Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751618AbdFIMai (ORCPT ); Fri, 9 Jun 2017 08:30:38 -0400 Received: from mail-wr0-f196.google.com ([209.85.128.196]:33783 "EHLO mail-wr0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751534AbdFIMag (ORCPT ); Fri, 9 Jun 2017 08:30:36 -0400 Subject: Re: [PATCH v2] perf: libdw support for powerpc [ping] From: Paolo Bonzini To: linux-kernel@vger.kernel.org Cc: acme@kernel.org, "Naveen N. Rao" , Ravi Bangoria , linuxppc-dev@lists.ozlabs.org References: <1496312681-20133-1-git-send-email-pbonzini@redhat.com> Message-ID: Date: Fri, 9 Jun 2017 14:30:31 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.1.0 MIME-Version: 1.0 In-Reply-To: <1496312681-20133-1-git-send-email-pbonzini@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4649 Lines: 139 On 01/06/2017 12:24, Paolo Bonzini wrote: > 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. > > Cc: acme@kernel.org > Cc: Naveen N. Rao > Cc: Ravi Bangoria > Cc: linuxppc-dev@lists.ozlabs.org > Signed-off-by: Paolo Bonzini > --- > v1->v2: fix for 4.11->4.12 changes Ravi, Naveen, any reviews? Thanks, Paolo > > tools/perf/Makefile.config | 2 +- > tools/perf/arch/powerpc/util/Build | 2 + > tools/perf/arch/powerpc/util/unwind-libdw.c | 73 +++++++++++++++++++++++++++++ > 3 files changed, 76 insertions(+), 1 deletion(-) > create mode 100644 tools/perf/arch/powerpc/util/unwind-libdw.c > > diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config > index 8354d04b392f..e7b04a729417 100644 > --- 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 ($(ARCH),$(filter $(ARCH),x86 arm)) > +ifneq ($(ARCH),$(filter $(ARCH),x86 arm powerpc)) > NO_LIBDW_DWARF_UNWIND := 1 > endif > > diff --git a/tools/perf/arch/powerpc/util/Build b/tools/perf/arch/powerpc/util/Build > index 90ad64b231cd..2e6595310420 100644 > --- a/tools/perf/arch/powerpc/util/Build > +++ b/tools/perf/arch/powerpc/util/Build > @@ -5,4 +5,6 @@ libperf-y += perf_regs.o > > libperf-$(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 > index 000000000000..3a24b3c43273 > --- /dev/null > +++ b/tools/perf/arch/powerpc/util/unwind-libdw.c > @@ -0,0 +1,73 @@ > +#include > +#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; > +} >