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/srccode.c | 171 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 171 insertions(+) create mode 100644 tools/perf/util/srccode.c (limited to 'tools/perf/util/srccode.c') diff --git a/tools/perf/util/srccode.c b/tools/perf/util/srccode.c new file mode 100644 index 000000000..0f4907843 --- /dev/null +++ b/tools/perf/util/srccode.c @@ -0,0 +1,171 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Manage printing of source lines + * Copyright (c) 2017, Intel Corporation. + * Author: Andi Kleen + */ +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include "srccode.h" +#include "debug.h" +#include // page_size +#include "hashmap.h" + +#define MAXSRCCACHE (32*1024*1024) +#define MAXSRCFILES 64 +#define SRC_HTAB_SZ 64 + +struct srcfile { + struct hlist_node hash_nd; + struct list_head nd; + char *fn; + char **lines; + char *map; + unsigned numlines; + size_t maplen; +}; + +static struct hlist_head srcfile_htab[SRC_HTAB_SZ]; +static LIST_HEAD(srcfile_list); +static long map_total_sz; +static int num_srcfiles; + +static int countlines(char *map, int maplen) +{ + int numl; + char *end = map + maplen; + char *p = map; + + if (maplen == 0) + return 0; + numl = 0; + while (p < end && (p = memchr(p, '\n', end - p)) != NULL) { + numl++; + p++; + } + if (p < end) + numl++; + return numl; +} + +static void fill_lines(char **lines, int maxline, char *map, int maplen) +{ + int l; + char *end = map + maplen; + char *p = map; + + if (maplen == 0 || maxline == 0) + return; + l = 0; + lines[l++] = map; + while (p < end && (p = memchr(p, '\n', end - p)) != NULL) { + if (l >= maxline) + return; + lines[l++] = ++p; + } + if (p < end) + lines[l] = p; +} + +static void free_srcfile(struct srcfile *sf) +{ + list_del_init(&sf->nd); + hlist_del(&sf->hash_nd); + map_total_sz -= sf->maplen; + munmap(sf->map, sf->maplen); + zfree(&sf->lines); + zfree(&sf->fn); + free(sf); + num_srcfiles--; +} + +static struct srcfile *find_srcfile(char *fn) +{ + struct stat st; + struct srcfile *h; + int fd; + unsigned long sz; + size_t hval = str_hash(fn) % SRC_HTAB_SZ; + + hlist_for_each_entry (h, &srcfile_htab[hval], hash_nd) { + if (!strcmp(fn, h->fn)) { + /* Move to front */ + list_move(&h->nd, &srcfile_list); + return h; + } + } + + /* Only prune if there is more than one entry */ + while ((num_srcfiles > MAXSRCFILES || map_total_sz > MAXSRCCACHE) && + srcfile_list.next != &srcfile_list) { + assert(!list_empty(&srcfile_list)); + h = list_entry(srcfile_list.prev, struct srcfile, nd); + free_srcfile(h); + } + + fd = open(fn, O_RDONLY); + if (fd < 0 || fstat(fd, &st) < 0) { + pr_debug("cannot open source file %s\n", fn); + return NULL; + } + + h = malloc(sizeof(struct srcfile)); + if (!h) + return NULL; + + h->fn = strdup(fn); + if (!h->fn) + goto out_h; + + h->maplen = st.st_size; + sz = (h->maplen + page_size - 1) & ~(page_size - 1); + h->map = mmap(NULL, sz, PROT_READ, MAP_SHARED, fd, 0); + close(fd); + if (h->map == (char *)-1) { + pr_debug("cannot mmap source file %s\n", fn); + goto out_fn; + } + h->numlines = countlines(h->map, h->maplen); + h->lines = calloc(h->numlines, sizeof(char *)); + if (!h->lines) + goto out_map; + fill_lines(h->lines, h->numlines, h->map, h->maplen); + list_add(&h->nd, &srcfile_list); + hlist_add_head(&h->hash_nd, &srcfile_htab[hval]); + map_total_sz += h->maplen; + num_srcfiles++; + return h; + +out_map: + munmap(h->map, sz); +out_fn: + zfree(&h->fn); +out_h: + free(h); + return NULL; +} + +/* Result is not 0 terminated */ +char *find_sourceline(char *fn, unsigned line, int *lenp) +{ + char *l, *p; + struct srcfile *sf = find_srcfile(fn); + if (!sf) + return NULL; + line--; + if (line >= sf->numlines) + return NULL; + l = sf->lines[line]; + if (!l) + return NULL; + p = memchr(l, '\n', sf->map + sf->maplen - l); + *lenp = p - l; + return l; +} -- cgit v1.3.1