From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Andi Kleen <andi@firstfloor.org>
Cc: tglx@linutronix.de, torvalds@linux-foundation.org,
gregkh@linux-foundation.org, linux-kernel@vger.kernel.org,
tim.c.chen@linux.intel.com, Andi Kleen <ak@linux.intel.com>
Subject: Re: [PATCH v2 11/12] retpoline/objtool: Disable some objtool warnings
Date: Thu, 4 Jan 2018 08:38:14 -0600 [thread overview]
Message-ID: <20180104143814.bhvtsjiwpyhtgjph@treble> (raw)
In-Reply-To: <20180104020019.1173-12-andi@firstfloor.org>
On Wed, Jan 03, 2018 at 06:00:18PM -0800, Andi Kleen wrote:
> From: Andi Kleen <ak@linux.intel.com>
>
> With the indirect call thunk enabled compiler two objtool
> warnings are triggered very frequently and make the build
> very noisy.
>
> I don't see a good way to avoid them, so just disable them
> for now.
>
> Signed-off-by: Andi Kleen <ak@linux.intel.com>
>
> ---
> tools/objtool/check.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/tools/objtool/check.c b/tools/objtool/check.c
> index 9b341584eb1b..435c71f944dc 100644
> --- a/tools/objtool/check.c
> +++ b/tools/objtool/check.c
> @@ -503,8 +503,13 @@ static int add_call_destinations(struct objtool_file *file)
> insn->call_dest = find_symbol_by_offset(insn->sec,
> dest_off);
> if (!insn->call_dest) {
> +#if 0
> + /* Compilers with -mindirect-branch=thunk-extern trigger
> + * this everywhere on x86. Disable for now.
> + */
> WARN_FUNC("can't find call dest symbol at offset 0x%lx",
> insn->sec, insn->offset, dest_off);
> +#endif
> return -1;
> }
> } else if (rela->sym->type == STT_SECTION) {
> @@ -1716,8 +1721,14 @@ static int validate_branch(struct objtool_file *file, struct instruction *first,
> return 1;
>
> } else if (func && has_modified_stack_frame(&state)) {
> +#if 0
> + /* Compilers with -mindirect-branch=thunk-extern trigger
> + * this everywhere on x86. Disable for now.
> + */
> +
> WARN_FUNC("sibling call from callable instruction with modified stack frame",
> sec, insn->offset);
> +#endif
> return 1;
> }
>
> --
> 2.14.3
NAK. We can't blindly disable objtool warnings, that will break
livepatch and the ORC unwinder. If you share a .o file (or the GCC
code) I can look at adding retpoline support.
--
Josh
next prev parent reply other threads:[~2018-01-04 14:38 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-04 2:00 Avoid speculative indirect calls in kernel Andi Kleen
2018-01-04 2:00 ` [PATCH v2 01/12] x86/retpoline: Define retpoline indirect thunk and macros Andi Kleen
2018-01-04 2:15 ` Brian Gerst
2018-01-04 2:32 ` Alan Cox
2018-01-04 2:00 ` [PATCH v2 02/12] x86/retpoline/crypto: Convert crypto assembler indirect jumps Andi Kleen
2018-01-04 2:00 ` [PATCH v2 03/12] x86/retpoline/entry: Convert entry " Andi Kleen
2018-01-04 8:42 ` David Woodhouse
2018-01-04 2:00 ` [PATCH v2 04/12] x86/retpoline/ftrace: Convert ftrace " Andi Kleen
2018-01-04 2:00 ` [PATCH v2 05/12] x86/retpoline/hyperv: Convert " Andi Kleen
2018-01-04 2:00 ` [PATCH v2 06/12] x86/retpoline/crypto: Convert xen " Andi Kleen
2018-01-04 6:48 ` Juergen Gross
2018-01-04 6:50 ` Andi Kleen
2018-01-04 2:00 ` [PATCH v2 07/12] x86/retpoline/checksum32: Convert " Andi Kleen
2018-01-04 2:00 ` [PATCH v2 08/12] x86/retpoline/irq32: " Andi Kleen
2018-01-04 2:00 ` [PATCH v2 09/12] x86/retpoline: Finally enable retpoline for C code Andi Kleen
2018-01-04 2:00 ` [PATCH v2 10/12] retpoline/taint: Taint kernel for missing retpoline in compiler Andi Kleen
2018-01-04 2:00 ` [PATCH v2 11/12] retpoline/objtool: Disable some objtool warnings Andi Kleen
2018-01-04 14:38 ` Josh Poimboeuf [this message]
2018-01-04 14:46 ` David Woodhouse
2018-01-04 15:59 ` Andi Kleen
2018-01-04 16:06 ` Josh Poimboeuf
2018-01-04 16:13 ` Andi Kleen
2018-01-04 16:32 ` Josh Poimboeuf
2018-01-04 17:35 ` Josh Poimboeuf
2018-01-04 2:00 ` [PATCH v2 12/12] retpoline: Attempt to quiten objtool warning for unreachable code Andi Kleen
2018-01-04 11:49 ` Avoid speculative indirect calls in kernel Pavel Machek
2018-01-04 12:09 ` Alan Cox
2018-01-04 13:32 ` Pavel Machek
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