Commit 6b643a07 authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

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: default avatarMarco Elver <elver@google.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarMarco Elver <elver@google.com>
parent 14d3b376

include/linux/compiler_types.h

+1 −1
Original line number Diff line number Diff line
@@ -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__ */

tools/objtool/check.c

+27 −1
Original line number Diff line number Diff line
@@ -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;