[PATCH V2 1/7] perf tools: Display build warning if x86 instruction decoder differs from kernel

[Adrian Hunter]

perf tools has a copy of the x86 instruction decoder used by the kernel.
The expectation is that the copy will be kept more-or-less in-synch
with the kernel version.  Consequently it is helpful to know if there are
differences.  This patch adds a check into the perf tools build so that
a diff is done on the sources, and a warning is printed if they are
different.  Note that the warning is not fatal and the build continues
as normal.

The check is done as part of building the instruction decoder, so, like a
compiler warning, it is not seen unless the instruction decoder has to be
re-compiled. e.g.

    $ make -C tools/perf >/dev/null
    $ echo "/* blah */" >> tools/perf/util/intel-pt-decoder/inat_types.h
    $ make -C tools/perf >/dev/null
    Warning: Intel PT: x86 instruction decoder differs from kernel
    $ make -C tools/perf >/dev/null
    $

Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
---
 tools/perf/util/intel-pt-decoder/Build | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/intel-pt-decoder/Build b/tools/perf/util/intel-pt-decoder/Build
index 2386322ece4f..0611d619a42e 100644
--- a/tools/perf/util/intel-pt-decoder/Build
+++ b/tools/perf/util/intel-pt-decoder/Build
@@ -7,6 +7,17 @@ $(OUTPUT)util/intel-pt-decoder/inat-tables.c: $(inat_tables_script) $(inat_table
 	$(call rule_mkdir)
 	@$(call echo-cmd,gen)$(AWK) -f $(inat_tables_script) $(inat_tables_maps) > $@ || rm -f $@
 
-$(OUTPUT)util/intel-pt-decoder/intel-pt-insn-decoder.o: util/intel-pt-decoder/inat.c $(OUTPUT)util/intel-pt-decoder/inat-tables.c
+$(OUTPUT)util/intel-pt-decoder/intel-pt-insn-decoder.o: util/intel-pt-decoder/intel-pt-insn-decoder.c util/intel-pt-decoder/inat.c $(OUTPUT)util/intel-pt-decoder/inat-tables.c
+	@(test -d ../../kernel -a -d ../../tools -a -d ../perf && (( \
+	diff -B -I'^#include' util/intel-pt-decoder/insn.c ../../arch/x86/lib/insn.c >/dev/null && \
+	diff -B -I'^#include' util/intel-pt-decoder/inat.c ../../arch/x86/lib/inat.c >/dev/null && \
+	diff -B util/intel-pt-decoder/x86-opcode-map.txt ../../arch/x86/lib/x86-opcode-map.txt >/dev/null && \
+	diff -B util/intel-pt-decoder/gen-insn-attr-x86.awk ../../arch/x86/tools/gen-insn-attr-x86.awk >/dev/null && \
+	diff -B -I'^#include' util/intel-pt-decoder/insn.h ../../arch/x86/include/asm/insn.h >/dev/null && \
+	diff -B -I'^#include' util/intel-pt-decoder/inat.h ../../arch/x86/include/asm/inat.h >/dev/null && \
+	diff -B -I'^#include' util/intel-pt-decoder/inat_types.h ../../arch/x86/include/asm/inat_types.h >/dev/null) \
+	|| echo "Warning: Intel PT: x86 instruction decoder differs from kernel" >&2 )) || true
+	$(call rule_mkdir)
+	$(call if_changed_dep,cc_o_c)
 
 CFLAGS_intel-pt-insn-decoder.o += -I$(OUTPUT)util/intel-pt-decoder -Wno-override-init
-- 
1.9.1

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