protos/limine: Require and use a requests segment for base rev 3

common/lib/elf.c

@@ -75,45 +75,6 @@
 #define EI_VERSION  6
 #define EI_OSABI    7
 
-struct elf32_hdr {
-    uint8_t  ident[16];
-    uint16_t type;
-    uint16_t machine;
-    uint32_t version;
-    uint32_t entry;
-    uint32_t phoff;
-    uint32_t shoff;
-    uint32_t flags;
-    uint16_t hdr_size;
-    uint16_t phdr_size;
-    uint16_t ph_num;
-    uint16_t shdr_size;
-    uint16_t sh_num;
-    uint16_t shstrndx;
-};
-
-struct elf64_phdr {
-    uint32_t p_type;
-    uint32_t p_flags;
-    uint64_t p_offset;
-    uint64_t p_vaddr;
-    uint64_t p_paddr;
-    uint64_t p_filesz;
-    uint64_t p_memsz;
-    uint64_t p_align;
-};
-
-struct elf32_phdr {
-    uint32_t p_type;
-    uint32_t p_offset;
-    uint32_t p_vaddr;
-    uint32_t p_paddr;
-    uint32_t p_filesz;
-    uint32_t p_memsz;
-    uint32_t p_flags;
-    uint32_t p_align;
-};
-
 struct elf64_rela {
     uint64_t r_addr;
     uint32_t r_info;

common/lib/elf.h

@@ -54,6 +54,45 @@ struct elf64_hdr {
     uint16_t shstrndx;
 };
 
+struct elf32_hdr {
+    uint8_t  ident[16];
+    uint16_t type;
+    uint16_t machine;
+    uint32_t version;
+    uint32_t entry;
+    uint32_t phoff;
+    uint32_t shoff;
+    uint32_t flags;
+    uint16_t hdr_size;
+    uint16_t phdr_size;
+    uint16_t ph_num;
+    uint16_t shdr_size;
+    uint16_t sh_num;
+    uint16_t shstrndx;
+};
+
+struct elf64_phdr {
+    uint32_t p_type;
+    uint32_t p_flags;
+    uint64_t p_offset;
+    uint64_t p_vaddr;
+    uint64_t p_paddr;
+    uint64_t p_filesz;
+    uint64_t p_memsz;
+    uint64_t p_align;
+};
+
+struct elf32_phdr {
+    uint32_t p_type;
+    uint32_t p_offset;
+    uint32_t p_vaddr;
+    uint32_t p_paddr;
+    uint32_t p_filesz;
+    uint32_t p_memsz;
+    uint32_t p_flags;
+    uint32_t p_align;
+};
+
 struct elf64_shdr {
     uint32_t sh_name;
     uint32_t sh_type;

common/protos/limine.c

@@ -480,9 +480,59 @@ noreturn void limine_load(char *config, char *cmdline) {
     }
 
     // Load requests
+    uint64_t common_magic[2] = { LIMINE_COMMON_MAGIC };
     uint64_t *limine_reqs = NULL;
     requests = ext_mem_alloc(MAX_REQUESTS * sizeof(void *));
     requests_count = 0;
+    if (base_revision >= 3) {
+        uint64_t reqs_start = 0, reqs_size = 0;
+
+        struct elf64_hdr *hdr = (void *)(uintptr_t)physical_base;
+
+        for (uint16_t i = 0; i < hdr->ph_num; i++) {
+            struct elf64_phdr *phdr = (void *)(uintptr_t)physical_base + (hdr->phoff + i * hdr->phdr_size);
+
+            if (phdr->p_type != 0x67e16835) {
+                continue;
+            }
+
+            reqs_start = physical_base + phdr->p_vaddr;
+            reqs_size = phdr->p_filesz;
+
+            printv("limine: Requests segment starts at %X and ends at %X\n", reqs_start, reqs_start + reqs_size);
+
+            break;
+        }
+
+        if (reqs_start == 0) {
+            panic(true, "limine: Base protocol revision 3 requires a requests segment");
+        }
+
+        for (size_t i = 0; i < ALIGN_DOWN(reqs_size, 8); i += 8) {
+            uint64_t *p = (void *)(uintptr_t)reqs_start + i;
+
+            if (p[0] != common_magic[0]) {
+                continue;
+            }
+            if (p[1] != common_magic[1]) {
+                continue;
+            }
+
+            if (requests_count == MAX_REQUESTS) {
+                panic(true, "limine: Maximum requests exceeded");
+            }
+
+            // Check for a conflict
+            if (_get_request(p) != NULL) {
+                panic(true, "limine: Conflict detected for request ID %X %X", p[2], p[3]);
+            }
+
+            requests[requests_count++] = p;
+        }
+
+        goto reqs_done;
+    }
+
     if (base_revision == 0 && elf64_load_section(kernel, &limine_reqs, ".limine_reqs", 0, slide)) {
         for (size_t i = 0; ; i++) {
             if (limine_reqs[i] == 0) {
@@ -492,7 +542,6 @@ noreturn void limine_load(char *config, char *cmdline) {
             requests_count++;
         }
     } else {
-        uint64_t common_magic[2] = { LIMINE_COMMON_MAGIC };
         for (size_t i = 0; i < ALIGN_DOWN(image_size_before_bss, 8); i += 8) {
             uint64_t *p = (void *)(uintptr_t)physical_base + i;
 
@@ -528,6 +577,8 @@ noreturn void limine_load(char *config, char *cmdline) {
         }
     }
 
+reqs_done:;
+
 #if defined (__x86_64__) || defined (__i386__)
     // Check if 64 bit CPU
     if (!cpuid(0x80000001, 0, &eax, &ebx, &ecx, &edx) || !(edx & (1 << 29))) {

test/limine.c

@@ -11,9 +11,6 @@ static volatile LIMINE_BASE_REVISION(3);
 
 static void limine_main(void);
 
-__attribute__((used, section(".limine_requests_start_marker")))
-static volatile LIMINE_REQUESTS_START_MARKER;
-
 __attribute__((used, section(".limine_requests")))
 static volatile struct limine_entry_point_request entry_point_request = {
     .id = LIMINE_ENTRY_POINT_REQUEST,
@@ -152,9 +149,6 @@ static volatile struct limine_paging_mode_request _pm_request = {
     .min_mode = LIMINE_PAGING_MODE_MIN
 };
 
-__attribute__((used, section(".limine_requests_end_marker")))
-static volatile LIMINE_REQUESTS_END_MARKER;
-
 static char *get_memmap_type(uint64_t type) {
     switch (type) {
         case LIMINE_MEMMAP_USABLE:

test/linker.ld

@@ -4,6 +4,7 @@ PHDRS
     text    PT_LOAD FILEHDR PHDRS;
     rodata  PT_LOAD;
     data    PT_LOAD;
+    limine_requests 0x67e16835;
     dynamic PT_DYNAMIC;
 }
 
@@ -26,14 +27,13 @@ SECTIONS
 
     .data : {
         *(.data .data.*)
-
-        KEEP(*(.limine_requests_start_marker))
-        KEEP(*(.limine_requests))
-        KEEP(*(.limine_requests_end_marker))
-
         *(.sdata .sdata.*)
     } :data
 
+    .limine_requests : {
+        KEEP(*(.limine_requests))
+    } :data :limine_requests
+
     .dynamic : {
         *(.dynamic)
     } :data :dynamic