[PATCH 7/8] perf tools: regs_query_register_offset() infrastructure

[Arnaldo Carvalho de Melo]

From: Wang Nan <wangnan0@xxxxxxxxxx>

regs_query_register_offset() is a helper function which converts
register name like "%rax" to offset of a register in 'struct pt_regs',
which is required by BPF prologue generator.

PERF_HAVE_ARCH_REGS_QUERY_REGISTER_OFFSET indicates an architecture
supports converting name of a register to its offset in 'struct
pt_regs'.

HAVE_ARCH_REGS_QUERY_REGISTER_OFFSET is introduced as the corresponding
CFLAGS of PERF_HAVE_ARCH_REGS_QUERY_REGISTER_OFFSET.

Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxxxx>
Cc: Brendan Gregg <brendan.d.gregg@xxxxxxxxx>
Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Kaixu Xia <xiakaixu@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Zefan Li <lizefan@xxxxxxxxxx>
Cc: pi3orama@xxxxxxx
Link: http://lkml.kernel.org/r/1441523623-152703-19-git-send-email-wangnan0@xxxxxxxxxx
Signed-off-by: He Kuang <hekuang@xxxxxxxxxx>
[ Extracted from eBPF patches ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/config/Makefile           | 4 ++++
 tools/perf/util/include/dwarf-regs.h | 8 ++++++++
 2 files changed, 12 insertions(+)

diff --git a/tools/perf/config/Makefile b/tools/perf/config/Makefile
index 827557fc7511..0435ac41cea9 100644
--- a/tools/perf/config/Makefile
+++ b/tools/perf/config/Makefile
@@ -109,6 +109,10 @@ endif
 # include ARCH specific config
 -include $(src-perf)/arch/$(ARCH)/Makefile
 
+ifdef PERF_HAVE_ARCH_REGS_QUERY_REGISTER_OFFSET
+  CFLAGS += -DHAVE_ARCH_REGS_QUERY_REGISTER_OFFSET
+endif
+
 include $(src-perf)/config/utilities.mak
 
 ifeq ($(call get-executable,$(FLEX)),)
diff --git a/tools/perf/util/include/dwarf-regs.h b/tools/perf/util/include/dwarf-regs.h
index 8f149655f497..07c644ed64c4 100644
--- a/tools/perf/util/include/dwarf-regs.h
+++ b/tools/perf/util/include/dwarf-regs.h
@@ -5,4 +5,12 @@
 const char *get_arch_regstr(unsigned int n);
 #endif
 
+#ifdef HAVE_ARCH_REGS_QUERY_REGISTER_OFFSET
+/*
+ * Arch should support fetching the offset of a register in pt_regs
+ * by its name. See kernel's regs_query_register_offset in
+ * arch/xxx/kernel/ptrace.c.
+ */
+int regs_query_register_offset(const char *name);
+#endif
 #endif
-- 
2.1.0

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