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 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 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