[tip:perf/core] perf tools arm64: Add libdw DWARF post unwind support for ARM64

[tip-bot for Kim Phillips <tipbot@zytor.com>]

Commit-ID:  744e9a91cf898bf027dbe65cc61a5d7565335cba
Gitweb:     https://git.kernel.org/tip/744e9a91cf898bf027dbe65cc61a5d7565335cba
Author:     Kim Phillips <kim.phillips@arm.com>
AuthorDate: Thu, 8 Mar 2018 21:10:30 -0600
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Fri, 16 Mar 2018 13:53:46 -0300

perf tools arm64: Add libdw DWARF post unwind support for ARM64

Based on prior work:

  https://lkml.org/lkml/2014/5/6/395

and on how other arches add libdw unwind support.  Includes support for
running the unwind test, e.g., on a system with only elfutils' libdw
0.170, the test now runs, and successfully:

  $ ./perf test unwind
  56: Test dwarf unwind                 : Ok

Originally-by: Jean Pihet <jean.pihet@linaro.org>
Reported-by: Christian Hansen <chansen3@cisco.com>
Signed-off-by: Kim Phillips <kim.phillips@arm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20180308211030.4ee4a0d6ff6dc5cda1b567d4@arm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/Makefile.config                 |  2 +-
 tools/perf/arch/arm64/include/arch-tests.h | 12 ++++++
 tools/perf/arch/arm64/tests/Build          |  2 +
 tools/perf/arch/arm64/tests/arch-tests.c   | 16 ++++++++
 tools/perf/arch/arm64/util/Build           |  1 +
 tools/perf/arch/arm64/util/unwind-libdw.c  | 60 ++++++++++++++++++++++++++++++
 6 files changed, 92 insertions(+), 1 deletion(-)

diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index 89cb2a36b8ff..98ff73648b51 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -75,7 +75,7 @@ endif
 # Disable it on all other architectures in case libdw unwind
 # support is detected in system. Add supported architectures
 # to the check.
-ifneq ($(SRCARCH),$(filter $(SRCARCH),x86 arm powerpc s390))
+ifneq ($(SRCARCH),$(filter $(SRCARCH),x86 arm arm64 powerpc s390))
   NO_LIBDW_DWARF_UNWIND := 1
 endif
 
diff --git a/tools/perf/arch/arm64/include/arch-tests.h b/tools/perf/arch/arm64/include/arch-tests.h
new file mode 100644
index 000000000000..90ec4c8cb880
--- /dev/null
+++ b/tools/perf/arch/arm64/include/arch-tests.h
@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef ARCH_TESTS_H
+#define ARCH_TESTS_H
+
+#ifdef HAVE_DWARF_UNWIND_SUPPORT
+struct thread;
+struct perf_sample;
+#endif
+
+extern struct test arch_tests[];
+
+#endif
diff --git a/tools/perf/arch/arm64/tests/Build b/tools/perf/arch/arm64/tests/Build
index b30eff9bcc83..883c57ff0c08 100644
--- a/tools/perf/arch/arm64/tests/Build
+++ b/tools/perf/arch/arm64/tests/Build
@@ -1,2 +1,4 @@
 libperf-y += regs_load.o
 libperf-y += dwarf-unwind.o
+
+libperf-y += arch-tests.o
diff --git a/tools/perf/arch/arm64/tests/arch-tests.c b/tools/perf/arch/arm64/tests/arch-tests.c
new file mode 100644
index 000000000000..5b1543c98022
--- /dev/null
+++ b/tools/perf/arch/arm64/tests/arch-tests.c
@@ -0,0 +1,16 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <string.h>
+#include "tests/tests.h"
+#include "arch-tests.h"
+
+struct test arch_tests[] = {
+#ifdef HAVE_DWARF_UNWIND_SUPPORT
+	{
+		.desc = "DWARF unwind",
+		.func = test__dwarf_unwind,
+	},
+#endif
+	{
+		.func = NULL,
+	},
+};
diff --git a/tools/perf/arch/arm64/util/Build b/tools/perf/arch/arm64/util/Build
index c0b8dfef98ba..68f8a8eb3ad0 100644
--- a/tools/perf/arch/arm64/util/Build
+++ b/tools/perf/arch/arm64/util/Build
@@ -2,6 +2,7 @@ libperf-y += header.o
 libperf-y += sym-handling.o
 libperf-$(CONFIG_DWARF)     += dwarf-regs.o
 libperf-$(CONFIG_LOCAL_LIBUNWIND) += unwind-libunwind.o
+libperf-$(CONFIG_LIBDW_DWARF_UNWIND) += unwind-libdw.o
 
 libperf-$(CONFIG_AUXTRACE) += ../../arm/util/pmu.o \
 			      ../../arm/util/auxtrace.o \
diff --git a/tools/perf/arch/arm64/util/unwind-libdw.c b/tools/perf/arch/arm64/util/unwind-libdw.c
new file mode 100644
index 000000000000..7623d85e77f3
--- /dev/null
+++ b/tools/perf/arch/arm64/util/unwind-libdw.c
@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <elfutils/libdwfl.h>
+#include "../../util/unwind-libdw.h"
+#include "../../util/perf_regs.h"
+#include "../../util/event.h"
+
+bool libdw__arch_set_initial_registers(Dwfl_Thread *thread, void *arg)
+{
+	struct unwind_info *ui = arg;
+	struct regs_dump *user_regs = &ui->sample->user_regs;
+	Dwarf_Word dwarf_regs[PERF_REG_ARM64_MAX], dwarf_pc;
+
+#define REG(r) ({						\
+	Dwarf_Word val = 0;					\
+	perf_reg_value(&val, user_regs, PERF_REG_ARM64_##r);	\
+	val;							\
+})
+
+	dwarf_regs[0]  = REG(X0);
+	dwarf_regs[1]  = REG(X1);
+	dwarf_regs[2]  = REG(X2);
+	dwarf_regs[3]  = REG(X3);
+	dwarf_regs[4]  = REG(X4);
+	dwarf_regs[5]  = REG(X5);
+	dwarf_regs[6]  = REG(X6);
+	dwarf_regs[7]  = REG(X7);
+	dwarf_regs[8]  = REG(X8);
+	dwarf_regs[9]  = REG(X9);
+	dwarf_regs[10] = REG(X10);
+	dwarf_regs[11] = REG(X11);
+	dwarf_regs[12] = REG(X12);
+	dwarf_regs[13] = REG(X13);
+	dwarf_regs[14] = REG(X14);
+	dwarf_regs[15] = REG(X15);
+	dwarf_regs[16] = REG(X16);
+	dwarf_regs[17] = REG(X17);
+	dwarf_regs[18] = REG(X18);
+	dwarf_regs[19] = REG(X19);
+	dwarf_regs[20] = REG(X20);
+	dwarf_regs[21] = REG(X21);
+	dwarf_regs[22] = REG(X22);
+	dwarf_regs[23] = REG(X23);
+	dwarf_regs[24] = REG(X24);
+	dwarf_regs[25] = REG(X25);
+	dwarf_regs[26] = REG(X26);
+	dwarf_regs[27] = REG(X27);
+	dwarf_regs[28] = REG(X28);
+	dwarf_regs[29] = REG(X29);
+	dwarf_regs[30] = REG(LR);
+	dwarf_regs[31] = REG(SP);
+
+	if (!dwfl_thread_state_registers(thread, 0, PERF_REG_ARM64_MAX,
+					 dwarf_regs))
+		return false;
+
+	dwarf_pc = REG(PC);
+	dwfl_thread_state_register_pc(thread, dwarf_pc);
+
+	return true;
+}