perf unwind: Support for powerpc

Porting PPC to libdw only needs an architecture-specific hook to move
the register state from perf to libdw.

The ARM and x86 architectures already use libdw, and it is useful to
have as much common code for the unwinder as possible.  Mark Wielaard
has contributed a frame-based unwinder to libdw, so that unwinding works
even for binaries that do not have CFI information.  In addition,
libunwind is always preferred to libdw by the build machinery so this
cannot introduce regressions on machines that have both libunwind and
libdw installed.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Milian Wolff <milian.wolff@kdab.com>
Acked-by: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/1496312681-20133-1-git-send-email-pbonzini@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index 1f4fbc9a3292e06b6ae48c47297e795ccbc45809..bdf0e87f9b2938c33dc94b0541c8a63d1965cb35 100644 (file)
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -61,7 +61,7 @@ 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 $(SRCARCH),x86 arm))
+ifneq ($(SRCARCH),$(filter $(SRCARCH),x86 arm powerpc))
   NO_LIBDW_DWARF_UNWIND := 1
 endif
 

diff --git a/tools/perf/arch/powerpc/util/Build b/tools/perf/arch/powerpc/util/Build
index 90ad64b231cd821abe8756ed92d68d7c4c367804..2e6595310420104a40fe4ee813f41ee0bc213349 100644 (file)
--- a/tools/perf/arch/powerpc/util/Build
+++ b/tools/perf/arch/powerpc/util/Build
@@ -5,4 +5,6 @@ libperf-y += perf_regs.o
 
 libperf-$(CONFIG_DWARF) += dwarf-regs.o
 libperf-$(CONFIG_DWARF) += skip-callchain-idx.o
+
 libperf-$(CONFIG_LIBUNWIND) += unwind-libunwind.o
+libperf-$(CONFIG_LIBDW_DWARF_UNWIND) += unwind-libdw.o

diff --git a/tools/perf/arch/powerpc/util/unwind-libdw.c b/tools/perf/arch/powerpc/util/unwind-libdw.c
new file mode 100644 (file)
index 0000000..3a24b3c
--- /dev/null
+++ b/tools/perf/arch/powerpc/util/unwind-libdw.c
@@ -0,0 +1,73 @@
+#include <elfutils/libdwfl.h>
+#include "../../util/unwind-libdw.h"
+#include "../../util/perf_regs.h"
+#include "../../util/event.h"
+
+/* See backends/ppc_initreg.c and backends/ppc_regs.c in elfutils.  */
+static const int special_regs[3][2] = {
+       { 65, PERF_REG_POWERPC_LINK },
+       { 101, PERF_REG_POWERPC_XER },
+       { 109, PERF_REG_POWERPC_CTR },
+};
+
+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[32], dwarf_nip;
+       size_t i;
+
+#define REG(r) ({                                              \
+       Dwarf_Word val = 0;                                     \
+       perf_reg_value(&val, user_regs, PERF_REG_POWERPC_##r);  \
+       val;                                                    \
+})
+
+       dwarf_regs[0]  = REG(R0);
+       dwarf_regs[1]  = REG(R1);
+       dwarf_regs[2]  = REG(R2);
+       dwarf_regs[3]  = REG(R3);
+       dwarf_regs[4]  = REG(R4);
+       dwarf_regs[5]  = REG(R5);
+       dwarf_regs[6]  = REG(R6);
+       dwarf_regs[7]  = REG(R7);
+       dwarf_regs[8]  = REG(R8);
+       dwarf_regs[9]  = REG(R9);
+       dwarf_regs[10] = REG(R10);
+       dwarf_regs[11] = REG(R11);
+       dwarf_regs[12] = REG(R12);
+       dwarf_regs[13] = REG(R13);
+       dwarf_regs[14] = REG(R14);
+       dwarf_regs[15] = REG(R15);
+       dwarf_regs[16] = REG(R16);
+       dwarf_regs[17] = REG(R17);
+       dwarf_regs[18] = REG(R18);
+       dwarf_regs[19] = REG(R19);
+       dwarf_regs[20] = REG(R20);
+       dwarf_regs[21] = REG(R21);
+       dwarf_regs[22] = REG(R22);
+       dwarf_regs[23] = REG(R23);
+       dwarf_regs[24] = REG(R24);
+       dwarf_regs[25] = REG(R25);
+       dwarf_regs[26] = REG(R26);
+       dwarf_regs[27] = REG(R27);
+       dwarf_regs[28] = REG(R28);
+       dwarf_regs[29] = REG(R29);
+       dwarf_regs[30] = REG(R30);
+       dwarf_regs[31] = REG(R31);
+       if (!dwfl_thread_state_registers(thread, 0, 32, dwarf_regs))
+               return false;
+
+       dwarf_nip = REG(NIP);
+       dwfl_thread_state_register_pc(thread, dwarf_nip);
+       for (i = 0; i < ARRAY_SIZE(special_regs); i++) {
+               Dwarf_Word val = 0;
+               perf_reg_value(&val, user_regs, special_regs[i][1]);
+               if (!dwfl_thread_state_registers(thread,
+                                                special_regs[i][0], 1,
+                                                &val))
+                       return false;
+       }
+
+       return true;
+}