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Subject[PATCH 1/3] perf tests: Introduce perf_regs_load function on ARM64
Date
Introducing perf_regs_load function, which is going
to be used for dwarf unwind test in following patches.

It takes single argument as a pointer to the regs dump
buffer and populates it with current registers values, as
expected by the perf built-in unwinding test.

Signed-off-by: Jean Pihet <jean.pihet@linaro.org>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
---
tools/perf/arch/arm64/Makefile | 1 +
tools/perf/arch/arm64/include/perf_regs.h | 2 ++
tools/perf/arch/arm64/tests/regs_load.S | 39 +++++++++++++++++++++++++++++++
3 files changed, 42 insertions(+)
create mode 100644 tools/perf/arch/arm64/tests/regs_load.S

diff --git a/tools/perf/arch/arm64/Makefile b/tools/perf/arch/arm64/Makefile
index 67e9b3d..9b8f87e 100644
--- a/tools/perf/arch/arm64/Makefile
+++ b/tools/perf/arch/arm64/Makefile
@@ -4,4 +4,5 @@ LIB_OBJS += $(OUTPUT)arch/$(ARCH)/util/dwarf-regs.o
endif
ifndef NO_LIBUNWIND
LIB_OBJS += $(OUTPUT)arch/$(ARCH)/util/unwind-libunwind.o
+LIB_OBJS += $(OUTPUT)arch/$(ARCH)/tests/regs_load.o
endif
diff --git a/tools/perf/arch/arm64/include/perf_regs.h b/tools/perf/arch/arm64/include/perf_regs.h
index 2359546..1e052f1 100644
--- a/tools/perf/arch/arm64/include/perf_regs.h
+++ b/tools/perf/arch/arm64/include/perf_regs.h
@@ -9,6 +9,8 @@
#define PERF_REG_IP PERF_REG_ARM64_PC
#define PERF_REG_SP PERF_REG_ARM64_SP

+void perf_regs_load(u64 *regs);
+
static inline const char *perf_reg_name(int id)
{
switch (id) {
diff --git a/tools/perf/arch/arm64/tests/regs_load.S b/tools/perf/arch/arm64/tests/regs_load.S
new file mode 100644
index 0000000..92ab968
--- /dev/null
+++ b/tools/perf/arch/arm64/tests/regs_load.S
@@ -0,0 +1,39 @@
+#include <linux/linkage.h>
+
+/*
+ * Implementation of void perf_regs_load(u64 *regs);
+ *
+ * This functions fills in the 'regs' buffer from the actual registers values,
+ * in the way the perf built-in unwinding test expects them:
+ * - the PC at the time at the call to this function. Since this function
+ * is called using a bl instruction, the PC value is taken from LR,
+ * - the current SP (not touched by this function),
+ * - the current value of LR is merely retrieved and stored because the
+ * value before the call to this function is unknown at this time; it will
+ * be unwound from the dwarf information in unwind__get_entries.
+ */
+
+.text
+.type perf_regs_load,%function
+ENTRY(perf_regs_load)
+ stp x0, x1, [x0], #16 // store x0..x29
+ stp x2, x3, [x0], #16
+ stp x4, x5, [x0], #16
+ stp x6, x7, [x0], #16
+ stp x8, x9, [x0], #16
+ stp x10, x11, [x0], #16
+ stp x12, x13, [x0], #16
+ stp x14, x15, [x0], #16
+ stp x16, x17, [x0], #16
+ stp x18, x19, [x0], #16
+ stp x20, x21, [x0], #16
+ stp x22, x23, [x0], #16
+ stp x24, x25, [x0], #16
+ stp x26, x27, [x0], #16
+ stp x28, x29, [x0], #16
+ mov x1, sp
+ stp x30, x1, [x0], #16 // store lr and sp
+ str x30, [x0] // store pc as lr in order to skip the call
+ // to this function
+ ret
+ENDPROC(perf_regs_load)
--
1.7.11.7


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