arm64: insn: avoid virt_to_page() translations on core kernel symbols

Before restricting virt_to_page() to the linear mapping, ensure that
the text patching code does not use it to resolve references into the
core kernel text, which is mapped in the vmalloc area.
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

arch/arm64/kernel/insn.c

@@ -96,7 +96,7 @@ static void __kprobes *patch_map(void *addr, int fixmap)
 	if (module && IS_ENABLED(CONFIG_DEBUG_SET_MODULE_RONX))
 		page = vmalloc_to_page(addr);
 	else if (!module && IS_ENABLED(CONFIG_DEBUG_RODATA))
-		page = virt_to_page(addr);
+		page = pfn_to_page(PHYS_PFN(__pa(addr)));
 	else
 		return addr;