boot: Add EFISTUB and refactor boot protocols

2026-10-27 22:50:43 +01:00
parent 6827dc309e
commit 196543c3d3
40 changed files with 1923 additions and 208 deletions
@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: ISC
+
+#include <bits/elf.h>
+#include <stddef.h>
+#include <stdint.h>
+#include "efi.h"
+
+efi_status efistub_relocate(uintptr_t base, const elf64_dyn_t* dynamic) {
+    uintptr_t rela = 0;
+    size_t rela_size = 0;
+    size_t rela_ent = sizeof(elf64_rela_t);
+    uintptr_t relr = 0;
+    size_t relr_size = 0;
+
+    for (const elf64_dyn_t* dyn = dynamic; dyn->d_tag != DT_NULL; dyn++) {
+        switch (dyn->d_tag) {
+        case DT_RELA:
+            rela = base + dyn->d_un.d_val;
+            break;
+        case DT_RELASZ:
+            rela_size = dyn->d_un.d_val;
+            break;
+        case DT_RELAENT:
+            rela_ent = dyn->d_un.d_val;
+            break;
+        case DT_RELR:
+            relr = base + dyn->d_un.d_val;
+            break;
+        case DT_RELRSZ:
+            relr_size = dyn->d_un.d_val;
+            break;
+        }
+    }
+
+    for (size_t off = 0; rela && off + rela_ent <= rela_size; off += rela_ent) {
+        const elf64_rela_t* r = (const elf64_rela_t*)(rela + off);
+        const uint32_t type = ELF64_R_TYPE(r->r_info);
+        if (type == R_NONE)
+            continue;
+        if (type != R_RELATIVE)
+            return EFI_LOAD_ERROR;
+        *(uint64_t*)(base + r->r_offset) = base + r->r_addend;
+    }
+
+    uint64_t* where = nullptr;
+    for (size_t off = 0; relr && off + sizeof(uint64_t) <= relr_size; off += sizeof(uint64_t)) {
+        uint64_t entry = *(const uint64_t*)(relr + off);
+        if (!(entry & 1)) {
+            where = (uint64_t*)(base + entry);
+            *where++ += base;
+            continue;
+        }
+        for (size_t i = 0; (entry >>= 1) != 0; i++) {
+            if (entry & 1)
+                where[i] += base;
+        }
+        where += 63;
+    }
+
+    return EFI_SUCCESS;
+}