From: Marco Elver <elver@google.com>
To: Arnd Bergmann <arnd@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Alexander Potapenko <glider@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
kasan-dev@googlegroups.com, Dmitry Vyukov <dvyukov@google.com>,
Andrey Ryabinin <ryabinin.a.a@gmail.com>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Andrey Konovalov <andreyknvl@gmail.com>,
Arnd Bergmann <arnd@arndb.de>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/4] kmsan: disable ftrace in kmsan core code
Date: Wed, 8 Feb 2023 18:00:38 +0100 [thread overview]
Message-ID: <CANpmjNNYcVJxeuJPFknf=wCaapgYSn0+as4+iseJGpeBZdi4tw@mail.gmail.com> (raw)
In-Reply-To: <20230208164011.2287122-2-arnd@kernel.org>
On Wed, 8 Feb 2023 at 17:40, Arnd Bergmann <arnd@kernel.org> wrote:
>
> From: Arnd Bergmann <arnd@arndb.de>
>
> objtool warns about some suspicous code inside of kmsan:
>
> vmlinux.o: warning: objtool: __msan_metadata_ptr_for_load_n+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: __msan_metadata_ptr_for_store_n+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: __msan_metadata_ptr_for_load_1+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: __msan_metadata_ptr_for_store_1+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: __msan_metadata_ptr_for_load_2+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: __msan_metadata_ptr_for_store_2+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: __msan_metadata_ptr_for_load_4+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: __msan_metadata_ptr_for_store_4+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: __msan_metadata_ptr_for_load_8+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: __msan_metadata_ptr_for_store_8+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: __msan_instrument_asm_store+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: __msan_chain_origin+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: __msan_poison_alloca+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: __msan_warning+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: __msan_get_context_state+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: kmsan_copy_to_user+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: kmsan_unpoison_memory+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: kmsan_unpoison_entry_regs+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: kmsan_report+0x4: call to __fentry__() with UACCESS enabled
>
> Similar code already exists in kasan, which avoids this by skipping
> ftrace annotations, so do the same thing here.
>
> Fixes: f80be4571b19 ("kmsan: add KMSAN runtime core")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> mm/kmsan/Makefile | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/mm/kmsan/Makefile b/mm/kmsan/Makefile
> index 98eab2856626..389fd767a11f 100644
> --- a/mm/kmsan/Makefile
> +++ b/mm/kmsan/Makefile
> @@ -16,6 +16,14 @@ CC_FLAGS_KMSAN_RUNTIME += -DDISABLE_BRANCH_PROFILING
>
> CFLAGS_REMOVE.o = $(CC_FLAGS_FTRACE)
That means this CFLAGS_REMOVE.o didn't work, right? Can it be removed?
> +# Disable ftrace to avoid recursion.
> +CFLAGS_REMOVE_core.o = $(CC_FLAGS_FTRACE)
> +CFLAGS_REMOVE_hooks.o = $(CC_FLAGS_FTRACE)
> +CFLAGS_REMOVE_init.o = $(CC_FLAGS_FTRACE)
> +CFLAGS_REMOVE_instrumentation.o = $(CC_FLAGS_FTRACE)
> +CFLAGS_REMOVE_report.o = $(CC_FLAGS_FTRACE)
> +CFLAGS_REMOVE_shadow.o = $(CC_FLAGS_FTRACE)
> +
> CFLAGS_core.o := $(CC_FLAGS_KMSAN_RUNTIME)
> CFLAGS_hooks.o := $(CC_FLAGS_KMSAN_RUNTIME)
> CFLAGS_init.o := $(CC_FLAGS_KMSAN_RUNTIME)
> --
> 2.39.1
>
next prev parent reply other threads:[~2023-02-08 17:01 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-08 16:39 [PATCH 1/4] kasan: mark addr_has_metadata __always_inline Arnd Bergmann
2023-02-08 16:39 ` [PATCH 2/4] kmsan: disable ftrace in kmsan core code Arnd Bergmann
2023-02-08 17:00 ` Marco Elver [this message]
2023-02-08 19:31 ` Arnd Bergmann
2023-02-09 15:42 ` Alexander Potapenko
2023-02-08 17:01 ` [PATCH 1/4] kasan: mark addr_has_metadata __always_inline Marco Elver
2023-02-08 18:10 ` Peter Zijlstra
2023-02-09 19:26 ` Josh Poimboeuf
2023-02-09 22:21 ` Andrey Konovalov
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