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imf23.hostedemail.com; dkim=none; dmarc=none; spf=pass (imf23.hostedemail.com: domain of zhangqing@loongson.cn designates 114.242.206.163 as permitted sender) smtp.mailfrom=zhangqing@loongson.cn ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1680055329; a=rsa-sha256; cv=none; b=uXKimStQJTt5QV7Mh15Ntyn6H50IbajdzpPgsCqUoQpraQyBASZMEkio6LbtDl9cWmTflc DucooOOFWIrl8h9lYdLT17HShVHKNZ3Qf6+UI7fLE17Cts0cZyIvUNECj2Fsh/lS6jHAjk tIEZvHoieX6YLJErFimQT2Ot2Vlde0s= Received: from loongson.cn (unknown [113.200.148.30]) by gateway (Coremail) with SMTP id _____8BxMI8ZnCNkkHsTAA--.30128S3; Wed, 29 Mar 2023 10:02:01 +0800 (CST) Received: from [10.130.0.102] (unknown [113.200.148.30]) by localhost.localdomain (Coremail) with SMTP id AQAAf8CxPL4XnCNkIQQQAA--.12984S3; Wed, 29 Mar 2023 10:02:01 +0800 (CST) Subject: Re: [PATCH] LoongArch: Add kernel address sanitizer support To: Huacai Chen Cc: Xi Ruoyao , Andrey Ryabinin , Jonathan Corbet , Andrew Morton , Alexander Potapenko , Andrey Konovalov , Dmitry Vyukov , Vincenzo Frascino , WANG Xuerui , Jiaxun Yang , kasan-dev@googlegroups.com, linux-doc@vger.kernel.org, linux-mm@kvack.org, loongarch@lists.linux.dev, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org References: <20230328111714.2056-1-zhangqing@loongson.cn> <9817aaa043e9f0ed964bd523773447bd64f6e2c0.camel@xry111.site> <1c231587-3b70-22ab-d554-ebe3de407909@loongson.cn> From: Qing Zhang Message-ID: <9a6f11a3-d01c-e0c9-a4f3-47db25ce02f3@loongson.cn> Date: Wed, 29 Mar 2023 10:01:59 +0800 User-Agent: Mozilla/5.0 (X11; Linux mips64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 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-CM-TRANSID:AQAAf8CxPL4XnCNkIQQQAA--.12984S3 X-CM-SenderInfo: x2kd0wptlqwqxorr0wxvrqhubq/ X-Coremail-Antispam: 1Uk129KBjvJXoW7uF43ur1UArykKF4xtw43Wrg_yoW8tw4Upr y8GF4rtw48Jr40vrs2q34Duryjv3Z2qw1agr4DK34rZ3sF9F98Kr4DWr13uF929r1j9F4Y vFWrtFWa934UJaDanT9S1TB71UUUUjUqnTZGkaVYY2UrUUUUj1kv1TuYvTs0mT0YCTnIWj qI5I8CrVACY4xI64kE6c02F40Ex7xfYxn0WfASr-VFAUDa7-sFnT9fnUUIcSsGvfJTRUUU bDAYFVCjjxCrM7AC8VAFwI0_Jr0_Gr1l1xkIjI8I6I8E6xAIw20EY4v20xvaj40_Wr0E3s 1l1IIY67AEw4v_Jrv_JF1l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0rcxSw2x7M28EF7xv wVC0I7IYx2IY67AKxVW8JVW5JwA2z4x0Y4vE2Ix0cI8IcVCY1x0267AKxVW8JVWxJwA2z4 x0Y4vEx4A2jsIE14v26F4j6r4UJwA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_Gr0_Gr1UM2kK e7AKxVWUXVWUAwAS0I0E0xvYzxvE52x082IY62kv0487Mc804VCY07AIYIkI8VC2zVCFFI 0UMc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7IYx2IY67AKxVWUAVWUtwAv7VC2z280 aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4UM4x0Y48IcVAKI48JMxk0xIA0c2IEe2 xFo4CEbIxvr21lc7CjxVAaw2AFwI0_JF0_Jw1l42xK82IYc2Ij64vIr41l4I8I3I0E4IkC 6x0Yz7v_Jr0_Gr1l4IxYO2xFxVAFwI0_Jrv_JF1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s 026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r4a6rW5MIIYrxkI7VAKI48JMIIF 0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E14v26r1j6r4UMIIF0x vE42xK8VAvwI8IcIk0rVWUJVWUCwCI42IY6I8E87Iv67AKxVWUJVW8JwCI42IY6I8E87Iv 6xkF7I0E14v26r1j6r4UYxBIdaVFxhVjvjDU0xZFpf9x07jOiSdUUUUU= X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: AED7B14001A X-Stat-Signature: psi18rhktmbr544ttthtof1ywt6xoch8 X-HE-Tag: 1680055326-374660 X-HE-Meta: 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 XsOq5mq6 604/yLRB8J7u7QCDTKb76jFHGUJ/UMWLEBLTxgt7lmwd/dAUUjK5lwonlnQKnNNPm89It0eNjYxi8geXe+YcIwMh8Jyl7HQMwxF+5EeMf2bzvDhO0WMyshUledm68GMZDsNsJRBgEB9jSLrk= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Hi, Huacai On 2023/3/29 上午8:22, Huacai Chen wrote: > On Tue, Mar 28, 2023 at 8:15 PM Qing Zhang wrote: >> >> Hi, Ruoyao >> >> On 2023/3/28 下午7:39, Xi Ruoyao wrote: >>> On Tue, 2023-03-28 at 19:17 +0800, Qing Zhang wrote: >>> >>> /* snip */ >>> >>> >>>> -void * __init relocate_kernel(void) >>>> +unsigned long __init relocate_kernel(void) >>> >>> Why we must modify relocate_kernel for KASAN? >> >> When the CONFIG_RANDOMIZE_BASE is enabled, the kernel will be updated to >> a random new address. >> Kasan needs to call kasan_early_init before start_kernel. >> There are two situations: >> 1> After enabling CONFIG_RELOCATABLE, call kasan_early_init. >> 2> After CONFIG_RELOCATABLE is not enabled, call kasan_early_init. >> >> In order to prevent code redundancy and semantic problems caused by >> calling kasan_early_init (before jr a0) at the old PC. > In my opinion, you can call kasan_early_init before relocate_kernel in > head.S, then no redundancy. > It has no effect now, but kasan_early_init generally maps everything to a single page of zeroes in kasan area, if placed Before relocate_kernel, when the kernel was relocated, I worried that there were changes other than the memory layout. Thanks, - Qing > Huacai >> >> Thanks, >> -Qing >>> >>>> { >>>> unsigned long kernel_length; >>>> unsigned long random_offset = 0; >>>> void *location_new = _text; /* Default to original kernel start */ >>>> - void *kernel_entry = start_kernel; /* Default to original kernel entry point */ >>>> char *cmdline = early_ioremap(fw_arg1, COMMAND_LINE_SIZE); /* Boot command line is passed in fw_arg1 */ >>>> >>>> strscpy(boot_command_line, cmdline, COMMAND_LINE_SIZE); >>>> @@ -190,9 +189,6 @@ void * __init relocate_kernel(void) >>>> >>>> reloc_offset += random_offset; >>>> >>>> - /* Return the new kernel's entry point */ >>>> - kernel_entry = RELOCATED_KASLR(start_kernel); >>>> - >>>> /* The current thread is now within the relocated kernel */ >>>> __current_thread_info = RELOCATED_KASLR(__current_thread_info); >>>> >>>> @@ -204,7 +200,7 @@ void * __init relocate_kernel(void) >>>> >>>> relocate_absolute(random_offset); >>>> >>>> - return kernel_entry; >>>> + return random_offset; >>> >>