efi/libstub: arm64: Fix KASLR and memmap= collision

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5J0X7
CVE: NA

--------------------------------

CONFIG_RANDOMIZE_BASE=y relocates the kernel to a random base address.

However, on arm64, it does not take into account the memmap= parameter
passed in from the kernel command line. This results in the kernel
sometimes being put in the middle of memmap.

Add support for memmap kernel parameters parsing on ARM64. The below
modes are only supported:

memmap=nn[KMG]$ss[KMG]

Region of memory to be reserved is from ss to ss+nn, the region must
be in the range of existed memory, otherwise will be ignored.

Teach KASLR to not insert the kernel in memmap defined regions. We
support up to 32 memmap regions: any additional regions will cause
KASLR to disable.
Signed-off-by: NCui GaoSheng <cuigaosheng1@huawei.com>
Reviewed-by: NWang Weiyang <wangweiyang2@huawei.com>
Reviewed-by: NXiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

drivers/firmware/efi/libstub/arm64-stub.c

@@ -15,6 +15,95 @@
 
 #include "efistub.h"
 
+#define MAX_MEMMAP_REGIONS 32
+
+struct mem_vector {
+	unsigned long long start;
+	unsigned long long size;
+};
+
+static struct mem_vector mem_avoid[MAX_MEMMAP_REGIONS];
+
+static int
+efi_parse_memmap(char *p, unsigned long long *start, unsigned long long *size)
+{
+	char *oldp;
+	u64 mem_size;
+
+	if (!p)
+		return -EINVAL;
+
+	oldp = p;
+	mem_size = memparse(p, &p);
+	if (p == oldp)
+		return -EINVAL;
+	if (!mem_size)
+		return -EINVAL;
+	if (*p != '$')
+		return -EINVAL;
+
+	*start = memparse(p + 1, &p);
+	*size = mem_size;
+
+	return 0;
+}
+
+void efi_parse_option_memmap(const char *str)
+{
+	int rc;
+	static int idx;
+	char *k, *p = (char *)str;
+
+	while (p && (idx < MAX_MEMMAP_REGIONS)) {
+		k = strchr(p, ',');
+		if (k)
+			*k++ = 0;
+
+		rc = efi_parse_memmap(p, &mem_avoid[idx].start, &mem_avoid[idx].size);
+		if (rc < 0)
+			efi_err("Failed to parse memmap cmdlines, index: %d, str: %s\n", idx, p);
+
+		p = k;
+		idx++;
+	}
+}
+
+void mem_avoid_memmap(void)
+{
+	int i;
+	efi_status_t status;
+	unsigned long nr_pages;
+	unsigned long long start, end;
+
+	for (i = 0; i < MAX_MEMMAP_REGIONS; i++) {
+		if (!mem_avoid[i].size)
+			continue;
+		start = round_down(mem_avoid[i].start, EFI_ALLOC_ALIGN);
+		end = round_up(mem_avoid[i].start + mem_avoid[i].size, EFI_ALLOC_ALIGN);
+		nr_pages = (end - start) / EFI_PAGE_SIZE;
+
+		mem_avoid[i].start = start;
+		mem_avoid[i].size = end - start;
+		status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS,
+				     EFI_LOADER_DATA, nr_pages, &mem_avoid[i].start);
+		if (status != EFI_SUCCESS) {
+			efi_err("Failed to reserve memmap, index: %d, status: %lu\n", i, status);
+			mem_avoid[i].size = 0;
+		}
+	}
+}
+
+void free_avoid_memmap(void)
+{
+	int i;
+
+	for (i = 0; i < MAX_MEMMAP_REGIONS; i++) {
+		if (!mem_avoid[i].size)
+			continue;
+		efi_free(mem_avoid[i].size, mem_avoid[i].start);
+	}
+}
+
 efi_status_t check_platform_features(void)
 {
 	u64 tg;

drivers/firmware/efi/libstub/efi-stub-helper.c

@@ -232,6 +232,8 @@ efi_status_t efi_parse_options(char const *cmdline)
 		} else if (!strcmp(param, "video") &&
 			   val && strstarts(val, "efifb:")) {
 			efi_parse_option_graphics(val + strlen("efifb:"));
+		} else if (!strcmp(param, "memmap") && val) {
+			efi_parse_option_memmap(val);
 		}
 	}
 	efi_bs_call(free_pool, buf);

drivers/firmware/efi/libstub/efi-stub.c

@@ -194,6 +194,8 @@ efi_status_t __efiapi efi_pe_entry(efi_handle_t handle,
 
 	si = setup_graphics();
 
+	mem_avoid_memmap();
+
 	status = handle_kernel_image(&image_addr, &image_size,
 				     &reserve_addr,
 				     &reserve_size,
@@ -311,6 +313,7 @@ efi_status_t __efiapi efi_pe_entry(efi_handle_t handle,
 	efi_free(image_size, image_addr);
 	efi_free(reserve_size, reserve_addr);
 fail_free_screeninfo:
+	free_avoid_memmap();
 	free_screen_info(si);
 fail_free_cmdline:
 	efi_bs_call(free_pool, cmdline_ptr);

drivers/firmware/efi/libstub/efistub.h

@@ -805,6 +805,16 @@ efi_status_t efi_parse_options(char const *cmdline);
 
 void efi_parse_option_graphics(char *option);
 
+#ifdef CONFIG_ARM64
+void efi_parse_option_memmap(const char *str);
+void mem_avoid_memmap(void);
+void free_avoid_memmap(void);
+#else
+static inline void efi_parse_option_memmap(const char *str) { }
+static inline void mem_avoid_memmap(void) { }
+static inline void free_avoid_memmap(void) { }
+#endif
+
 efi_status_t efi_setup_gop(struct screen_info *si, efi_guid_t *proto,
 			   unsigned long size);