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-rw-r--r--tools/perf/Documentation/Makefile2
-rw-r--r--tools/perf/Makefile.config6
-rw-r--r--tools/perf/arch/riscv/Build1
-rw-r--r--tools/perf/arch/riscv/Makefile4
-rw-r--r--tools/perf/arch/riscv/include/perf_regs.h96
-rw-r--r--tools/perf/arch/riscv/util/Build2
-rw-r--r--tools/perf/arch/riscv/util/dwarf-regs.c72
-rw-r--r--tools/perf/arch/riscv/util/unwind-libdw.c57
-rw-r--r--tools/perf/arch/s390/util/machine.c31
-rw-r--r--tools/perf/bench/numa.c6
-rw-r--r--tools/perf/builtin-ftrace.c2
-rw-r--r--tools/perf/pmu-events/jevents.c1
-rw-r--r--tools/perf/ui/browser.c9
-rw-r--r--tools/perf/ui/tui/progress.c2
-rw-r--r--tools/perf/util/annotate.c2
-rw-r--r--tools/perf/util/cpumap.c5
-rw-r--r--tools/perf/util/machine.c3
-rw-r--r--tools/perf/util/machine.h2
-rw-r--r--tools/perf/util/symbol.c7
-rw-r--r--tools/perf/util/symbol.h1
-rw-r--r--tools/perf/util/thread.c12
21 files changed, 306 insertions, 17 deletions
diff --git a/tools/perf/Documentation/Makefile b/tools/perf/Documentation/Makefile
index 6d148a40551c..adc5a7e44b98 100644
--- a/tools/perf/Documentation/Makefile
+++ b/tools/perf/Documentation/Makefile
@@ -242,7 +242,7 @@ $(OUTPUT)doc.dep : $(wildcard *.txt) build-docdep.perl
$(PERL_PATH) ./build-docdep.perl >$@+ $(QUIET_STDERR) && \
mv $@+ $@
--include $(OUPTUT)doc.dep
+-include $(OUTPUT)doc.dep
_cmds_txt = cmds-ancillaryinterrogators.txt \
cmds-ancillarymanipulators.txt \
diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index 89ac5a1f1550..eaf25ee104e4 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -60,6 +60,10 @@ ifeq ($(SRCARCH),arm64)
LIBUNWIND_LIBS = -lunwind -lunwind-aarch64
endif
+ifeq ($(SRCARCH),riscv)
+ NO_PERF_REGS := 0
+endif
+
ifeq ($(SRCARCH),csky)
NO_PERF_REGS := 0
endif
@@ -82,7 +86,7 @@ endif
# Disable it on all other architectures in case libdw unwind
# support is detected in system. Add supported architectures
# to the check.
-ifneq ($(SRCARCH),$(filter $(SRCARCH),x86 arm arm64 powerpc s390 csky))
+ifneq ($(SRCARCH),$(filter $(SRCARCH),x86 arm arm64 powerpc s390 csky riscv))
NO_LIBDW_DWARF_UNWIND := 1
endif
diff --git a/tools/perf/arch/riscv/Build b/tools/perf/arch/riscv/Build
new file mode 100644
index 000000000000..e4e5f33c84d8
--- /dev/null
+++ b/tools/perf/arch/riscv/Build
@@ -0,0 +1 @@
+perf-y += util/
diff --git a/tools/perf/arch/riscv/Makefile b/tools/perf/arch/riscv/Makefile
new file mode 100644
index 000000000000..1aa9dd772489
--- /dev/null
+++ b/tools/perf/arch/riscv/Makefile
@@ -0,0 +1,4 @@
+ifndef NO_DWARF
+PERF_HAVE_DWARF_REGS := 1
+endif
+PERF_HAVE_ARCH_REGS_QUERY_REGISTER_OFFSET := 1
diff --git a/tools/perf/arch/riscv/include/perf_regs.h b/tools/perf/arch/riscv/include/perf_regs.h
new file mode 100644
index 000000000000..7a8bcde7a2b1
--- /dev/null
+++ b/tools/perf/arch/riscv/include/perf_regs.h
@@ -0,0 +1,96 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (C) 2019 Hangzhou C-SKY Microsystems co.,ltd. */
+
+#ifndef ARCH_PERF_REGS_H
+#define ARCH_PERF_REGS_H
+
+#include <stdlib.h>
+#include <linux/types.h>
+#include <asm/perf_regs.h>
+
+#define PERF_REGS_MASK ((1ULL << PERF_REG_RISCV_MAX) - 1)
+#define PERF_REGS_MAX PERF_REG_RISCV_MAX
+#if __riscv_xlen == 64
+#define PERF_SAMPLE_REGS_ABI PERF_SAMPLE_REGS_ABI_64
+#else
+#define PERF_SAMPLE_REGS_ABI PERF_SAMPLE_REGS_ABI_32
+#endif
+
+#define PERF_REG_IP PERF_REG_RISCV_PC
+#define PERF_REG_SP PERF_REG_RISCV_SP
+
+static inline const char *perf_reg_name(int id)
+{
+ switch (id) {
+ case PERF_REG_RISCV_PC:
+ return "pc";
+ case PERF_REG_RISCV_RA:
+ return "ra";
+ case PERF_REG_RISCV_SP:
+ return "sp";
+ case PERF_REG_RISCV_GP:
+ return "gp";
+ case PERF_REG_RISCV_TP:
+ return "tp";
+ case PERF_REG_RISCV_T0:
+ return "t0";
+ case PERF_REG_RISCV_T1:
+ return "t1";
+ case PERF_REG_RISCV_T2:
+ return "t2";
+ case PERF_REG_RISCV_S0:
+ return "s0";
+ case PERF_REG_RISCV_S1:
+ return "s1";
+ case PERF_REG_RISCV_A0:
+ return "a0";
+ case PERF_REG_RISCV_A1:
+ return "a1";
+ case PERF_REG_RISCV_A2:
+ return "a2";
+ case PERF_REG_RISCV_A3:
+ return "a3";
+ case PERF_REG_RISCV_A4:
+ return "a4";
+ case PERF_REG_RISCV_A5:
+ return "a5";
+ case PERF_REG_RISCV_A6:
+ return "a6";
+ case PERF_REG_RISCV_A7:
+ return "a7";
+ case PERF_REG_RISCV_S2:
+ return "s2";
+ case PERF_REG_RISCV_S3:
+ return "s3";
+ case PERF_REG_RISCV_S4:
+ return "s4";
+ case PERF_REG_RISCV_S5:
+ return "s5";
+ case PERF_REG_RISCV_S6:
+ return "s6";
+ case PERF_REG_RISCV_S7:
+ return "s7";
+ case PERF_REG_RISCV_S8:
+ return "s8";
+ case PERF_REG_RISCV_S9:
+ return "s9";
+ case PERF_REG_RISCV_S10:
+ return "s10";
+ case PERF_REG_RISCV_S11:
+ return "s11";
+ case PERF_REG_RISCV_T3:
+ return "t3";
+ case PERF_REG_RISCV_T4:
+ return "t4";
+ case PERF_REG_RISCV_T5:
+ return "t5";
+ case PERF_REG_RISCV_T6:
+ return "t6";
+ default:
+ return NULL;
+ }
+
+ return NULL;
+}
+
+#endif /* ARCH_PERF_REGS_H */
diff --git a/tools/perf/arch/riscv/util/Build b/tools/perf/arch/riscv/util/Build
new file mode 100644
index 000000000000..1160bb2332ba
--- /dev/null
+++ b/tools/perf/arch/riscv/util/Build
@@ -0,0 +1,2 @@
+perf-$(CONFIG_DWARF) += dwarf-regs.o
+perf-$(CONFIG_LIBDW_DWARF_UNWIND) += unwind-libdw.o
diff --git a/tools/perf/arch/riscv/util/dwarf-regs.c b/tools/perf/arch/riscv/util/dwarf-regs.c
new file mode 100644
index 000000000000..cd0504c02e2e
--- /dev/null
+++ b/tools/perf/arch/riscv/util/dwarf-regs.c
@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 Hangzhou C-SKY Microsystems co.,ltd.
+ * Mapping of DWARF debug register numbers into register names.
+ */
+
+#include <stddef.h>
+#include <errno.h> /* for EINVAL */
+#include <string.h> /* for strcmp */
+#include <dwarf-regs.h>
+
+struct pt_regs_dwarfnum {
+ const char *name;
+ unsigned int dwarfnum;
+};
+
+#define REG_DWARFNUM_NAME(r, num) {.name = r, .dwarfnum = num}
+#define REG_DWARFNUM_END {.name = NULL, .dwarfnum = 0}
+
+struct pt_regs_dwarfnum riscv_dwarf_regs_table[] = {
+ REG_DWARFNUM_NAME("%zero", 0),
+ REG_DWARFNUM_NAME("%ra", 1),
+ REG_DWARFNUM_NAME("%sp", 2),
+ REG_DWARFNUM_NAME("%gp", 3),
+ REG_DWARFNUM_NAME("%tp", 4),
+ REG_DWARFNUM_NAME("%t0", 5),
+ REG_DWARFNUM_NAME("%t1", 6),
+ REG_DWARFNUM_NAME("%t2", 7),
+ REG_DWARFNUM_NAME("%s0", 8),
+ REG_DWARFNUM_NAME("%s1", 9),
+ REG_DWARFNUM_NAME("%a0", 10),
+ REG_DWARFNUM_NAME("%a1", 11),
+ REG_DWARFNUM_NAME("%a2", 12),
+ REG_DWARFNUM_NAME("%a3", 13),
+ REG_DWARFNUM_NAME("%a4", 14),
+ REG_DWARFNUM_NAME("%a5", 15),
+ REG_DWARFNUM_NAME("%a6", 16),
+ REG_DWARFNUM_NAME("%a7", 17),
+ REG_DWARFNUM_NAME("%s2", 18),
+ REG_DWARFNUM_NAME("%s3", 19),
+ REG_DWARFNUM_NAME("%s4", 20),
+ REG_DWARFNUM_NAME("%s5", 21),
+ REG_DWARFNUM_NAME("%s6", 22),
+ REG_DWARFNUM_NAME("%s7", 23),
+ REG_DWARFNUM_NAME("%s8", 24),
+ REG_DWARFNUM_NAME("%s9", 25),
+ REG_DWARFNUM_NAME("%s10", 26),
+ REG_DWARFNUM_NAME("%s11", 27),
+ REG_DWARFNUM_NAME("%t3", 28),
+ REG_DWARFNUM_NAME("%t4", 29),
+ REG_DWARFNUM_NAME("%t5", 30),
+ REG_DWARFNUM_NAME("%t6", 31),
+ REG_DWARFNUM_END,
+};
+
+#define RISCV_MAX_REGS ((sizeof(riscv_dwarf_regs_table) / \
+ sizeof(riscv_dwarf_regs_table[0])) - 1)
+
+const char *get_arch_regstr(unsigned int n)
+{
+ return (n < RISCV_MAX_REGS) ? riscv_dwarf_regs_table[n].name : NULL;
+}
+
+int regs_query_register_offset(const char *name)
+{
+ const struct pt_regs_dwarfnum *roff;
+
+ for (roff = riscv_dwarf_regs_table; roff->name; roff++)
+ if (!strcmp(roff->name, name))
+ return roff->dwarfnum;
+ return -EINVAL;
+}
diff --git a/tools/perf/arch/riscv/util/unwind-libdw.c b/tools/perf/arch/riscv/util/unwind-libdw.c
new file mode 100644
index 000000000000..19536e172850
--- /dev/null
+++ b/tools/perf/arch/riscv/util/unwind-libdw.c
@@ -0,0 +1,57 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2019 Hangzhou C-SKY Microsystems co.,ltd. */
+
+#include <elfutils/libdwfl.h>
+#include "../../util/unwind-libdw.h"
+#include "../../util/perf_regs.h"
+#include "../../util/event.h"
+
+bool libdw__arch_set_initial_registers(Dwfl_Thread *thread, void *arg)
+{
+ struct unwind_info *ui = arg;
+ struct regs_dump *user_regs = &ui->sample->user_regs;
+ Dwarf_Word dwarf_regs[32];
+
+#define REG(r) ({ \
+ Dwarf_Word val = 0; \
+ perf_reg_value(&val, user_regs, PERF_REG_RISCV_##r); \
+ val; \
+})
+
+ dwarf_regs[0] = 0;
+ dwarf_regs[1] = REG(RA);
+ dwarf_regs[2] = REG(SP);
+ dwarf_regs[3] = REG(GP);
+ dwarf_regs[4] = REG(TP);
+ dwarf_regs[5] = REG(T0);
+ dwarf_regs[6] = REG(T1);
+ dwarf_regs[7] = REG(T2);
+ dwarf_regs[8] = REG(S0);
+ dwarf_regs[9] = REG(S1);
+ dwarf_regs[10] = REG(A0);
+ dwarf_regs[11] = REG(A1);
+ dwarf_regs[12] = REG(A2);
+ dwarf_regs[13] = REG(A3);
+ dwarf_regs[14] = REG(A4);
+ dwarf_regs[15] = REG(A5);
+ dwarf_regs[16] = REG(A6);
+ dwarf_regs[17] = REG(A7);
+ dwarf_regs[18] = REG(S2);
+ dwarf_regs[19] = REG(S3);
+ dwarf_regs[20] = REG(S4);
+ dwarf_regs[21] = REG(S5);
+ dwarf_regs[22] = REG(S6);
+ dwarf_regs[23] = REG(S7);
+ dwarf_regs[24] = REG(S8);
+ dwarf_regs[25] = REG(S9);
+ dwarf_regs[26] = REG(S10);
+ dwarf_regs[27] = REG(S11);
+ dwarf_regs[28] = REG(T3);
+ dwarf_regs[29] = REG(T4);
+ dwarf_regs[30] = REG(T5);
+ dwarf_regs[31] = REG(T6);
+ dwfl_thread_state_register_pc(thread, REG(PC));
+
+ return dwfl_thread_state_registers(thread, 0, PERF_REG_RISCV_MAX,
+ dwarf_regs);
+}
diff --git a/tools/perf/arch/s390/util/machine.c b/tools/perf/arch/s390/util/machine.c
index a19690a17291..c8c86a0c9b79 100644
--- a/tools/perf/arch/s390/util/machine.c
+++ b/tools/perf/arch/s390/util/machine.c
@@ -6,8 +6,9 @@
#include "machine.h"
#include "api/fs/fs.h"
#include "debug.h"
+#include "symbol.h"
-int arch__fix_module_text_start(u64 *start, const char *name)
+int arch__fix_module_text_start(u64 *start, u64 *size, const char *name)
{
u64 m_start = *start;
char path[PATH_MAX];
@@ -17,7 +18,35 @@ int arch__fix_module_text_start(u64 *start, const char *name)
if (sysfs__read_ull(path, (unsigned long long *)start) < 0) {
pr_debug2("Using module %s start:%#lx\n", path, m_start);
*start = m_start;
+ } else {
+ /* Successful read of the modules segment text start address.
+ * Calculate difference between module start address
+ * in memory and module text segment start address.
+ * For example module load address is 0x3ff8011b000
+ * (from /proc/modules) and module text segment start
+ * address is 0x3ff8011b870 (from file above).
+ *
+ * Adjust the module size and subtract the GOT table
+ * size located at the beginning of the module.
+ */
+ *size -= (*start - m_start);
}
return 0;
}
+
+/* On s390 kernel text segment start is located at very low memory addresses,
+ * for example 0x10000. Modules are located at very high memory addresses,
+ * for example 0x3ff xxxx xxxx. The gap between end of kernel text segment
+ * and beginning of first module's text segment is very big.
+ * Therefore do not fill this gap and do not assign it to the kernel dso map.
+ */
+void arch__symbols__fixup_end(struct symbol *p, struct symbol *c)
+{
+ if (strchr(p->name, '[') == NULL && strchr(c->name, '['))
+ /* Last kernel symbol mapped to end of page */
+ p->end = roundup(p->end, page_size);
+ else
+ p->end = c->start;
+ pr_debug4("%s sym:%s end:%#lx\n", __func__, p->name, p->end);
+}
diff --git a/tools/perf/bench/numa.c b/tools/perf/bench/numa.c
index a640ca7aaada..513cb2f2fa32 100644
--- a/tools/perf/bench/numa.c
+++ b/tools/perf/bench/numa.c
@@ -379,8 +379,10 @@ static u8 *alloc_data(ssize_t bytes0, int map_flags,
/* Allocate and initialize all memory on CPU#0: */
if (init_cpu0) {
- orig_mask = bind_to_node(0);
- bind_to_memnode(0);
+ int node = numa_node_of_cpu(0);
+
+ orig_mask = bind_to_node(node);
+ bind_to_memnode(node);
}
bytes = bytes0 + HPSIZE;
diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
index 66d5a6658daf..019312810405 100644
--- a/tools/perf/builtin-ftrace.c
+++ b/tools/perf/builtin-ftrace.c
@@ -173,7 +173,7 @@ static int set_tracing_cpumask(struct cpu_map *cpumap)
int last_cpu;
last_cpu = cpu_map__cpu(cpumap, cpumap->nr - 1);
- mask_size = (last_cpu + 3) / 4 + 1;
+ mask_size = last_cpu / 4 + 2; /* one more byte for EOS */
mask_size += last_cpu / 32; /* ',' is needed for every 32th cpus */
cpumask = malloc(mask_size);
diff --git a/tools/perf/pmu-events/jevents.c b/tools/perf/pmu-events/jevents.c
index 1a91a197cafb..d413761621b0 100644
--- a/tools/perf/pmu-events/jevents.c
+++ b/tools/perf/pmu-events/jevents.c
@@ -453,6 +453,7 @@ static struct fixed {
{ "inst_retired.any_p", "event=0xc0" },
{ "cpu_clk_unhalted.ref", "event=0x0,umask=0x03" },
{ "cpu_clk_unhalted.thread", "event=0x3c" },
+ { "cpu_clk_unhalted.core", "event=0x3c" },
{ "cpu_clk_unhalted.thread_any", "event=0x3c,any=1" },
{ NULL, NULL},
};
diff --git a/tools/perf/ui/browser.c b/tools/perf/ui/browser.c
index f80c51d53565..d227d74b28f8 100644
--- a/tools/perf/ui/browser.c
+++ b/tools/perf/ui/browser.c
@@ -1,7 +1,8 @@
// SPDX-License-Identifier: GPL-2.0
-#include "../string2.h"
-#include "../config.h"
-#include "../../perf.h"
+#include "../util/util.h"
+#include "../util/string2.h"
+#include "../util/config.h"
+#include "../perf.h"
#include "libslang.h"
#include "ui.h"
#include "util.h"
@@ -14,7 +15,7 @@
#include "browser.h"
#include "helpline.h"
#include "keysyms.h"
-#include "../color.h"
+#include "../util/color.h"
#include <linux/ctype.h>
#include <linux/zalloc.h>
diff --git a/tools/perf/ui/tui/progress.c b/tools/perf/ui/tui/progress.c
index bc134b82829d..5a24dd3ce4db 100644
--- a/tools/perf/ui/tui/progress.c
+++ b/tools/perf/ui/tui/progress.c
@@ -1,6 +1,6 @@
// SPDX-License-Identifier: GPL-2.0
#include <linux/kernel.h>
-#include "../cache.h"
+#include "../../util/cache.h"
#include "../progress.h"
#include "../libslang.h"
#include "../ui.h"
diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c
index ac9ad2330f93..163536720149 100644
--- a/tools/perf/util/annotate.c
+++ b/tools/perf/util/annotate.c
@@ -1122,7 +1122,7 @@ static int disasm_line__parse(char *line, const char **namep, char **rawp)
goto out;
(*rawp)[0] = tmp;
- *rawp = skip_spaces(*rawp);
+ *rawp = strim(*rawp);
return 0;
diff --git a/tools/perf/util/cpumap.c b/tools/perf/util/cpumap.c
index 3acfbe34ebaf..39cce66b4ebc 100644
--- a/tools/perf/util/cpumap.c
+++ b/tools/perf/util/cpumap.c
@@ -751,7 +751,10 @@ size_t cpu_map__snprint_mask(struct cpu_map *map, char *buf, size_t size)
unsigned char *bitmap;
int last_cpu = cpu_map__cpu(map, map->nr - 1);
- bitmap = zalloc((last_cpu + 7) / 8);
+ if (buf == NULL)
+ return 0;
+
+ bitmap = zalloc(last_cpu / 8 + 1);
if (bitmap == NULL) {
buf[0] = '\0';
return 0;
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index cf826eca3aaf..83b2fbbeeb90 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -1378,6 +1378,7 @@ static int machine__set_modules_path(struct machine *machine)
return map_groups__set_modules_path_dir(&machine->kmaps, modules_path, 0);
}
int __weak arch__fix_module_text_start(u64 *start __maybe_unused,
+ u64 *size __maybe_unused,
const char *name __maybe_unused)
{
return 0;
@@ -1389,7 +1390,7 @@ static int machine__create_module(void *arg, const char *name, u64 start,
struct machine *machine = arg;
struct map *map;
- if (arch__fix_module_text_start(&start, name) < 0)
+ if (arch__fix_module_text_start(&start, &size, name) < 0)
return -1;
map = machine__findnew_module_map(machine, start, name);
diff --git a/tools/perf/util/machine.h b/tools/perf/util/machine.h
index f70ab98a7bde..7aa38da26427 100644
--- a/tools/perf/util/machine.h
+++ b/tools/perf/util/machine.h
@@ -222,7 +222,7 @@ struct symbol *machine__find_kernel_symbol_by_name(struct machine *machine,
struct map *machine__findnew_module_map(struct machine *machine, u64 start,
const char *filename);
-int arch__fix_module_text_start(u64 *start, const char *name);
+int arch__fix_module_text_start(u64 *start, u64 *size, const char *name);
int machine__load_kallsyms(struct machine *machine, const char *filename);
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 173f3378aaa0..4efde7879474 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -92,6 +92,11 @@ static int prefix_underscores_count(const char *str)
return tail - str;
}
+void __weak arch__symbols__fixup_end(struct symbol *p, struct symbol *c)
+{
+ p->end = c->start;
+}
+
const char * __weak arch__normalize_symbol_name(const char *name)
{
return name;
@@ -218,7 +223,7 @@ void symbols__fixup_end(struct rb_root_cached *symbols)
curr = rb_entry(nd, struct symbol, rb_node);
if (prev->end == prev->start && prev->end != curr->start)
- prev->end = curr->start;
+ arch__symbols__fixup_end(prev, curr);
}
/* Last entry */
diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
index 12755b42ea93..183f630cb5f1 100644
--- a/tools/perf/util/symbol.h
+++ b/tools/perf/util/symbol.h
@@ -288,6 +288,7 @@ const char *arch__normalize_symbol_name(const char *name);
#define SYMBOL_A 0
#define SYMBOL_B 1
+void arch__symbols__fixup_end(struct symbol *p, struct symbol *c);
int arch__compare_symbol_names(const char *namea, const char *nameb);
int arch__compare_symbol_names_n(const char *namea, const char *nameb,
unsigned int n);
diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
index 873ab505ca80..590793cc5142 100644
--- a/tools/perf/util/thread.c
+++ b/tools/perf/util/thread.c
@@ -214,14 +214,24 @@ struct comm *thread__comm(const struct thread *thread)
struct comm *thread__exec_comm(const struct thread *thread)
{
- struct comm *comm, *last = NULL;
+ struct comm *comm, *last = NULL, *second_last = NULL;
list_for_each_entry(comm, &thread->comm_list, list) {
if (comm->exec)
return comm;
+ second_last = last;
last = comm;
}
+ /*
+ * 'last' with no start time might be the parent's comm of a synthesized
+ * thread (created by processing a synthesized fork event). For a main
+ * thread, that is very probably wrong. Prefer a later comm to avoid
+ * that case.
+ */
+ if (second_last && !last->start && thread->pid_ == thread->tid)
+ return second_last;
+
return last;
}