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| author | Peter Zijlstra <peterz@infradead.org> | 2022-11-03 20:57:51 +0100 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2022-11-05 11:28:02 +0100 |
| commit | 023f2340f053537cce170c31c430b0886c6f07ca (patch) | |
| tree | 675254caef52385eaef8c2d344d6ed27df6277c3 /tools/objtool | |
| parent | 19526717f768bf2f89ca01bd2a595728ebe57540 (diff) | |
| download | linux-023f2340f053537cce170c31c430b0886c6f07ca.tar.gz | |
objtool: Fix weak hole vs prefix symbol
Boris (and the robot) reported that objtool grew a new complaint about
unreachable instructions. Upon inspection it was immediately clear
the __weak zombie instructions struck again.
For the unweary, the linker will simply remove the symbol for
overriden __weak symbols but leave the instructions in place, creating
unreachable instructions -- and objtool likes to report these.
Commit 4adb23686795 ("objtool: Ignore extra-symbol code") was supposed
to have dealt with that, but the new commit 9f2899fe36a6 ("objtool:
Add option to generate prefix symbols") subtly broke that logic by
created unvisited symbols.
Fixes: 9f2899fe36a6 ("objtool: Add option to generate prefix symbols")
Reported-by: Borislav Petkov <bp@alien8.de>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Diffstat (limited to 'tools/objtool')
| -rw-r--r-- | tools/objtool/check.c | 22 |
1 files changed, 21 insertions, 1 deletions
diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 55066c4935702..4f1a7384426b4 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -4053,8 +4053,28 @@ static int add_prefix_symbol(struct objtool_file *file, struct symbol *func, offset = func->offset - prev->offset; if (offset >= opts.prefix) { - if (offset == opts.prefix) + if (offset == opts.prefix) { + /* + * Since the sec->symbol_list is ordered by + * offset (see elf_add_symbol()) the added + * symbol will not be seen by the iteration in + * validate_section(). + * + * Hence the lack of list_for_each_entry_safe() + * there. + * + * The direct concequence is that prefix symbols + * don't get visited (because pointless), except + * for the logic in ignore_unreachable_insn() + * that needs the terminating insn to be visited + * otherwise it will report the hole. + * + * Hence mark the first instruction of the + * prefix symbol as visisted. + */ + prev->visited |= VISITED_BRANCH; elf_create_prefix_symbol(file->elf, func, opts.prefix); + } break; } insn = prev; |