From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4ECE8C7618B for ; Mon, 29 Jul 2019 13:35:55 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id A089E206E0 for ; Mon, 29 Jul 2019 13:35:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A089E206E0 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-16611-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 15536 invoked by uid 550); 29 Jul 2019 13:35:48 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Received: (qmail 15497 invoked from network); 29 Jul 2019 13:35:47 -0000 Subject: Re: [RFC PATCH 05/10] powerpc/fsl_booke/32: introduce reloc_kernel_entry() helper To: Christophe Leroy , , , , , , , , CC: , , , , , References: <20190717080621.40424-1-yanaijie@huawei.com> <20190717080621.40424-6-yanaijie@huawei.com> From: Jason Yan Message-ID: <60238fe3-a6ec-3537-d56d-29ebeb38f5fd@huawei.com> Date: Mon, 29 Jul 2019 21:35:18 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.5.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-Originating-IP: [10.177.96.203] X-CFilter-Loop: Reflected On 2019/7/29 19:08, Christophe Leroy wrote: > > > Le 17/07/2019 à 10:06, Jason Yan a écrit : >> Add a new helper reloc_kernel_entry() to jump back to the start of the >> new kernel. After we put the new kernel in a randomized place we can use >> this new helper to enter the kernel and begin to relocate again. >> >> Signed-off-by: Jason Yan >> Cc: Diana Craciun >> Cc: Michael Ellerman >> Cc: Christophe Leroy >> Cc: Benjamin Herrenschmidt >> Cc: Paul Mackerras >> Cc: Nicholas Piggin >> Cc: Kees Cook >> --- >>   arch/powerpc/kernel/head_fsl_booke.S | 16 ++++++++++++++++ >>   arch/powerpc/mm/mmu_decl.h           |  1 + >>   2 files changed, 17 insertions(+) >> >> diff --git a/arch/powerpc/kernel/head_fsl_booke.S >> b/arch/powerpc/kernel/head_fsl_booke.S >> index a57d44638031..ce40f96dae20 100644 >> --- a/arch/powerpc/kernel/head_fsl_booke.S >> +++ b/arch/powerpc/kernel/head_fsl_booke.S >> @@ -1144,6 +1144,22 @@ _GLOBAL(create_tlb_entry) >>       sync >>       blr >> +/* >> + * Return to the start of the relocated kernel and run again >> + * r3 - virtual address of fdt >> + * r4 - entry of the kernel >> + */ >> +_GLOBAL(reloc_kernel_entry) >> +    mfmsr    r7 >> +    li    r8,(MSR_IS | MSR_DS) >> +    andc    r7,r7,r8 > > Instead of the li/andc, what about the following: > > rlwinm r7, r7, 0, ~(MSR_IS | MSR_DS) > Good idea. >> + >> +    mtspr    SPRN_SRR0,r4 >> +    mtspr    SPRN_SRR1,r7 >> +    isync >> +    sync >> +    rfi > > Are the isync/sync really necessary ? AFAIK, rfi is context synchronising. > I see some code with sync before rfi so I'm not sure. I will check this and drop the isync/sync if it's true. Thanks. >> + >>   /* >>    * Create a tlb entry with the same effective and physical address as >>    * the tlb entry used by the current running code. But set the TS to 1. >> diff --git a/arch/powerpc/mm/mmu_decl.h b/arch/powerpc/mm/mmu_decl.h >> index d7737cf97cee..dae8e9177574 100644 >> --- a/arch/powerpc/mm/mmu_decl.h >> +++ b/arch/powerpc/mm/mmu_decl.h >> @@ -143,6 +143,7 @@ extern void adjust_total_lowmem(void); >>   extern int switch_to_as1(void); >>   extern void restore_to_as0(int esel, int offset, void *dt_ptr, int >> bootcpu); >>   extern void create_tlb_entry(phys_addr_t phys, unsigned long virt, >> int entry); >> +extern void reloc_kernel_entry(void *fdt, int addr); > > No new 'extern' please, see > https://openpower.xyz/job/snowpatch/job/snowpatch-linux-checkpatch/8125//artifact/linux/checkpatch.log > > > >>   #endif >>   extern void loadcam_entry(unsigned int index); >>   extern void loadcam_multi(int first_idx, int num, int tmp_idx); >> > > Christophe > > . >