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