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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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e457ed516a
The efi_get_fdt_params() routine uses the early OF device tree traversal helpers, that iterate over each node in the DT and invoke a caller provided callback that can inspect the node's contents and look for the required data. This requires a special param struct to be passed around, with pointers into param enumeration structs that contain (and duplicate) property names and offsets into yet another struct that carries the collected data. Since we know the data we look for is either under /hypervisor/uefi or under /chosen, it is much simpler to use the libfdt routines, and just try to grab a reference to either node directly, and read each property in sequence. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
126 lines
2.9 KiB
C
126 lines
2.9 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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#define pr_fmt(fmt) "efi: " fmt
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/efi.h>
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#include <linux/libfdt.h>
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#include <linux/of_fdt.h>
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#include <asm/unaligned.h>
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enum {
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SYSTAB,
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MMBASE,
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MMSIZE,
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DCSIZE,
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DCVERS,
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PARAMCOUNT
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};
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static __initconst const char name[][22] = {
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[SYSTAB] = "System Table ",
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[MMBASE] = "MemMap Address ",
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[MMSIZE] = "MemMap Size ",
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[DCSIZE] = "MemMap Desc. Size ",
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[DCVERS] = "MemMap Desc. Version ",
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};
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static __initconst const struct {
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const char path[17];
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const char params[PARAMCOUNT][26];
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} dt_params[] = {
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{
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#ifdef CONFIG_XEN // <-------17------>
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.path = "/hypervisor/uefi",
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.params = {
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[SYSTAB] = "xen,uefi-system-table",
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[MMBASE] = "xen,uefi-mmap-start",
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[MMSIZE] = "xen,uefi-mmap-size",
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[DCSIZE] = "xen,uefi-mmap-desc-size",
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[DCVERS] = "xen,uefi-mmap-desc-ver",
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}
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}, {
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#endif
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.path = "/chosen",
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.params = { // <-----------26----------->
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[SYSTAB] = "linux,uefi-system-table",
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[MMBASE] = "linux,uefi-mmap-start",
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[MMSIZE] = "linux,uefi-mmap-size",
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[DCSIZE] = "linux,uefi-mmap-desc-size",
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[DCVERS] = "linux,uefi-mmap-desc-ver",
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}
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}
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};
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static int __init efi_get_fdt_prop(const void *fdt, int node, const char *pname,
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const char *rname, void *var, int size)
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{
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const void *prop;
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int len;
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u64 val;
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prop = fdt_getprop(fdt, node, pname, &len);
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if (!prop)
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return 1;
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val = (len == 4) ? (u64)be32_to_cpup(prop) : get_unaligned_be64(prop);
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if (size == 8)
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*(u64 *)var = val;
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else
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*(u32 *)var = (val < U32_MAX) ? val : U32_MAX; // saturate
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if (efi_enabled(EFI_DBG))
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pr_info(" %s: 0x%0*llx\n", rname, size * 2, val);
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return 0;
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}
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u64 __init efi_get_fdt_params(struct efi_memory_map_data *mm)
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{
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const void *fdt = initial_boot_params;
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unsigned long systab;
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int i, j, node;
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struct {
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void *var;
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int size;
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} target[] = {
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[SYSTAB] = { &systab, sizeof(systab) },
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[MMBASE] = { &mm->phys_map, sizeof(mm->phys_map) },
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[MMSIZE] = { &mm->size, sizeof(mm->size) },
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[DCSIZE] = { &mm->desc_size, sizeof(mm->desc_size) },
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[DCVERS] = { &mm->desc_version, sizeof(mm->desc_version) },
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};
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BUILD_BUG_ON(ARRAY_SIZE(target) != ARRAY_SIZE(name));
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BUILD_BUG_ON(ARRAY_SIZE(target) != ARRAY_SIZE(dt_params[0].params));
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for (i = 0; i < ARRAY_SIZE(dt_params); i++) {
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node = fdt_path_offset(fdt, dt_params[i].path);
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if (node < 0)
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continue;
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if (efi_enabled(EFI_DBG))
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pr_info("Getting UEFI parameters from %s in DT:\n",
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dt_params[i].path);
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for (j = 0; j < ARRAY_SIZE(target); j++) {
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const char *pname = dt_params[i].params[j];
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if (!efi_get_fdt_prop(fdt, node, pname, name[j],
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target[j].var, target[j].size))
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continue;
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if (!j)
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goto notfound;
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pr_err("Can't find property '%s' in DT!\n", pname);
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return 0;
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}
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return systab;
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}
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notfound:
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pr_info("UEFI not found.\n");
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return 0;
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}
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