drivers/firmware/efi/fdtparams.c

   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 }