From: Huacai Chen <chenhuacai@kernel.org>
To: Qing Zhang <zhangqing@loongson.cn>
Cc: Xi Ruoyao <xry111@xry111.site>,
Andrey Ryabinin <ryabinin.a.a@gmail.com>,
Jonathan Corbet <corbet@lwn.net>,
Andrew Morton <akpm@linux-foundation.org>,
Alexander Potapenko <glider@google.com>,
Andrey Konovalov <andreyknvl@gmail.com>,
Dmitry Vyukov <dvyukov@google.com>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
WANG Xuerui <kernel@xen0n.name>,
Jiaxun Yang <jiaxun.yang@flygoat.com>,
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
Subject: Re: [PATCH] LoongArch: Add kernel address sanitizer support
Date: Wed, 29 Mar 2023 08:22:37 +0800 [thread overview]
Message-ID: <CAAhV-H5APsBxC8nNa81t3HXum1EU1hOj4S6UC7xLHD7_BCJd7g@mail.gmail.com> (raw)
In-Reply-To: <1c231587-3b70-22ab-d554-ebe3de407909@loongson.cn>
On Tue, Mar 28, 2023 at 8:15 PM Qing Zhang <zhangqing@loongson.cn> 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.
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;
> >
>
next prev parent reply other threads:[~2023-03-29 0:22 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-28 11:17 Qing Zhang
2023-03-28 11:39 ` Xi Ruoyao
2023-03-28 12:15 ` Qing Zhang
2023-03-29 0:22 ` Huacai Chen [this message]
2023-03-29 2:01 ` Qing Zhang
2023-03-28 11:57 ` Youling Tang
2023-03-28 12:08 ` Youling Tang
2023-03-28 12:27 ` Qing Zhang
2023-03-29 19:02 ` Andrey Konovalov
2023-03-30 2:06 ` Qing Zhang
2023-03-30 2:55 ` Andrey Konovalov
2023-03-30 4:32 ` Qing Zhang
2023-03-31 15:58 ` Andrey Konovalov
2023-04-01 3:23 ` Qing Zhang
2023-03-30 6:50 ` Youling Tang
2023-03-30 8:53 ` Qing Zhang
2023-03-31 8:07 ` Youling Tang
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