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Subject[PATCH v2 2/2] kbuild: fix asm-offset generation to work with clang
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From: Jeroen Hofstee <jeroen@myspectrum.nl>

KBuild abuses the asm statement to write to a file and
clang chokes about these invalid asm statements. Hack it
even more by fooling this is actual valid asm code.

[masahiro:
Import Jeroen's work for U-Boot:
http://patchwork.ozlabs.org/patch/375026/
Tweak sed script a little to avoid garbage '#' for GCC case, like
#define NR_PAGEFLAGS 23 /* __NR_PAGEFLAGS # */ ]

Signed-off-by: Jeroen Hofstee <jeroen@myspectrum.nl>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Tested-by: Matthias Kaehlcke <mka@chromium.org>
---

Changes in v2:
- V1 did not work with LLVM's integrated assembler because
it uses <tab> instead of <space> around the .ascii string.
Restore [:space:].

include/linux/kbuild.h | 6 +++---
scripts/Makefile.lib | 8 ++++++--
2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/include/linux/kbuild.h b/include/linux/kbuild.h
index 22a7219..4e80f3a 100644
--- a/include/linux/kbuild.h
+++ b/include/linux/kbuild.h
@@ -2,14 +2,14 @@
#define __LINUX_KBUILD_H

#define DEFINE(sym, val) \
- asm volatile("\n->" #sym " %0 " #val : : "i" (val))
+ asm volatile("\n.ascii \"->" #sym " %0 " #val "\"" : : "i" (val))

-#define BLANK() asm volatile("\n->" : : )
+#define BLANK() asm volatile("\n.ascii \"->\"" : : )

#define OFFSET(sym, str, mem) \
DEFINE(sym, offsetof(struct str, mem))

#define COMMENT(x) \
- asm volatile("\n->#" x)
+ asm volatile("\n.ascii \"->#" x "\"")

#endif
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 9c20690..9e70196 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -413,10 +413,14 @@ cmd_xzmisc = (cat $(filter-out FORCE,$^) | \
# ---------------------------------------------------------------------------

# Default sed regexp - multiline due to syntax constraints
+#
+# Use [:space:] because LLVM's integrated assembler inserts <tab> around
+# the .ascii directive whereas GCC keeps the <space> as-is.
define sed-offsets
- "/^->/{s:->#\(.*\):/* \1 */:; \
+ 's:^[[:space:]]*\.ascii[[:space:]]*"\(.*\)".*:\1:; \
+ /^->/{s:->#\(.*\):/* \1 */:; \
s:^->\([^ ]*\) [\$$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; \
- s:->::; p;}"
+ s:->::; p;}'
endef

# Use filechk to avoid rebuilds when a header changes, but the resulting file
--
2.7.4
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