From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELvhROllq4Jtwmb4qFD/JRv2LHQaiH1F8TqAwS5UbZdpGc4ZswjSR1KZAPWuNyEAPRMsB5l2 ARC-Seal: i=1; a=rsa-sha256; t=1521214689; cv=none; d=google.com; s=arc-20160816; b=tE0ixxb9XUv9XFWQIgd8uUg4KfUA+PuhSSY/O1DR+JuWuN9SRDH3wbM4CJjdQUkhIi 5ONoIAUs7xPdvR5qfwYicfFd6YQ2kkki+7FwnEbS63uSG7/oP3ZekvlwH9002WlsKVET P/1yDC0BzWOkq7QlX0LW5VnpbLeseIFecD04xpHvouWdzXu2hj3UhqFna3FHxuG0AZOH mxygwFOsZ4n9ZrHtpS3UgEWJ4Bc0cGKbK8KiLs8YIUQzxBdRLsJpxSkTeNUd7yO6IVSr BGep17I07JmThmjJfZfNacQoS1kyKOrowSGMBp0dOCanuTGE1HVMqfQfMPng14thMB+i WaqA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=6TW5MAXvNYXwelzG6rgACMqpjrGkLbgeh69SckMcyuo=; b=jWg/h8Za0kc0E519waEIBSktT1aBrTe6D25IyRbkeFxgps6g3OgLdlUT8cXR6iPzEc RaPvi344ubvfFzmOofEG/t0ztDu3T9or6K4BnGczTXghTYkGFQK07/7Vlzp/hCuIAYTh tcbd3vKDzJRcmHcnH/whWzT54xBAw1OtykmyKDFGw+CAVSnXo26sLBDPUvFPSk3ZmIUq 4rUIgx9ZR1QmSD6V7hN1zxov3Tj5dpQ/6Si1HugUBuLmUuk6yvHkmvtX15zBY9IiHTDy HElk0SVjRAoZArfcO71/dfhK8jXtzhsKC3RqQlu1D3uYvv9WnyUScxbuUx7zVxVz8wqE QBiQ== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.61.202 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.61.202 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Josh Poimboeuf , "Naveen N. Rao" , Michael Ellerman , Sasha Levin Subject: [PATCH 4.14 093/109] powerpc/modules: Dont try to restore r2 after a sibling call Date: Fri, 16 Mar 2018 16:24:02 +0100 Message-Id: <20180316152334.964491242@linuxfoundation.org> X-Mailer: git-send-email 2.16.2 In-Reply-To: <20180316152329.844663293@linuxfoundation.org> References: <20180316152329.844663293@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1595109214413990117?= X-GMAIL-MSGID: =?utf-8?q?1595109214413990117?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Josh Poimboeuf [ Upstream commit b9eab08d012fa093947b230f9a87257c27fb829b ] When attempting to load a livepatch module, I got the following error: module_64: patch_module: Expect noop after relocate, got 3c820000 The error was triggered by the following code in unregister_netdevice_queue(): 14c: 00 00 00 48 b 14c 14c: R_PPC64_REL24 net_set_todo 150: 00 00 82 3c addis r4,r2,0 GCC didn't insert a nop after the branch to net_set_todo() because it's a sibling call, so it never returns. The nop isn't needed after the branch in that case. Signed-off-by: Josh Poimboeuf Acked-by: Naveen N. Rao Reviewed-and-tested-by: Kamalesh Babulal Signed-off-by: Michael Ellerman Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/include/asm/code-patching.h | 1 + arch/powerpc/kernel/module_64.c | 12 +++++++++++- arch/powerpc/lib/code-patching.c | 5 +++++ 3 files changed, 17 insertions(+), 1 deletion(-) --- a/arch/powerpc/include/asm/code-patching.h +++ b/arch/powerpc/include/asm/code-patching.h @@ -33,6 +33,7 @@ int patch_branch(unsigned int *addr, uns int patch_instruction(unsigned int *addr, unsigned int instr); int instr_is_relative_branch(unsigned int instr); +int instr_is_relative_link_branch(unsigned int instr); int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr); unsigned long branch_target(const unsigned int *instr); unsigned int translate_branch(const unsigned int *dest, --- a/arch/powerpc/kernel/module_64.c +++ b/arch/powerpc/kernel/module_64.c @@ -486,7 +486,17 @@ static bool is_early_mcount_callsite(u32 restore r2. */ static int restore_r2(u32 *instruction, struct module *me) { - if (is_early_mcount_callsite(instruction - 1)) + u32 *prev_insn = instruction - 1; + + if (is_early_mcount_callsite(prev_insn)) + return 1; + + /* + * Make sure the branch isn't a sibling call. Sibling calls aren't + * "link" branches and they don't return, so they don't need the r2 + * restore afterwards. + */ + if (!instr_is_relative_link_branch(*prev_insn)) return 1; if (*instruction != PPC_INST_NOP) { --- a/arch/powerpc/lib/code-patching.c +++ b/arch/powerpc/lib/code-patching.c @@ -302,6 +302,11 @@ int instr_is_relative_branch(unsigned in return instr_is_branch_iform(instr) || instr_is_branch_bform(instr); } +int instr_is_relative_link_branch(unsigned int instr) +{ + return instr_is_relative_branch(instr) && (instr & BRANCH_SET_LINK); +} + static unsigned long branch_iform_target(const unsigned int *instr) { signed long imm;