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Accepting request 280978 from devel:libraries:c_c++

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OBS-URL: https://build.opensuse.org/request/show/280978
OBS-URL: https://build.opensuse.org/package/show/openSUSE:Factory/gperftools?expand=0&rev=14
This commit is contained in:
Dominique Leuenberger 2015-01-14 10:45:19 +00:00 committed by Git OBS Bridge
commit 363288ea3b
5 changed files with 60 additions and 426 deletions
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3
gperftools-2.2.tar.gz
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@ -1,3 +0,0 @@
version https://git-lfs.github.com/spec/v1
oid sha256:2407799467db2753a4a70c00dbb1b8429e23998427df31ee96361d2115cd63a4
size 1367117

3
gperftools-2.4.tar.gz Normal file
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@ -0,0 +1,3 @@
version https://git-lfs.github.com/spec/v1
oid sha256:982a37226eb42f40714e26b8076815d5ea677a422fb52ff8bfca3704d9c30a2d
size 1346075

56
gperftools.changes
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@ -1,3 +1,59 @@
-------------------------------------------------------------------
Mon Jan 10 16:30:24 UTC 2015 - cgardner@suse.com
- gperftools 2.4, available 10 Jan 2015.
Skipped version 2.3, release 7 Dec 2014. 2.3 changes included:
* ( issue 631 ) fixed debugallocation miscompilation on mmap-less
platforms (courtesy of user iamxujian)
* ( issue 630 ) reference to wrong PROFILE (vs. correct CPUPROFILE)
environment variable was fixed (courtesy of WenSheng He)
* pprof now has option to display stack traces in output for heap
checker (courtesy of Michael Pasieka)
* ( issue 636 ) pprof web command now works on mingw
* ( issue 635 ) pprof now handles library paths that contain spaces
(courtesy of user mich...@sebesbefut.com)
* ( issue 637 ) pprof now has an option to not strip template
arguments (patch by jiakai)
* ( issue 644 ) possible out-of-bounds access in GetenvBeforeMain
was fixed (thanks to user abyss.7)
* ( issue 641 ) pprof now has an option --show_addresses (thanks to
user yurivict). New option prints instruction address in addition
to function name in stack traces
* ( issue 646 ) pprof now works around some issues of addr2line
reportedly when DWARF v4 format is used (patch by Adam McNeeney)
* ( issue 645 ) heap profiler exit message now includes remaining
memory allocated info (patch by user yurivict)
* pprof code that finds location of /proc/pid/maps in cpu profile
files is now fixed (patch by Ricardo M. Correia)
* ( issue 654 ) pprof now handles "split text segments" feature of
Chromium for Android (patch by simonb)
* ( issue 655 ) potential deadlock on windows caused by early call
to getenv in malloc initialization code was fixed (bug reported
and fix proposed by user zndmitry)
* incorrect detection of arm 6zk instruction set support
(-mcpu=arm1176jzf-s) was fixed. (Reported by pedronavf on old issue-493)
* new cpu profiling mode on Linux is now implemented. It sets up separate
profiling timers for separate threads. Which improves accuracy of
profiling on Linux a lot. It is off by default. And is enabled if both
librt.f is loaded and CPUPROFILE_PER_THREAD_TIMERS environment
variable is set. But note that all threads need to be registered
via ProfilerRegisterThread.
Changes for version 2.4~rc
* enabled aggressive decommit option by default. It was found to
significantly improve memory fragmentation with negligible impact
on performance. (Thanks to investigation work performed by Adhemerval
Zanella)
* added ./configure flags for tcmalloc pagesize and tcmalloc allocation
alignment. Larger page sizes have been reported to improve performance
occasionally. (Patch by Raphael Moreira Zinsly)
* sped-up hot-path of malloc/free. By about 5% on static library and
about 10% on shared library. Mainly due to more efficient checking
of malloc hooks.
* improved accuracy of stacktrace capturing in cpu profiler (due to
issue found by Arun Sharma). As part of that issue pprof's handling
of cpu profiles was also improved.
- Removed missing_includes.patch; incorporated upstream.
-------------------------------------------------------------------
Sun Sep 28 18:44:03 UTC 2014 - jengelh@inai.de

9
gperftools.spec
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@ -15,9 +15,8 @@
# Please submit bugfixes or comments via http://bugs.opensuse.org/
#
Name: gperftools
Version: 2.2
Version: 2.4
Release: 0
Summary: Performance Tools for C++
License: BSD-3-Clause
@ -28,8 +27,6 @@ Source0: %{name}-%{version}.tar.gz
Patch4: %{name}-fix_docdir.patch
Patch12: %{name}_fix_unassigned_malloc_in_unittest.patch
Patch14: %{name}_gcc46.patch
#PATCH-FIX-UPSTREAM https://code.google.com/p/gperftools/issues/detail?id=268
Patch15: missing_includes.patch
BuildRequires: autoconf >= 2.59
BuildRequires: automake
BuildRequires: gcc-c++
@ -82,7 +79,6 @@ files for developing applications that use the gperftools package.
%patch4 -p1
%patch12 -p1
%patch14 -p1
%patch15 -p1
%build
autoreconf -fi
@ -109,7 +105,6 @@ make DESTDIR=$RPM_BUILD_ROOT install
%files -n libprofiler0
%defattr(-,root,root)
%_libdir/libprofiler.so.0*
# %_libdir/libstacktrace.so.0* # libstacktrace.so got removed in 0.96
%files -n libtcmalloc4
%defattr(-,root,root)
@ -124,8 +119,6 @@ make DESTDIR=$RPM_BUILD_ROOT install
%_includedir/google
%_includedir/gperftools
%_libdir/libprofiler.so
# %_libdir/libstacktrace.*a # libstacktrace.so got removed in 0.96
# %_libdir/libstacktrace.so # libstacktrace.so got removed in 0.96
%_libdir/libtcmalloc.so
%_libdir/libtcmalloc_debug.so
%_libdir/libtcmalloc_minimal.so

415
missing_includes.patch
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@ -1,415 +0,0 @@
commit 75b65f96b0bb44d70e0a461a03a3f8c928390283
Author: Raphael Moreira Zinsly <rzinsly@linux.vnet.ibm.com>
Date: Tue Apr 8 17:45:13 2014 -0300
PowerPC: stacktrace function refactor and fixes
This patch fixes the stacktrace creating when the function is
interrupted by a signal. For Linux, the vDSO signal trampoline symbol is
compared against LR from stack backchain and handled different in that
case (since the signal trampoline layout a different stack frame).
Because of this extensive change the PowerPC stacktrace code has now
been refactored to split in Linux and Darwin specific codes.
diff --git a/src/stacktrace_powerpc-darwin-inl.h b/src/stacktrace_powerpc-darwin-inl.h
new file mode 100644
index 0000000..c4c2edb
--- /dev/null
+++ b/src/stacktrace_powerpc-darwin-inl.h
@@ -0,0 +1,158 @@
+// Copyright (c) 2007, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+// * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+// * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+// * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// ---
+// Produce stack trace. ABI documentation reference can be found at:
+// * PowerPC32 ABI: https://www.power.org/documentation/
+// power-architecture-32-bit-abi-supplement-1-0-embeddedlinuxunified/
+// * PowerPC64 ABI:
+// http://www.linux-foundation.org/spec/ELF/ppc64/PPC-elf64abi-1.9.html#STACK
+
+#ifndef BASE_STACKTRACE_POWERPC_INL_H_
+#define BASE_STACKTRACE_POWERPC_INL_H_
+// Note: this file is included into stacktrace.cc more than once.
+// Anything that should only be defined once should be here:
+
+#include <stdint.h> // for uintptr_t
+#include <stdlib.h> // for NULL
+#include <gperftools/stacktrace.h>
+
+// Given a pointer to a stack frame, locate and return the calling
+// stackframe, or return NULL if no stackframe can be found. Perform sanity
+// checks (the strictness of which is controlled by the boolean parameter
+// "STRICT_UNWINDING") to reduce the chance that a bad pointer is returned.
+template<bool STRICT_UNWINDING>
+static void **NextStackFrame(void **old_sp) {
+ void **new_sp = (void **) *old_sp;
+
+ // Check that the transition from frame pointer old_sp to frame
+ // pointer new_sp isn't clearly bogus
+ if (STRICT_UNWINDING) {
+ // With the stack growing downwards, older stack frame must be
+ // at a greater address that the current one.
+ if (new_sp <= old_sp) return NULL;
+ // Assume stack frames larger than 100,000 bytes are bogus.
+ if ((uintptr_t)new_sp - (uintptr_t)old_sp > 100000) return NULL;
+ } else {
+ // In the non-strict mode, allow discontiguous stack frames.
+ // (alternate-signal-stacks for example).
+ if (new_sp == old_sp) return NULL;
+ // And allow frames upto about 1MB.
+ if ((new_sp > old_sp)
+ && ((uintptr_t)new_sp - (uintptr_t)old_sp > 1000000)) return NULL;
+ }
+ if ((uintptr_t)new_sp & (sizeof(void *) - 1)) return NULL;
+ return new_sp;
+}
+
+// This ensures that GetStackTrace stes up the Link Register properly.
+void StacktracePowerPCDummyFunction() __attribute__((noinline));
+void StacktracePowerPCDummyFunction() { __asm__ volatile(""); }
+#endif // BASE_STACKTRACE_POWERPC_INL_H_
+
+// Note: this part of the file is included several times.
+// Do not put globals below.
+
+// The following 4 functions are generated from the code below:
+// GetStack{Trace,Frames}()
+// GetStack{Trace,Frames}WithContext()
+//
+// These functions take the following args:
+// void** result: the stack-trace, as an array
+// int* sizes: the size of each stack frame, as an array
+// (GetStackFrames* only)
+// int max_depth: the size of the result (and sizes) array(s)
+// int skip_count: how many stack pointers to skip before storing in result
+// void* ucp: a ucontext_t* (GetStack{Trace,Frames}WithContext only)
+int GET_STACK_TRACE_OR_FRAMES {
+ void **sp;
+ // Apple OS X uses an old version of gnu as -- both Darwin 7.9.0 (Panther)
+ // and Darwin 8.8.1 (Tiger) use as 1.38. This means we have to use a
+ // different asm syntax. I don't know quite the best way to discriminate
+ // systems using the old as from the new one; I've gone with __APPLE__.
+ // TODO(csilvers): use autoconf instead, to look for 'as --version' == 1 or 2
+ __asm__ volatile ("mr %0,r1" : "=r" (sp));
+
+ // On PowerPC, the "Link Register" or "Link Record" (LR), is a stack
+ // entry that holds the return address of the subroutine call (what
+ // instruction we run after our function finishes). This is the
+ // same as the stack-pointer of our parent routine, which is what we
+ // want here. While the compiler will always(?) set up LR for
+ // subroutine calls, it may not for leaf functions (such as this one).
+ // This routine forces the compiler (at least gcc) to push it anyway.
+ StacktracePowerPCDummyFunction();
+
+#if IS_STACK_FRAMES
+ // Note we do *not* increment skip_count here for the SYSV ABI. If
+ // we did, the list of stack frames wouldn't properly match up with
+ // the list of return addresses. Note this means the top pc entry
+ // is probably bogus for linux/ppc (and other SYSV-ABI systems).
+#else
+ // The LR save area is used by the callee, so the top entry is bogus.
+ skip_count++;
+#endif
+
+ int n = 0;
+ while (sp && n < max_depth) {
+ // The GetStackFrames routine is called when we are in some
+ // informational context (the failure signal handler for example).
+ // Use the non-strict unwinding rules to produce a stack trace
+ // that is as complete as possible (even if it contains a few
+ // bogus entries in some rare cases).
+ void **next_sp = NextStackFrame<!IS_STACK_FRAMES>(sp);
+
+ if (skip_count > 0) {
+ skip_count--;
+ } else {
+ // PowerPC has 3 main ABIs, which say where in the stack the
+ // Link Register is. For DARWIN and AIX (used by apple and
+ // linux ppc64), it's in sp[2]. For SYSV (used by linux ppc),
+ // it's in sp[1].
+#if defined(__PPC64__)
+ // This check is in case the compiler doesn't define _CALL_AIX/etc.
+ result[n] = *(sp+2);
+#elif defined(__linux)
+ // This check is in case the compiler doesn't define _CALL_SYSV.
+ result[n] = *(sp+1);
+#endif
+
+#if IS_STACK_FRAMES
+ if (next_sp > sp) {
+ sizes[n] = (uintptr_t)next_sp - (uintptr_t)sp;
+ } else {
+ // A frame-size of 0 is used to indicate unknown frame size.
+ sizes[n] = 0;
+ }
+#endif
+ n++;
+ }
+ sp = next_sp;
+ }
+ return n;
+}
diff --git a/src/stacktrace_powerpc-linux-inl.h b/src/stacktrace_powerpc-linux-inl.h
new file mode 100644
index 0000000..5d16fa1
--- /dev/null
+++ b/src/stacktrace_powerpc-linux-inl.h
@@ -0,0 +1,231 @@
+// -*- Mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*-
+// Copyright (c) 2007, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+// * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+// * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+// * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// ---
+// Author: Craig Silverstein
+//
+// Produce stack trace. ABI documentation reference can be found at:
+// * PowerPC32 ABI: https://www.power.org/documentation/
+// power-architecture-32-bit-abi-supplement-1-0-embeddedlinuxunified/
+// * PowerPC64 ABI:
+// http://www.linux-foundation.org/spec/ELF/ppc64/PPC-elf64abi-1.9.html#STACK
+
+#ifndef BASE_STACKTRACE_POWERPC_INL_H_
+#define BASE_STACKTRACE_POWERPC_INL_H_
+// Note: this file is included into stacktrace.cc more than once.
+// Anything that should only be defined once should be here:
+
+#include <stdint.h> // for uintptr_t
+#include <stdlib.h> // for NULL
+#include <gperftools/stacktrace.h>
+#include <base/vdso_support.h>
+
+#if defined(HAVE_SYS_UCONTEXT_H)
+#include <sys/ucontext.h>
+#elif defined(HAVE_UCONTEXT_H)
+#include <ucontext.h> // for ucontext_t
+#endif
+typedef ucontext ucontext_t;
+
+// PowerPC64 Little Endian follows BE wrt. backchain, condition register,
+// and LR save area, so no need to adjust the reading struct.
+struct layout_ppc {
+ struct layout_ppc *next;
+#ifdef __PPC64__
+ long condition_register;
+#endif
+ void *return_addr;
+};
+
+// Signal callbacks are handled by the vDSO symbol:
+//
+// * PowerPC64 Linux (arch/powerpc/kernel/vdso64/sigtramp.S):
+// __kernel_sigtramp_rt64
+// * PowerPC32 Linux (arch/powerpc/kernel/vdso32/sigtramp.S):
+// __kernel_sigtramp32
+// __kernel_sigtramp_rt32
+//
+// So a backtrace may need to specially handling if the symbol readed is
+// the signal trampoline.
+
+// Given a pointer to a stack frame, locate and return the calling
+// stackframe, or return NULL if no stackframe can be found. Perform sanity
+// checks (the strictness of which is controlled by the boolean parameter
+// "STRICT_UNWINDING") to reduce the chance that a bad pointer is returned.
+template<bool STRICT_UNWINDING>
+static layout_ppc *NextStackFrame(layout_ppc *current) {
+ uintptr_t old_sp = (uintptr_t)(current);
+ uintptr_t new_sp = (uintptr_t)(current->next);
+
+ // Check that the transition from frame pointer old_sp to frame
+ // pointer new_sp isn't clearly bogus
+ if (STRICT_UNWINDING) {
+ // With the stack growing downwards, older stack frame must be
+ // at a greater address that the current one.
+ if (new_sp <= old_sp)
+ return NULL;
+ // Assume stack frames larger than 100,000 bytes are bogus.
+ if (new_sp - old_sp > 100000)
+ return NULL;
+ } else {
+ // In the non-strict mode, allow discontiguous stack frames.
+ // (alternate-signal-stacks for example).
+ if (new_sp == old_sp)
+ return NULL;
+ // And allow frames upto about 1MB.
+ if ((new_sp > old_sp) && (new_sp - old_sp > 1000000))
+ return NULL;
+ }
+ if (new_sp & (sizeof(void *) - 1))
+ return NULL;
+ return current->next;
+}
+
+// This ensures that GetStackTrace stes up the Link Register properly.
+void StacktracePowerPCDummyFunction() __attribute__((noinline));
+void StacktracePowerPCDummyFunction() { __asm__ volatile(""); }
+#endif // BASE_STACKTRACE_POWERPC_INL_H_
+
+// Note: this part of the file is included several times.
+// Do not put globals below.
+
+// Load instruction used on top-of-stack get.
+#if defined(__PPC64__) || defined(__LP64__)
+# define LOAD "ld"
+#else
+# define LOAD "lwz"
+#endif
+
+// The following 4 functions are generated from the code below:
+// GetStack{Trace,Frames}()
+// GetStack{Trace,Frames}WithContext()
+//
+// These functions take the following args:
+// void** result: the stack-trace, as an array
+// int* sizes: the size of each stack frame, as an array
+// (GetStackFrames* only)
+// int max_depth: the size of the result (and sizes) array(s)
+// int skip_count: how many stack pointers to skip before storing in result
+// void* ucp: a ucontext_t* (GetStack{Trace,Frames}WithContext only)
+static int GET_STACK_TRACE_OR_FRAMES {
+ layout_ppc *current;
+ int n;
+
+ // Get the address on top-of-stack
+ current = reinterpret_cast<layout_ppc*> (__builtin_frame_address (0));
+ // And ignore the current symbol
+ current = current->next;
+
+ StacktracePowerPCDummyFunction();
+
+ n = 0;
+ skip_count++; // skip parent's frame due to indirection in
+ // stacktrace.cc
+
+ base::VDSOSupport vdso;
+ base::ElfMemImage::SymbolInfo rt_sigreturn_symbol_info;
+#ifdef __PPC64__
+ const void *sigtramp64_vdso = 0;
+ if (vdso.LookupSymbol("__kernel_sigtramp_rt64", "LINUX_2.6.15", STT_NOTYPE,
+ &rt_sigreturn_symbol_info))
+ sigtramp64_vdso = rt_sigreturn_symbol_info.address;
+#else
+ const void *sigtramp32_vdso = 0;
+ if (vdso.LookupSymbol("__kernel_sigtramp32", "LINUX_2.6.15", STT_NOTYPE,
+ &rt_sigreturn_symbol_info))
+ sigtramp32_vdso = rt_sigreturn_symbol_info.address;
+ const void *sigtramp32_rt_vdso = 0;
+ if (vdso.LookupSymbol("__kernel_sigtramp_rt32", "LINUX_2.6.15", STT_NOTYPE,
+ &rt_sigreturn_symbol_info))
+ sigtramp32_rt_vdso = rt_sigreturn_symbol_info.address;
+#endif
+
+ while (current && n < max_depth) {
+
+ // The GetStackFrames routine is called when we are in some
+ // informational context (the failure signal handler for example).
+ // Use the non-strict unwinding rules to produce a stack trace
+ // that is as complete as possible (even if it contains a few
+ // bogus entries in some rare cases).
+ layout_ppc *next = NextStackFrame<!IS_STACK_FRAMES>(current);
+ if (skip_count > 0) {
+ skip_count--;
+ } else {
+ result[n] = current->return_addr;
+#ifdef __PPC64__
+ if (sigtramp64_vdso && (sigtramp64_vdso == current->return_addr)) {
+ struct signal_frame_64 {
+ char dummy[128];
+ ucontext_t uc;
+ // We don't care about the rest, since the IP value is at 'uc' field.
+ } *sigframe = reinterpret_cast<signal_frame_64*>(current);
+ result[n] = (void*) sigframe->uc.uc_mcontext.gp_regs[PT_NIP];
+ }
+#else
+ if (sigtramp32_vdso && (sigtramp32_vdso == current->return_addr)) {
+ struct signal_frame_32 {
+ char dummy[64];
+ struct sigcontext sctx;
+ mcontext_t mctx;
+ // We don't care about the rest, since IP value is at 'mctx' field.
+ } *sigframe = reinterpret_cast<signal_frame_32*>(current);
+ result[n] = (void*) sigframe->mctx.gregs[PT_NIP];
+ } else if (sigtramp32_rt_vdso && (sigtramp32_rt_vdso == current->return_addr)) {
+ struct rt_signal_frame_32 {
+ char dummy[64 + 16];
+ siginfo_t info;
+ struct ucontext uc;
+ // We don't care about the rest, since IP value is at 'uc' field.A
+ } *sigframe = reinterpret_cast<rt_signal_frame_32*>(current);
+ result[n] = (void*) sigframe->uc.uc_mcontext.uc_regs->gregs[PT_NIP];
+ }
+#endif
+
+#if IS_STACK_FRAMES
+ if (next > current) {
+ sizes[n] = (uintptr_t)next - (uintptr_t)current;
+ } else {
+ // A frame-size of 0 is used to indicate unknown frame size.
+ sizes[n] = 0;
+ }
+#endif
+ n++;
+ }
+ current = next;
+ }
+
+ // It's possible the second-last stack frame can't return
+ // (that is, it's __libc_start_main), in which case
+ // the CRT startup code will have set its LR to 'NULL'.
+ if (n > 0 && result[n-1] == NULL)
+ n--;
+
+ return n;
+}