From patchwork Wed May 18 13:16:34 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Xu Kuohai X-Patchwork-Id: 12853708 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id A4B15C433F5 for ; Wed, 18 May 2022 13:55:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Date:Subject:CC:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=XohEwOUiPKsZ0SGFsvNKMKZVVHNjGDiptNyTiJRipUE=; b=woHwNKL8Ss7yk5 /YNYd1PRjBbDgUtdGgnVqS8+nV7ApqhTzAL10EfzGR4UkZb3YqY6sNumde30NqSwaFn0FWodQ8RKs t5on7kFiNbWm+z9ia+weEqWCCss1oT1CpbrcoGh/pCPxPUu+Do2En7Gk+9JlwdItWFgWnVqr7oakS i8JsSXjyqwCK8JPp5w0OxfeuCz674w2/2g9tBtKDxoBaulGuquyNkXtTZq8y9UNJToxfhspv35L4U O0D3oaA+G2Pzb9UvWp6oy3VOLyyUBrjwcTAXF9MzR9mtA+0wb7zxgve6jCaHtex6k+9++mv2H8P6H v0YBVXrunG1JY5rwInbA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nrK80-002NQQ-8Z; Wed, 18 May 2022 13:54:16 +0000 Received: from szxga02-in.huawei.com ([45.249.212.188]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nrK7j-002NEg-DV for linux-arm-kernel@lists.infradead.org; Wed, 18 May 2022 13:54:01 +0000 Received: from kwepemi500013.china.huawei.com (unknown [172.30.72.55]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4L3Dw02VrgzhZBP; Wed, 18 May 2022 21:53:04 +0800 (CST) Received: from huawei.com (10.67.174.197) by kwepemi500013.china.huawei.com (7.221.188.120) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Wed, 18 May 2022 21:53:52 +0800 From: Xu Kuohai To: , , , , CC: Catalin Marinas , Will Deacon , Steven Rostedt , Ingo Molnar , Daniel Borkmann , Alexei Starovoitov , Zi Shen Lim , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , "David S . Miller" , Hideaki YOSHIFUJI , David Ahern , Thomas Gleixner , Borislav Petkov , Dave Hansen , , , Shuah Khan , Jakub Kicinski , Jesper Dangaard Brouer , Mark Rutland , Pasha Tatashin , Ard Biesheuvel , Daniel Kiss , Steven Price , Sudeep Holla , Marc Zyngier , Peter Collingbourne , Mark Brown , Delyan Kratunov , Kumar Kartikeya Dwivedi Subject: [PATCH bpf-next v5 2/6] ftrace: Fix deadloop caused by direct call in ftrace selftest Date: Wed, 18 May 2022 09:16:34 -0400 Message-ID: <20220518131638.3401509-3-xukuohai@huawei.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220518131638.3401509-1-xukuohai@huawei.com> References: <20220518131638.3401509-1-xukuohai@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.67.174.197] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To kwepemi500013.china.huawei.com (7.221.188.120) X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220518_065359_935630_6EBCD9AE X-CRM114-Status: GOOD ( 12.99 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org After direct call is enabled for arm64, ftrace selftest enters a dead loop: : 00 bti c 01 mov x9, x30 : 02 bl ----------> ret | lr/x30 is 03, return to 03 | 03 mov w0, #0x0 <-----------------------------| | | | dead loop! | | | 04 ret ---- lr/x30 is still 03, go back to 03 ----| The reason is that when the direct caller trace_direct_tramp() returns to the patched function trace_selftest_dynamic_test_func(), lr is still the address after the instrumented instruction in the patched function, so when the patched function exits, it returns to itself! To fix this issue, we need to restore lr before trace_direct_tramp() exits, so rewrite a dedicated trace_direct_tramp() for arm64. Reported-by: Li Huafei Signed-off-by: Xu Kuohai --- arch/arm64/include/asm/ftrace.h | 10 ++++++++++ arch/arm64/kernel/entry-ftrace.S | 10 ++++++++++ kernel/trace/trace_selftest.c | 2 ++ 3 files changed, 22 insertions(+) diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h index 14a35a5df0a1..6f6b184e72fb 100644 --- a/arch/arm64/include/asm/ftrace.h +++ b/arch/arm64/include/asm/ftrace.h @@ -126,6 +126,16 @@ static inline bool arch_syscall_match_sym_name(const char *sym, */ return !strcmp(sym + 8, name); } + +#ifdef CONFIG_FTRACE_SELFTEST +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS + +#define trace_direct_tramp trace_direct_tramp +extern void trace_direct_tramp(void); + +#endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */ +#endif /* CONFIG_FTRACE_SELFTEST */ + #endif /* ifndef __ASSEMBLY__ */ #endif /* __ASM_FTRACE_H */ diff --git a/arch/arm64/kernel/entry-ftrace.S b/arch/arm64/kernel/entry-ftrace.S index dfe62c55e3a2..a47e87d4d3dd 100644 --- a/arch/arm64/kernel/entry-ftrace.S +++ b/arch/arm64/kernel/entry-ftrace.S @@ -357,3 +357,13 @@ SYM_CODE_START(return_to_handler) ret SYM_CODE_END(return_to_handler) #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ + +#ifdef CONFIG_FTRACE_SELFTEST +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS +SYM_FUNC_START(trace_direct_tramp) + mov x10, x30 + mov x30, x9 + ret x10 +SYM_FUNC_END(trace_direct_tramp) +#endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */ +#endif /* CONFIG_FTRACE_SELFTEST */ diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c index abcadbe933bb..e7ccd0d10c39 100644 --- a/kernel/trace/trace_selftest.c +++ b/kernel/trace/trace_selftest.c @@ -785,8 +785,10 @@ static struct fgraph_ops fgraph_ops __initdata = { }; #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS +#ifndef trace_direct_tramp noinline __noclone static void trace_direct_tramp(void) { } #endif +#endif /* * Pretty much the same than for the function tracer from which the selftest