From: kernel test robot <lkp@intel.com>
To: David Laight <david.laight.linux@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Petr Mladek <pmladek@suse.com>, Kees Cook <kees@kernel.org>,
linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org,
bpf@vger.kernel.org, Jim Cromie <jim.cromie@gmail.com>,
Lorenzo Stoakes <ljs@kernel.org>
Cc: llvm@lists.linux.dev, oe-kbuild-all@lists.linux.dev,
Linux Memory Management List <linux-mm@kvack.org>,
Luis Chamberlain <mcgrof@kernel.org>,
Andrey Grodzovsky <andrey.grodzovsky@crowdstrike.com>,
Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH 14/15] kallsyms: scripts/kallsyms: Reduce the output file size
Date: Tue, 20 Oct 2026 03:50:35 +0800 [thread overview]
Message-ID: <202610200336.6v4SE96n-lkp@intel.com> (raw)
In-Reply-To: <20261018155206.132411-15-david.laight.linux@gmail.com>
Hi David,
kernel test robot noticed the following build warnings:
[auto build test WARNING on akpm-mm/mm-everything]
[also build test WARNING on linus/master v7.3]
[cannot apply to next-20261016 next-20261016]
[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/David-Laight/kallsyms-scripts-kallsyms-c-Avoid-overrunning-on-stack-buffer/20261018-165152
base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link: https://lore.kernel.org/r/20261018155206.132411-15-david.laight.linux%40gmail.com
patch subject: [PATCH 14/15] kallsyms: scripts/kallsyms: Reduce the output file size
config: um-allmodconfig (https://download.01.org/0day-ci/archive/20261020/202610200336.6v4SE96n-lkp@intel.com/config)
compiler: clang version 17.0.6 (https://github.com/llvm/llvm-project 6009708b4367171ccdbf4b5905cb6a803753fe18)
rustc: rustc 1.96.0 (ac68faa20 2026-05-25)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20261020/202610200336.6v4SE96n-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/oe-kbuild-all/202610200336.6v4SE96n-lkp@intel.com/
All warnings (new ones prefixed by >>):
>> scripts/kallsyms.c:371:26: warning: adding 'int' to a string does not append to the string [-Wstring-plus-int]
371 | printf("\n\t.short\t" + !i);
| ~~~~~~~~~~~~~~~^~~~
scripts/kallsyms.c:371:26: note: use array indexing to silence this warning
371 | printf("\n\t.short\t" + !i);
| ^
| & [ ]
>> scripts/kallsyms.c:371:11: warning: format string is not a string literal (potentially insecure) [-Wformat-security]
371 | printf("\n\t.short\t" + !i);
| ^~~~~~~~~~~~~~~~~~~
scripts/kallsyms.c:371:11: note: treat the string as an argument to avoid this
371 | printf("\n\t.short\t" + !i);
| ^
| "%s",
scripts/kallsyms.c:428:25: warning: adding 'int' to a string does not append to the string [-Wstring-plus-int]
428 | printf("\n\t.long\t" + !k);
| ~~~~~~~~~~~~~~^~~~
scripts/kallsyms.c:428:25: note: use array indexing to silence this warning
428 | printf("\n\t.long\t" + !k);
| ^
| & [ ]
scripts/kallsyms.c:428:11: warning: format string is not a string literal (potentially insecure) [-Wformat-security]
428 | printf("\n\t.long\t" + !k);
| ^~~~~~~~~~~~~~~~~~
scripts/kallsyms.c:428:11: note: treat the string as an argument to avoid this
428 | printf("\n\t.long\t" + !k);
| ^
| "%s",
4 warnings generated.
--
>> scripts/kallsyms.c:371:26: warning: adding 'int' to a string does not append to the string [-Wstring-plus-int]
371 | printf("\n\t.short\t" + !i);
| ~~~~~~~~~~~~~~~^~~~
scripts/kallsyms.c:371:26: note: use array indexing to silence this warning
371 | printf("\n\t.short\t" + !i);
| ^
| & [ ]
>> scripts/kallsyms.c:371:11: warning: format string is not a string literal (potentially insecure) [-Wformat-security]
371 | printf("\n\t.short\t" + !i);
| ^~~~~~~~~~~~~~~~~~~
scripts/kallsyms.c:371:11: note: treat the string as an argument to avoid this
371 | printf("\n\t.short\t" + !i);
| ^
| "%s",
scripts/kallsyms.c:428:25: warning: adding 'int' to a string does not append to the string [-Wstring-plus-int]
428 | printf("\n\t.long\t" + !k);
| ~~~~~~~~~~~~~~^~~~
scripts/kallsyms.c:428:25: note: use array indexing to silence this warning
428 | printf("\n\t.long\t" + !k);
| ^
| & [ ]
scripts/kallsyms.c:428:11: warning: format string is not a string literal (potentially insecure) [-Wformat-security]
428 | printf("\n\t.long\t" + !k);
| ^~~~~~~~~~~~~~~~~~
scripts/kallsyms.c:428:11: note: treat the string as an argument to avoid this
428 | printf("\n\t.long\t" + !k);
| ^
| "%s",
4 warnings generated.
In file included from kernel/sched/rq-offsets.c:5:
In file included from kernel/sched/sched.h:28:
In file included from include/linux/cgroup_api.h:1:
In file included from include/linux/cgroup.h:27:
In file included from include/linux/kernel_stat.h:8:
In file included from include/linux/interrupt.h:11:
In file included from include/linux/hardirq.h:11:
In file included from arch/um/include/asm/hardirq.h:24:
In file included from include/linux/irq.h:20:
In file included from include/linux/io.h:12:
In file included from arch/um/include/asm/io.h:24:
include/asm-generic/io.h:1209:55: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
1209 | return (port > MMIO_UPPER_LIMIT) ? NULL : PCI_IOBASE + port;
| ~~~~~~~~~~ ^
1 warning generated.
In file included from rust/helpers/helpers.c:48:
In file included from rust/helpers/blk.c:3:
In file included from include/linux/blk-mq.h:5:
In file included from include/linux/blkdev.h:9:
In file included from include/linux/blk_types.h:10:
In file included from include/linux/bvec.h:10:
In file included from include/linux/highmem.h:12:
In file included from include/linux/hardirq.h:11:
In file included from arch/um/include/asm/hardirq.h:24:
In file included from include/linux/irq.h:20:
In file included from include/linux/io.h:12:
In file included from arch/um/include/asm/io.h:24:
include/asm-generic/io.h:1209:55: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
1209 | return (port > MMIO_UPPER_LIMIT) ? NULL : PCI_IOBASE + port;
| ~~~~~~~~~~ ^
clang diag: include/asm-generic/io.h:1209:55: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/asm-generic/io.h:1209:55: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/asm-generic/io.h:1209:55: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
1 warning generated.
vim +/int +371 scripts/kallsyms.c
344
345 static void write_src(void)
346 {
347 unsigned int i, k, off, off_size, table_size;
348 unsigned int best_idx[256];
349 char buf[1 + KSYM_NAME_LEN];
350 struct sym_entry *se;
351
352 printf("\t.section .rodata, \"a\"\n");
353 printf("\n");
354
355 output_label("kallsyms_token_table");
356 off = 0;
357 for (i = 0; i < 256; i++) {
358 best_idx[i] = off;
359 off += token_table[i].len + 1;
360 printf("\t.asciz\t\"%s\"\t/* %u: %u */\n",
361 token_table[i].str, i, token_table[i].refs);
362 }
363 printf(".size kallsyms_token_table, . - kallsyms_token_table\n");
364 printf("\n");
365
366 output_label("kallsyms_token_index");
367 for (i = 0; i < 256; i++) {
368 if (i & 15)
369 printf(",");
370 else
> 371 printf("\n\t.short\t" + !i);
372 printf("%u", best_idx[i]);
373 }
374 printf("\n");
375 printf(".size kallsyms_token_index, . - kallsyms_token_index\n");
376 printf("\n");
377
378 output_value("kallsyms_num_syms", symbol_cnt);
379
380 output_label("kallsyms_names");
381 off = 0;
382 for (i = 0; i < symbol_cnt; i++) {
383 se = symbol[i];
384 se->seq = off;
385
386 /* The length must be less than that of the original symbol. */
387 if (!se->len || se->len > KSYM_NAME_LEN)
388 errx(1, "symbol %d has corrupt compressed length %d\n",
389 i, se->len);
390
391 /*
392 * Output the number that identifies the symbol at the start
393 * of the line so that they line up nicely.
394 */
395 printf("\t/* n:%u */\t.byte\t", off);
396
397 /* Encode length with ULEB128. */
398 if (se->len <= 0x7F) {
399 /* Most symbols use a single byte for the length. */
400 printf("%u", se->len);
401 off += se->len + 1;
402 } else {
403 /* "Big" symbols use two bytes. */
404 printf("%u,%u", (se->len & 0x7F) | 0x80, (se->len >> 7) & 0x7F);
405 off += se->len + 2;
406 }
407 for (k = 0; k < se->len; k++)
408 printf(",%u", se->sym[k]);
409 printf("\n");
410
411 /*
412 * Now that we wrote out the compressed symbol name, restore the
413 * original name.
414 */
415 se->len = expand_symbol(se->sym, se->len, buf);
416 memcpy(se->sym, buf, se->len + 1);
417 }
418 table_size = off;
419 printf(".size kallsyms_names, . - kallsyms_names\n");
420 printf("\n");
421
422 output_value("kallsyms_marker_shift", marker_shift);
423 output_label("kallsyms_markers");
424 for (i = 0, k = 0; i < symbol_cnt; i += 1u << marker_shift, k++) {
425 if (k & 7)
426 printf(",");
427 else
428 printf("\n\t.long\t" + !k);
429 printf("%u", symbol[i]->seq);
430 }
431 printf("\n");
432 printf(".size kallsyms_markers, . - kallsyms_markers\n");
433 printf("\n");
434
435 output_label("kallsyms_offsets");
436
437 for (i = 0; i < symbol_cnt; i++) {
438 se = symbol[i];
439 if (pc_relative) {
440 long long offset = se->addr - _text;
441
442 if (offset < INT_MIN || offset > INT_MAX)
443 errx(1, "relative symbol %s value %#llx out of range\n",
444 se->sym + 1, se->addr);
445 printf("\t.long\t_text-.+%d\t/* n:%u %c %s */\n",
446 (int)offset, se->seq, se->sym[0], se->sym + 1);
447 } else {
448 printf("\t.long\t%#x\t/* n:%u %c %s */\n",
449 (unsigned int)se->addr, se->seq, se->sym[0], se->sym + 1);
450 }
451 }
452 printf(".size kallsyms_offsets, . - kallsyms_offsets\n");
453 printf("\n");
454
455 sort_symbols_by_name();
456 off_size = table_size < (1u << 23) ? 24 : 32;
457 output_value("kallsyms_off_size", off_size);
458 output_label(off_size == 24 ? "kallsyms_off_24_of_names" : "kallsyms_off_32_of_names");
459 for (i = 0; i < symbol_cnt; i++) {
460 se = symbol[i];
461 off = se->seq << 1;
462 if (i && symbol[i - 1]->len == se->len &&
463 !memcmp(symbol[i - 1]->sym + 1, se->sym + 1, se->len - 1))
464 /* Mark that this is a duplicate of the previous symbol */
465 off |= 1;
466 if (off_size == 24) {
467 #ifdef CONFIG_CPU_BIG_ENDIAN
468 off = __builtin_bswap32(off) >> 8;
469 #endif
470 /* The three spaces before the tab line up the comments */
471 printf("\t.byte\t%u,%u,%u \t/* n:%u */\n",
472 off & 0xff, (off >> 8) & 0xff, off >> 16, se->seq);
473 } else {
474 printf("\t.long\t%#04x\t/* n:%u */\n", off, se->seq);
475 }
476 }
477 /* Terminator without the 'duplicate' flag. */
478 if (off_size == 24)
479 printf("\t.byte\t0,0,0\n");
480 else
481 printf("\t.long\t0\n");
482 printf(".size kallsyms_off_%d_of_names, . - kallsyms_off_%d_of_names\n", off_size, off_size);
483
484 fflush(stdout);
485 if (ferror(stdout))
486 errx(1, "error writing to output file");
487 }
488
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
next prev parent reply other threads:[~2026-10-19 19:50 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-18 15:51 [PATCH v2 next 00/15] kallsyms: optimise symbol search by name David Laight
2026-10-18 15:51 ` [PATCH v2 next 01/15] kallsyms: scripts/kallsyms.c: Avoid overrunning on-stack buffer David Laight
2026-10-18 15:51 ` [PATCH v2 next 02/15] kallsyms: Fix selftest startup delay David Laight
2026-10-18 15:51 ` [PATCH v2 next 03/15] kallsyms: Improve selftest test_perf_kallsyms_lookup_name() output David Laight
2026-10-19 16:07 ` kernel test robot
2026-10-19 17:08 ` David Laight
2026-10-19 20:57 ` kernel test robot
2026-10-18 15:51 ` [PATCH v2 next 04/15] kallsyms: scripts/kallsyms: Check for output file write errors David Laight
2026-10-18 15:51 ` [PATCH v2 next 05/15] kallsyms: Match compressed tokens on the fly during binary search David Laight
2026-10-18 15:51 ` [PATCH v2 next 06/15] kallsyms: Optimise symbol name search David Laight
2026-10-18 15:51 ` [PATCH v2 next 07/15] kallsyms: Optimise detection of duplicate symbol names David Laight
2026-10-18 15:51 ` [PATCH v2 next 08/15] kallsyms: Support changing the density of the kallsyms_markers[] array David Laight
2026-10-18 15:52 ` [PATCH v2 next 09/15] kallsyms: Add a kernel parameter for the marker shift David Laight
2026-10-18 15:52 ` [PATCH v2 next 10/15] kallsyms: scripts/kallsyms: Rename some variables for clarity David Laight
2026-10-18 15:52 ` [PATCH v2 next 11/15] kallsyms: scripts/kallsyms: Keep full expansion of tokens David Laight
2026-10-18 15:52 ` [PATCH v2 next 12/15] kallsyms: scripts/kallsyms: Optimise compress_symbols() David Laight
2026-10-18 15:52 ` [PATCH v2 next 13/15] kallsyms: scripts/kallsyms: Reuse tokens that have no references David Laight
2026-10-18 15:52 ` [PATCH 14/15] kallsyms: scripts/kallsyms: Reduce the output file size David Laight
2026-10-19 19:50 ` kernel test robot [this message]
2026-10-18 15:52 ` [PATCH 15/15] kallsyms: scripts/kallsyms: Improve compression by about 2% David Laight
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