The following commit has been merged into the x86/entry branch of tip:
Commit-ID: 6b643a07a7e41f9e11cfbb9bba4c5c9791ac2997
Gitweb: https://git.kernel.org/tip/6b643a07a7e41f9e11cfbb9bba4c5c9791ac2997
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Wed, 03 Jun 2020 20:09:06 +02:00
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Mon, 15 Jun 2020 14:10:09 +02:00
x86/entry, ubsan, objtool: Whitelist __ubsan_handle_*()
The UBSAN instrumentation only inserts external CALLs when things go
'BAD', much like WARN(). So treat them similar to WARN()s for noinstr,
that is: allow them, at the risk of taking the machine down, to get
their message out.
Suggested-by: Marco Elver <elver@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Acked-by: Marco Elver <elver@xxxxxxxxxx>
---
include/linux/compiler_types.h | 2 +-
tools/objtool/check.c | 28 +++++++++++++++++++++++++++-
2 files changed, 28 insertions(+), 2 deletions(-)
diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
index 85b8d23..14513e8 100644
--- a/include/linux/compiler_types.h
+++ b/include/linux/compiler_types.h
@@ -199,7 +199,7 @@ struct ftrace_likely_data {
/* Section for code which can't be instrumented at all */
#define noinstr \
noinline notrace __attribute((__section__(".noinstr.text"))) \
- __no_kcsan __no_sanitize_address __no_sanitize_undefined
+ __no_kcsan __no_sanitize_address
#endif /* __KERNEL__ */
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 5fbb90a..3e214f8 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2190,10 +2190,36 @@ static inline const char *call_dest_name(struct instruction *insn)
return "{dynamic}";
}
+static inline bool noinstr_call_dest(struct symbol *func)
+{
+ /*
+ * We can't deal with indirect function calls at present;
+ * assume they're instrumented.
+ */
+ if (!func)
+ return false;
+
+ /*
+ * If the symbol is from a noinstr section; we good.
+ */
+ if (func->sec->noinstr)
+ return true;
+
+ /*
+ * The __ubsan_handle_*() calls are like WARN(), they only happen when
+ * something 'BAD' happened. At the risk of taking the machine down,
+ * let them proceed to get the message out.
+ */
+ if (!strncmp(func->name, "__ubsan_handle_", 15))
+ return true;
+
+ return false;
+}
+
static int validate_call(struct instruction *insn, struct insn_state *state)
{
if (state->noinstr && state->instr <= 0 &&
- (!insn->call_dest || !insn->call_dest->sec->noinstr)) {
+ !noinstr_call_dest(insn->call_dest)) {
WARN_FUNC("call to %s() leaves .noinstr.text section",
insn->sec, insn->offset, call_dest_name(insn));
return 1;
|