From: "tip-bot2 for Josh Poimboeuf" <tip-bot2@linutronix.de>
To: linux-tip-commits@vger.kernel.org
Cc: Nick Desaulniers <ndesaulniers@google.com>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Borislav Petkov <bp@suse.de>,
Nathan Chancellor <natechancellor@gmail.com>,
x86 <x86@kernel.org>, LKML <linux-kernel@vger.kernel.org>
Subject: [tip: core/objtool] objtool: Improve call destination function detection
Date: Fri, 21 Feb 2020 09:50:52 -0000 [thread overview]
Message-ID: <158227865224.28353.12310568117533168509.tip-bot2@tip-bot2> (raw)
In-Reply-To: <0a7ee320bc0ea4469bd3dc450a7b4725669e0ea9.1581997059.git.jpoimboe@redhat.com>
The following commit has been merged into the core/objtool branch of tip:
Commit-ID: 7acfe5315312fc56c2a94c9216448087b38ae909
Gitweb: https://git.kernel.org/tip/7acfe5315312fc56c2a94c9216448087b38ae909
Author: Josh Poimboeuf <jpoimboe@redhat.com>
AuthorDate: Mon, 17 Feb 2020 21:41:54 -06:00
Committer: Borislav Petkov <bp@suse.de>
CommitterDate: Fri, 21 Feb 2020 10:20:34 +01:00
objtool: Improve call destination function detection
A recent clang change, combined with a binutils bug, can trigger a
situation where a ".Lprintk$local" STT_NOTYPE symbol gets created at the
same offset as the "printk" STT_FUNC symbol. This confuses objtool:
kernel/printk/printk.o: warning: objtool: ignore_loglevel_setup()+0x10: can't find call dest symbol at .text+0xc67
Improve the call destination detection by looking specifically for an
STT_FUNC symbol.
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/872
Link: https://sourceware.org/bugzilla/show_bug.cgi?id=25551
Link: https://lkml.kernel.org/r/0a7ee320bc0ea4469bd3dc450a7b4725669e0ea9.1581997059.git.jpoimboe@redhat.com
---
tools/objtool/check.c | 27 ++++++++++++++++++---------
tools/objtool/elf.c | 14 ++++++++++++--
tools/objtool/elf.h | 1 +
3 files changed, 31 insertions(+), 11 deletions(-)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 4d6e283..6b6178e 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -420,8 +420,8 @@ static void add_ignores(struct objtool_file *file)
break;
case STT_SECTION:
- func = find_symbol_by_offset(rela->sym->sec, rela->addend);
- if (!func || func->type != STT_FUNC)
+ func = find_func_by_offset(rela->sym->sec, rela->addend);
+ if (!func)
continue;
break;
@@ -665,10 +665,14 @@ static int add_call_destinations(struct objtool_file *file)
insn->len);
if (!rela) {
dest_off = insn->offset + insn->len + insn->immediate;
- insn->call_dest = find_symbol_by_offset(insn->sec,
- dest_off);
+ insn->call_dest = find_func_by_offset(insn->sec, dest_off);
+ if (!insn->call_dest)
+ insn->call_dest = find_symbol_by_offset(insn->sec, dest_off);
- if (!insn->call_dest && !insn->ignore) {
+ if (insn->ignore)
+ continue;
+
+ if (!insn->call_dest) {
WARN_FUNC("unsupported intra-function call",
insn->sec, insn->offset);
if (retpoline)
@@ -676,11 +680,16 @@ static int add_call_destinations(struct objtool_file *file)
return -1;
}
+ if (insn->func && insn->call_dest->type != STT_FUNC) {
+ WARN_FUNC("unsupported call to non-function",
+ insn->sec, insn->offset);
+ return -1;
+ }
+
} else if (rela->sym->type == STT_SECTION) {
- insn->call_dest = find_symbol_by_offset(rela->sym->sec,
- rela->addend+4);
- if (!insn->call_dest ||
- insn->call_dest->type != STT_FUNC) {
+ insn->call_dest = find_func_by_offset(rela->sym->sec,
+ rela->addend+4);
+ if (!insn->call_dest) {
WARN_FUNC("can't find call dest symbol at %s+0x%x",
insn->sec, insn->offset,
rela->sym->sec->name,
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index edba474..cc4601c 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -62,8 +62,18 @@ struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset)
struct symbol *sym;
list_for_each_entry(sym, &sec->symbol_list, list)
- if (sym->type != STT_SECTION &&
- sym->offset == offset)
+ if (sym->type != STT_SECTION && sym->offset == offset)
+ return sym;
+
+ return NULL;
+}
+
+struct symbol *find_func_by_offset(struct section *sec, unsigned long offset)
+{
+ struct symbol *sym;
+
+ list_for_each_entry(sym, &sec->symbol_list, list)
+ if (sym->type == STT_FUNC && sym->offset == offset)
return sym;
return NULL;
diff --git a/tools/objtool/elf.h b/tools/objtool/elf.h
index 4415020..a196325 100644
--- a/tools/objtool/elf.h
+++ b/tools/objtool/elf.h
@@ -77,6 +77,7 @@ struct elf {
struct elf *elf_read(const char *name, int flags);
struct section *find_section_by_name(struct elf *elf, const char *name);
+struct symbol *find_func_by_offset(struct section *sec, unsigned long offset);
struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset);
struct symbol *find_symbol_by_name(struct elf *elf, const char *name);
struct symbol *find_symbol_containing(struct section *sec, unsigned long offset);
next prev parent reply other threads:[~2020-02-21 9:51 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-18 3:41 [PATCH 0/2] objtool: clang-related fixes Josh Poimboeuf
2020-02-18 3:41 ` [PATCH 1/2] objtool: Fix clang switch table edge case Josh Poimboeuf
2020-02-18 19:57 ` Nathan Chancellor
2020-02-21 9:50 ` [tip: core/objtool] " tip-bot2 for Josh Poimboeuf
2020-02-18 3:41 ` [PATCH 2/2] objtool: Improve call destination function detection Josh Poimboeuf
2020-02-18 18:13 ` Nick Desaulniers
2020-02-18 19:58 ` Nathan Chancellor
2020-02-21 9:50 ` tip-bot2 for Josh Poimboeuf [this message]
2020-02-20 19:06 ` [PATCH 0/2] objtool: clang-related fixes Nick Desaulniers
2020-02-20 19:27 ` Borislav Petkov
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