Re: [patch 10.2/12] Fix Immediate Values x86_64 support old gcc

Mathieu Desnoyers
2009-09-24T15:35:36Z

GCC < 4, on x86_64, does not accept symbol+offset operands for "i" constraints
asm statements. Fallback on a memory read in lieue of immediate value if this
compiler is detected.

Changelog :
- USE_IMMEDIATE must now be used in lieue of CONFIG_IMMEDIATE in Makefiles and
in C code.
- Every architecture implementing immediate values must declare USE_IMMEDIATE
in their Makefile.
- Tab -> spaces in Makefiles.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
CC: "H. Peter Anvin" <hpa@zytor.com>
CC: Jeremy Fitzhardinge <jeremy@goop.org>
CC: Ingo Molnar <mingo@elte.hu>
CC: David Miller <davem@davemloft.net>
CC: Paul Mackerras <paulus@samba.org>
---
Makefile | 5 +++++
arch/powerpc/Makefile | 2 ++
arch/x86/Makefile | 5 +++++
include/linux/immediate.h | 2 +-
include/linux/module.h | 2 +-
kernel/Makefile | 2 +-
kernel/module.c | 6 +++---
7 files changed, 18 insertions(+), 6 deletions(-)

Index: linux.trees.git/arch/x86/Makefile
===================================================================
--- linux.trees.git.orig/arch/x86/Makefile 2009-09-24 08:52:41.000000000 -0400
+++ linux.trees.git/arch/x86/Makefile 2009-09-24 10:53:59.000000000 -0400
@@ -41,6 +41,7 @@ ifeq ($(CONFIG_X86_32),y)

# temporary until string.h is fixed
KBUILD_CFLAGS += -ffreestanding
+ export USE_IMMEDIATE := $(CONFIG_IMMEDIATE)
else
BITS := 64
UTS_MACHINE := x86_64
@@ -70,6 +71,10 @@ else
# this works around some issues with generating unwind tables in older gccs
# newer gccs do it by default
KBUILD_CFLAGS += -maccumulate-outgoing-args
+
+ # x86_64 gcc 3.x has problems with passing symbol+offset in
+ # asm "i" constraint.
+ export USE_IMMEDIATE := $(call cc-ifversion, -ge, 0400, $(CONFIG_IMMEDIATE))
endif

ifdef CONFIG_CC_STACKPROTECTOR
Index: linux.trees.git/include/linux/immediate.h
===================================================================
--- linux.trees.git.orig/include/linux/immediate.h 2009-09-24 10:53:51.000000000 -0400
+++ linux.trees.git/include/linux/immediate.h 2009-09-24 10:53:59.000000000 -0400
@@ -10,7 +10,7 @@
* See the file COPYING for more details.
*/

-#ifdef CONFIG_IMMEDIATE
+#ifdef USE_IMMEDIATE

struct __imv {
unsigned long var; /* Pointer to the identifier variable of the
Index: linux.trees.git/kernel/Makefile
===================================================================
--- linux.trees.git.orig/kernel/Makefile 2009-09-24 09:20:19.000000000 -0400
+++ linux.trees.git/kernel/Makefile 2009-09-24 10:55:09.000000000 -0400
@@ -88,7 +88,7 @@ obj-$(CONFIG_SYSCTL) += utsname_sysctl.o
obj-$(CONFIG_TASK_DELAY_ACCT) += delayacct.o
obj-$(CONFIG_TASKSTATS) += taskstats.o tsacct.o
obj-$(CONFIG_TRACEPOINTS) += tracepoint.o
-obj-$(CONFIG_IMMEDIATE) += immediate.o
+obj-$(USE_IMMEDIATE) += immediate.o
obj-$(CONFIG_LATENCYTOP) += latencytop.o
obj-$(CONFIG_FUNCTION_TRACER) += trace/
obj-$(CONFIG_TRACING) += trace/
Index: linux.trees.git/arch/powerpc/Makefile
===================================================================
--- linux.trees.git.orig/arch/powerpc/Makefile 2009-09-24 08:52:40.000000000 -0400
+++ linux.trees.git/arch/powerpc/Makefile 2009-09-24 10:53:59.000000000 -0400
@@ -96,6 +96,8 @@ else
LDFLAGS_MODULE += arch/powerpc/lib/crtsavres.o
endif

+export USE_IMMEDIATE := $(CONFIG_IMMEDIATE)
+
ifeq ($(CONFIG_TUNE_CELL),y)
KBUILD_CFLAGS += $(call cc-option,-mtune=cell)
endif
Index: linux.trees.git/Makefile
===================================================================
--- linux.trees.git.orig/Makefile 2009-09-24 08:52:38.000000000 -0400
+++ linux.trees.git/Makefile 2009-09-24 10:53:59.000000000 -0400
@@ -550,6 +550,11 @@ ifdef CONFIG_FUNCTION_TRACER
KBUILD_CFLAGS += -pg
endif

+# arch Makefile detects if the compiler permits use of immediate values
+ifdef USE_IMMEDIATE
+KBUILD_CFLAGS += -DUSE_IMMEDIATE
+endif
+
# We trigger additional mismatches with less inlining
ifdef CONFIG_DEBUG_SECTION_MISMATCH
KBUILD_CFLAGS += $(call cc-option, -fno-inline-functions-called-once)
Index: linux.trees.git/kernel/module.c
===================================================================
--- linux.trees.git.orig/kernel/module.c 2009-09-24 09:20:37.000000000 -0400
+++ linux.trees.git/kernel/module.c 2009-09-24 10:53:59.000000000 -0400
@@ -2237,7 +2237,7 @@ static noinline struct module *load_modu
mod->ctors = section_objs(hdr, sechdrs, secstrings, ".ctors",
sizeof(*mod->ctors), &mod->num_ctors);
#endif
-#ifdef CONFIG_IMMEDIATE
+#ifdef USE_IMMEDIATE
mod->immediate = section_objs(hdr, sechdrs, secstrings, "__imv",
sizeof(*mod->immediate),
&mod->num_immediate);
@@ -2491,7 +2491,7 @@ SYSCALL_DEFINE3(init_module, void __user
mutex_lock(&module_mutex);
/* Drop initial reference. */
module_put(mod);
-#ifdef CONFIG_IMMEDIATE
+#ifdef USE_IMMEDIATE
imv_unref(mod->immediate, mod->immediate + mod->num_immediate,
mod->module_init, mod->init_size);
#endif
@@ -3011,7 +3011,7 @@ int module_get_iter_tracepoints(struct t
}
#endif

-#ifdef CONFIG_IMMEDIATE
+#ifdef USE_IMMEDIATE
/**
* _module_imv_update - update all immediate values in the kernel
*
Index: linux.trees.git/include/linux/module.h
===================================================================
--- linux.trees.git.orig/include/linux/module.h 2009-09-24 10:53:51.000000000 -0400
+++ linux.trees.git/include/linux/module.h 2009-09-24 10:53:59.000000000 -0400
@@ -660,7 +660,7 @@ static inline int module_get_iter_tracep

#endif /* CONFIG_MODULES */

-#if defined(CONFIG_MODULES) && defined(CONFIG_IMMEDIATE)
+#if defined(CONFIG_MODULES) && defined(USE_IMMEDIATE)
extern void _module_imv_update(void);
extern void module_imv_update(void);
#else