* [PATCH] perf report: Support LLVM for addr2line()
@ 2024-05-17 18:54 Steinar H. Gunderson
2024-05-17 21:27 ` Ian Rogers
0 siblings, 1 reply; 3+ messages in thread
From: Steinar H. Gunderson @ 2024-05-17 18:54 UTC (permalink / raw)
To: acme; +Cc: linux-perf-users, linux-kernel, irogers, Steinar H. Gunderson
In addition to the existing support for libbfd and calling out to
an external addr2line command, add support for using libllvm directly.
This is both faster than libbfd, and can be enabled in distro builds
(the LLVM license has an explicit provision for GPLv2 compatibility).
Thus, it is set as the primary choice if available.
As an example, running perf report on a medium-size profile with
DWARF-based backtraces took 58 seconds with LLVM, 78 seconds with
libbfd, 153 seconds with external llvm-addr2line, and I got tired
and aborted the test after waiting for 55 minutes with external
bfd addr2line (which is the default for perf as compiled by distributions
today). Evidently, for this case, the bfd addr2line process needs
18 seconds (on a 5.2 GHz Zen 3) to load the .debug ELF in question,
hits the 1-second timeout and gets killed during initialization,
getting restarted anew every time. Having an in-process addr2line
makes this much more robust.
As future extensions, libllvm can be used in many other places where
we currently use libbfd or other libraries:
- Symbol enumeration (in particular, for PE binaries).
- Demangling (including non-Itanium demangling, e.g. Microsoft
or Rust).
- Disassembling (perf annotate).
However, these are much less pressing; most people don't profile
PE binaries, and perf has non-bfd paths for ELF. The same with
demangling; the default _cxa_demangle path works fine for most
users. And for disassembling, external objdump works fairly well;
bfd objdump can be slow on large binaries, but it is possible
to use --objdump=llvm-objdump to get the speed benefits.
(It appears LLVM-based demangling is very simple, and that LLVM-based
disassembling is somewhat more involved.)
Tested with LLVM 14, 16, 18 and 19. For some reason, LLVM 12 was not
correctly detected using feature_check, and thus was not tested.
Signed-off-by: Steinar H. Gunderson <sesse@google.com>
---
tools/perf/Makefile.config | 15 ++++
tools/perf/builtin-version.c | 1 +
tools/perf/util/Build | 1 +
tools/perf/util/llvm-addr2line.cpp | 134 +++++++++++++++++++++++++++++
tools/perf/util/llvm-addr2line.h | 42 +++++++++
tools/perf/util/srcline.c | 55 +++++++++++-
6 files changed, 247 insertions(+), 1 deletion(-)
create mode 100644 tools/perf/util/llvm-addr2line.cpp
create mode 100644 tools/perf/util/llvm-addr2line.h
diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index 7f1e016a9253..414a37f712bd 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -969,6 +969,21 @@ ifdef BUILD_NONDISTRO
endif
endif
+ifndef NO_LLVM
+ $(call feature_check,llvm)
+ ifeq ($(feature-llvm), 1)
+ CFLAGS += -DHAVE_LLVM_SUPPORT
+ CXXFLAGS += -DHAVE_LLVM_SUPPORT
+ CXXFLAGS += $(shell $(LLVM_CONFIG) --cxxflags)
+ LIBLLVM = $(shell $(LLVM_CONFIG) --libs all) $(shell $(LLVM_CONFIG) --system-libs)
+ EXTLIBS += -L$(shell $(LLVM_CONFIG) --libdir) $(LIBLLVM)
+ $(call detected,CONFIG_LLVM)
+ else
+ $(warning No libllvm found, slower source file resolution, please install llvm-devel/llvm-dev)
+ NO_LLVM := 1
+ endif
+endif
+
ifndef NO_DEMANGLE
$(call feature_check,cxa-demangle)
ifeq ($(feature-cxa-demangle), 1)
diff --git a/tools/perf/builtin-version.c b/tools/perf/builtin-version.c
index 398aa53e9e2e..4b252196de12 100644
--- a/tools/perf/builtin-version.c
+++ b/tools/perf/builtin-version.c
@@ -65,6 +65,7 @@ static void library_status(void)
STATUS(HAVE_LIBBFD_SUPPORT, libbfd);
STATUS(HAVE_DEBUGINFOD_SUPPORT, debuginfod);
STATUS(HAVE_LIBELF_SUPPORT, libelf);
+ STATUS(HAVE_LIBLLVM_SUPPORT, libllvm);
STATUS(HAVE_LIBNUMA_SUPPORT, libnuma);
STATUS(HAVE_LIBNUMA_SUPPORT, numa_num_possible_cpus);
STATUS(HAVE_LIBPERL_SUPPORT, libperl);
diff --git a/tools/perf/util/Build b/tools/perf/util/Build
index da64efd8718f..1cf17afd51f4 100644
--- a/tools/perf/util/Build
+++ b/tools/perf/util/Build
@@ -226,6 +226,7 @@ perf-$(CONFIG_CXX_DEMANGLE) += demangle-cxx.o
perf-y += demangle-ocaml.o
perf-y += demangle-java.o
perf-y += demangle-rust.o
+perf-$(CONFIG_LLVM) += llvm-addr2line.o
ifdef CONFIG_JITDUMP
perf-$(CONFIG_LIBELF) += jitdump.o
diff --git a/tools/perf/util/llvm-addr2line.cpp b/tools/perf/util/llvm-addr2line.cpp
new file mode 100644
index 000000000000..145488ed1346
--- /dev/null
+++ b/tools/perf/util/llvm-addr2line.cpp
@@ -0,0 +1,134 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/* Must come before the linux/compiler.h include, which defines several
+ * macros (e.g. noinline) that conflict with compiler builtins used by LLVM. */
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-parameter" /* Needed for LLVM 14. */
+#include <llvm/DebugInfo/Symbolize/Symbolize.h>
+#pragma GCC diagnostic pop
+
+#include <stdio.h>
+#include <sys/types.h>
+#include <linux/compiler.h>
+#include "symbol_conf.h"
+#include "llvm-addr2line.h"
+
+using namespace llvm;
+using llvm::symbolize::LLVMSymbolizer;
+
+/*
+ * Allocate a static LLVMSymbolizer, which will live to the end of the program.
+ * Unlike the bfd paths, LLVMSymbolizer has its own cache, so we do not need
+ * to store anything in the dso struct.
+ */
+static LLVMSymbolizer *GetSymbolizer()
+{
+ static LLVMSymbolizer *instance = nullptr;
+ if (instance == nullptr) {
+ LLVMSymbolizer::Options Opts;
+ /*
+ * LLVM sometimes demangles slightly different from the rest
+ * of the code, and this mismatch can cause new_inline_sym()
+ * to get confused and mark non-inline symbol as inlined
+ * (since the name does not properly match up with base_sym).
+ * Thus, disable the demangling and let the rest of the code
+ * handle it.
+ */
+ Opts.Demangle = false;
+ instance = new LLVMSymbolizer(Opts);
+ }
+ return instance;
+}
+
+/* Returns 0 on error, 1 on success. */
+static int extract_file_and_line(const DILineInfo& line_info, char **file,
+ unsigned int *line)
+{
+ if (file) {
+ if (line_info.FileName == "<invalid>") {
+ /* Match the convention of libbfd. */
+ *file = nullptr;
+ } else {
+ /* The caller expects to get something it can free(). */
+ *file = strdup(line_info.FileName.c_str());
+ if (*file == nullptr) {
+ return 0;
+ }
+ }
+ }
+ if (line) {
+ *line = line_info.Line;
+ }
+ return 1;
+}
+
+extern "C"
+int llvm_addr2line(const char *dso_name, u64 addr,
+ char **file, unsigned int *line,
+ bool unwind_inlines,
+ llvm_a2l_frame** inline_frames)
+{
+ LLVMSymbolizer *symbolizer = GetSymbolizer();
+ object::SectionedAddress sectioned_addr = {
+ addr,
+ object::SectionedAddress::UndefSection
+ };
+
+ if (unwind_inlines) {
+ Expected<DIInliningInfo> res_or_err =
+ symbolizer->symbolizeInlinedCode(dso_name,
+ sectioned_addr);
+ if (!res_or_err) {
+ return 0;
+ }
+ unsigned num_frames = res_or_err->getNumberOfFrames();
+ if (num_frames == 0) {
+ return 0;
+ }
+
+ if (extract_file_and_line(
+ res_or_err->getFrame(0), file, line) == 0) {
+ return 0;
+ }
+
+ *inline_frames = (llvm_a2l_frame*)malloc(
+ sizeof(**inline_frames) * num_frames);
+ if (*inline_frames == nullptr) {
+ return 0;
+ }
+
+ for (unsigned i = 0; i < num_frames; ++i) {
+ const DILineInfo& src = res_or_err->getFrame(i);
+ llvm_a2l_frame& dst = (*inline_frames)[i];
+ if (src.FileName == "<invalid>") {
+ /* Match the convention of libbfd. */
+ dst.filename = nullptr;
+ } else {
+ dst.filename = strdup(src.FileName.c_str());
+ }
+ dst.funcname = strdup(src.FunctionName.c_str());
+ dst.line = src.Line;
+
+ if (dst.filename == nullptr ||
+ dst.funcname == nullptr) {
+ for (unsigned j = 0; j <= i; ++j) {
+ free((*inline_frames)[j].filename);
+ free((*inline_frames)[j].funcname);
+ }
+ free(*inline_frames);
+ return 0;
+ }
+ }
+
+ return num_frames;
+ } else {
+ *inline_frames = nullptr;
+
+ Expected<DILineInfo> res_or_err =
+ symbolizer->symbolizeCode(dso_name, sectioned_addr);
+ if (!res_or_err) {
+ return 0;
+ }
+ return extract_file_and_line(*res_or_err, file, line);
+ }
+}
diff --git a/tools/perf/util/llvm-addr2line.h b/tools/perf/util/llvm-addr2line.h
new file mode 100644
index 000000000000..2de4fe79a3d0
--- /dev/null
+++ b/tools/perf/util/llvm-addr2line.h
@@ -0,0 +1,42 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __PERF_LLVM_ADDR2LINE
+#define __PERF_LLVM_ADDR2LINE 1
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct llvm_a2l_frame {
+ char *filename;
+ char *funcname;
+ unsigned int line;
+};
+
+/*
+ * Implement addr2line() using libLLVM. LLVM is a C++ API, and
+ * many of the linux/ headers cannot be included in a C++ compile unit,
+ * so we need to make a little bridge code here. llvm_addr2line() will
+ * convert the inline frame information from LLVM's internal structures
+ * and put them into a flat array given in inline_frames. The caller
+ * is then responsible for taking that array and convert it into perf's
+ * regular inline frame structures (which depend on e.g. struct list_head).
+ *
+ * If the address could not be resolved, or an error occurred (e.g. OOM),
+ * returns 0. Otherwise, returns the number of inline frames (which means 1
+ * if the address was not part of an inlined function). If unwind_inlines
+ * is set and the return code is nonzero, inline_frames will be set to
+ * a newly allocated array with that length. The caller is then responsible
+ * for freeing both the strings and the array itself.
+ */
+int llvm_addr2line(const char *dso_name,
+ u64 addr,
+ char **file,
+ unsigned int *line,
+ bool unwind_inlines,
+ struct llvm_a2l_frame **inline_frames);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __PERF_LLVM_ADDR2LINE */
diff --git a/tools/perf/util/srcline.c b/tools/perf/util/srcline.c
index 9d670d8c1c08..f69ad21a18d4 100644
--- a/tools/perf/util/srcline.c
+++ b/tools/perf/util/srcline.c
@@ -16,6 +16,7 @@
#include "util/debug.h"
#include "util/callchain.h"
#include "util/symbol_conf.h"
+#include "util/llvm-addr2line.h"
#include "srcline.h"
#include "string2.h"
#include "symbol.h"
@@ -130,7 +131,59 @@ static struct symbol *new_inline_sym(struct dso *dso,
#define MAX_INLINE_NEST 1024
-#ifdef HAVE_LIBBFD_SUPPORT
+#ifdef HAVE_LLVM_SUPPORT
+
+static void free_llvm_inline_frames(struct llvm_a2l_frame *inline_frames,
+ int num_frames)
+{
+ if (inline_frames != NULL) {
+ for (int i = 0; i < num_frames; ++i) {
+ free(inline_frames[i].filename);
+ free(inline_frames[i].funcname);
+ }
+ free(inline_frames);
+ }
+}
+
+static int addr2line(const char *dso_name, u64 addr,
+ char **file, unsigned int *line, struct dso *dso,
+ bool unwind_inlines, struct inline_node *node,
+ struct symbol *sym)
+{
+ struct llvm_a2l_frame *inline_frames = NULL;
+ int num_frames = llvm_addr2line(dso_name, addr, file, line,
+ node && unwind_inlines, &inline_frames);
+
+ if (num_frames == 0 || !inline_frames) {
+ /* Error, or we didn't want inlines. */
+ return num_frames;
+ }
+
+ for (int i = 0; i < num_frames; ++i) {
+ struct symbol *inline_sym =
+ new_inline_sym(dso, sym, inline_frames[i].funcname);
+ char *srcline = NULL;
+
+ if (inline_frames[i].filename)
+ srcline = srcline_from_fileline(
+ inline_frames[i].filename,
+ inline_frames[i].line);
+ if (inline_list__append(inline_sym, srcline, node) != 0) {
+ free_llvm_inline_frames(inline_frames, num_frames);
+ return 0;
+ }
+ }
+ free_llvm_inline_frames(inline_frames, num_frames);
+
+ return num_frames;
+}
+
+void dso__free_a2l(struct dso *)
+{
+ /* Nothing to free. */
+}
+
+#elif defined(HAVE_LIBBFD_SUPPORT)
/*
* Implement addr2line using libbfd.
--
2.43.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] perf report: Support LLVM for addr2line()
2024-05-17 18:54 [PATCH] perf report: Support LLVM for addr2line() Steinar H. Gunderson
@ 2024-05-17 21:27 ` Ian Rogers
2024-05-18 16:52 ` Steinar H. Gunderson
0 siblings, 1 reply; 3+ messages in thread
From: Ian Rogers @ 2024-05-17 21:27 UTC (permalink / raw)
To: Steinar H. Gunderson, Namhyung Kim; +Cc: acme, linux-perf-users, linux-kernel
On Fri, May 17, 2024 at 11:54 AM Steinar H. Gunderson <sesse@google.com> wrote:
>
> In addition to the existing support for libbfd and calling out to
> an external addr2line command, add support for using libllvm directly.
> This is both faster than libbfd, and can be enabled in distro builds
> (the LLVM license has an explicit provision for GPLv2 compatibility).
> Thus, it is set as the primary choice if available.
>
> As an example, running perf report on a medium-size profile with
> DWARF-based backtraces took 58 seconds with LLVM, 78 seconds with
> libbfd, 153 seconds with external llvm-addr2line, and I got tired
> and aborted the test after waiting for 55 minutes with external
> bfd addr2line (which is the default for perf as compiled by distributions
> today). Evidently, for this case, the bfd addr2line process needs
> 18 seconds (on a 5.2 GHz Zen 3) to load the .debug ELF in question,
> hits the 1-second timeout and gets killed during initialization,
> getting restarted anew every time. Having an in-process addr2line
> makes this much more robust.
This is great! There has been talk about the code being slow and I
think libelf may have been another alternative for this (maybe also
capstone). We should probably build a `perf bench` for this given the
variety of choice.
> As future extensions, libllvm can be used in many other places where
> we currently use libbfd or other libraries:
>
> - Symbol enumeration (in particular, for PE binaries).
> - Demangling (including non-Itanium demangling, e.g. Microsoft
> or Rust).
> - Disassembling (perf annotate).
>
> However, these are much less pressing; most people don't profile
> PE binaries, and perf has non-bfd paths for ELF. The same with
> demangling; the default _cxa_demangle path works fine for most
> users. And for disassembling, external objdump works fairly well;
> bfd objdump can be slow on large binaries, but it is possible
> to use --objdump=llvm-objdump to get the speed benefits.
> (It appears LLVM-based demangling is very simple, and that LLVM-based
> disassembling is somewhat more involved.)
>
> Tested with LLVM 14, 16, 18 and 19. For some reason, LLVM 12 was not
> correctly detected using feature_check, and thus was not tested.
>
> Signed-off-by: Steinar H. Gunderson <sesse@google.com>
> ---
> tools/perf/Makefile.config | 15 ++++
> tools/perf/builtin-version.c | 1 +
> tools/perf/util/Build | 1 +
> tools/perf/util/llvm-addr2line.cpp | 134 +++++++++++++++++++++++++++++
> tools/perf/util/llvm-addr2line.h | 42 +++++++++
> tools/perf/util/srcline.c | 55 +++++++++++-
> 6 files changed, 247 insertions(+), 1 deletion(-)
> create mode 100644 tools/perf/util/llvm-addr2line.cpp
> create mode 100644 tools/perf/util/llvm-addr2line.h
>
> diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
> index 7f1e016a9253..414a37f712bd 100644
> --- a/tools/perf/Makefile.config
> +++ b/tools/perf/Makefile.config
> @@ -969,6 +969,21 @@ ifdef BUILD_NONDISTRO
> endif
> endif
>
> +ifndef NO_LLVM
> + $(call feature_check,llvm)
> + ifeq ($(feature-llvm), 1)
> + CFLAGS += -DHAVE_LLVM_SUPPORT
> + CXXFLAGS += -DHAVE_LLVM_SUPPORT
> + CXXFLAGS += $(shell $(LLVM_CONFIG) --cxxflags)
> + LIBLLVM = $(shell $(LLVM_CONFIG) --libs all) $(shell $(LLVM_CONFIG) --system-libs)
> + EXTLIBS += -L$(shell $(LLVM_CONFIG) --libdir) $(LIBLLVM)
> + $(call detected,CONFIG_LLVM)
> + else
> + $(warning No libllvm found, slower source file resolution, please install llvm-devel/llvm-dev)
> + NO_LLVM := 1
> + endif
> +endif
> +
> ifndef NO_DEMANGLE
> $(call feature_check,cxa-demangle)
> ifeq ($(feature-cxa-demangle), 1)
> diff --git a/tools/perf/builtin-version.c b/tools/perf/builtin-version.c
> index 398aa53e9e2e..4b252196de12 100644
> --- a/tools/perf/builtin-version.c
> +++ b/tools/perf/builtin-version.c
> @@ -65,6 +65,7 @@ static void library_status(void)
> STATUS(HAVE_LIBBFD_SUPPORT, libbfd);
> STATUS(HAVE_DEBUGINFOD_SUPPORT, debuginfod);
> STATUS(HAVE_LIBELF_SUPPORT, libelf);
> + STATUS(HAVE_LIBLLVM_SUPPORT, libllvm);
> STATUS(HAVE_LIBNUMA_SUPPORT, libnuma);
> STATUS(HAVE_LIBNUMA_SUPPORT, numa_num_possible_cpus);
> STATUS(HAVE_LIBPERL_SUPPORT, libperl);
> diff --git a/tools/perf/util/Build b/tools/perf/util/Build
> index da64efd8718f..1cf17afd51f4 100644
> --- a/tools/perf/util/Build
> +++ b/tools/perf/util/Build
> @@ -226,6 +226,7 @@ perf-$(CONFIG_CXX_DEMANGLE) += demangle-cxx.o
> perf-y += demangle-ocaml.o
> perf-y += demangle-java.o
> perf-y += demangle-rust.o
> +perf-$(CONFIG_LLVM) += llvm-addr2line.o
>
> ifdef CONFIG_JITDUMP
> perf-$(CONFIG_LIBELF) += jitdump.o
> diff --git a/tools/perf/util/llvm-addr2line.cpp b/tools/perf/util/llvm-addr2line.cpp
> new file mode 100644
> index 000000000000..145488ed1346
> --- /dev/null
> +++ b/tools/perf/util/llvm-addr2line.cpp
> @@ -0,0 +1,134 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +/* Must come before the linux/compiler.h include, which defines several
> + * macros (e.g. noinline) that conflict with compiler builtins used by LLVM. */
> +#pragma GCC diagnostic push
> +#pragma GCC diagnostic ignored "-Wunused-parameter" /* Needed for LLVM 14. */
> +#include <llvm/DebugInfo/Symbolize/Symbolize.h>
> +#pragma GCC diagnostic pop
> +
> +#include <stdio.h>
> +#include <sys/types.h>
> +#include <linux/compiler.h>
> +#include "symbol_conf.h"
> +#include "llvm-addr2line.h"
> +
> +using namespace llvm;
> +using llvm::symbolize::LLVMSymbolizer;
> +
> +/*
> + * Allocate a static LLVMSymbolizer, which will live to the end of the program.
> + * Unlike the bfd paths, LLVMSymbolizer has its own cache, so we do not need
> + * to store anything in the dso struct.
> + */
> +static LLVMSymbolizer *GetSymbolizer()
> +{
> + static LLVMSymbolizer *instance = nullptr;
> + if (instance == nullptr) {
> + LLVMSymbolizer::Options Opts;
> + /*
> + * LLVM sometimes demangles slightly different from the rest
> + * of the code, and this mismatch can cause new_inline_sym()
> + * to get confused and mark non-inline symbol as inlined
> + * (since the name does not properly match up with base_sym).
> + * Thus, disable the demangling and let the rest of the code
> + * handle it.
> + */
> + Opts.Demangle = false;
> + instance = new LLVMSymbolizer(Opts);
> + }
> + return instance;
> +}
> +
> +/* Returns 0 on error, 1 on success. */
> +static int extract_file_and_line(const DILineInfo& line_info, char **file,
> + unsigned int *line)
> +{
> + if (file) {
> + if (line_info.FileName == "<invalid>") {
> + /* Match the convention of libbfd. */
> + *file = nullptr;
> + } else {
> + /* The caller expects to get something it can free(). */
> + *file = strdup(line_info.FileName.c_str());
> + if (*file == nullptr) {
> + return 0;
> + }
> + }
> + }
> + if (line) {
> + *line = line_info.Line;
> + }
nit: kernel style is no curly braces for a single line. If there are
curlies for the if or the else then curlies should be on both sides.
./scripts/checkpatch.pl should be able to catch things like this, but
it may ignore C++ files.
> + return 1;
> +}
> +
> +extern "C"
> +int llvm_addr2line(const char *dso_name, u64 addr,
> + char **file, unsigned int *line,
> + bool unwind_inlines,
> + llvm_a2l_frame** inline_frames)
> +{
> + LLVMSymbolizer *symbolizer = GetSymbolizer();
> + object::SectionedAddress sectioned_addr = {
> + addr,
> + object::SectionedAddress::UndefSection
> + };
> +
> + if (unwind_inlines) {
> + Expected<DIInliningInfo> res_or_err =
> + symbolizer->symbolizeInlinedCode(dso_name,
> + sectioned_addr);
nit: this may fit on a line as we wrap at 100 characters
> + if (!res_or_err) {
> + return 0;
> + }
nit: curlies
> + unsigned num_frames = res_or_err->getNumberOfFrames();
> + if (num_frames == 0) {
> + return 0;
> + }
nit: curlies.
> +
> + if (extract_file_and_line(
> + res_or_err->getFrame(0), file, line) == 0) {
> + return 0;
> + }
> +
> + *inline_frames = (llvm_a2l_frame*)malloc(
> + sizeof(**inline_frames) * num_frames);
> + if (*inline_frames == nullptr) {
> + return 0;
> + }
nit: curlies
> +
> + for (unsigned i = 0; i < num_frames; ++i) {
> + const DILineInfo& src = res_or_err->getFrame(i);
> + llvm_a2l_frame& dst = (*inline_frames)[i];
> + if (src.FileName == "<invalid>") {
> + /* Match the convention of libbfd. */
> + dst.filename = nullptr;
> + } else {
> + dst.filename = strdup(src.FileName.c_str());
> + }
> + dst.funcname = strdup(src.FunctionName.c_str());
> + dst.line = src.Line;
> +
> + if (dst.filename == nullptr ||
> + dst.funcname == nullptr) {
> + for (unsigned j = 0; j <= i; ++j) {
> + free((*inline_frames)[j].filename);
> + free((*inline_frames)[j].funcname);
> + }
> + free(*inline_frames);
> + return 0;
> + }
> + }
> +
> + return num_frames;
> + } else {
> + *inline_frames = nullptr;
> +
> + Expected<DILineInfo> res_or_err =
> + symbolizer->symbolizeCode(dso_name, sectioned_addr);
> + if (!res_or_err) {
> + return 0;
> + }
nit: curlies
Thanks,
Ian
> + return extract_file_and_line(*res_or_err, file, line);
> + }
> +}
> diff --git a/tools/perf/util/llvm-addr2line.h b/tools/perf/util/llvm-addr2line.h
> new file mode 100644
> index 000000000000..2de4fe79a3d0
> --- /dev/null
> +++ b/tools/perf/util/llvm-addr2line.h
> @@ -0,0 +1,42 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef __PERF_LLVM_ADDR2LINE
> +#define __PERF_LLVM_ADDR2LINE 1
> +
> +#ifdef __cplusplus
> +extern "C" {
> +#endif
> +
> +struct llvm_a2l_frame {
> + char *filename;
> + char *funcname;
> + unsigned int line;
> +};
> +
> +/*
> + * Implement addr2line() using libLLVM. LLVM is a C++ API, and
> + * many of the linux/ headers cannot be included in a C++ compile unit,
> + * so we need to make a little bridge code here. llvm_addr2line() will
> + * convert the inline frame information from LLVM's internal structures
> + * and put them into a flat array given in inline_frames. The caller
> + * is then responsible for taking that array and convert it into perf's
> + * regular inline frame structures (which depend on e.g. struct list_head).
> + *
> + * If the address could not be resolved, or an error occurred (e.g. OOM),
> + * returns 0. Otherwise, returns the number of inline frames (which means 1
> + * if the address was not part of an inlined function). If unwind_inlines
> + * is set and the return code is nonzero, inline_frames will be set to
> + * a newly allocated array with that length. The caller is then responsible
> + * for freeing both the strings and the array itself.
> + */
> +int llvm_addr2line(const char *dso_name,
> + u64 addr,
> + char **file,
> + unsigned int *line,
> + bool unwind_inlines,
> + struct llvm_a2l_frame **inline_frames);
> +
> +#ifdef __cplusplus
> +}
> +#endif
> +
> +#endif /* __PERF_LLVM_ADDR2LINE */
> diff --git a/tools/perf/util/srcline.c b/tools/perf/util/srcline.c
> index 9d670d8c1c08..f69ad21a18d4 100644
> --- a/tools/perf/util/srcline.c
> +++ b/tools/perf/util/srcline.c
> @@ -16,6 +16,7 @@
> #include "util/debug.h"
> #include "util/callchain.h"
> #include "util/symbol_conf.h"
> +#include "util/llvm-addr2line.h"
> #include "srcline.h"
> #include "string2.h"
> #include "symbol.h"
> @@ -130,7 +131,59 @@ static struct symbol *new_inline_sym(struct dso *dso,
>
> #define MAX_INLINE_NEST 1024
>
> -#ifdef HAVE_LIBBFD_SUPPORT
> +#ifdef HAVE_LLVM_SUPPORT
> +
> +static void free_llvm_inline_frames(struct llvm_a2l_frame *inline_frames,
> + int num_frames)
> +{
> + if (inline_frames != NULL) {
> + for (int i = 0; i < num_frames; ++i) {
> + free(inline_frames[i].filename);
> + free(inline_frames[i].funcname);
> + }
> + free(inline_frames);
> + }
> +}
> +
> +static int addr2line(const char *dso_name, u64 addr,
> + char **file, unsigned int *line, struct dso *dso,
> + bool unwind_inlines, struct inline_node *node,
> + struct symbol *sym)
> +{
> + struct llvm_a2l_frame *inline_frames = NULL;
> + int num_frames = llvm_addr2line(dso_name, addr, file, line,
> + node && unwind_inlines, &inline_frames);
> +
> + if (num_frames == 0 || !inline_frames) {
> + /* Error, or we didn't want inlines. */
> + return num_frames;
> + }
> +
> + for (int i = 0; i < num_frames; ++i) {
> + struct symbol *inline_sym =
> + new_inline_sym(dso, sym, inline_frames[i].funcname);
> + char *srcline = NULL;
> +
> + if (inline_frames[i].filename)
> + srcline = srcline_from_fileline(
> + inline_frames[i].filename,
> + inline_frames[i].line);
> + if (inline_list__append(inline_sym, srcline, node) != 0) {
> + free_llvm_inline_frames(inline_frames, num_frames);
> + return 0;
> + }
> + }
> + free_llvm_inline_frames(inline_frames, num_frames);
> +
> + return num_frames;
> +}
> +
> +void dso__free_a2l(struct dso *)
> +{
> + /* Nothing to free. */
> +}
> +
> +#elif defined(HAVE_LIBBFD_SUPPORT)
>
> /*
> * Implement addr2line using libbfd.
> --
> 2.43.0
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] perf report: Support LLVM for addr2line()
2024-05-17 21:27 ` Ian Rogers
@ 2024-05-18 16:52 ` Steinar H. Gunderson
0 siblings, 0 replies; 3+ messages in thread
From: Steinar H. Gunderson @ 2024-05-18 16:52 UTC (permalink / raw)
To: Ian Rogers; +Cc: Namhyung Kim, acme, linux-perf-users, linux-kernel
On Fri, May 17, 2024 at 02:27:43PM -0700, Ian Rogers wrote:
> This is great! There has been talk about the code being slow and I
> think libelf may have been another alternative for this (maybe also
> capstone). We should probably build a `perf bench` for this given the
> variety of choice.
I'm not sure if capstone can do this, but I don't know it very well.
libelf probably can, but LLVM has a nice advantage in that it also
supports, well, non-ELF.
I took the time to write an LLVM-based disassembler, too; it took some
coaxing (there's basically a C and a C++ API that are very different,
where the C API is much easier to set up but has some limitations),
but I think it ended up not too bad at all. I'm tacking it on to the
next patch series. I think after this, the only things really requiring
BUILD_NONDISTRO=1 would be non-ELF debuglink support, slightly different
demangling, and loading of PE symbols?
> nit: kernel style is no curly braces for a single line. If there are
> curlies for the if or the else then curlies should be on both sides.
> ./scripts/checkpatch.pl should be able to catch things like this, but
> it may ignore C++ files.
Ack. (I did run checkpatch, but as you guessed, it didn't complain.)
/* Steinar */
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2024-05-18 16:52 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2024-05-17 18:54 [PATCH] perf report: Support LLVM for addr2line() Steinar H. Gunderson
2024-05-17 21:27 ` Ian Rogers
2024-05-18 16:52 ` Steinar H. Gunderson
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).