mm: add memmap interface to reserved memory for mremap syscall useage

euleros inclusion
category: feature
feature: memmap

add memap interface to reserved memory for mremap syscall useage.
Signed-off-by: Nzhong jiang <zhongjiang@huawei.com>
Reviewed-by: NJing xiangfeng <jingxiangfeng@huawei.com>
Signed-off-by: Nzhong jiang <zhongjiang@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

arch/arm64/include/asm/mmu.h

@@ -31,6 +31,16 @@ typedef struct {
 	unsigned long	flags;
 } mm_context_t;
 
+#define MAX_RES_REGIONS	32
+
+struct res_mem {
+	phys_addr_t base;
+	phys_addr_t size;
+};
+
+extern struct res_mem res_mem[MAX_RES_REGIONS];
+extern int res_mem_count;
+
 /*
  * This macro is only used by the TLBI code, which cannot race with an
  * ASID change and therefore doesn't need to reload the counter using

arch/arm64/kernel/setup.c

@@ -63,6 +63,7 @@
 #include <asm/efi.h>
 #include <asm/xen/hypervisor.h>
 #include <asm/mmu_context.h>
+#include <asm/mmu.h>
 
 static int num_standard_resources;
 static struct resource *standard_resources;
@@ -208,8 +209,8 @@ static void __init setup_machine_fdt(phys_addr_t dt_phys)
 static void __init request_standard_resources(void)
 {
 	struct memblock_region *region;
-	struct resource *res;
-	unsigned long i = 0;
+	struct resource *res, *res_resources;
+	unsigned long i = 0, j = 0, res_count;
 
 	kernel_code.start   = __pa_symbol(_text);
 	kernel_code.end     = __pa_symbol(__init_begin - 1);
@@ -219,6 +220,16 @@ static void __init request_standard_resources(void)
 	num_standard_resources = memblock.memory.cnt;
 	standard_resources = alloc_bootmem_low(num_standard_resources *
 					       sizeof(*standard_resources));
+	res_resources = alloc_bootmem_low(res_mem_count *
+					       sizeof(struct resource));
+
+	for (res_count = 0; res_count < res_mem_count; res_count++) {
+		res_resources[res_count].name = "memmap reserved";
+		res_resources[res_count].flags = IORESOURCE_MEM;
+		res_resources[res_count].start = res_mem[res_count].base;
+		res_resources[res_count].end = res_resources[res_count].start +
+					       res_mem[res_count].size - 1;
+	}
 
 	for_each_memblock(memory, region) {
 		res = &standard_resources[i++];
@@ -246,6 +257,12 @@ static void __init request_standard_resources(void)
 		    crashk_res.end <= res->end)
 			request_resource(res, &crashk_res);
 #endif
+
+		for (; j < res_mem_count; j++) {
+			if (res_resources[j].start >= res->start &&
+			    res_resources[j].end <= res->end)
+				request_resource(res, &res_resources[j]);
+		}
 	}
 }
 

arch/arm64/mm/init.c

@@ -62,6 +62,9 @@
 s64 memstart_addr __ro_after_init = -1;
 phys_addr_t arm64_dma_phys_limit __ro_after_init;
 
+struct res_mem res_mem[MAX_RES_REGIONS];
+int res_mem_count;
+
 #ifdef CONFIG_BLK_DEV_INITRD
 static int __init early_initrd(char *p)
 {
@@ -371,6 +374,70 @@ static void __init fdt_enforce_memory_region(void)
 		memblock_cap_memory_range(reg.base, reg.size);
 }
 
+static int __init parse_memmap_one(char *p)
+{
+	char *oldp;
+	phys_addr_t start_at, mem_size;
+	int ret;
+
+	if (!p)
+		return -EINVAL;
+
+	oldp = p;
+	mem_size = memparse(p, &p);
+	if (p == oldp)
+		return -EINVAL;
+
+	if (!mem_size)
+		return -EINVAL;
+
+	mem_size = PAGE_ALIGN(mem_size);
+
+	if (*p == '$') {
+		start_at = memparse(p+1, &p);
+		if (!IS_ALIGNED(start_at, SZ_2M)) {
+			pr_warn("cannot reserve memory: bad address is not 2MB aligned\n");
+			return -EINVAL;
+		}
+
+		if (!memblock_is_region_memory(start_at, mem_size)) {
+			pr_warn("cannot reserve memory: region is not meory\n");
+			return -EINVAL;
+		}
+
+		if (memblock_is_region_reserved(start_at, mem_size)) {
+			pr_warn("cannot reserve memory: region overlaps reserved memory\n");
+			return -EINVAL;
+		}
+
+		ret = memblock_reserve(start_at, mem_size);
+		if (!ret) {
+			res_mem[res_mem_count].base = start_at;
+			res_mem[res_mem_count].size = mem_size;
+			res_mem_count++;
+		} else
+			pr_warn("memmap memblock_reserve failed.\n");
+	}
+
+	return *p == '\0' ? 0 : -EINVAL;
+}
+
+static int __init parse_memmap_opt(char *str)
+{
+	while (str) {
+		char *k = strchr(str, ',');
+
+		if (k)
+			*k++ = 0;
+
+		parse_memmap_one(str);
+		str = k;
+	}
+
+	return 0;
+}
+early_param("memmap", parse_memmap_opt);
+
 void __init arm64_memblock_init(void)
 {
 	const s64 linear_region_size = -(s64)PAGE_OFFSET;