linux-kernel - [PATCH v3] kbuild: simpler generation of assembly constants

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Date:	Wed, 13 Jul 2016 20:36:46 +0300
From:	Alexey Dobriyan <adobriyan@...il.com>
To:	akpm@...ux-foundation.org
Cc:	mmarek@...e.cz, tony.luck@...el.com, linux-kernel@...r.kernel.org
Subject: [PATCH v3] kbuild: simpler generation of assembly constants

gcc doesn't really look inside "asm" statements and more or less
directly emits it into assembly. So pretend "#define" is CPU
instruction.

C++ comment can't be used because sparc assembler doesn't understand it.

Signed-off-by: Alexey Dobriyan <adobriyan@...il.com>
---

	This one compiles on Sparc and UML.

 Kbuild                                     |   12 +-----------
 arch/ia64/kernel/Makefile                  |    8 +-------
 arch/um/Makefile                           |    2 +-
 arch/x86/um/shared/sysdep/kernel-offsets.h |    2 +-
 arch/x86/um/user-offsets.c                 |    4 ++--
 include/linux/kbuild.h                     |    2 +-
 scripts/mod/Makefile                       |   11 +----------
 7 files changed, 8 insertions(+), 33 deletions(-)

--- a/Kbuild
+++ b/Kbuild
@@ -7,14 +7,6 @@
 # 4) Check for missing system calls
 # 5) Generate constants.py (may need bounds.h)
 
-# Default sed regexp - multiline due to syntax constraints
-define sed-y
-	"/^->/{s:->#\(.*\):/* \1 */:; \
-	s:^->\([^ ]*\) [\$$#]*\([-0-9]*\) \(.*\):#define \1 \2 /* \3 */:; \
-	s:^->\([^ ]*\) [\$$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; \
-	s:->::; p;}"
-endef
-
 # Use filechk to avoid rebuilds when a header changes, but the resulting file
 # does not
 define filechk_offsets
@@ -26,9 +18,7 @@ define filechk_offsets
 	 echo " *"; \
 	 echo " * This file was generated by Kbuild"; \
 	 echo " */"; \
-	 echo ""; \
-	 sed -ne $(sed-y); \
-	 echo ""; \
+	 sed -ne '/#define/{s/\$$//;s/#//2;s/$$/*\//;p;}'; \
 	 echo "#endif" )
 endef
 
--- a/arch/ia64/kernel/Makefile
+++ b/arch/ia64/kernel/Makefile
@@ -50,10 +50,6 @@ CFLAGS_traps.o  += -mfixed-range=f2-f5,f16-f31
 # The gate DSO image is built using a special linker script.
 include $(src)/Makefile.gate
 
-# Calculate NR_IRQ = max(IA64_NATIVE_NR_IRQS, XEN_NR_IRQS, ...) based on config
-define sed-y
-	"/^->/{s:^->\([^ ]*\) [\$$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; s:->::; p;}"
-endef
 quiet_cmd_nr_irqs = GEN     $@
 define cmd_nr_irqs
 	(set -e; \
@@ -65,9 +61,7 @@ define cmd_nr_irqs
 	 echo " * This file was generated by Kbuild"; \
 	 echo " *"; \
 	 echo " */"; \
-	 echo ""; \
-	 sed -ne $(sed-y) $<; \
-	 echo ""; \
+	 sed -ne '/#define/{s/\$$//;s/#//2;s/$$/*\//p;}' $<; \
 	 echo "#endif" ) > $@
 endef
 
--- a/arch/um/Makefile
+++ b/arch/um/Makefile
@@ -158,7 +158,7 @@ define filechk_gen-asm-offsets
          echo " *"; \
          echo " */"; \
          echo ""; \
-         sed -ne "/^->/{s:^->\([^ ]*\) [\$$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; s:->::; p;}"; \
+         sed -ne '/#define/{s/\$$//;s/#//2;s/$$/*\//p;}'; \
          echo ""; )
 endef
 
--- a/arch/x86/um/shared/sysdep/kernel-offsets.h
+++ b/arch/x86/um/shared/sysdep/kernel-offsets.h
@@ -5,7 +5,7 @@
 #include <asm/mman.h>
 
 #define DEFINE(sym, val) \
-	asm volatile("\n->" #sym " %0 " #val : : "i" (val))
+	asm volatile ("#define " #sym " %0 /*" #val :: "i" (val))
 
 #define BLANK() asm volatile("\n->" : : )
 
--- a/arch/x86/um/user-offsets.c
+++ b/arch/x86/um/user-offsets.c
@@ -21,10 +21,10 @@ static char syscalls[] = {
 #endif
 
 #define DEFINE(sym, val) \
-	asm volatile("\n->" #sym " %0 " #val : : "i" (val))
+	asm volatile ("#define " #sym " %0 /*" #val :: "i" (val))
 
 #define DEFINE_LONGS(sym, val) \
-	asm volatile("\n->" #sym " %0 " #val : : "i" (val/sizeof(unsigned long)))
+	asm volatile ("#define " #sym " %0 /*" #val :: "i" (val / sizeof(unsigned long)))
 
 void foo(void)
 {
--- a/include/linux/kbuild.h
+++ b/include/linux/kbuild.h
@@ -2,7 +2,7 @@
 #define __LINUX_KBUILD_H
 
 #define DEFINE(sym, val) \
-        asm volatile("\n->" #sym " %0 " #val : : "i" (val))
+	asm volatile ("#define " #sym " %0 /*" #val :: "i" (val))
 
 #define BLANK() asm volatile("\n->" : : )
 
--- a/scripts/mod/Makefile
+++ b/scripts/mod/Makefile
@@ -7,13 +7,6 @@ modpost-objs	:= modpost.o file2alias.o sumversion.o
 
 devicetable-offsets-file := devicetable-offsets.h
 
-define sed-y
-	"/^->/{s:->#\(.*\):/* \1 */:; \
-	s:^->\([^ ]*\) [\$$#]*\([-0-9]*\) \(.*\):#define \1 \2 /* \3 */:; \
-	s:^->\([^ ]*\) [\$$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; \
-	s:->::; p;}"
-endef
-
 quiet_cmd_offsets = GEN     $@
 define cmd_offsets
 	(set -e; \
@@ -25,9 +18,7 @@ define cmd_offsets
 	 echo " * This file was generated by Kbuild"; \
 	 echo " *"; \
 	 echo " */"; \
-	 echo ""; \
-	 sed -ne $(sed-y) $<; \
-	 echo ""; \
+	 sed -ne '/#define/{s/\$$//;s/#//2;s/$$/*\//;p;}' $<; \
 	 echo "#endif" ) > $@
 endef