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NeQuissimusNeQuissimus
committedJul 15, 2017
perf: Apply patch for offline kernels
As per https://lkml.org/lkml/2017/7/13/314, perf is broken in 4.9.36 and 4.9.37 Patches in this commit are taken from https://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git/commit/?id=39f4f2c018bd831c325e11983f8893caf72fd9eb This will allow perf to build again and should be included in a future 4.9.x release, allowing the custom patching to be removed again
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‎pkgs/os-specific/linux/kernel/perf-offline-probe.patch

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From 8a937a25a7e3c19d5fb3f9d92f605cf5fda219d8 Mon Sep 17 00:00:00 2001
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From: Masami Hiramatsu <mhiramat@kernel.org>
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Date: Wed, 4 Jan 2017 12:30:19 +0900
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Subject: perf probe: Fix to probe on gcc generated symbols for offline kernel
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From: Masami Hiramatsu <mhiramat@kernel.org>
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commit 8a937a25a7e3c19d5fb3f9d92f605cf5fda219d8 upstream.
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Fix perf-probe to show probe definition on gcc generated symbols for
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offline kernel (including cross-arch kernel image).
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gcc sometimes optimizes functions and generate new symbols with suffixes
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such as ".constprop.N" or ".isra.N" etc. Since those symbol names are
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not recorded in DWARF, we have to find correct generated symbols from
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offline ELF binary to probe on it (kallsyms doesn't correct it). For
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online kernel or uprobes we don't need it because those are rebased on
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_text, or a section relative address.
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E.g. Without this:
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$ perf probe -k build-arm/vmlinux -F __slab_alloc*
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__slab_alloc.constprop.9
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$ perf probe -k build-arm/vmlinux -D __slab_alloc
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p:probe/__slab_alloc __slab_alloc+0
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If you put above definition on target machine, it should fail
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because there is no __slab_alloc in kallsyms.
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With this fix, perf probe shows correct probe definition on
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__slab_alloc.constprop.9:
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$ perf probe -k build-arm/vmlinux -D __slab_alloc
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p:probe/__slab_alloc __slab_alloc.constprop.9+0
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Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
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Cc: Jiri Olsa <jolsa@redhat.com>
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Cc: Namhyung Kim <namhyung@kernel.org>
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Cc: Peter Zijlstra <peterz@infradead.org>
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Link: http://lkml.kernel.org/r/148350060434.19001.11864836288580083501.stgit@devbox
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Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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Cc: Krister Johansen <kjlx@templeofstupid.com>
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Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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---
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tools/perf/util/probe-event.c | 48 +++++++++++++++++++++++++++++++++++++++++-
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1 file changed, 47 insertions(+), 1 deletion(-)
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--- a/tools/perf/util/probe-event.c
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+++ b/tools/perf/util/probe-event.c
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@@ -618,6 +618,51 @@ error:
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return ret ? : -ENOENT;
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}
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+/*
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+ * Rename DWARF symbols to ELF symbols -- gcc sometimes optimizes functions
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+ * and generate new symbols with suffixes such as .constprop.N or .isra.N
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+ * etc. Since those symbols are not recorded in DWARF, we have to find
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+ * correct generated symbols from offline ELF binary.
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+ * For online kernel or uprobes we don't need this because those are
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+ * rebased on _text, or already a section relative address.
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+ */
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+static int
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+post_process_offline_probe_trace_events(struct probe_trace_event *tevs,
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+ int ntevs, const char *pathname)
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+{
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+ struct symbol *sym;
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+ struct map *map;
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+ unsigned long stext = 0;
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+ u64 addr;
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+ int i;
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+
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+ /* Prepare a map for offline binary */
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+ map = dso__new_map(pathname);
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+ if (!map || get_text_start_address(pathname, &stext) < 0) {
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+ pr_warning("Failed to get ELF symbols for %s\n", pathname);
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+ return -EINVAL;
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+ }
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+
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+ for (i = 0; i < ntevs; i++) {
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+ addr = tevs[i].point.address + tevs[i].point.offset - stext;
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+ sym = map__find_symbol(map, addr);
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+ if (!sym)
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+ continue;
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+ if (!strcmp(sym->name, tevs[i].point.symbol))
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+ continue;
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+ /* If we have no realname, use symbol for it */
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+ if (!tevs[i].point.realname)
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+ tevs[i].point.realname = tevs[i].point.symbol;
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+ else
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+ free(tevs[i].point.symbol);
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+ tevs[i].point.symbol = strdup(sym->name);
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+ tevs[i].point.offset = addr - sym->start;
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+ }
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+ map__put(map);
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+
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+ return 0;
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+}
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+
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static int add_exec_to_probe_trace_events(struct probe_trace_event *tevs,
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int ntevs, const char *exec)
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{
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@@ -694,7 +739,8 @@ post_process_kernel_probe_trace_events(s
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/* Skip post process if the target is an offline kernel */
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if (symbol_conf.ignore_vmlinux_buildid)
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- return 0;
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+ return post_process_offline_probe_trace_events(tevs, ntevs,
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+ symbol_conf.vmlinux_name);
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reloc_sym = kernel_get_ref_reloc_sym();
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if (!reloc_sym) {
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---
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From 3e96dac7c956089d3f23aca98c4dfca57b6aaf8a Mon Sep 17 00:00:00 2001
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From: Masami Hiramatsu <mhiramat@kernel.org>
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Date: Wed, 11 Jan 2017 15:00:47 +0900
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Subject: perf probe: Add error checks to offline probe post-processing
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From: Masami Hiramatsu <mhiramat@kernel.org>
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commit 3e96dac7c956089d3f23aca98c4dfca57b6aaf8a upstream.
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Add error check codes on post processing and improve it for offline
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probe events as:
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- post processing fails if no matched symbol found in map(-ENOENT)
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or strdup() failed(-ENOMEM).
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- Even if the symbol name is the same, it updates symbol address
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and offset.
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Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
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Cc: Jiri Olsa <jolsa@redhat.com>
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Cc: Namhyung Kim <namhyung@kernel.org>
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Cc: Peter Zijlstra <peterz@infradead.org>
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Link: http://lkml.kernel.org/r/148411443738.9978.4617979132625405545.stgit@devbox
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Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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Cc: Krister Johansen <kjlx@templeofstupid.com>
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Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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---
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tools/perf/util/probe-event.c | 50 +++++++++++++++++++++++++++---------------
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1 file changed, 33 insertions(+), 17 deletions(-)
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--- a/tools/perf/util/probe-event.c
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+++ b/tools/perf/util/probe-event.c
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@@ -618,6 +618,33 @@ error:
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return ret ? : -ENOENT;
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}
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+/* Adjust symbol name and address */
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+static int post_process_probe_trace_point(struct probe_trace_point *tp,
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+ struct map *map, unsigned long offs)
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+{
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+ struct symbol *sym;
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+ u64 addr = tp->address + tp->offset - offs;
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+
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+ sym = map__find_symbol(map, addr);
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+ if (!sym)
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+ return -ENOENT;
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+
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+ if (strcmp(sym->name, tp->symbol)) {
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+ /* If we have no realname, use symbol for it */
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+ if (!tp->realname)
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+ tp->realname = tp->symbol;
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+ else
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+ free(tp->symbol);
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+ tp->symbol = strdup(sym->name);
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+ if (!tp->symbol)
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+ return -ENOMEM;
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+ }
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+ tp->offset = addr - sym->start;
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+ tp->address -= offs;
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+
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+ return 0;
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+}
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+
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/*
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* Rename DWARF symbols to ELF symbols -- gcc sometimes optimizes functions
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* and generate new symbols with suffixes such as .constprop.N or .isra.N
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@@ -630,11 +657,9 @@ static int
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post_process_offline_probe_trace_events(struct probe_trace_event *tevs,
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int ntevs, const char *pathname)
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{
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- struct symbol *sym;
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struct map *map;
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unsigned long stext = 0;
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- u64 addr;
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- int i;
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+ int i, ret = 0;
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/* Prepare a map for offline binary */
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map = dso__new_map(pathname);
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@@ -644,23 +669,14 @@ post_process_offline_probe_trace_events(
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}
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for (i = 0; i < ntevs; i++) {
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- addr = tevs[i].point.address + tevs[i].point.offset - stext;
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- sym = map__find_symbol(map, addr);
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- if (!sym)
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- continue;
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- if (!strcmp(sym->name, tevs[i].point.symbol))
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- continue;
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- /* If we have no realname, use symbol for it */
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- if (!tevs[i].point.realname)
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- tevs[i].point.realname = tevs[i].point.symbol;
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- else
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- free(tevs[i].point.symbol);
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- tevs[i].point.symbol = strdup(sym->name);
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- tevs[i].point.offset = addr - sym->start;
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+ ret = post_process_probe_trace_point(&tevs[i].point,
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+ map, stext);
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+ if (ret < 0)
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+ break;
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}
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map__put(map);
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- return 0;
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+ return ret;
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}
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static int add_exec_to_probe_trace_events(struct probe_trace_event *tevs,

‎pkgs/os-specific/linux/kernel/perf.nix

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@@ -13,7 +13,7 @@ stdenv.mkDerivation {
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inherit (kernel) src;
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patches = kernel.patches ++ [ ./perf-binutils-path.patch ];
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patches = kernel.patches ++ [ ./perf-binutils-path.patch ./perf-offline-probe.patch ];
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preConfigure = ''
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cd tools/perf

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