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LoongArch: Simplify the processing of jumping new kernel for KASLR

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Modified relocate_kernel() doesn't return new kernel's entry point but
the random_offset. In this way we share the start_kernel() processing
with the normal kernel, which avoids calling 'jr a0' directly and allows
some other operations (e.g, kasan_early_init) before start_kernel() when
KASLR (CONFIG_RANDOMIZE_BASE) is turned on.

Signed-off-by: Qing Zhang <zhangqing@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
This commit is contained in:
Qing Zhang 2023-09-06 22:54:16 +08:00 committed by Huacai Chen
parent fb6d5c1d99
commit 9fbcc07679
3 changed files with 9 additions and 12 deletions
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2
arch/loongarch/include/asm/setup.h
View File

@ -34,7 +34,7 @@ extern long __la_abs_end;
extern long __rela_dyn_begin;
extern long __rela_dyn_end;
extern void * __init relocate_kernel(void);
extern unsigned long __init relocate_kernel(void);
#endif

11
arch/loongarch/kernel/head.S
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@ -95,13 +95,14 @@ SYM_CODE_START(kernel_entry) # kernel entry point
PTR_LI sp, (_THREAD_SIZE - PT_SIZE)
PTR_ADD sp, sp, tp
set_saved_sp sp, t0, t1
#endif
/* relocate_kernel() returns the new kernel entry point */
jr a0
ASM_BUG()
/* Jump to the new kernel: new_pc = current_pc + random_offset */
pcaddi t0, 0
add.d t0, t0, a0
jirl zero, t0, 0xc
#endif /* CONFIG_RANDOMIZE_BASE */
#endif
#endif /* CONFIG_RELOCATABLE */
bl start_kernel
ASM_BUG()

8
arch/loongarch/kernel/relocate.c
View File

@ -157,12 +157,11 @@ static inline void __init update_reloc_offset(unsigned long *addr, long random_o
*new_addr = (unsigned long)reloc_offset;
}
void * __init relocate_kernel(void)
unsigned long __init relocate_kernel(void)
{
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;
}
/*