Messages in this thread | | | Subject | Re: [PATCH] LoongArch: Add kernel address sanitizer support | From | Qing Zhang <> | Date | Wed, 29 Mar 2023 10:01:59 +0800 |
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Hi, Huacai
On 2023/3/29 上午8:22, Huacai Chen wrote: > 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. > 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; >>> >>
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