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| author | Josh Poimboeuf <jpoimboe@redhat.com> | 2020-02-18 04:41:53 +0100 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2020-02-21 10:12:52 +0100 |
| commit | 113d4bc9048336ba7c3d2ad972dbad4aef6e148a (patch) | |
| tree | 2c0a8e6d52e3b29ae17f63241d81afbcf23866dd /tools/objtool/check.c | |
| parent | objtool: Add relocation check for alternative sections (diff) | |
| download | linux-113d4bc9048336ba7c3d2ad972dbad4aef6e148a.tar.xz linux-113d4bc9048336ba7c3d2ad972dbad4aef6e148a.zip | |
objtool: Fix clang switch table edge case
Clang has the ability to create a switch table which is not a jump
table, but is rather a table of string pointers. This confuses objtool,
because it sees the relocations for the string pointers and assumes
they're part of a jump table:
drivers/ata/sata_dwc_460ex.o: warning: objtool: sata_dwc_bmdma_start_by_tag()+0x3a2: can't find switch jump table
net/ceph/messenger.o: warning: objtool: ceph_con_workfn()+0x47c: can't find switch jump table
Make objtool's find_jump_table() smart enough to distinguish between a
switch jump table (which has relocations to text addresses in the same
function as the original instruction) and other anonymous rodata (which
may have relocations to elsewhere).
Reported-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Link: https://github.com/ClangBuiltLinux/linux/issues/485
Link: https://lkml.kernel.org/r/263f6aae46d33da0b86d7030ced878cb5cab1788.1581997059.git.jpoimboe@redhat.com
Diffstat (limited to 'tools/objtool/check.c')
| -rw-r--r-- | tools/objtool/check.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/tools/objtool/check.c b/tools/objtool/check.c index b038de2ccd71..4d6e283951ec 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -1025,7 +1025,7 @@ static struct rela *find_jump_table(struct objtool_file *file, struct instruction *insn) { struct rela *text_rela, *table_rela; - struct instruction *orig_insn = insn; + struct instruction *dest_insn, *orig_insn = insn; struct section *table_sec; unsigned long table_offset; @@ -1077,10 +1077,17 @@ static struct rela *find_jump_table(struct objtool_file *file, strcmp(table_sec->name, C_JUMP_TABLE_SECTION)) continue; - /* Each table entry has a rela associated with it. */ + /* + * Each table entry has a rela associated with it. The rela + * should reference text in the same function as the original + * instruction. + */ table_rela = find_rela_by_dest(table_sec, table_offset); if (!table_rela) continue; + dest_insn = find_insn(file, table_rela->sym->sec, table_rela->addend); + if (!dest_insn || !dest_insn->func || dest_insn->func->pfunc != func) + continue; /* * Use of RIP-relative switch jumps is quite rare, and |