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;
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