Fix kselftest builds when specifying an output dir

From: "Tyler Hicks" <[email protected]>

When attempting to build kselftests with a separate output directory, a number of the tests fail to build.

For example,

 $ rm -rf build && \
   make INSTALL_HDR_PATH=build/usr headers_install > /dev/null && \
   make O=build FORCE_TARGETS=1 TARGETS=breakpoints -C tools/testing/selftests > /dev/null
 /usr/bin/ld: cannot open output file
 build/kselftest/breakpoints/step_after_suspend_test: No such file or directory
 collect2: error: ld returned 1 exit status
 make[1]: *** [../lib.mk:146: build/kselftest/breakpoints/step_after_suspend_test] Error 1
 make: *** [Makefile:163: all] Error 2

This has already been addressed upstream with v5.18 commit 5ad51ab618de ("selftests: set the BUILD variable to absolute path"). It does not cleanly cherry pick to the linux-5.4.y branch without v5.7 commit 29e911ef7b70 ("selftests: Fix kselftest O=objdir build from cluttering top level objdir"). Commit 5ad51ab618de was written in a way that assumes that the kselftests aren't build in the top level objdir so it makes sense to bring the pre-req commit back but it does represent a slight change in behavior since the kselftests will now be built in a subdir of the specified objdir (O=).

Tyler

Muhammad Usama Anjum (1):
selftests: set the BUILD variable to absolute path

Shuah Khan (1):
selftests: Fix kselftest O=objdir build from cluttering top level
objdir

 tools/testing/selftests/Makefile | 28 ++++++++++++++++++----------
 1 file changed, 18 insertions(+), 10 deletions(-)

2.34.1

From: Shuah Khan <[email protected]>

commit 29e911ef7b706215caf02a82b0d3076611d6abe8 upstream.

make kselftest-all O=objdir builds create generated objects in objdir. This clutters the top level directory with kselftest objects. Fix it to create sub-directory under objdir for kselftest objects.

---
 tools/testing/selftests/Makefile | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

index 612f6757015d..0eb5567bb94a 100644
@@ -78,7 +78,7 @@ override LDFLAGS =
 override MAKEFLAGS =
 endif
 
-# Append kselftest to KBUILD_OUTPUT to avoid cluttering
+# Append kselftest to KBUILD_OUTPUT and O to avoid cluttering
 # KBUILD_OUTPUT with selftest objects and headers installed
 # by selftests Makefile or lib.mk.
 ifdef building_out_of_srctree

@@ -86,7 +86,7 @@ override LDFLAGS =
 endif
 
 ifneq ($(O),)
-	BUILD := $(O)
+	BUILD := $(O)/kselftest
 else
 	ifneq ($(KBUILD_OUTPUT),)
 		BUILD := $(KBUILD_OUTPUT)/kselftest

2.34.1

From: Muhammad Usama Anjum <[email protected]>

commit 5ad51ab618de5d05f4e692ebabeb6fe6289aaa57 upstream.

The build of kselftests fails if relative path is specified through KBUILD_OUTPUT or O=<path> method. BUILD variable is used to determine the path of the output objects. When make is run from other directories with relative paths, the exact path of the build objects is ambiguous and build fails.

make[1]: Entering directory '/home/usama/repos/kernel/linux_mainline2/tools/testing/selftests/alsa'
gcc mixer-test.c -L/usr/lib/x86_64-linux-gnu -lasound -o build/kselftest/alsa/mixer-test
/usr/bin/ld: cannot open output file build/kselftest/alsa/mixer-test

Set the BUILD variable to the absolute path of the output directory. Make the logic readable and easy to follow. Use spaces instead of tabs for indentation as if with tab indentation is considered recipe in make.

---
 tools/testing/selftests/Makefile | 26 +++++++++++++++++---------
 1 file changed, 17 insertions(+), 9 deletions(-)

index 0eb5567bb94a..40ee6f57af78 100644
@@ -85,19 +85,27 @@ ifdef building_out_of_srctree
 override LDFLAGS =
 endif
 
-ifneq ($(O),)
-	BUILD := $(O)/kselftest
+top_srcdir ?= ../../..
+
+ifeq ("$(origin O)", "command line")
+  KBUILD_OUTPUT := $(O)
+endif
+
+ifneq ($(KBUILD_OUTPUT),)
+  # Make's built-in functions such as $(abspath ...), $(realpath ...) cannot
+  # expand a shell special character '~'. We use a somewhat tedious way here.
+  abs_objtree := $(shell cd $(top_srcdir) && mkdir -p $(KBUILD_OUTPUT) && cd $(KBUILD_OUTPUT) && pwd)
+  $(if $(abs_objtree),, \
+    $(error failed to create output directory "$(KBUILD_OUTPUT)"))
+  # $(realpath ...) resolves symlinks
+  abs_objtree := $(realpath $(abs_objtree))
+  BUILD := $(abs_objtree)/kselftest
 else
-	ifneq ($(KBUILD_OUTPUT),)
-		BUILD := $(KBUILD_OUTPUT)/kselftest
-	else
-		BUILD := $(shell pwd)
-		DEFAULT_INSTALL_HDR_PATH := 1
-	endif
+  BUILD := $(CURDIR)
+  DEFAULT_INSTALL_HDR_PATH := 1
 endif
 
 # Prepare for headers install
-top_srcdir ?= ../../..
 include $(top_srcdir)/scripts/subarch.include
 ARCH           ?= $(SUBARCH)
 export KSFT_KHDR_INSTALL_DONE := 1

2.34.1

Now queued up, thanks.

greg k-h