[PATCH v8 1/3] perf report: Support LLVM for addr2line()

[PATCH v8 1/3] perf report: Support LLVM for addr2line()

[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 while bfd objdump can be slow on large binaries,
it is possible to use --objdump=llvm-objdump to get the speed benefits.
(It appears LLVM-based demangling is very simple, should we want
that.)

Tested with LLVM 14, 15, 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>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/build/Makefile.feature       |   1 +
 tools/perf/Makefile.config         |  15 ++++
 tools/perf/builtin-version.c       |   1 +
 tools/perf/util/Build              |   1 +
 tools/perf/util/llvm-c-helpers.cpp | 134 +++++++++++++++++++++++++++++
 tools/perf/util/llvm-c-helpers.h   |  49 +++++++++++
 tools/perf/util/srcline.c          |  57 +++++++++++-
 7 files changed, 257 insertions(+), 1 deletion(-)
 create mode 100644 tools/perf/util/llvm-c-helpers.cpp
 create mode 100644 tools/perf/util/llvm-c-helpers.h

diff --git a/tools/build/Makefile.feature b/tools/build/Makefile.feature
index 1e2ab148d5db..278b26216254 100644
--- a/tools/build/Makefile.feature
+++ b/tools/build/Makefile.feature
@@ -136,6 +136,7 @@ FEATURE_DISPLAY ?=              \
          libunwind              \
          libdw-dwarf-unwind     \
          libcapstone            \
+         llvm                   \
          zlib                   \
          lzma                   \
          get_cpuid              \
diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index 7f1e016a9253..42f5ad89c0ca 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -969,6 +969,21 @@ ifdef BUILD_NONDISTRO
   endif
 endif
 
+ifndef NO_LIBLLVM
+  $(call feature_check,llvm)
+  ifeq ($(feature-llvm), 1)
+    CFLAGS += -DHAVE_LIBLLVM_SUPPORT
+    CXXFLAGS += -DHAVE_LIBLLVM_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_LIBLLVM)
+  else
+    $(warning No libllvm found, slower source file resolution, please install llvm-devel/llvm-dev)
+    NO_LIBLLVM := 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..6a1fd8f1a488 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_LIBLLVM) += llvm-c-helpers.o
 
 ifdef CONFIG_JITDUMP
 perf-$(CONFIG_LIBELF) += jitdump.o
diff --git a/tools/perf/util/llvm-c-helpers.cpp b/tools/perf/util/llvm-c-helpers.cpp
new file mode 100644
index 000000000000..3cc967ec6f28
--- /dev/null
+++ b/tools/perf/util/llvm-c-helpers.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 <= 15 */
+#include <llvm/DebugInfo/Symbolize/Symbolize.h>
+#pragma GCC diagnostic pop
+
+#include <stdio.h>
+#include <sys/types.h>
+#include <linux/compiler.h>
+extern "C" {
+#include <linux/zalloc.h>
+}
+#include "symbol_conf.h"
+#include "llvm-c-helpers.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 *get_symbolizer()
+{
+	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 = get_symbolizer();
+	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 *)calloc(
+			num_frames, sizeof(**inline_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) {
+					zfree(&(*inline_frames)[j].filename);
+					zfree(&(*inline_frames)[j].funcname);
+				}
+				zfree(inline_frames);
+				return 0;
+			}
+		}
+
+		return num_frames;
+	} else {
+		if (inline_frames)
+			*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-c-helpers.h b/tools/perf/util/llvm-c-helpers.h
new file mode 100644
index 000000000000..19332dd98e14
--- /dev/null
+++ b/tools/perf/util/llvm-c-helpers.h
@@ -0,0 +1,49 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __PERF_LLVM_C_HELPERS
+#define __PERF_LLVM_C_HELPERS 1
+
+/*
+ * Helpers to call into LLVM C++ code from C, for the parts that do not have
+ * C APIs.
+ */
+
+#include <linux/compiler.h>
+
+#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_C_HELPERS */
diff --git a/tools/perf/util/srcline.c b/tools/perf/util/srcline.c
index 9d670d8c1c08..74091ecc21df 100644
--- a/tools/perf/util/srcline.c
+++ b/tools/perf/util/srcline.c
@@ -16,6 +16,9 @@
 #include "util/debug.h"
 #include "util/callchain.h"
 #include "util/symbol_conf.h"
+#ifdef HAVE_LIBLLVM_SUPPORT
+#include "util/llvm-c-helpers.h"
+#endif
 #include "srcline.h"
 #include "string2.h"
 #include "symbol.h"
@@ -130,7 +133,59 @@ static struct symbol *new_inline_sym(struct dso *dso,
 
 #define MAX_INLINE_NEST 1024
 
-#ifdef HAVE_LIBBFD_SUPPORT
+#ifdef HAVE_LIBLLVM_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) {
+			zfree(&inline_frames[i].filename);
+			zfree(&inline_frames[i].funcname);
+		}
+		zfree(&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.
-- 
2.45.1

[PATCH v8 2/3] perf annotate: split out read_symbol()

[Steinar H. Gunderson]

The Capstone disassembler code has a useful code snippet to read
the bytes for a given code symbol into memory. Split it out into
its own function, so that the LLVM disassembler can use it in
the next patch.

Signed-off-by: Steinar H. Gunderson <sesse@google.com>
---
 tools/perf/util/disasm.c | 90 +++++++++++++++++++++++++---------------
 1 file changed, 56 insertions(+), 34 deletions(-)

diff --git a/tools/perf/util/disasm.c b/tools/perf/util/disasm.c
index 72aec8f61b94..c0dbb955e61a 100644
--- a/tools/perf/util/disasm.c
+++ b/tools/perf/util/disasm.c
@@ -1396,6 +1396,53 @@ static int find_file_offset(u64 start, u64 len, u64 pgoff, void *arg)
 	return 0;
 }
 
+static u8 *
+read_symbol(const char *filename, struct map *map, struct symbol *sym,
+	    u64 *len, bool *is_64bit)
+{
+	struct dso *dso = map__dso(map);
+	struct nscookie nsc;
+	u64 start = map__rip_2objdump(map, sym->start);
+	u64 end = map__rip_2objdump(map, sym->end);
+	int fd, count;
+	u8 *buf = NULL;
+	struct find_file_offset_data data = {
+		.ip = start,
+	};
+
+	*is_64bit = false;
+
+	nsinfo__mountns_enter(dso__nsinfo(dso), &nsc);
+	fd = open(filename, O_RDONLY);
+	nsinfo__mountns_exit(&nsc);
+	if (fd < 0)
+		return NULL;
+
+	if (file__read_maps(fd, /*exe=*/true, find_file_offset, &data,
+			    is_64bit) == 0)
+		goto err;
+
+	*len = end - start;
+	buf = malloc(*len);
+	if (buf == NULL)
+		goto err;
+
+	count = pread(fd, buf, *len, data.offset);
+	close(fd);
+	fd = -1;
+
+	if ((u64)count != *len)
+		goto err;
+
+	return buf;
+
+err:
+	if (fd >= 0)
+		close(fd);
+	free(buf);
+	return NULL;
+}
+
 static void print_capstone_detail(cs_insn *insn, char *buf, size_t len,
 				  struct annotate_args *args, u64 addr)
 {
@@ -1458,19 +1505,13 @@ static int symbol__disassemble_capstone(char *filename, struct symbol *sym,
 {
 	struct annotation *notes = symbol__annotation(sym);
 	struct map *map = args->ms.map;
-	struct dso *dso = map__dso(map);
-	struct nscookie nsc;
 	u64 start = map__rip_2objdump(map, sym->start);
-	u64 end = map__rip_2objdump(map, sym->end);
-	u64 len = end - start;
+	u64 len;
 	u64 offset;
-	int i, fd, count;
+	int i, count;
 	bool is_64bit = false;
 	bool needs_cs_close = false;
 	u8 *buf = NULL;
-	struct find_file_offset_data data = {
-		.ip = start,
-	};
 	csh handle;
 	cs_insn *insn;
 	char disasm_buf[512];
@@ -1479,31 +1520,9 @@ static int symbol__disassemble_capstone(char *filename, struct symbol *sym,
 	if (args->options->objdump_path)
 		return -1;
 
-	nsinfo__mountns_enter(dso__nsinfo(dso), &nsc);
-	fd = open(filename, O_RDONLY);
-	nsinfo__mountns_exit(&nsc);
-	if (fd < 0)
-		return -1;
-
-	if (file__read_maps(fd, /*exe=*/true, find_file_offset, &data,
-			    &is_64bit) == 0)
-		goto err;
-
-	if (open_capstone_handle(args, is_64bit, &handle) < 0)
-		goto err;
-
-	needs_cs_close = true;
-
-	buf = malloc(len);
+	buf = read_symbol(filename, map, sym, &len, &is_64bit);
 	if (buf == NULL)
-		goto err;
-
-	count = pread(fd, buf, len, data.offset);
-	close(fd);
-	fd = -1;
-
-	if ((u64)count != len)
-		goto err;
+		return -1;
 
 	/* add the function address and name */
 	scnprintf(disasm_buf, sizeof(disasm_buf), "%#"PRIx64" <%s>:",
@@ -1521,6 +1540,11 @@ static int symbol__disassemble_capstone(char *filename, struct symbol *sym,
 
 	annotation_line__add(&dl->al, &notes->src->source);
 
+	if (open_capstone_handle(args, is_64bit, &handle) < 0)
+		goto err;
+
+	needs_cs_close = true;
+
 	count = cs_disasm(handle, buf, len, start, len, &insn);
 	for (i = 0, offset = 0; i < count; i++) {
 		int printed;
@@ -1565,8 +1589,6 @@ static int symbol__disassemble_capstone(char *filename, struct symbol *sym,
 	return count < 0 ? count : 0;
 
 err:
-	if (fd >= 0)
-		close(fd);
 	if (needs_cs_close) {
 		struct disasm_line *tmp;
 
-- 
2.45.1

[PATCH v8 3/3] perf annotate: LLVM-based disassembler

[Steinar H. Gunderson]

Support using LLVM as a disassembler method, allowing helperless
annotation in non-distro builds. (It is also much faster than
using libbfd or bfd objdump on binaries with a lot of debug
information.)

This is nearly identical to the output of llvm-objdump; there are
some very rare whitespace differences, some minor changes to demangling
(since we use perf's regular demangling and not LLVM's own) and
the occasional case where llvm-objdump makes a different choice
when multiple symbols share the same address. It should work across
all of LLVM's supported architectures, although I've only tested 64-bit
x86, and finding the right triple from perf's idea of machine
architecture can sometimes be a bit tricky. Ideally, we should have
some way of finding the triplet just from the file itself.

Signed-off-by: Steinar H. Gunderson <sesse@google.com>
---
 tools/perf/util/disasm.c           | 193 +++++++++++++++++++++++++++++
 tools/perf/util/llvm-c-helpers.cpp |  62 +++++++++
 tools/perf/util/llvm-c-helpers.h   |  11 ++
 3 files changed, 266 insertions(+)

diff --git a/tools/perf/util/disasm.c b/tools/perf/util/disasm.c
index c0dbb955e61a..4946e9ccf93b 100644
--- a/tools/perf/util/disasm.c
+++ b/tools/perf/util/disasm.c
@@ -43,6 +43,7 @@ static int call__scnprintf(struct ins *ins, char *bf, size_t size,
 
 static void ins__sort(struct arch *arch);
 static int disasm_line__parse(char *line, const char **namep, char **rawp);
+static char *expand_tabs(char *line, char **storage, size_t *storage_len);
 
 static __attribute__((constructor)) void symbol__init_regexpr(void)
 {
@@ -1378,7 +1379,9 @@ static int open_capstone_handle(struct annotate_args *args, bool is_64bit,
 
 	return 0;
 }
+#endif
 
+#if defined(HAVE_LIBCAPSTONE_SUPPORT) || defined(HAVE_LIBLLVM_SUPPORT)
 struct find_file_offset_data {
 	u64 ip;
 	u64 offset;
@@ -1442,7 +1445,9 @@ read_symbol(const char *filename, struct map *map, struct symbol *sym,
 	free(buf);
 	return NULL;
 }
+#endif
 
+#ifdef HAVE_LIBCAPSTONE_SUPPORT
 static void print_capstone_detail(cs_insn *insn, char *buf, size_t len,
 				  struct annotate_args *args, u64 addr)
 {
@@ -1606,6 +1611,189 @@ static int symbol__disassemble_capstone(char *filename, struct symbol *sym,
 }
 #endif
 
+#ifdef HAVE_LIBLLVM_SUPPORT
+#include <llvm-c/Disassembler.h>
+#include <llvm-c/Target.h>
+#include "util/llvm-c-helpers.h"
+
+struct symbol_lookup_storage {
+	u64 branch_addr;
+	u64 pcrel_load_addr;
+};
+
+/*
+ * Whenever LLVM wants to resolve an address into a symbol, it calls this
+ * callback. We don't ever actually _return_ anything (in particular, because
+ * it puts quotation marks around what we return), but we use this as a hint
+ * that there is a branch or PC-relative address in the expression that we
+ * should add some textual annotation for after the instruction. The caller
+ * will use this information to add the actual annotation.
+ */
+static const char *
+symbol_lookup_callback(void *disinfo, uint64_t value,
+		       uint64_t *ref_type,
+		       uint64_t address __maybe_unused,
+		       const char **ref __maybe_unused)
+{
+	struct symbol_lookup_storage *storage = disinfo;
+
+	if (*ref_type == LLVMDisassembler_ReferenceType_In_Branch)
+		storage->branch_addr = value;
+	else if (*ref_type == LLVMDisassembler_ReferenceType_In_PCrel_Load)
+		storage->pcrel_load_addr = value;
+	*ref_type = LLVMDisassembler_ReferenceType_InOut_None;
+	return NULL;
+}
+
+static int symbol__disassemble_llvm(char *filename, struct symbol *sym,
+				    struct annotate_args *args)
+{
+	struct annotation *notes = symbol__annotation(sym);
+	struct map *map = args->ms.map;
+	struct dso *dso = map__dso(map);
+	u64 start = map__rip_2objdump(map, sym->start);
+	u8 *buf;
+	u64 len;
+	u64 pc;
+	bool is_64bit;
+	char triplet[64];
+	char disasm_buf[2048];
+	size_t disasm_len;
+	struct disasm_line *dl;
+	LLVMDisasmContextRef disasm = NULL;
+	struct symbol_lookup_storage storage;
+	char *line_storage = NULL;
+	size_t line_storage_len = 0;
+	int ret = -1;
+
+	if (args->options->objdump_path)
+		return -1;
+
+	LLVMInitializeAllTargetInfos();
+	LLVMInitializeAllTargetMCs();
+	LLVMInitializeAllDisassemblers();
+
+	buf = read_symbol(filename, map, sym, &len, &is_64bit);
+	if (buf == NULL)
+		return -1;
+
+	if (arch__is(args->arch, "x86")) {
+		if (is_64bit)
+			scnprintf(triplet, sizeof(triplet), "x86_64-pc-linux");
+		else
+			scnprintf(triplet, sizeof(triplet), "i686-pc-linux");
+	} else {
+		scnprintf(triplet, sizeof(triplet), "%s-linux-gnu",
+			  args->arch->name);
+	}
+
+	disasm = LLVMCreateDisasm(triplet, &storage, 0, NULL,
+				  symbol_lookup_callback);
+	if (disasm == NULL)
+		goto err;
+
+	if (args->options->disassembler_style &&
+	    !strcmp(args->options->disassembler_style, "intel"))
+		LLVMSetDisasmOptions(disasm,
+				     LLVMDisassembler_Option_AsmPrinterVariant);
+
+	/*
+	 * This needs to be set after AsmPrinterVariant, due to a bug in LLVM;
+	 * setting AsmPrinterVariant makes a new instruction printer, making it
+	 * forget about the PrintImmHex flag (which is applied before if both
+	 * are given to the same call).
+	 */
+	LLVMSetDisasmOptions(disasm, LLVMDisassembler_Option_PrintImmHex);
+
+	/* add the function address and name */
+	scnprintf(disasm_buf, sizeof(disasm_buf), "%#"PRIx64" <%s>:",
+		  start, sym->name);
+
+	args->offset = -1;
+	args->line = disasm_buf;
+	args->line_nr = 0;
+	args->fileloc = NULL;
+	args->ms.sym = sym;
+
+	dl = disasm_line__new(args);
+	if (dl == NULL)
+		goto err;
+
+	annotation_line__add(&dl->al, &notes->src->source);
+
+	pc = start;
+	for (u64 offset = 0; offset < len; ) {
+		unsigned int ins_len;
+
+		storage.branch_addr = 0;
+		storage.pcrel_load_addr = 0;
+
+		ins_len = LLVMDisasmInstruction(disasm, buf + offset,
+						len - offset, pc,
+						disasm_buf, sizeof(disasm_buf));
+		if (ins_len == 0)
+			goto err;
+		disasm_len = strlen(disasm_buf);
+
+		if (storage.branch_addr != 0) {
+			char *name = llvm_name_for_code(dso, filename,
+							storage.branch_addr);
+			if (name != NULL) {
+				disasm_len += scnprintf(disasm_buf + disasm_len,
+							sizeof(disasm_buf) -
+								disasm_len,
+							" <%s>", name);
+				free(name);
+			}
+		}
+		if (storage.pcrel_load_addr != 0) {
+			char *name = llvm_name_for_data(dso, filename,
+							storage.pcrel_load_addr);
+			disasm_len += scnprintf(disasm_buf + disasm_len,
+						sizeof(disasm_buf) - disasm_len,
+						"  # %#"PRIx64,
+						storage.pcrel_load_addr);
+			if (name) {
+				disasm_len += scnprintf(disasm_buf + disasm_len,
+							sizeof(disasm_buf) -
+							disasm_len,
+							" <%s>", name);
+				free(name);
+			}
+		}
+
+		args->offset = offset;
+		args->line = expand_tabs(disasm_buf, &line_storage,
+					 &line_storage_len);
+		args->line_nr = 0;
+		args->fileloc = NULL;
+		args->ms.sym = sym;
+
+		llvm_addr2line(filename, pc, &args->fileloc,
+			       (unsigned int *)&args->line_nr, false, NULL);
+
+		dl = disasm_line__new(args);
+		if (dl == NULL)
+			goto err;
+
+		annotation_line__add(&dl->al, &notes->src->source);
+
+		free(args->fileloc);
+		pc += ins_len;
+		offset += ins_len;
+	}
+
+	ret = 0;
+
+err:
+	LLVMDisasmDispose(disasm);
+	free(buf);
+	free(line_storage);
+	return ret;
+}
+#endif
+
+
 /*
  * Possibly create a new version of line with tabs expanded. Returns the
  * existing or new line, storage is updated if a new line is allocated. If
@@ -1730,6 +1918,11 @@ int symbol__disassemble(struct symbol *sym, struct annotate_args *args)
 		strcpy(symfs_filename, tmp);
 	}
 
+#ifdef HAVE_LIBLLVM_SUPPORT
+	err = symbol__disassemble_llvm(symfs_filename, sym, args);
+	if (err == 0)
+		goto out_remove_tmp;
+#endif
 #ifdef HAVE_LIBCAPSTONE_SUPPORT
 	err = symbol__disassemble_capstone(symfs_filename, sym, args);
 	if (err == 0)
diff --git a/tools/perf/util/llvm-c-helpers.cpp b/tools/perf/util/llvm-c-helpers.cpp
index 3cc967ec6f28..4070e2d5682f 100644
--- a/tools/perf/util/llvm-c-helpers.cpp
+++ b/tools/perf/util/llvm-c-helpers.cpp
@@ -8,6 +8,7 @@
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wunused-parameter"  /* Needed for LLVM <= 15 */
 #include <llvm/DebugInfo/Symbolize/Symbolize.h>
+#include <llvm/Support/TargetSelect.h>
 #pragma GCC diagnostic pop
 
 #include <stdio.h>
@@ -19,6 +20,9 @@ extern "C" {
 #include "symbol_conf.h"
 #include "llvm-c-helpers.h"
 
+extern "C"
+char *dso__demangle_sym(struct dso *dso, int kmodule, const char *elf_name);
+
 using namespace llvm;
 using llvm::symbolize::LLVMSymbolizer;
 
@@ -132,3 +136,61 @@ int llvm_addr2line(const char *dso_name, u64 addr,
 		return extract_file_and_line(*res_or_err, file, line);
 	}
 }
+
+static char *
+make_symbol_relative_string(struct dso *dso, const char *sym_name,
+			    u64 addr, u64 base_addr)
+{
+	if (!strcmp(sym_name, "<invalid>"))
+		return NULL;
+
+	char *demangled = dso__demangle_sym(dso, 0, sym_name);
+	if (base_addr && base_addr != addr) {
+		char buf[256];
+		snprintf(buf, sizeof(buf), "%s+0x%lx",
+			 demangled ? demangled : sym_name, addr - base_addr);
+		free(demangled);
+		return strdup(buf);
+	} else {
+		if (demangled)
+			return demangled;
+		else
+			return strdup(sym_name);
+	}
+}
+
+extern "C"
+char *llvm_name_for_code(struct dso *dso, const char *dso_name, u64 addr)
+{
+	LLVMSymbolizer *symbolizer = get_symbolizer();
+	object::SectionedAddress sectioned_addr = {
+		addr,
+		object::SectionedAddress::UndefSection
+	};
+	Expected<DILineInfo> res_or_err =
+		symbolizer->symbolizeCode(dso_name, sectioned_addr);
+	if (!res_or_err) {
+		return NULL;
+	}
+	return make_symbol_relative_string(
+		dso, res_or_err->FunctionName.c_str(),
+		addr, res_or_err->StartAddress ? *res_or_err->StartAddress : 0);
+}
+
+extern "C"
+char *llvm_name_for_data(struct dso *dso, const char *dso_name, u64 addr)
+{
+	LLVMSymbolizer *symbolizer = get_symbolizer();
+	object::SectionedAddress sectioned_addr = {
+		addr,
+		object::SectionedAddress::UndefSection
+	};
+	Expected<DIGlobal> res_or_err =
+		symbolizer->symbolizeData(dso_name, sectioned_addr);
+	if (!res_or_err) {
+		return NULL;
+	}
+	return make_symbol_relative_string(
+		dso, res_or_err->Name.c_str(),
+		addr, res_or_err->Start);
+}
diff --git a/tools/perf/util/llvm-c-helpers.h b/tools/perf/util/llvm-c-helpers.h
index 19332dd98e14..d2b99637a28a 100644
--- a/tools/perf/util/llvm-c-helpers.h
+++ b/tools/perf/util/llvm-c-helpers.h
@@ -13,6 +13,8 @@
 extern "C" {
 #endif
 
+struct dso;
+
 struct llvm_a2l_frame {
   char* filename;
   char* funcname;
@@ -42,6 +44,15 @@ int llvm_addr2line(const char* dso_name,
                    bool unwind_inlines,
                    struct llvm_a2l_frame** inline_frames);
 
+/*
+ * Simple symbolizers for addresses; will convert something like
+ * 0x12345 to "func+0x123". Will return NULL if no symbol was found.
+ *
+ * The returned value must be freed by the caller, with free().
+ */
+char *llvm_name_for_code(struct dso *dso, const char *dso_name, u64 addr);
+char *llvm_name_for_data(struct dso *dso, const char *dso_name, u64 addr);
+
 #ifdef __cplusplus
 }
 #endif
-- 
2.45.1

Re: [PATCH v8 3/3] perf annotate: LLVM-based disassembler

[Namhyung Kim]

Hello,

On Sun, Jun 02, 2024 at 10:42:08PM +0200, Steinar H. Gunderson wrote:
> Support using LLVM as a disassembler method, allowing helperless
> annotation in non-distro builds. (It is also much faster than
> using libbfd or bfd objdump on binaries with a lot of debug
> information.)
> 
> This is nearly identical to the output of llvm-objdump; there are
> some very rare whitespace differences, some minor changes to demangling
> (since we use perf's regular demangling and not LLVM's own) and
> the occasional case where llvm-objdump makes a different choice
> when multiple symbols share the same address. It should work across
> all of LLVM's supported architectures, although I've only tested 64-bit
> x86, and finding the right triple from perf's idea of machine
> architecture can sometimes be a bit tricky. Ideally, we should have
> some way of finding the triplet just from the file itself.
> 
> Signed-off-by: Steinar H. Gunderson <sesse@google.com>

I got a build error like this:

    CC      util/disasm.o
  util/disasm.c:1615:10: fatal error: llvm-c/Disassembler.h: No such file or directory
   1615 | #include <llvm-c/Disassembler.h>
        |          ^~~~~~~~~~~~~~~~~~~~~~~
  compilation terminated.

My LLVM version is 16.

  $ llvm-config --version
  16.0.6

Thanks,
Namhyung

> ---
>  tools/perf/util/disasm.c           | 193 +++++++++++++++++++++++++++++
>  tools/perf/util/llvm-c-helpers.cpp |  62 +++++++++
>  tools/perf/util/llvm-c-helpers.h   |  11 ++
>  3 files changed, 266 insertions(+)
> 
> diff --git a/tools/perf/util/disasm.c b/tools/perf/util/disasm.c
> index c0dbb955e61a..4946e9ccf93b 100644
> --- a/tools/perf/util/disasm.c
> +++ b/tools/perf/util/disasm.c
> @@ -43,6 +43,7 @@ static int call__scnprintf(struct ins *ins, char *bf, size_t size,
>  
>  static void ins__sort(struct arch *arch);
>  static int disasm_line__parse(char *line, const char **namep, char **rawp);
> +static char *expand_tabs(char *line, char **storage, size_t *storage_len);
>  
>  static __attribute__((constructor)) void symbol__init_regexpr(void)
>  {
> @@ -1378,7 +1379,9 @@ static int open_capstone_handle(struct annotate_args *args, bool is_64bit,
>  
>  	return 0;
>  }
> +#endif
>  
> +#if defined(HAVE_LIBCAPSTONE_SUPPORT) || defined(HAVE_LIBLLVM_SUPPORT)
>  struct find_file_offset_data {
>  	u64 ip;
>  	u64 offset;
> @@ -1442,7 +1445,9 @@ read_symbol(const char *filename, struct map *map, struct symbol *sym,
>  	free(buf);
>  	return NULL;
>  }
> +#endif
>  
> +#ifdef HAVE_LIBCAPSTONE_SUPPORT
>  static void print_capstone_detail(cs_insn *insn, char *buf, size_t len,
>  				  struct annotate_args *args, u64 addr)
>  {
> @@ -1606,6 +1611,189 @@ static int symbol__disassemble_capstone(char *filename, struct symbol *sym,
>  }
>  #endif
>  
> +#ifdef HAVE_LIBLLVM_SUPPORT
> +#include <llvm-c/Disassembler.h>
> +#include <llvm-c/Target.h>
> +#include "util/llvm-c-helpers.h"
> +
> +struct symbol_lookup_storage {
> +	u64 branch_addr;
> +	u64 pcrel_load_addr;
> +};
> +
> +/*
> + * Whenever LLVM wants to resolve an address into a symbol, it calls this
> + * callback. We don't ever actually _return_ anything (in particular, because
> + * it puts quotation marks around what we return), but we use this as a hint
> + * that there is a branch or PC-relative address in the expression that we
> + * should add some textual annotation for after the instruction. The caller
> + * will use this information to add the actual annotation.
> + */
> +static const char *
> +symbol_lookup_callback(void *disinfo, uint64_t value,
> +		       uint64_t *ref_type,
> +		       uint64_t address __maybe_unused,
> +		       const char **ref __maybe_unused)
> +{
> +	struct symbol_lookup_storage *storage = disinfo;
> +
> +	if (*ref_type == LLVMDisassembler_ReferenceType_In_Branch)
> +		storage->branch_addr = value;
> +	else if (*ref_type == LLVMDisassembler_ReferenceType_In_PCrel_Load)
> +		storage->pcrel_load_addr = value;
> +	*ref_type = LLVMDisassembler_ReferenceType_InOut_None;
> +	return NULL;
> +}
> +
> +static int symbol__disassemble_llvm(char *filename, struct symbol *sym,
> +				    struct annotate_args *args)
> +{
> +	struct annotation *notes = symbol__annotation(sym);
> +	struct map *map = args->ms.map;
> +	struct dso *dso = map__dso(map);
> +	u64 start = map__rip_2objdump(map, sym->start);
> +	u8 *buf;
> +	u64 len;
> +	u64 pc;
> +	bool is_64bit;
> +	char triplet[64];
> +	char disasm_buf[2048];
> +	size_t disasm_len;
> +	struct disasm_line *dl;
> +	LLVMDisasmContextRef disasm = NULL;
> +	struct symbol_lookup_storage storage;
> +	char *line_storage = NULL;
> +	size_t line_storage_len = 0;
> +	int ret = -1;
> +
> +	if (args->options->objdump_path)
> +		return -1;
> +
> +	LLVMInitializeAllTargetInfos();
> +	LLVMInitializeAllTargetMCs();
> +	LLVMInitializeAllDisassemblers();
> +
> +	buf = read_symbol(filename, map, sym, &len, &is_64bit);
> +	if (buf == NULL)
> +		return -1;
> +
> +	if (arch__is(args->arch, "x86")) {
> +		if (is_64bit)
> +			scnprintf(triplet, sizeof(triplet), "x86_64-pc-linux");
> +		else
> +			scnprintf(triplet, sizeof(triplet), "i686-pc-linux");
> +	} else {
> +		scnprintf(triplet, sizeof(triplet), "%s-linux-gnu",
> +			  args->arch->name);
> +	}
> +
> +	disasm = LLVMCreateDisasm(triplet, &storage, 0, NULL,
> +				  symbol_lookup_callback);
> +	if (disasm == NULL)
> +		goto err;
> +
> +	if (args->options->disassembler_style &&
> +	    !strcmp(args->options->disassembler_style, "intel"))
> +		LLVMSetDisasmOptions(disasm,
> +				     LLVMDisassembler_Option_AsmPrinterVariant);
> +
> +	/*
> +	 * This needs to be set after AsmPrinterVariant, due to a bug in LLVM;
> +	 * setting AsmPrinterVariant makes a new instruction printer, making it
> +	 * forget about the PrintImmHex flag (which is applied before if both
> +	 * are given to the same call).
> +	 */
> +	LLVMSetDisasmOptions(disasm, LLVMDisassembler_Option_PrintImmHex);
> +
> +	/* add the function address and name */
> +	scnprintf(disasm_buf, sizeof(disasm_buf), "%#"PRIx64" <%s>:",
> +		  start, sym->name);
> +
> +	args->offset = -1;
> +	args->line = disasm_buf;
> +	args->line_nr = 0;
> +	args->fileloc = NULL;
> +	args->ms.sym = sym;
> +
> +	dl = disasm_line__new(args);
> +	if (dl == NULL)
> +		goto err;
> +
> +	annotation_line__add(&dl->al, &notes->src->source);
> +
> +	pc = start;
> +	for (u64 offset = 0; offset < len; ) {
> +		unsigned int ins_len;
> +
> +		storage.branch_addr = 0;
> +		storage.pcrel_load_addr = 0;
> +
> +		ins_len = LLVMDisasmInstruction(disasm, buf + offset,
> +						len - offset, pc,
> +						disasm_buf, sizeof(disasm_buf));
> +		if (ins_len == 0)
> +			goto err;
> +		disasm_len = strlen(disasm_buf);
> +
> +		if (storage.branch_addr != 0) {
> +			char *name = llvm_name_for_code(dso, filename,
> +							storage.branch_addr);
> +			if (name != NULL) {
> +				disasm_len += scnprintf(disasm_buf + disasm_len,
> +							sizeof(disasm_buf) -
> +								disasm_len,
> +							" <%s>", name);
> +				free(name);
> +			}
> +		}
> +		if (storage.pcrel_load_addr != 0) {
> +			char *name = llvm_name_for_data(dso, filename,
> +							storage.pcrel_load_addr);
> +			disasm_len += scnprintf(disasm_buf + disasm_len,
> +						sizeof(disasm_buf) - disasm_len,
> +						"  # %#"PRIx64,
> +						storage.pcrel_load_addr);
> +			if (name) {
> +				disasm_len += scnprintf(disasm_buf + disasm_len,
> +							sizeof(disasm_buf) -
> +							disasm_len,
> +							" <%s>", name);
> +				free(name);
> +			}
> +		}
> +
> +		args->offset = offset;
> +		args->line = expand_tabs(disasm_buf, &line_storage,
> +					 &line_storage_len);
> +		args->line_nr = 0;
> +		args->fileloc = NULL;
> +		args->ms.sym = sym;
> +
> +		llvm_addr2line(filename, pc, &args->fileloc,
> +			       (unsigned int *)&args->line_nr, false, NULL);
> +
> +		dl = disasm_line__new(args);
> +		if (dl == NULL)
> +			goto err;
> +
> +		annotation_line__add(&dl->al, &notes->src->source);
> +
> +		free(args->fileloc);
> +		pc += ins_len;
> +		offset += ins_len;
> +	}
> +
> +	ret = 0;
> +
> +err:
> +	LLVMDisasmDispose(disasm);
> +	free(buf);
> +	free(line_storage);
> +	return ret;
> +}
> +#endif
> +
> +
>  /*
>   * Possibly create a new version of line with tabs expanded. Returns the
>   * existing or new line, storage is updated if a new line is allocated. If
> @@ -1730,6 +1918,11 @@ int symbol__disassemble(struct symbol *sym, struct annotate_args *args)
>  		strcpy(symfs_filename, tmp);
>  	}
>  
> +#ifdef HAVE_LIBLLVM_SUPPORT
> +	err = symbol__disassemble_llvm(symfs_filename, sym, args);
> +	if (err == 0)
> +		goto out_remove_tmp;
> +#endif
>  #ifdef HAVE_LIBCAPSTONE_SUPPORT
>  	err = symbol__disassemble_capstone(symfs_filename, sym, args);
>  	if (err == 0)
> diff --git a/tools/perf/util/llvm-c-helpers.cpp b/tools/perf/util/llvm-c-helpers.cpp
> index 3cc967ec6f28..4070e2d5682f 100644
> --- a/tools/perf/util/llvm-c-helpers.cpp
> +++ b/tools/perf/util/llvm-c-helpers.cpp
> @@ -8,6 +8,7 @@
>  #pragma GCC diagnostic push
>  #pragma GCC diagnostic ignored "-Wunused-parameter"  /* Needed for LLVM <= 15 */
>  #include <llvm/DebugInfo/Symbolize/Symbolize.h>
> +#include <llvm/Support/TargetSelect.h>
>  #pragma GCC diagnostic pop
>  
>  #include <stdio.h>
> @@ -19,6 +20,9 @@ extern "C" {
>  #include "symbol_conf.h"
>  #include "llvm-c-helpers.h"
>  
> +extern "C"
> +char *dso__demangle_sym(struct dso *dso, int kmodule, const char *elf_name);
> +
>  using namespace llvm;
>  using llvm::symbolize::LLVMSymbolizer;
>  
> @@ -132,3 +136,61 @@ int llvm_addr2line(const char *dso_name, u64 addr,
>  		return extract_file_and_line(*res_or_err, file, line);
>  	}
>  }
> +
> +static char *
> +make_symbol_relative_string(struct dso *dso, const char *sym_name,
> +			    u64 addr, u64 base_addr)
> +{
> +	if (!strcmp(sym_name, "<invalid>"))
> +		return NULL;
> +
> +	char *demangled = dso__demangle_sym(dso, 0, sym_name);
> +	if (base_addr && base_addr != addr) {
> +		char buf[256];
> +		snprintf(buf, sizeof(buf), "%s+0x%lx",
> +			 demangled ? demangled : sym_name, addr - base_addr);
> +		free(demangled);
> +		return strdup(buf);
> +	} else {
> +		if (demangled)
> +			return demangled;
> +		else
> +			return strdup(sym_name);
> +	}
> +}
> +
> +extern "C"
> +char *llvm_name_for_code(struct dso *dso, const char *dso_name, u64 addr)
> +{
> +	LLVMSymbolizer *symbolizer = get_symbolizer();
> +	object::SectionedAddress sectioned_addr = {
> +		addr,
> +		object::SectionedAddress::UndefSection
> +	};
> +	Expected<DILineInfo> res_or_err =
> +		symbolizer->symbolizeCode(dso_name, sectioned_addr);
> +	if (!res_or_err) {
> +		return NULL;
> +	}
> +	return make_symbol_relative_string(
> +		dso, res_or_err->FunctionName.c_str(),
> +		addr, res_or_err->StartAddress ? *res_or_err->StartAddress : 0);
> +}
> +
> +extern "C"
> +char *llvm_name_for_data(struct dso *dso, const char *dso_name, u64 addr)
> +{
> +	LLVMSymbolizer *symbolizer = get_symbolizer();
> +	object::SectionedAddress sectioned_addr = {
> +		addr,
> +		object::SectionedAddress::UndefSection
> +	};
> +	Expected<DIGlobal> res_or_err =
> +		symbolizer->symbolizeData(dso_name, sectioned_addr);
> +	if (!res_or_err) {
> +		return NULL;
> +	}
> +	return make_symbol_relative_string(
> +		dso, res_or_err->Name.c_str(),
> +		addr, res_or_err->Start);
> +}
> diff --git a/tools/perf/util/llvm-c-helpers.h b/tools/perf/util/llvm-c-helpers.h
> index 19332dd98e14..d2b99637a28a 100644
> --- a/tools/perf/util/llvm-c-helpers.h
> +++ b/tools/perf/util/llvm-c-helpers.h
> @@ -13,6 +13,8 @@
>  extern "C" {
>  #endif
>  
> +struct dso;
> +
>  struct llvm_a2l_frame {
>    char* filename;
>    char* funcname;
> @@ -42,6 +44,15 @@ int llvm_addr2line(const char* dso_name,
>                     bool unwind_inlines,
>                     struct llvm_a2l_frame** inline_frames);
>  
> +/*
> + * Simple symbolizers for addresses; will convert something like
> + * 0x12345 to "func+0x123". Will return NULL if no symbol was found.
> + *
> + * The returned value must be freed by the caller, with free().
> + */
> +char *llvm_name_for_code(struct dso *dso, const char *dso_name, u64 addr);
> +char *llvm_name_for_data(struct dso *dso, const char *dso_name, u64 addr);
> +
>  #ifdef __cplusplus
>  }
>  #endif
> -- 
> 2.45.1
> 

Re: [PATCH v8 1/3] perf report: Support LLVM for addr2line()

[Namhyung Kim]

On Sun, Jun 02, 2024 at 10:42:06PM +0200, Steinar H. Gunderson 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.
> 
> 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 while bfd objdump can be slow on large binaries,
> it is possible to use --objdump=llvm-objdump to get the speed benefits.
> (It appears LLVM-based demangling is very simple, should we want
> that.)
> 
> Tested with LLVM 14, 15, 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>
> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
> ---
[SNIP]
> +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);

Please fix the coding style.  Also you may add a pair of brackets to
multi-line code even if it's a single statement.

Thanks,
Namhyung


> +		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.
> -- 
> 2.45.1
> 

Re: [PATCH v8 1/3] perf report: Support LLVM for addr2line()

[Steinar H. Gunderson]

On Wed, Jun 05, 2024 at 10:39:41AM -0700, Namhyung Kim wrote:
> Please fix the coding style.  Also you may add a pair of brackets to
> multi-line code even if it's a single statement.

Fixed (I think?). Sending out a v9 also with added build test plus a fix
for /usr/include/llvm-c not existing.

/* Steinar */

Re: [PATCH v8 1/3] perf report: Support LLVM for addr2line()

[kernel test robot]

:::::: 
:::::: Manual check reason: "low confidence bisect report"
:::::: 

BCC: lkp@intel.com
CC: oe-kbuild-all@lists.linux.dev
In-Reply-To: <20240602204208.735793-1-sesse@google.com>
References: <20240602204208.735793-1-sesse@google.com>
TO: "Steinar H. Gunderson" <sesse@google.com>
TO: acme@kernel.org
CC: linux-perf-users@vger.kernel.org
CC: linux-kernel@vger.kernel.org
CC: irogers@google.com
CC: "Steinar H. Gunderson" <sesse@google.com>
CC: Arnaldo Carvalho de Melo <acme@redhat.com>

Hi Steinar,

kernel test robot noticed the following build errors:

[auto build test ERROR on perf-tools-next/perf-tools-next]
[also build test ERROR on tip/perf/core perf-tools/perf-tools linus/master v6.10-rc2 next-20240606]
[cannot apply to acme/perf/core]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Steinar-H-Gunderson/perf-annotate-split-out-read_symbol/20240603-044420
base:   https://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git perf-tools-next
patch link:    https://lore.kernel.org/r/20240602204208.735793-1-sesse%40google.com
patch subject: [PATCH v8 1/3] perf report: Support LLVM for addr2line()
:::::: branch date: 4 days ago
:::::: commit date: 4 days ago
compiler: clang version 18.1.5 (https://github.com/llvm/llvm-project 617a15a9eac96088ae5e9134248d8236e34b91b1)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240606/202406061836.rCHPTTLb-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/r/202406061836.rCHPTTLb-lkp@intel.com/

All errors (new ones prefixed by >>):

   Makefile.config:663: No libunwind found. Please install libunwind-dev[el] >= 1.1 and/or set LIBUNWIND_DIR
     PERF_VERSION = 6.10.rc1.gd3c83c542797
>> util/srcline.c:183:32: error: omitting the parameter name in a function definition is a C23 extension [-Werror,-Wc23-extensions]
     183 | void dso__free_a2l(struct dso *)
         |                                ^
   1 error generated.
   make[7]: *** [tools/build/Makefile.build:105: tools/perf/util/srcline.o] Error 1
   make[7]: *** Waiting for unfinished jobs....
   make[6]: *** [tools/build/Makefile.build:158: util] Error 2
   make[5]: *** [Makefile.perf:727: tools/perf/perf-in.o] Error 2
   make[5]: *** Waiting for unfinished jobs....
   make[4]: *** [Makefile.perf:264: sub-make] Error 2
   make[3]: *** [Makefile:70: all] Error 2


vim +183 tools/perf/util/srcline.c

d3c83c542797774 Steinar H. Gunderson 2024-06-02  182  
d3c83c542797774 Steinar H. Gunderson 2024-06-02 @183  void dso__free_a2l(struct dso *)
d3c83c542797774 Steinar H. Gunderson 2024-06-02  184  {
d3c83c542797774 Steinar H. Gunderson 2024-06-02  185  	/* Nothing to free. */
d3c83c542797774 Steinar H. Gunderson 2024-06-02  186  }
d3c83c542797774 Steinar H. Gunderson 2024-06-02  187  

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki