1 // SPDX-License-Identifier: GPL-2.0-only
2 
3 #define pr_fmt(fmt) "efi: " fmt
4 
5 #include <linux/module.h>
6 #include <linux/init.h>
7 #include <linux/efi.h>
8 #include <linux/libfdt.h>
9 #include <linux/of_fdt.h>
10 
11 #include <asm/unaligned.h>
12 
13 enum {
14 	SYSTAB,
15 	MMBASE,
16 	MMSIZE,
17 	DCSIZE,
18 	DCVERS,
19 
20 	PARAMCOUNT
21 };
22 
23 static __initconst const char name[][22] = {
24 	[SYSTAB] = "System Table         ",
25 	[MMBASE] = "MemMap Address       ",
26 	[MMSIZE] = "MemMap Size          ",
27 	[DCSIZE] = "MemMap Desc. Size    ",
28 	[DCVERS] = "MemMap Desc. Version ",
29 };
30 
31 static __initconst const struct {
32 	const char	path[17];
33 	u8		paravirt;
34 	const char	params[PARAMCOUNT][26];
35 } dt_params[] = {
36 	{
37 #ifdef CONFIG_XEN    //  <-------17------>
38 		.path = "/hypervisor/uefi",
39 		.paravirt = 1,
40 		.params = {
41 			[SYSTAB] = "xen,uefi-system-table",
42 			[MMBASE] = "xen,uefi-mmap-start",
43 			[MMSIZE] = "xen,uefi-mmap-size",
44 			[DCSIZE] = "xen,uefi-mmap-desc-size",
45 			[DCVERS] = "xen,uefi-mmap-desc-ver",
46 		}
47 	}, {
48 #endif
49 		.path = "/chosen",
50 		.params = {	//  <-----------26----------->
51 			[SYSTAB] = "linux,uefi-system-table",
52 			[MMBASE] = "linux,uefi-mmap-start",
53 			[MMSIZE] = "linux,uefi-mmap-size",
54 			[DCSIZE] = "linux,uefi-mmap-desc-size",
55 			[DCVERS] = "linux,uefi-mmap-desc-ver",
56 		}
57 	}
58 };
59 
efi_get_fdt_prop(const void * fdt,int node,const char * pname,const char * rname,void * var,int size)60 static int __init efi_get_fdt_prop(const void *fdt, int node, const char *pname,
61 				   const char *rname, void *var, int size)
62 {
63 	const void *prop;
64 	int len;
65 	u64 val;
66 
67 	prop = fdt_getprop(fdt, node, pname, &len);
68 	if (!prop)
69 		return 1;
70 
71 	val = (len == 4) ? (u64)be32_to_cpup(prop) : get_unaligned_be64(prop);
72 
73 	if (size == 8)
74 		*(u64 *)var = val;
75 	else
76 		*(u32 *)var = (val < U32_MAX) ? val : U32_MAX; // saturate
77 
78 	if (efi_enabled(EFI_DBG))
79 		pr_info("  %s: 0x%0*llx\n", rname, size * 2, val);
80 
81 	return 0;
82 }
83 
efi_get_fdt_params(struct efi_memory_map_data * mm)84 u64 __init efi_get_fdt_params(struct efi_memory_map_data *mm)
85 {
86 	const void *fdt = initial_boot_params;
87 	unsigned long systab;
88 	int i, j, node;
89 	struct {
90 		void	*var;
91 		int	size;
92 	} target[] = {
93 		[SYSTAB] = { &systab,		sizeof(systab) },
94 		[MMBASE] = { &mm->phys_map,	sizeof(mm->phys_map) },
95 		[MMSIZE] = { &mm->size,		sizeof(mm->size) },
96 		[DCSIZE] = { &mm->desc_size,	sizeof(mm->desc_size) },
97 		[DCVERS] = { &mm->desc_version,	sizeof(mm->desc_version) },
98 	};
99 
100 	BUILD_BUG_ON(ARRAY_SIZE(target) != ARRAY_SIZE(name));
101 	BUILD_BUG_ON(ARRAY_SIZE(target) != ARRAY_SIZE(dt_params[0].params));
102 
103 	if (!fdt)
104 		return 0;
105 
106 	for (i = 0; i < ARRAY_SIZE(dt_params); i++) {
107 		node = fdt_path_offset(fdt, dt_params[i].path);
108 		if (node < 0)
109 			continue;
110 
111 		if (efi_enabled(EFI_DBG))
112 			pr_info("Getting UEFI parameters from %s in DT:\n",
113 				dt_params[i].path);
114 
115 		for (j = 0; j < ARRAY_SIZE(target); j++) {
116 			const char *pname = dt_params[i].params[j];
117 
118 			if (!efi_get_fdt_prop(fdt, node, pname, name[j],
119 					      target[j].var, target[j].size))
120 				continue;
121 			if (!j)
122 				goto notfound;
123 			pr_err("Can't find property '%s' in DT!\n", pname);
124 			return 0;
125 		}
126 		if (dt_params[i].paravirt)
127 			set_bit(EFI_PARAVIRT, &efi.flags);
128 		return systab;
129 	}
130 notfound:
131 	pr_info("UEFI not found.\n");
132 	return 0;
133 }
134