gcov: compile specific gcov implementation based on gcc version

Compile the correct gcov implementation file for the specific gcc version.

Signed-off-by: Frantisek Hrbata <fhrbata@redhat.com>
Cc: Jan Stancek <jstancek@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Acked-by: Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Andy Gospodarek <agospoda@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/Documentation/gcov.txt b/Documentation/gcov.txt
index e7ca647..7b72778 100644 (file)
--- a/Documentation/gcov.txt
+++ b/Documentation/gcov.txt
@@ -50,6 +50,10 @@ Configure the kernel with:
         CONFIG_DEBUG_FS=y
         CONFIG_GCOV_KERNEL=y
 
+select the gcc's gcov format, default is autodetect based on gcc version:
+
+        CONFIG_GCOV_FORMAT_AUTODETECT=y
+
 and to get coverage data for the entire kernel:
 
         CONFIG_GCOV_PROFILE_ALL=y

diff --git a/kernel/gcov/Kconfig b/kernel/gcov/Kconfig
index d4da55d..d04ce8a 100644 (file)
--- a/kernel/gcov/Kconfig
+++ b/kernel/gcov/Kconfig
@@ -46,4 +46,34 @@ config GCOV_PROFILE_ALL
        larger and run slower. Also be sure to exclude files from profiling
        which are not linked to the kernel image to prevent linker errors.
 
+choice
+       prompt "Specify GCOV format"
+       depends on GCOV_KERNEL
+       default GCOV_FORMAT_AUTODETECT
+       ---help---
+       The gcov format is usually determined by the GCC version, but there are
+       exceptions where format changes are integrated in lower-version GCCs.
+       In such a case use this option to adjust the format used in the kernel
+       accordingly.
+
+       If unsure, choose "Autodetect".
+
+config GCOV_FORMAT_AUTODETECT
+       bool "Autodetect"
+       ---help---
+       Select this option to use the format that corresponds to your GCC
+       version.
+
+config GCOV_FORMAT_3_4
+       bool "GCC 3.4 format"
+       ---help---
+       Select this option to use the format defined by GCC 3.4.
+
+config GCOV_FORMAT_4_7
+       bool "GCC 4.7 format"
+       ---help---
+       Select this option to use the format defined by GCC 4.7.
+
+endchoice
+
 endmenu

diff --git a/kernel/gcov/Makefile b/kernel/gcov/Makefile
index e97ca59..52aa7e8 100644 (file)
--- a/kernel/gcov/Makefile
+++ b/kernel/gcov/Makefile
@@ -1,3 +1,33 @@
 ccflags-y := -DSRCTREE='"$(srctree)"' -DOBJTREE='"$(objtree)"'
 
-obj-$(CONFIG_GCOV_KERNEL) := base.o fs.o gcc_3_4.o
+# if-lt
+# Usage VAR := $(call if-lt, $(a), $(b))
+# Returns 1 if (a < b)
+if-lt = $(shell [ $(1) -lt $(2) ] && echo 1)
+
+ifeq ($(CONFIG_GCOV_FORMAT_3_4),y)
+  cc-ver := 0304
+else ifeq ($(CONFIG_GCOV_FORMAT_4_7),y)
+  cc-ver := 0407
+else
+# Use cc-version if available, otherwise set 0
+#
+# scripts/Kbuild.include, which contains cc-version function, is not included
+# during make clean "make -f scripts/Makefile.clean obj=kernel/gcov"
+# Meaning cc-ver is empty causing if-lt test to fail with
+# "/bin/sh: line 0: [: -lt: unary operator expected" error mesage.
+# This has no affect on the clean phase, but the error message could be
+# confusing/annoying. So this dummy workaround sets cc-ver to zero if cc-version
+# is not available. We can probably move if-lt to Kbuild.include, so it's also
+# not defined during clean or to include Kbuild.include in
+# scripts/Makefile.clean. But the following workaround seems least invasive.
+  cc-ver := $(if $(call cc-version),$(call cc-version),0)
+endif
+
+obj-$(CONFIG_GCOV_KERNEL) := base.o fs.o
+
+ifeq ($(call if-lt, $(cc-ver), 0407),1)
+  obj-$(CONFIG_GCOV_KERNEL) += gcc_3_4.o
+else
+  obj-$(CONFIG_GCOV_KERNEL) += gcc_4_7.o
+endif