arm64: kprobes: check the return value of set_memory_rox()

Since commit a166563 ("arm64: mm: support large block mapping when
rodata=full"), __change_memory_common has more chance to fail due to
memory allocation failure when splitting page table. So check the return
value of set_memory_rox(), then bail out if it fails otherwise we may have
RW memory mapping for kprobes insn page.

Fixes: 195a1b7 ("arm64: kprobes: call set_memory_rox() for kprobe page")
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Reviewed-by: Dev Jain <dev.jain@arm.com>
Signed-off-by: Yang Shi <yang@os.amperecomputing.com>
Signed-off-by: Will Deacon <will@kernel.org>

Author: Yang Shi

arch/arm64/kernel/probes/kprobes.c

@@ -49,7 +49,10 @@ void *alloc_insn_page(void)
 	addr = execmem_alloc(EXECMEM_KPROBES, PAGE_SIZE);
 	if (!addr)
 		return NULL;
-	set_memory_rox((unsigned long)addr, 1);
+	if (set_memory_rox((unsigned long)addr, 1)) {
+		execmem_free(addr);
+		return NULL;
+	}
 	return addr;
 }