!880 LoongArch: kdump: Add high memory reservation

Merge Pull Request from: @Hongchen_Zhang 
 
kdump function test failed on 3C5000+7A2000 dual-bridge machine,
we fix it as following:
reserve high memory for the capture kernel to avoid kdump operation
failure on 3C5000 machines with old firmware.

after apply this patch,the following test case passed:
1) add crashkernel=512M in commandline 
2) systemctl start kdump
3) echo c >/proc/sysrq-trigger
4) after reboot, vmcore file created in /var/crash directory
 
 
Link:https://gitee.com/openeuler/kernel/pulls/880 

Reviewed-by: Jialin Zhang <zhangjialin11@huawei.com> 
Reviewed-by: Guo Dongtai <guodongtai@kylinos.cn> 
Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com> 

arch/loongarch/kernel/setup.c

@@ -306,13 +306,49 @@ static void __init arch_parse_crashkernel(void)
  * memory area used by the previous production kernel should be reserved to
  * avoid destroy to the captured data.
  */
-static void reserve_oldmem_region(void)
+static void reserve_oldmem_region(int node, unsigned long s0, unsigned long e0)
 {
 #ifdef CONFIG_CRASH_DUMP
+	unsigned long s1, e1;
+
 	if (!is_kdump_kernel())
 		return;
 
-	memblock_cap_memory_range(crashmem_start, crashmem_size);
+	if ((e0 - s0) > (SZ_1G >> PAGE_SHIFT))
+		e0 = e0 - (SZ_512M >> PAGE_SHIFT);
+
+	/* crashmem_start is crashk_res reserved by primary production kernel */
+	s1 = PFN_UP(crashmem_start);
+	e1 = PFN_DOWN(crashmem_start + crashmem_size);
+
+	if (s1 == 0)
+		return;
+
+	if (node == 0) {
+		memblock_reserve(PFN_PHYS(s0), (s1 - s0) << PAGE_SHIFT);
+		memblock_reserve(PFN_PHYS(e1), (e0 - e1) << PAGE_SHIFT);
+	} else {
+		memblock_reserve(PFN_PHYS(s0), (e0 - s0) << PAGE_SHIFT);
+	}
+#endif
+}
+
+/* Traditionally, LoongArch's contiguous low memory is 256M, so crashkernel=X@Y is
+ * unable to be large enough in some cases. Thus, if the total memory of a node
+ * is more than 1GB, we reserve the top 512MB for the capture kernel
+ */
+static void reserve_crashm_region(int node, unsigned long s0, unsigned long e0)
+{
+#ifdef CONFIG_KEXEC
+	if (crashk_res.start == crashk_res.end)
+		return;
+
+	if ((e0 - s0) <= (SZ_1G >> PAGE_SHIFT))
+		return;
+
+	s0 = e0 - (SZ_512M >> PAGE_SHIFT);
+
+	memblock_reserve(PFN_PHYS(s0), (e0 - s0) << PAGE_SHIFT);
 #endif
 }
 
@@ -356,9 +392,16 @@ static void __init check_kernel_sections_mem(void)
  */
 static void __init arch_mem_init(char **cmdline_p)
 {
+	unsigned int node;
+	unsigned long start_pfn, end_pfn;
+
 	arch_reserve_vmcore();
 	arch_parse_crashkernel();
-	reserve_oldmem_region();
+	for_each_online_node(node) {
+		get_pfn_range_for_nid(node, &start_pfn, &end_pfn);
+		reserve_crashm_region(node, start_pfn, end_pfn);
+		reserve_oldmem_region(node, start_pfn, end_pfn);
+	}
 
 	if (usermem)
 		pr_info("User-defined physical RAM map overwrite\n");