ptos: ex: Add loader dispatch + ELF64 loader

Signed-off-by: Chloe M <chloe@mensia.org>
2026-07-14 22:13:17 -04:00
parent cb12ab9518
commit cbb440b8e9
4 changed files with 324 additions and 0 deletions
@@ -0,0 +1,216 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause.
+ *
+ * Description: ELF64 loader
+ * Author:      Chloe M.
+ */
+
+#include <ex/elf64.h>
+#include <ex/pool.h>
+#include <hal/page.h>
+#include <ptapi/ptmm.h>
+#include <elf.h>
+#include <mm/vm.h>
+#include <string.h>
+
+/* When allocating ELF related pools */
+#define ELF_POOL_TAG 'ELF'
+
+/* Maximum loadable program headers */
+#define MAX_PHDRS 64
+
+/* Prototypes */
+static PT_STATUS Elf64Load(MMU_VAS *Vas, VOID *Data, LOADER_PROGRAM *Result);
+
+/* ELF64 operations */
+LOADER_OPS gElf64Ops = {
+    .LoadProgram = Elf64Load
+};
+
+/*
+ * Program data associated with a loader
+ *
+ * @LoadedSegments: Segments that have been loaded
+ * @SegmentCount:   Number of loaded segments
+ */
+typedef struct {
+    MM_RANGE LoadedSegments[MAX_PHDRS];
+    USIZE SegmentCount;
+} ELF64_PROGDATA;
+
+/*
+ * Verify the header of an ELF64 binary to see if it is
+ * compatible with PTOS.
+ */
+static BOOLEAN
+Elf64Verify(const Elf64_Ehdr *Eh)
+{
+    if (Eh == NULL) {
+        return false;
+    }
+
+    if (RtlMemCmp(&Eh->e_ident[EI_MAG0], ELFMAG, SELFMAG) != 0)
+        return false;
+    if (Eh->e_ident[EI_CLASS] != ELFCLASS64)
+        return false;
+    if (Eh->e_ident[EI_DATA] != ELFDATA2LSB)
+        return false;
+    if (Eh->e_version != EV_CURRENT)
+        return false;
+
+    return true;
+}
+
+/*
+ * Load an ELF64 program header
+ *
+ * @Vas:    Virtual address space to map within
+ * @Phdr:   Program header to load
+ * @Image:  Image result is written here
+ */
+static PT_STATUS
+ElfLoadPhdr(MMU_VAS *Vas, Elf64_Ehdr *Eh, Elf64_Phdr *Phdr, ELF64_PROGDATA *Image)
+{
+    USIZE MapLength, MisAlign;
+    USIZE PageCount;
+    PT_STATUS Status;
+    MM_PROT Prot = PAGE_READ | PAGE_WRITE | PAGE_USER;
+    MM_RANGE AllocatedPages, MapRange;
+    VOID *Src, *Dest;
+
+    if (Vas == NULL || Eh == NULL) {
+        return STATUS_INVALID_PARAM;
+    }
+
+    if (Phdr == NULL || Image == NULL) {
+        return STATUS_INVALID_PARAM;
+    }
+
+    /* Set the permissions (TODO: Make unwritable by default) */
+    if (ISSET(Phdr->p_flags, PF_X))
+        Prot |= PAGE_EXEC;
+
+    /* Compute the number of pages to map */
+    MisAlign = Phdr->p_vaddr & (PAGESIZE - 1);
+    MapLength = ALIGN_UP(Phdr->p_memsz + MisAlign, PAGESIZE);
+    PageCount = MapLength / PAGESIZE;
+
+    /* Grab some pages for our segment data */
+    Status = MmAllocatePages(PageCount, &AllocatedPages);
+    if (PT_ERROR(Status)) {
+        return STATUS_NO_MEMORY;
+    }
+
+    MapRange.VirtualBase = Phdr->p_vaddr;
+    MapRange.PhysicalBase = AllocatedPages.PhysicalBase;
+    MapRange.Length = MapLength;
+    Status = MmMapRange(
+        Vas,
+        &MapRange,
+        Prot,
+        PAGESIZE_4K
+    );
+
+    /* TODO: Free previously allocated pages */
+    if (PT_ERROR(Status)) {
+        return Status;
+    }
+
+    Src = PTR_OFFSET(Eh, Phdr->p_offset);
+    Dest = PMA_TO_VMA(AllocatedPages.PhysicalBase);
+    RtlMemCpy(Dest, Src, Phdr->p_filesz);
+    Image->LoadedSegments[Image->SegmentCount++] = MapRange;
+    return STATUS_SUCCESS;
+}
+
+/*
+ * Load every program header of an ELF binary
+ *
+ * @Vas:    Virtual address space to map within
+ * @Eh:     ELF header
+ * @Image:  Loaded program image
+ */
+static PT_STATUS
+ElfLoad(MMU_VAS *Vas, Elf64_Ehdr *Eh, LOADER_PROGRAM *Image)
+{
+    Elf64_Phdr *PhdrBase, *Phdr;
+    USIZE PhdrIndex;
+    PT_STATUS Status;
+
+    if (Vas == NULL || Eh == NULL) {
+        return STATUS_INVALID_PARAM;
+    }
+
+    if (Image == NULL) {
+        return STATUS_INVALID_PARAM;
+    }
+
+    /* Allocate our own program data */
+    Image->ProgramData = ExAllocatePoolWithTag(
+        POOL_NON_PAGED,
+        sizeof(ELF64_PROGDATA),
+        ELF_POOL_TAG
+    );
+
+    if (Image->ProgramData == NULL) {
+        return STATUS_NO_MEMORY;
+    }
+
+#define PHDR_INDEX(INDEX)   \
+    PTR_OFFSET(PhdrBase, (INDEX) * Eh->e_phentsize)
+    PhdrBase = PTR_OFFSET(Eh, Eh->e_phoff);
+    for (PhdrIndex = 0; PhdrIndex < Eh->e_phnum; ++PhdrIndex) {
+        Phdr = PHDR_INDEX(PhdrIndex);
+
+        switch (Phdr->p_type) {
+        case PT_LOAD:
+            /* TODO: Clean up on failure */
+            Status = ElfLoadPhdr(Vas, Eh, Phdr, Image->ProgramData);
+            if (PT_ERROR(Status)) {
+                ExFreePoolWithTag(Image->ProgramData, ELF_POOL_TAG);
+                Image->ProgramData = NULL;
+                return Status;
+            }
+
+            break;
+        default:
+            continue;
+        }
+    }
+#undef PHDR_INDEX
+
+    return STATUS_SUCCESS;
+}
+
+/*
+ * Load an ELF64 program
+ */
+static PT_STATUS
+Elf64Load(MMU_VAS *Vas, VOID *Data, LOADER_PROGRAM *Result)
+{
+    Elf64_Ehdr *Eh;
+    PT_STATUS Status;
+
+    if (Data == NULL || Result == NULL) {
+        return STATUS_INVALID_PARAM;
+    }
+
+    /* Verify that it is executable */
+    Eh = (Elf64_Ehdr *)Data;
+    if (!Elf64Verify(Eh)) {
+        return STATUS_NOT_EXEC;
+    }
+
+    Status = ElfLoad(
+        Vas,
+        Eh,
+        Result
+    );
+
+    if (PT_ERROR(Status)) {
+        return Status;
+    }
+
+    return STATUS_SUCCESS;
+}
@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause.
+ *
+ * Description: Program loader dispatch
+ * Author:      Chloe M.
+ */
+
+#include <ex/loader.h>
+#include <ex/elf64.h>
+
+/* Loader dispatch table */
+static LOADER_OPS *LoaderOpsTable[] = {
+    [LOADER_ELF64] = &gElf64Ops
+};
+
+PT_STATUS
+ExLoadProgramOf(LOADER_TYPE LoaderType, MMU_VAS *Vas, VOID *Data, LOADER_PROGRAM *Result)
+{
+    LOADER_OPS *Ops;
+
+    if (Data == NULL || Result == NULL) {
+        return STATUS_INVALID_PARAM;
+    }
+
+    if (LoaderType >= NELEM(LoaderOpsTable)) {
+        return STATUS_NOT_FOUND;
+    }
+
+    Ops = LoaderOpsTable[LoaderType];
+    return Ops->LoadProgram(Vas, Data, Result);
+}
@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause.
+ *
+ * Description: ELF64 loader
+ * Author:      Chloe M.
+ */
+
+#ifndef _EX_ELF64_H_
+#define _EX_ELF64_H_ 1
+
+#include <ex/loader.h>
+#include <ptdef.h>
+
+/* Externs */
+extern LOADER_OPS gElf64Ops;
+
+#endif  /* !_EX_ELF64_H_ */
@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause.
+ *
+ * Description: Program loader dispatch
+ * Author:      Chloe M.
+ */
+
+#ifndef _EX_LOADER_H_
+#define _EX_LOADER_H_ 1
+
+#include <hal/mmu.h>
+#include <ptapi/status.h>
+#include <ptdef.h>
+
+/*
+ * Valid loader types that can be dispatched
+ */
+typedef enum {
+    LOADER_ELF64
+} LOADER_TYPE;
+
+/*
+ * Represents a loaded program that has been loaded
+ * by a specific loader.
+ *
+ * @EntryPoint:  Entrypoint of program
+ * @ProgramData: Loaded program data
+ */
+typedef struct {
+    UPTR EntryPoint;
+    VOID *ProgramData;
+} LOADER_PROGRAM;
+
+/*
+ * Loader operations associated with a specific
+ * loader.
+ *
+ * @LoadProgram:  Callback used to invoke the loader
+ */
+typedef struct {
+    PT_STATUS(*LoadProgram)(MMU_VAS *Vas, VOID *Data, LOADER_PROGRAM *Result);
+} LOADER_OPS;
+
+/*
+ * Load a specific program using a specific loader type
+ *
+ * @LoaderType:   Type of loader to invoke
+ * @Vas:          Virtual address space to load in
+ * @Data:         Program binary to load
+ * @Result:       Loader program result is written here
+ */
+PT_STATUS ExLoadProgramOf(
+    LOADER_TYPE LoaderType, MMU_VAS *Vas,
+    VOID *Data, LOADER_PROGRAM *Result
+);
+
+#endif  /* !_EX_LOADER_H_ */