perf/urgent fixes

Hi Ingo,

Please consider pulling,

- Arnaldo

The following changes since commit 65ea03e31e5ab47f784b1a701419264af97d3205:

Merge tag 'perf-urgent-for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/urgent (2015-07-15 13:31:21 +0200)

are available in the git repository at:

git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git tags/perf-urgent-for-mingo

for you to fetch changes up to 3c71ba3f80bbd476bbfb2a008da9b676031cbd32:

perf tools: Really allow to specify custom CC, AR or LD (2015-07-15 11:57:28 -0300)

----------------------------------------------------------------
perf/urgent fixes:

User visible:

- Fix misplaced check for HAVE_SYNC_COMPARE_AND_SWAP_SUPPORT in the auxtrace code, which made 'perf record' fail straight away in some architectures, even when auxtrace wasn't involved. (Adrian Hunter)

Developer stuff:

- Really allow to specify custom CC, AR or LD (Alexey Brodkin)

----------------------------------------------------------------
Adrian Hunter (1):
perf auxtrace: Fix misplaced check for HAVE_SYNC_COMPARE_AND_SWAP_SUPPORT

Alexey Brodkin (1):
perf tools: Really allow to specify custom CC, AR or LD

 tools/perf/Makefile.perf   | 19 ++++++++++++++++---
 tools/perf/util/auxtrace.c | 10 +++++-----
 2 files changed, 21 insertions(+), 8 deletions(-)

From: Adrian Hunter <[email protected]>

Move the checking for HAVE_SYNC_COMPARE_AND_SWAP_SUPPORT for AUX area mmaps until after checking if such mmaps are used anyway.

---
 tools/perf/util/auxtrace.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

index 7e7405c9b936..83d9dd96fe08 100644
@@ -53,11 +53,6 @@ int auxtrace_mmap__mmap(struct auxtrace_mmap *mm,
 {
 	struct perf_event_mmap_page *pc = userpg;
 
-#if BITS_PER_LONG != 64 && !defined(HAVE_SYNC_COMPARE_AND_SWAP_SUPPORT)
-	pr_err("Cannot use AUX area tracing mmaps\n");
-	return -1;
-#endif
-
 	WARN_ONCE(mm->base, "Uninitialized auxtrace_mmap\n");
 
 	mm->userpg = userpg;

@@ -73,6 +68,11 @@ int auxtrace_mmap__mmap(struct auxtrace_mmap *mm,
 		return 0;
 	}
 
+#if BITS_PER_LONG != 64 && !defined(HAVE_SYNC_COMPARE_AND_SWAP_SUPPORT)
+	pr_err("Cannot use AUX area tracing mmaps\n");
+	return -1;
+#endif
+
 	pc->aux_offset = mp->offset;
 	pc->aux_size = mp->len;
 

2.1.0

From: Alexey Brodkin <[email protected]>

Commit 5ef7bbb09f7b ("perf tools: Allow to specify custom linker command") was meant to enable usage non $(CROSS_COMPILE)ld linker during perf building.

But implementation didn't take into account the fact that LD is a pre-defined variable in GNU Make. I.e. it is always defined.

Which means there's no point to check "LD ?= ..." because it will never succeed.

And so LD will be either that explicitly passed to make like this:

------->8-------
make LD=path_to_my_ld ...
------->8-------
or default value, which is host's "ld".

Latter leads to failure of cross-linkage because instead of cross linker "$(CROSS_COMPILE)ld" host's "ld" is used.

Fortunately there's a way to do correct substitution of $(CROSS_COMPILE)ld with user defined LD on command-line.

As a reference was used implementation in "tools/lib/traceevent/Makefile".

Build tested for x86_64 and ARC.

Thanks Jiri for this hint.

---
 tools/perf/Makefile.perf | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

index 7a4b549214e3..bba34636b733 100644
@@ -109,9 +109,22 @@ $(OUTPUT)PERF-VERSION-FILE: ../../.git/HEAD
 	$(Q)$(SHELL_PATH) util/PERF-VERSION-GEN $(OUTPUT)
 	$(Q)touch $(OUTPUT)PERF-VERSION-FILE
 
-CC = $(CROSS_COMPILE)gcc
-LD ?= $(CROSS_COMPILE)ld
-AR = $(CROSS_COMPILE)ar
+# Makefiles suck: This macro sets a default value of $(2) for the
+# variable named by $(1), unless the variable has been set by
+# environment or command line. This is necessary for CC and AR
+# because make sets default values, so the simpler ?= approach
+# won't work as expected.
+define allow-override
+  $(if $(or $(findstring environment,$(origin $(1))),\
+            $(findstring command line,$(origin $(1)))),,\
+    $(eval $(1) = $(2)))
+endef
+
+# Allow setting CC and AR and LD, or setting CROSS_COMPILE as a prefix.
+$(call allow-override,CC,$(CROSS_COMPILE)gcc)
+$(call allow-override,AR,$(CROSS_COMPILE)ar)
+$(call allow-override,LD,$(CROSS_COMPILE)ld)
+
 PKG_CONFIG = $(CROSS_COMPILE)pkg-config
 
 RM      = rm -f

2.1.0

Pulled, thanks Arnaldo!

Ingo