/* Trap pasters of __FUNCTION__ at compile-time */
#define __FUNCTION__ (__func__)
-/* This helps us to avoid #ifdef CONFIG_SYMBOL_PREFIX */
-#ifdef CONFIG_SYMBOL_PREFIX
-#define SYMBOL_PREFIX CONFIG_SYMBOL_PREFIX
-#else
-#define SYMBOL_PREFIX ""
-#endif
-
/* Rebuild everything on CONFIG_FTRACE_MCOUNT_RECORD */
#ifdef CONFIG_FTRACE_MCOUNT_RECORD
# define REBUILD_DUE_TO_FTRACE_MCOUNT_RECORD
diff --git a/include/linux/module.h b/include/linux/module.h
index ead1b57..46f1ea0 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -190,7 +190,7 @@ extern int modules_disabled; /* for sysctl */
/* Get/put a kernel symbol (calls must be symmetric) */
void *__symbol_get(const char *symbol);
void *__symbol_get_gpl(const char *symbol);
-#define symbol_get(x) ((typeof(&x))(__symbol_get(MODULE_SYMBOL_PREFIX #x)))
+#define symbol_get(x) ((typeof(&x))(__symbol_get(VMLINUX_SYMBOL_STR(x))))
/* modules using other modules: kdb wants to see this. */
struct module_use {
@@ -453,7 +453,7 @@ extern void __module_put_and_exit(struct module *mod, long code)
#ifdef CONFIG_MODULE_UNLOAD
unsigned long module_refcount(struct module *mod);
void __symbol_put(const char *symbol);
-#define symbol_put(x) __symbol_put(MODULE_SYMBOL_PREFIX #x)
+#define symbol_put(x) __symbol_put(VMLINUX_SYMBOL_STR(x))
void symbol_put_addr(void *addr);
/* Sometimes we know we already have a refcount, and it's easier not
diff --git a/kernel/modsign_certificate.S b/kernel/modsign_certificate.S
index 246b4c6..4a9a86d 100644
--- a/kernel/modsign_certificate.S
+++ b/kernel/modsign_certificate.S
@@ -1,15 +1,8 @@
-/* SYMBOL_PREFIX defined on commandline from CONFIG_SYMBOL_PREFIX */
-#ifndef SYMBOL_PREFIX
-#define ASM_SYMBOL(sym) sym
-#else
-#define PASTE2(x,y) x##y
-#define PASTE(x,y) PASTE2(x,y)
-#define ASM_SYMBOL(sym) PASTE(SYMBOL_PREFIX, sym)
-#endif
+#include <linux/export.h>
#define GLOBAL(name) \
- .globl ASM_SYMBOL(name); \
- ASM_SYMBOL(name):
+ .globl VMLINUX_SYMBOL(name); \
+ VMLINUX_SYMBOL(name):
.section ".init.data","aw"
diff --git a/kernel/module.c b/kernel/module.c
index 0925c9a..cfd4a3f 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1209,7 +1209,7 @@ static inline int check_modstruct_version(Elf_Shdr *sechdrs,
/* Since this should be found in kernel (which can't be removed),
* no locking is necessary. */
- if (!find_symbol(MODULE_SYMBOL_PREFIX "module_layout", NULL,
+ if (!find_symbol(VMLINUX_SYMBOL_STR(module_layout), NULL,
&crc, true, false))
BUG();
return check_version(sechdrs, versindex, "module_layout", mod, crc,
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 07125e6..a373a1f 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -119,13 +119,6 @@ _c_flags += $(if $(patsubst n%,, \
$(CFLAGS_GCOV))
endif
-ifdef CONFIG_SYMBOL_PREFIX
-_sym_flags = -DSYMBOL_PREFIX=$(patsubst "%",%,$(CONFIG_SYMBOL_PREFIX))
-_cpp_flags += $(_sym_flags)
-_a_flags += $(_sym_flags)
-endif
-
-
# If building the kernel in a separate objtree expand all occurrences
# of -Idir to -I$(srctree)/dir except for absolute paths (starting with '/').
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index 3d569d6..d767681 100644
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -74,9 +74,8 @@ kallsyms()
info KSYM ${2}
local kallsymopt;
- if [ -n "${CONFIG_SYMBOL_PREFIX}" ]; then
- kallsymopt="${kallsymopt} \
- --symbol-prefix=${CONFIG_SYMBOL_PREFIX}"
+ if [ -n "${CONFIG_SYMBOL_PREFIX_UNDERSCORE}" ]; then
+ kallsymopt="${kallsymopt} --symbol-prefix=_"
fi
if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 78b30c1..6985021 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -18,14 +18,7 @@
#include "modpost.h"
#include "../../include/generated/autoconf.h"
#include "../../include/linux/license.h"
-
-/* Some toolchains use a `_' prefix for all user symbols. */
-#ifdef CONFIG_SYMBOL_PREFIX
-#define MODULE_SYMBOL_PREFIX CONFIG_SYMBOL_PREFIX
-#else
-#define MODULE_SYMBOL_PREFIX ""
-#endif
-
+#include "../../include/linux/export.h"
/* Are we using CONFIG_MODVERSIONS? */
int modversions = 0;
@@ -562,7 +555,7 @@ static void parse_elf_finish(struct elf_info *info)
static int ignore_undef_symbol(struct elf_info *info, const char *symname)
{
/* ignore __this_module, it will be resolved shortly */
- if (strcmp(symname, MODULE_SYMBOL_PREFIX "__this_module") == 0)
+ if (strcmp(symname, VMLINUX_SYMBOL_STR(__this_module)) == 0)
return 1;
/* ignore global offset table */
if (strcmp(symname, "_GLOBAL_OFFSET_TABLE_") == 0)
@@ -583,8 +576,8 @@ static int ignore_undef_symbol(struct elf_info *info, const char *symname)
return 0;
}
-#define CRC_PFX MODULE_SYMBOL_PREFIX "__crc_"
-#define KSYMTAB_PFX MODULE_SYMBOL_PREFIX "__ksymtab_"
+#define CRC_PFX VMLINUX_SYMBOL_STR(__crc_)
+#define KSYMTAB_PFX VMLINUX_SYMBOL_STR(__ksymtab_)
static void handle_modversions(struct module *mod, struct elf_info *info,
Elf_Sym *sym, const char *symname)
@@ -637,11 +630,11 @@ static void handle_modversions(struct module *mod, struct elf_info *info,
}
#endif
- if (memcmp(symname, MODULE_SYMBOL_PREFIX,
- strlen(MODULE_SYMBOL_PREFIX)) == 0) {
+ if (memcmp(symname, VMLINUX_SYMBOL_PREFIX_STR,
+ strlen(VMLINUX_SYMBOL_PREFIX_STR)) == 0) {
mod->unres =
alloc_symbol(symname +
- strlen(MODULE_SYMBOL_PREFIX),
+ strlen(VMLINUX_SYMBOL_PREFIX_STR),
ELF_ST_BIND(sym->st_info) == STB_WEAK,
mod->unres);
}
@@ -652,9 +645,9 @@ static void handle_modversions(struct module *mod, struct elf_info *info,
sym_add_exported(symname + strlen(KSYMTAB_PFX), mod,
export);
}
- if (strcmp(symname, MODULE_SYMBOL_PREFIX "init_module") == 0)
+ if (strcmp(symname, VMLINUX_SYMBOL_STR(init_module)) == 0)
mod->has_init = 1;
- if (strcmp(symname, MODULE_SYMBOL_PREFIX "cleanup_module") == 0)
+ if (strcmp(symname, VMLINUX_SYMBOL_STR(cleanup_module)) == 0)
mod->has_cleanup = 1;
break;
}
--
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