From 5febf432df1cfa5b25d99b54c32103fafbdd0eb9 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Sun, 16 Aug 2026 15:32:33 +0200 Subject: kbuild: rust: keep Rust objects out of Clang LTO with inline helpers Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit `objtool` errors such as: vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a: can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd The reason is that in such builds, the Clang invocation that compiles the combined Rust plus helpers bitcode emits LLVM bitcode (again) -- the final code generation happens in the linker's LTO step, which the `-mllvm` trap options passed to Clang do not reach. This, in turn, means that unreachable traps are missing, and the impossible paths do not merely fallthrough to the next symbol, but past the end of their own section, since LTO builds place each function in its own section. Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always emits machine code directly, with the traps in place. Assisted-by: LLM Cc: Gary Guo Cc: Boqun Feng Cc: Alice Ryhl Cc: Matthew Maurer Cc: Josh Poimboeuf Cc: Peter Zijlstra Cc: stable@vger.kernel.org Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust") Acked-by: Gary Guo Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- tools/perf/util/stream.c | 341 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 341 insertions(+) create mode 100644 tools/perf/util/stream.c (limited to 'tools/perf/util/stream.c') diff --git a/tools/perf/util/stream.c b/tools/perf/util/stream.c new file mode 100644 index 000000000..3de4a6130 --- /dev/null +++ b/tools/perf/util/stream.c @@ -0,0 +1,341 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Compare and figure out the top N hottest streams + * Copyright (c) 2020, Intel Corporation. + * Author: Jin Yao + */ + +#include +#include +#include +#include "debug.h" +#include "hist.h" +#include "sort.h" +#include "stream.h" +#include "evlist.h" + +static void evsel_streams__delete(struct evsel_streams *es, int nr_evsel) +{ + for (int i = 0; i < nr_evsel; i++) + zfree(&es[i].streams); + + free(es); +} + +void evlist_streams__delete(struct evlist_streams *els) +{ + evsel_streams__delete(els->ev_streams, els->nr_evsel); + free(els); +} + +static struct evlist_streams *evlist_streams__new(int nr_evsel, + int nr_streams_max) +{ + struct evlist_streams *els; + struct evsel_streams *es; + + els = zalloc(sizeof(*els)); + if (!els) + return NULL; + + es = calloc(nr_evsel, sizeof(struct evsel_streams)); + if (!es) { + free(els); + return NULL; + } + + for (int i = 0; i < nr_evsel; i++) { + struct evsel_streams *s = &es[i]; + + s->streams = calloc(nr_streams_max, sizeof(struct stream)); + if (!s->streams) + goto err; + + s->nr_streams_max = nr_streams_max; + } + + els->ev_streams = es; + els->nr_evsel = nr_evsel; + return els; + +err: + evsel_streams__delete(es, nr_evsel); + return NULL; +} + +/* + * The cnodes with high hit number are hot callchains. + */ +static void evsel_streams__set_hot_cnode(struct evsel_streams *es, + struct callchain_node *cnode) +{ + int i, idx = 0; + u64 hit; + + if (es->nr_streams < es->nr_streams_max) { + i = es->nr_streams; + es->streams[i].cnode = cnode; + es->nr_streams++; + return; + } + + /* + * Considering a few number of hot streams, only use simple + * way to find the cnode with smallest hit number and replace. + */ + hit = (es->streams[0].cnode)->hit; + for (i = 1; i < es->nr_streams; i++) { + if ((es->streams[i].cnode)->hit < hit) { + hit = (es->streams[i].cnode)->hit; + idx = i; + } + } + + if (cnode->hit > hit) + es->streams[idx].cnode = cnode; +} + +static void update_hot_callchain(struct hist_entry *he, + struct evsel_streams *es) +{ + struct rb_root *root = &he->sorted_chain; + struct rb_node *rb_node = rb_first(root); + struct callchain_node *cnode; + + while (rb_node) { + cnode = rb_entry(rb_node, struct callchain_node, rb_node); + evsel_streams__set_hot_cnode(es, cnode); + rb_node = rb_next(rb_node); + } +} + +static void init_hot_callchain(struct hists *hists, struct evsel_streams *es) +{ + struct rb_node *next = rb_first_cached(&hists->entries); + + while (next) { + struct hist_entry *he; + + he = rb_entry(next, struct hist_entry, rb_node); + update_hot_callchain(he, es); + next = rb_next(&he->rb_node); + } + + es->streams_hits = callchain_total_hits(hists); +} + +static int evlist__init_callchain_streams(struct evlist *evlist, + struct evlist_streams *els) +{ + struct evsel_streams *es = els->ev_streams; + struct evsel *pos; + int i = 0; + + BUG_ON(els->nr_evsel < evlist->core.nr_entries); + + evlist__for_each_entry(evlist, pos) { + struct hists *hists = evsel__hists(pos); + + hists__output_resort(hists, NULL); + init_hot_callchain(hists, &es[i]); + es[i].evsel = pos; + i++; + } + + return 0; +} + +struct evlist_streams *evlist__create_streams(struct evlist *evlist, + int nr_streams_max) +{ + int nr_evsel = evlist->core.nr_entries, ret = -1; + struct evlist_streams *els = evlist_streams__new(nr_evsel, + nr_streams_max); + + if (!els) + return NULL; + + ret = evlist__init_callchain_streams(evlist, els); + if (ret) { + evlist_streams__delete(els); + return NULL; + } + + return els; +} + +struct evsel_streams *evsel_streams__entry(struct evlist_streams *els, + const struct evsel *evsel) +{ + struct evsel_streams *es = els->ev_streams; + + for (int i = 0; i < els->nr_evsel; i++) { + if (es[i].evsel == evsel) + return &es[i]; + } + + return NULL; +} + +static struct stream *stream__callchain_match(struct stream *base_stream, + struct evsel_streams *es_pair) +{ + for (int i = 0; i < es_pair->nr_streams; i++) { + struct stream *pair_stream = &es_pair->streams[i]; + + if (callchain_cnode_matched(base_stream->cnode, + pair_stream->cnode)) { + return pair_stream; + } + } + + return NULL; +} + +static struct stream *stream__match(struct stream *base_stream, + struct evsel_streams *es_pair) +{ + return stream__callchain_match(base_stream, es_pair); +} + +static void stream__link(struct stream *base_stream, struct stream *pair_stream) +{ + base_stream->pair_cnode = pair_stream->cnode; + pair_stream->pair_cnode = base_stream->cnode; +} + +void evsel_streams__match(struct evsel_streams *es_base, + struct evsel_streams *es_pair) +{ + for (int i = 0; i < es_base->nr_streams; i++) { + struct stream *base_stream = &es_base->streams[i]; + struct stream *pair_stream; + + pair_stream = stream__match(base_stream, es_pair); + if (pair_stream) + stream__link(base_stream, pair_stream); + } +} + +static void print_callchain_pair(struct stream *base_stream, int idx, + struct evsel_streams *es_base, + struct evsel_streams *es_pair) +{ + struct callchain_node *base_cnode = base_stream->cnode; + struct callchain_node *pair_cnode = base_stream->pair_cnode; + struct callchain_list *base_chain, *pair_chain; + char buf1[512], buf2[512], cbuf1[256], cbuf2[256]; + char *s1, *s2; + double pct; + + printf("\nhot chain pair %d:\n", idx); + + pct = (double)base_cnode->hit / (double)es_base->streams_hits; + scnprintf(buf1, sizeof(buf1), "cycles: %ld, hits: %.2f%%", + callchain_avg_cycles(base_cnode), pct * 100.0); + + pct = (double)pair_cnode->hit / (double)es_pair->streams_hits; + scnprintf(buf2, sizeof(buf2), "cycles: %ld, hits: %.2f%%", + callchain_avg_cycles(pair_cnode), pct * 100.0); + + printf("%35s\t%35s\n", buf1, buf2); + + printf("%35s\t%35s\n", + "---------------------------", + "--------------------------"); + + pair_chain = list_first_entry(&pair_cnode->val, + struct callchain_list, + list); + + list_for_each_entry(base_chain, &base_cnode->val, list) { + if (&pair_chain->list == &pair_cnode->val) + return; + + s1 = callchain_list__sym_name(base_chain, cbuf1, sizeof(cbuf1), + false); + s2 = callchain_list__sym_name(pair_chain, cbuf2, sizeof(cbuf2), + false); + + scnprintf(buf1, sizeof(buf1), "%35s\t%35s", s1, s2); + printf("%s\n", buf1); + pair_chain = list_next_entry(pair_chain, list); + } +} + +static void print_stream_callchain(struct stream *stream, int idx, + struct evsel_streams *es, bool pair) +{ + struct callchain_node *cnode = stream->cnode; + struct callchain_list *chain; + char buf[512], cbuf[256], *s; + double pct; + + printf("\nhot chain %d:\n", idx); + + pct = (double)cnode->hit / (double)es->streams_hits; + scnprintf(buf, sizeof(buf), "cycles: %ld, hits: %.2f%%", + callchain_avg_cycles(cnode), pct * 100.0); + + if (pair) { + printf("%35s\t%35s\n", "", buf); + printf("%35s\t%35s\n", + "", "--------------------------"); + } else { + printf("%35s\n", buf); + printf("%35s\n", "--------------------------"); + } + + list_for_each_entry(chain, &cnode->val, list) { + s = callchain_list__sym_name(chain, cbuf, sizeof(cbuf), false); + + if (pair) + scnprintf(buf, sizeof(buf), "%35s\t%35s", "", s); + else + scnprintf(buf, sizeof(buf), "%35s", s); + + printf("%s\n", buf); + } +} + +static void callchain_streams_report(struct evsel_streams *es_base, + struct evsel_streams *es_pair) +{ + struct stream *base_stream; + int i, idx = 0; + + printf("[ Matched hot streams ]\n"); + for (i = 0; i < es_base->nr_streams; i++) { + base_stream = &es_base->streams[i]; + if (base_stream->pair_cnode) { + print_callchain_pair(base_stream, ++idx, + es_base, es_pair); + } + } + + idx = 0; + printf("\n[ Hot streams in old perf data only ]\n"); + for (i = 0; i < es_base->nr_streams; i++) { + base_stream = &es_base->streams[i]; + if (!base_stream->pair_cnode) { + print_stream_callchain(base_stream, ++idx, + es_base, false); + } + } + + idx = 0; + printf("\n[ Hot streams in new perf data only ]\n"); + for (i = 0; i < es_pair->nr_streams; i++) { + base_stream = &es_pair->streams[i]; + if (!base_stream->pair_cnode) { + print_stream_callchain(base_stream, ++idx, + es_pair, true); + } + } +} + +void evsel_streams__report(struct evsel_streams *es_base, + struct evsel_streams *es_pair) +{ + return callchain_streams_report(es_base, es_pair); +} -- cgit v1.3.1