From: Peter Zijlstra <peterz@infradead.org>
To: Marco Elver <elver@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
the arch/x86 maintainers <x86@kernel.org>,
"Paul E. McKenney" <paulmck@kernel.org>,
kasan-dev <kasan-dev@googlegroups.com>,
LKML <linux-kernel@vger.kernel.org>,
Will Deacon <will@kernel.org>, Dmitry Vyukov <dvyukov@google.com>,
Alexander Potapenko <glider@google.com>,
Andrey Konovalov <andreyknvl@google.com>
Subject: Re: [PATCH 0/9] x86/entry fixes
Date: Wed, 3 Jun 2020 20:16:38 +0200 [thread overview]
Message-ID: <20200603181638.GD2627@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20200603160722.GD2570@hirez.programming.kicks-ass.net>
On Wed, Jun 03, 2020 at 06:07:22PM +0200, Peter Zijlstra wrote:
> On Wed, Jun 03, 2020 at 04:47:54PM +0200, Marco Elver wrote:
> > With that in mind, you could whitelist "__ubsan_handle"-prefixed
> > functions in objtool. Given the __always_inline+noinstr+__ubsan_handle
> > case is quite rare, it might be reasonable.
>
> Yes, I think so. Let me go have dinner and then I'll try and do a patch
> to that effect.
Here's a slightly more radical patch, it unconditionally allows UBSAN.
I've not actually boot tested this.. yet.
---
Subject: x86/entry, ubsan, objtool: Whitelist __ubsan_handle_*()
From: Peter Zijlstra <peterz@infradead.org>
Date: Wed Jun 3 20:09:06 CEST 2020
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@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
include/linux/compiler_types.h | 2 +-
tools/objtool/check.c | 28 +++++++++++++++++++++++++++-
2 files changed, 28 insertions(+), 2 deletions(-)
--- 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__ */
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2190,10 +2190,36 @@ static inline const char *call_dest_name
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;
next prev parent reply other threads:[~2020-06-03 18:17 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-03 11:40 [PATCH 0/9] x86/entry fixes Peter Zijlstra
2020-06-03 11:40 ` [PATCH 1/9] x86/entry: Fix irq_exit() Peter Zijlstra
2020-06-03 11:40 ` [PATCH 2/9] rcu: Fixup noinstr warnings Peter Zijlstra
2020-06-03 16:46 ` Paul E. McKenney
2020-06-03 17:13 ` Peter Zijlstra
2020-06-04 3:34 ` Paul E. McKenney
2020-06-04 6:02 ` Marco Elver
2020-06-04 14:14 ` Paul E. McKenney
2020-06-04 8:05 ` Peter Zijlstra
2020-06-04 14:17 ` Paul E. McKenney
2020-06-15 15:30 ` Peter Zijlstra
2020-06-15 15:52 ` Paul E. McKenney
2020-06-15 16:06 ` Peter Zijlstra
2020-06-15 15:49 ` Peter Zijlstra
2020-06-15 15:55 ` Peter Zijlstra
2020-06-15 16:24 ` Peter Zijlstra
2020-06-15 17:14 ` Paul E. McKenney
2020-06-15 18:33 ` Peter Zijlstra
2020-06-15 18:59 ` Paul E. McKenney
2020-06-15 20:00 ` Paul E. McKenney
2020-06-19 22:15 ` Paul E. McKenney
2020-06-23 20:46 ` Peter Zijlstra
2020-06-23 21:44 ` Paul E. McKenney
2020-06-24 7:52 ` Peter Zijlstra
2020-06-24 13:03 ` Paul E. McKenney
2020-06-03 11:40 ` [PATCH 3/9] x86/entry: __always_inline debugreg for noinstr Peter Zijlstra
2020-06-03 17:50 ` [tip: x86/entry] " tip-bot2 for Peter Zijlstra
2020-06-03 11:40 ` [PATCH 4/9] x86/entry: __always_inline irqflags " Peter Zijlstra
2020-06-03 17:50 ` [tip: x86/entry] " tip-bot2 for Peter Zijlstra
2020-06-03 11:40 ` [PATCH 5/9] x86/entry: __always_inline arch_atomic_* " Peter Zijlstra
2020-06-03 17:50 ` [tip: x86/entry] " tip-bot2 for Peter Zijlstra
2020-06-03 11:40 ` [PATCH 6/9] x86/entry: Re-order #DB handler to avoid *SAN instrumentation Peter Zijlstra
2020-06-03 17:50 ` [tip: x86/entry] " tip-bot2 for Peter Zijlstra
2020-06-03 11:40 ` [PATCH 7/9] lockdep: __always_inline more for noinstr Peter Zijlstra
2020-06-03 17:50 ` [tip: x86/entry] " tip-bot2 for Peter Zijlstra
2020-06-03 11:40 ` [PATCH 8/9] x86/entry: __always_inline CR2 " Peter Zijlstra
2020-06-03 17:50 ` [tip: x86/entry] " tip-bot2 for Peter Zijlstra
2020-06-03 11:40 ` [PATCH 9/9] x86/entry, cpumask: Provide non-instrumented variant of cpu_is_offline() Peter Zijlstra
2020-06-03 17:50 ` [tip: x86/entry] " tip-bot2 for Peter Zijlstra
2020-06-03 12:00 ` [PATCH 0/9] x86/entry fixes Peter Zijlstra
2020-06-03 12:08 ` Peter Zijlstra
2020-06-03 12:08 ` Marco Elver
2020-06-03 12:18 ` Peter Zijlstra
2020-06-03 13:32 ` Marco Elver
2020-06-03 14:47 ` Marco Elver
2020-06-03 16:07 ` Peter Zijlstra
2020-06-03 17:26 ` Marco Elver
2020-06-03 18:16 ` Peter Zijlstra [this message]
2020-06-03 19:10 ` Marco Elver
2020-06-04 6:00 ` Marco Elver
2020-06-04 9:52 ` Marco Elver
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