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@xxxxxxxxxxx> 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;
