riscv: kasan: use local_tlb_flush_all() to avoid uninitialized __sbi_rfence

It fails to boot the v5.8-rc4 kernel with CONFIG_KASAN because kasan_init
and kasan_early_init use uninitialized __sbi_rfence as executing the
tlb_flush_all(). Actually, at this moment, only the CPU which is
responsible for the system initialization enables the MMU. Other CPUs are
parking at the .Lsecondary_start. Hence the tlb_flush_all() is able to be
replaced by local_tlb_flush_all() to avoid using uninitialized
__sbi_rfence.

Signed-off-by: Vincent Chen <vincent.chen@sifive.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Author: VincentZWC

arch/riscv/mm/kasan_init.c

@@ -44,7 +44,7 @@ asmlinkage void __init kasan_early_init(void)
 				(__pa(((uintptr_t) kasan_early_shadow_pmd))),
 				__pgprot(_PAGE_TABLE)));
 
-	flush_tlb_all();
+	local_flush_tlb_all();
 }
 
 static void __init populate(void *start, void *end)
@@ -79,7 +79,7 @@ static void __init populate(void *start, void *end)
 			pfn_pgd(PFN_DOWN(__pa(&pmd[offset])),
 				__pgprot(_PAGE_TABLE)));
 
-	flush_tlb_all();
+	local_flush_tlb_all();
 	memset(start, 0, end - start);
 }