From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELsbkDYqHjX0BJeWQ7ZCp/QULcqtpmTXtMDXMiK6bofS86yY/TU7vx9QSdsFmjMLx9IlZ7F4 ARC-Seal: i=1; a=rsa-sha256; t=1521484017; cv=none; d=google.com; s=arc-20160816; b=rpM+2STyiAjQL3PIAgiS6fczm61DbzAIJjjOF1MhBUm6gO7pvIXduqvlPf56v3Lxjo Du6df7arL5hN/xfVarnySw4YJ1brOkJWfjhpSi5bLB+g2+YTNssOuvczNAievJBi/K+1 dVBdRFMQagjcc/rV440HSzj7kp0EGC3hc8IeS0t/W5qxtfAz7ZLx17InREQeCjeqQ7Bl ti5Yjn+PxnDXQVqDb4Bd/MWM8ZkTqOw7TgI1DfFyKefV9YctdmiPbGKwyTiE5Zi2F5Vz EGAOP/o+jUarOZp7OwMOh3usjF4eqpqgkLVT5fGf8lo6jYdDa8hvf6hu87agLxIEGNFJ wVPg== 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=Z0UzZ5f8qH4TrSdNis7AXNzMMu7IdaZPv0vS8xnPW3I=; b=QVVNiTpliHFG3QXWutBSuBFPhNcftSlXrNTiWDs6LZolCCIJJZrW5SryK+f4odriQl VjL2/5SEnw/wVe2UnJUN9APmjh1Mku1qXAmXPMqv5g5tqpv4wkbvMgxGKq+N2SEbxykp EZqU8fssjVc/agG2qycJLjoST9HL4D892jral6/dxW3E6HZD6mHsyn3ZrnPj5CxYLqL+ W6S7nJkcOHZtdgi7iCRqLydtcesHGMm3BYwYV0HaLuT5MotT0xRkdo/ViDQDLYG18e2J k/eFp6NcE8o1jZPfPfWsNek6RX/5Lg1Z76t5CN5SmDMlUWMvciErjozBPvXYgizdlCHO U0Lg== 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 4.9 201/241] powerpc/modules: Dont try to restore r2 after a sibling call Date: Mon, 19 Mar 2018 19:07:46 +0100 Message-Id: <20180319180759.506954903@linuxfoundation.org> X-Mailer: git-send-email 2.16.2 In-Reply-To: <20180319180751.172155436@linuxfoundation.org> References: <20180319180751.172155436@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?1595391625449125176?= X-GMAIL-MSGID: =?utf-8?q?1595391625449125176?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.9-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 @@ -30,6 +30,7 @@ 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 @@ -494,7 +494,17 @@ 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 @@ -95,6 +95,11 @@ 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;