From 42462d5e56ba7966b3f5941e1b77136054fba3f4 Mon Sep 17 00:00:00 2001
From: Douglas Thain <dthain@nd.edu>
Date: Mon, 5 Jan 2026 17:12:25 -0500
Subject: [PATCH 1/8] Add note to assembly to quiet GNU tools complaining about
 executable stack.

---
 library/syscall.S | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/library/syscall.S b/library/syscall.S
index b4676eec..35511446 100644
--- a/library/syscall.S
+++ b/library/syscall.S
@@ -27,3 +27,8 @@ syscall:
 	addl	$4,%esp
 	leave
 	ret
+
+# This is a GNU peculiarity which indicates that
+# the stack does not need to be executable in this module.
+.section .note.GNU-stack,"",@progbits
+

From e7eeccd7e5870c1dc040e15b5c514251f134b457 Mon Sep 17 00:00:00 2001
From: Douglas Thain <dthain@nd.edu>
Date: Mon, 5 Jan 2026 17:13:05 -0500
Subject: [PATCH 2/8] Use explicit linker script for userspace programs, to
 avoid unexpected behaviors from platform linking scripts.

---
 Makefile.config               |  5 +++--
 kernel/Makefile               |  4 ++--
 user/Makefile                 |  2 +-
 user/basekernel.user.ldscript | 21 +++++++++++++++++++++
 4 files changed, 27 insertions(+), 5 deletions(-)
 create mode 100644 user/basekernel.user.ldscript

diff --git a/Makefile.config b/Makefile.config
index fea0f5c2..afd5bd5a 100644
--- a/Makefile.config
+++ b/Makefile.config
@@ -4,8 +4,8 @@ KERNEL_CCFLAGS=-Wall -c -ffreestanding -fno-pie -g -std=gnu99
 # which is likely to work on native linux-x86.
 #
 CC=gcc -m32
-LD=ld -melf_i386
-#LD=ld -arch i386
+LD=ld
+KERNEL_LD=ld -melf_i386
 AR=ar
 OBJCOPY=objcopy
 ISOGEN=genisoimage
@@ -15,6 +15,7 @@ ISOGEN=genisoimage
 # add cross/bin to your path, and uncomment these lines:
 #CC=i686-elf-gcc
 #LD=i686-elf-ld
+#KERNEL_LD=i686-elf-ld
 #AR=i686-elf-ar
 #OBJCOPY=i686-elf-objcopy
 
diff --git a/kernel/Makefile b/kernel/Makefile
index c73677a3..82c1ccee 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -12,10 +12,10 @@ bootblock: bootblock.elf
 	${OBJCOPY} -O binary $< $@
 
 kernel.elf: ${KERNEL_OBJECTS}
-	${LD} ${KERNEL_LDFLAGS} -Ttext 0x10000 ${KERNEL_OBJECTS} -o $@
+	${KERNEL_LD} ${KERNEL_LDFLAGS} -Ttext 0x10000 ${KERNEL_OBJECTS} -o $@
 
 bootblock.elf: bootblock.o
-	${LD} ${KERNEL_LDFLAGS} -Ttext 0 $< -o $@
+	${KERNEL_LD} ${KERNEL_LDFLAGS} -Ttext 0 $< -o $@
 
 %.o: %.c
 	${CC} ${KERNEL_CCFLAGS} -I ../include $< -o $@
diff --git a/user/Makefile b/user/Makefile
index a2a55e20..2e224502 100644
--- a/user/Makefile
+++ b/user/Makefile
@@ -9,7 +9,7 @@ all: $(USER_PROGRAMS)
 	${CC} ${KERNEL_CCFLAGS} -I ../include $< -o $@
 
 %.exe: %.o ../library/user-start.o ../library/baselib.a
-	${LD} ${KERNEL_LDFLAGS} -Ttext 0x80000000 ../library/user-start.o $< ../library/baselib.a -o $@
+	${LD} -T basekernel.user.ldscript $< ../library/baselib.a -o $@ -Map .
 
 clean:
 	rm -rf *.exe *.o
diff --git a/user/basekernel.user.ldscript b/user/basekernel.user.ldscript
new file mode 100644
index 00000000..3e8ed6c6
--- /dev/null
+++ b/user/basekernel.user.ldscript
@@ -0,0 +1,21 @@
+/* Linker script for userspace programs in basekernel */
+
+OUTPUT_FORMAT("elf32-i386", "elf32-i386", "elf32-i386")
+OUTPUT_ARCH(i386)
+
+STARTUP(../library/user-start.o)
+
+ENTRY(_start)
+
+MEMORY {
+RAM (rwx) : ORIGIN = 0x8000000, LENGTH = 2M
+}
+
+SECTIONS {
+.text   : ALIGN(4096) { *(.text) } > RAM
+.rodata : ALIGN(4096) { *(.rodata) } > RAM
+.data   : ALIGN(4096) { *(.data) } > RAM
+.bss    : ALIGN(4096) { *(.bss)  } > RAM
+.note   : { *(.note) } > RAM
+/DISCARD/ : { *(*) }
+}

From dc4d00f692af897e96ab98edcfc96aa38b3c7e36 Mon Sep 17 00:00:00 2001
From: Douglas Thain <dthain@nd.edu>
Date: Mon, 5 Jan 2026 17:29:31 -0500
Subject: [PATCH 3/8] Remove linker -Map argument used inconsistently.

---
 user/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/user/Makefile b/user/Makefile
index 2e224502..16eb7714 100644
--- a/user/Makefile
+++ b/user/Makefile
@@ -9,7 +9,7 @@ all: $(USER_PROGRAMS)
 	${CC} ${KERNEL_CCFLAGS} -I ../include $< -o $@
 
 %.exe: %.o ../library/user-start.o ../library/baselib.a
-	${LD} -T basekernel.user.ldscript $< ../library/baselib.a -o $@ -Map .
+	${LD} -T basekernel.user.ldscript $< ../library/baselib.a -o $@
 
 clean:
 	rm -rf *.exe *.o

From 84d753707519bd5667b1a9056021f4b79787114e Mon Sep 17 00:00:00 2001
From: Douglas Thain <dthain@nd.edu>
Date: Mon, 5 Jan 2026 17:42:26 -0500
Subject: [PATCH 4/8] Missing zero, how embarrassing!

---
 user/basekernel.user.ldscript | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/user/basekernel.user.ldscript b/user/basekernel.user.ldscript
index 3e8ed6c6..2e0218dc 100644
--- a/user/basekernel.user.ldscript
+++ b/user/basekernel.user.ldscript
@@ -8,7 +8,7 @@ STARTUP(../library/user-start.o)
 ENTRY(_start)
 
 MEMORY {
-RAM (rwx) : ORIGIN = 0x8000000, LENGTH = 2M
+RAM (rwx) : ORIGIN = 0x80000000, LENGTH = 2M
 }
 
 SECTIONS {

From d92998bdfd9d4b4b892023cd4de715fe41962e8a Mon Sep 17 00:00:00 2001
From: Douglas Thain <dthain@nd.edu>
Date: Tue, 6 Jan 2026 09:59:39 -0500
Subject: [PATCH 5/8] Update linker command line and scripts to generate
 executables that cleanly start at 0x8000000.

---
 user/Makefile                 |  2 +-
 user/basekernel.user.ldscript | 55 ++++++++++++++++++++++++++++-------
 2 files changed, 45 insertions(+), 12 deletions(-)

diff --git a/user/Makefile b/user/Makefile
index 16eb7714..573d9920 100644
--- a/user/Makefile
+++ b/user/Makefile
@@ -9,7 +9,7 @@ all: $(USER_PROGRAMS)
 	${CC} ${KERNEL_CCFLAGS} -I ../include $< -o $@
 
 %.exe: %.o ../library/user-start.o ../library/baselib.a
-	${LD} -T basekernel.user.ldscript $< ../library/baselib.a -o $@
+	${LD} -z max-page-size=4096 -T basekernel.user.ldscript $< ../library/baselib.a -o $@ -Map $@.map
 
 clean:
 	rm -rf *.exe *.o
diff --git a/user/basekernel.user.ldscript b/user/basekernel.user.ldscript
index 2e0218dc..20229578 100644
--- a/user/basekernel.user.ldscript
+++ b/user/basekernel.user.ldscript
@@ -1,21 +1,54 @@
 /* Linker script for userspace programs in basekernel */
 
-OUTPUT_FORMAT("elf32-i386", "elf32-i386", "elf32-i386")
+OUTPUT_FORMAT("elf32-i386")
 OUTPUT_ARCH(i386)
 
+/* The first module in every program is the startup code of the standard library. */
 STARTUP(../library/user-start.o)
 
+/* The entry point for execution is the symbol _start found in user-start.o */
 ENTRY(_start)
 
-MEMORY {
-RAM (rwx) : ORIGIN = 0x80000000, LENGTH = 2M
-}
-
 SECTIONS {
-.text   : ALIGN(4096) { *(.text) } > RAM
-.rodata : ALIGN(4096) { *(.rodata) } > RAM
-.data   : ALIGN(4096) { *(.data) } > RAM
-.bss    : ALIGN(4096) { *(.bss)  } > RAM
-.note   : { *(.note) } > RAM
-/DISCARD/ : { *(*) }
+
+/* User programs begin at 0x80000000, the top 2MB of memory. */
+. = 0x80000000;
+
+/* The text section contains executable code (rx) */
+.text   : { *(.text) }
+
+/* The rodata section contains constants, strings, etc. */
+.rodata : ALIGN(CONSTANT(MAXPAGESIZE)) { *(.rodata) }
+
+/* The data section contains initialized values. */
+.data   : ALIGN(CONSTANT(MAXPAGESIZE)) { *(.data) }
+
+/* The bss section describes uninitialized data. */
+/* This takes no space in the executable, but is allocated at runtime. */
+.bss    : { *(.bss) }
+
+/* Any other miscellanous sections produced by the compiler follow here. */
 }
+
+/*
+Note there are some subtle issues about alignment here.
+
+The GNU linker on Linux defines COMMONPAGESIZE to be typical 4KB pages
+and MAXPAGESIZE to be less-common 2MB superpages.  These are controlled
+by -z common-page-size and -z max-page-size on the command line, and
+can be used (but not set) in this file.
+
+The linker attempts to page-align items in the executable
+file on disk, so as to facilitate demand-paging at runtime.
+It uses MAXPAGESIZE to do this by default, and so we if don't take
+certain steps, the text section will be pushed to 2MB into the file,
+and all of a sudden, we have huge executable files.
+So, we set -z max-page-size=4096 on the command line.
+
+Next, we want sections with different permissions to be
+4KB page-aligned, so that the kernel can made code (RX),
+rodata (R), and data (RW) by apply the proper page protections.
+So, the start of the rodata and data sections are aligned
+to the start of the next page.
+*/
+

From 3e01bdee3bbf3c0595341dd6a7e6c24ab39c9ac5 Mon Sep 17 00:00:00 2001
From: Douglas Thain <dthain@nd.edu>
Date: Tue, 6 Jan 2026 11:27:20 -0500
Subject: [PATCH 6/8] Rework ELF loader to work correctly with multiple
 loadable segments that each may be partially initialized.

---
 kernel/elf.c | 134 +++++++++++++++++++++++++++++----------------------
 1 file changed, 77 insertions(+), 57 deletions(-)

diff --git a/kernel/elf.c b/kernel/elf.c
index c848efb4..5c591e26 100644
--- a/kernel/elf.c
+++ b/kernel/elf.c
@@ -52,7 +52,21 @@ struct elf_program {
 	uint32_t align;
 };
 
+#define ELF_PROGRAM_TYPE_NULL 0
 #define ELF_PROGRAM_TYPE_LOADABLE 1
+#define ELF_PROGRAM_TYPE_DYNAMIC 2
+#define ELF_PROGRAM_TYPE_INTERPRETER 3
+#define ELF_PROGRAM_TYPE_NOTE 4
+#define ELF_PROGRAM_TYPE_SHARED_LIBRARY 5
+#define ELF_PROGRAM_TYPE_PROGRAM_HEADER 6
+#define ELF_PROGRAM_TYPE_THREAD_LOCAL 7
+#define ELF_PROGRAM_TYPE_GNU_EH_FRAME 0x6474e550
+#define ELF_PROGRAM_TYPE_GNU_STACK 0x6474e551
+#define ELF_PROGRAM_TYPE_GNU_RELRO 0x6474e552
+
+#define ELF_PROGRAM_FLAGS_EXEC  1
+#define ELF_PROGRAM_FLAGS_WRITE 2
+#define ELF_PROGRAM_FLAGS_READ  4
 
 struct elf_section {
 	uint32_t name;
@@ -88,7 +102,6 @@ struct elf_section {
 #define ELF_SECTION_FLAGS_GROUP 512
 #define ELF_SECTION_FLAGS_TLS 1024
 
-
 /* Ensure that the current process has address space up to this value. */
 
 static int elf_ensure_address_space( struct process *p, uint32_t addr )
@@ -109,74 +122,81 @@ static int elf_ensure_address_space( struct process *p, uint32_t addr )
 
 	/* Return zero on success. */
 }
- 
+
+/* Load an ELF executable into user space. */
+
 int elf_load(struct process *p, struct fs_dirent *d, addr_t * entry)
 {
 	struct elf_header header;
 	struct elf_program program;
-	struct elf_section section;
 	int i;
 	uint32_t actual;
 
+	/* Load the overall ELF header from the beginning of the file. */
 	actual = fs_dirent_read(d, (char *) &header, sizeof(header), 0);
-	if(actual != sizeof(header))
-		goto noload;
-
-	if(strncmp(header.ident, "\177ELF", 4) || header.machine != ELF_HEADER_MACHINE_I386 || header.version != ELF_HEADER_VERSION)
-		goto noexec;
-
-	actual = fs_dirent_read(d, (char *) &program, sizeof(program), header.program_offset);
-	if(actual != sizeof(program))
-		goto noload;
-
-	//printf("elf: text %x bytes from offset %x at address %x length %x\n",program.file_size,program.offset,program.vaddr,program.memory_size);
-
-	if(program.type != ELF_PROGRAM_TYPE_LOADABLE || program.vaddr < PROCESS_ENTRY_POINT || program.memory_size > 0x8000000 || program.memory_size != program.file_size)
-		goto noexec;
-
-	process_data_size_set(p, program.memory_size);
-
-	actual = fs_dirent_read(d, (char *) program.vaddr, program.memory_size, program.offset);
-	if(actual != program.memory_size)
-		goto mustdie;
-
-	for(i = 0; i < header.shnum; i++) {
-		actual = fs_dirent_read(d, (char *) &section, sizeof(section), header.section_offset + i * header.shentsize);
-		if(actual != sizeof(section))
-			goto mustdie;
-
-		if(section.type == ELF_SECTION_TYPE_BSS) {
-			/* For BSS, just clear that address space to zero. */
-			actual = elf_ensure_address_space(p,section.address+section.size);
-			if(actual!=0) goto nomem;
-			memset((void *) section.address, section.size, 0);
-		} else if(section.type == ELF_SECTION_TYPE_PROGRAM && section.address!=0) {
-			/* For other loadable section types (usually data), load from file. */
-			actual = elf_ensure_address_space(p,section.address+section.size);
-			if(actual!=0) goto nomem;
-			actual = fs_dirent_read(d,(char*)section.address,section.size,section.offset);
-			if(actual != section.size) goto mustdie;
-		} else {
-			/* skip all other section types */
-		}
+	if(actual != sizeof(header)) {
+		printf("elf: unable to load elf header.\n");
+		return KERROR_NOT_EXECUTABLE;
 	}
 
-	*entry = header.entry;
-	return 0;
+	/* Bail out if the header doesnt not have the expected values. */
+	if(strncmp(header.ident, "\177ELF", 4) || header.machine != ELF_HEADER_MACHINE_I386 || header.version != ELF_HEADER_VERSION) {
+		printf("elf: not a valid i386 executable file.\n");
+		return KERROR_NOT_EXECUTABLE;
+	}
+
+	/* An elf file contains a sequence of "program headers" that correspond to loadable segments. */
+	for(i = 0; i < header.phnum; i++) {
 
-      noload:
-	printf("elf: failed to load correctly!\n");
-	return KERROR_NOT_FOUND;
+		/* Load in the segment header itself. */
+		actual = fs_dirent_read(d, (char *) &program, sizeof(program), header.program_offset + i * header.phentsize);
+		if(actual != sizeof(program)) {
+			printf("elf: unable to load segment header %d.\n",i);
+			return KERROR_NOT_EXECUTABLE;
+		}
 
-      noexec:
-	printf("elf: not a valid i386 ELF executable\n");
-	return KERROR_NOT_EXECUTABLE;
+		/* Safe to skip segments that are not loadable or zero size: */
+		if(program.type != ELF_PROGRAM_TYPE_LOADABLE || program.memory_size==0 ) {
+			continue;
+		}
 
-      nomem:
-	printf("elf: failed to allocate memory\n");
-	return KERROR_OUT_OF_MEMORY;
+		/* Each segment must be within the expected userspace range. */
+		if(program.vaddr < PROCESS_ENTRY_POINT || program.memory_size > 0x8000000) {
+			printf("elf: segment %d is invalid: vaddr %x size %x lies outside of user address space.\n",i,program.vaddr,program.memory_size);
+			return KERROR_NOT_EXECUTABLE;
+		}
 
-      mustdie:
-	printf("elf: did not load correctly\n");
-	return KERROR_EXECUTION_FAILED;
+		/* Check for unexpected segment configuration. */
+		if(program.file_size > program.memory_size) {
+			printf("elf: segment %d has unexpected file size %x smaller than memory size %x.\n",program.file_size,program.memory_size);
+			return KERROR_NOT_EXECUTABLE;
+		}
+
+
+		/* Expand the user address space if needed for this segment. */
+		if(elf_ensure_address_space(p,program.vaddr + program.memory_size)!=0) {
+			printf("elf: unable to allocate memory for segment %d vaddr %x size %x\n",i,program.vaddr,program.memory_size);
+			return KERROR_OUT_OF_MEMORY;
+		}
+
+		/* If some (or all) of this segment is on disk, load it in. */
+		if(program.file_size>0) {
+			actual = fs_dirent_read(d, (char *) program.vaddr, program.file_size, program.offset);
+			if(actual != program.file_size) {
+				printf("elf: unable to load segment %d from disk.\n");
+				return KERROR_NOT_EXECUTABLE;
+			}
+		}
+
+		/* If the remainder (or all) of this segment is BSS, initialize it. */
+		if(program.memory_size>program.file_size) {
+			memset( (char*) (program.vaddr+program.file_size), program.memory_size-program.file_size, 0 );
+		}
+		
+		/* XXX Set page table bits here. */
+	}
+
+	/* Capture the program entry point for the caller to use. */
+	*entry = header.entry;
+	return 0;
 }

From fcfa0980019e88212395199e48de9d855ba75038 Mon Sep 17 00:00:00 2001
From: Douglas Thain <dthain@nd.edu>
Date: Tue, 6 Jan 2026 11:31:33 -0500
Subject: [PATCH 7/8] Align bss section independently, so that it is not
 combined with prior sections.

---
 user/basekernel.user.ldscript | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/user/basekernel.user.ldscript b/user/basekernel.user.ldscript
index 20229578..5eaf35ef 100644
--- a/user/basekernel.user.ldscript
+++ b/user/basekernel.user.ldscript
@@ -25,7 +25,7 @@ SECTIONS {
 
 /* The bss section describes uninitialized data. */
 /* This takes no space in the executable, but is allocated at runtime. */
-.bss    : { *(.bss) }
+.bss    : ALIGN(CONSTANT(MAXPAGESIZE)) { *(.bss) }
 
 /* Any other miscellanous sections produced by the compiler follow here. */
 }
@@ -49,6 +49,8 @@ Next, we want sections with different permissions to be
 4KB page-aligned, so that the kernel can made code (RX),
 rodata (R), and data (RW) by apply the proper page protections.
 So, the start of the rodata and data sections are aligned
-to the start of the next page.
+to the start of the next page.  Each must be separately
+aligned, so that if one is eliminated, those following
+are not combined with the text segment.
 */
 

From a9ea785c7a2c8bd079ffa8c4076c0695ce5853df Mon Sep 17 00:00:00 2001
From: Douglas Thain <dthain@nd.edu>
Date: Wed, 7 Jan 2026 13:52:13 -0500
Subject: [PATCH 8/8] Separate elf definition in elf.h and process loader in
 loader.[ch]

---
 kernel/Makefile            |  2 +-
 kernel/elf.h               | 99 ++++++++++++++++++++++++++++++++++----
 kernel/{elf.c => loader.c} | 99 ++------------------------------------
 kernel/loader.h            | 23 +++++++++
 kernel/syscall_handler.c   |  8 +--
 5 files changed, 122 insertions(+), 109 deletions(-)
 rename kernel/{elf.c => loader.c} (57%)
 create mode 100644 kernel/loader.h

diff --git a/kernel/Makefile b/kernel/Makefile
index 82c1ccee..870be7f2 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -1,6 +1,6 @@
 include ../Makefile.config
 
-KERNEL_OBJECTS=kernelcore.o main.o console.o page.o keyboard.o mouse.o event_queue.o clock.o interrupt.o kmalloc.o pic.o ata.o cdromfs.o string.o bitmap.o graphics.o font.o syscall_handler.o process.o mutex.o list.o pagetable.o rtc.o kshell.o fs.o hash_set.o diskfs.o serial.o elf.o device.o kobject.o pipe.o bcache.o printf.o is_valid.o window.o
+KERNEL_OBJECTS=kernelcore.o main.o console.o page.o keyboard.o mouse.o event_queue.o clock.o interrupt.o kmalloc.o pic.o ata.o cdromfs.o string.o bitmap.o graphics.o font.o syscall_handler.o process.o mutex.o list.o pagetable.o rtc.o kshell.o fs.o hash_set.o diskfs.o serial.o loader.o device.o kobject.o pipe.o bcache.o printf.o is_valid.o window.o
 
 basekernel.img: bootblock kernel
 	cat bootblock kernel /dev/zero | head -c 1474560 > basekernel.img
diff --git a/kernel/elf.h b/kernel/elf.h
index 8fd47b5d..3365c060 100644
--- a/kernel/elf.h
+++ b/kernel/elf.h
@@ -1,5 +1,5 @@
 /*
-Copyright (C) 2015-2019 The University of Notre Dame
+Copyright (C) 2015-2025 The University of Notre Dame
 This software is distributed under the GNU General Public License.
 See the file LICENSE for details.
 */
@@ -8,16 +8,95 @@ See the file LICENSE for details.
 #define ELF_H
 
 #include "kernel/types.h"
-#include "process.h"
-#include "fs.h"
 
-/*
-elf_load opens the given filename, and if it contains a valid
-ELF executable, allocates space in the current process' pagetable,
-loads the text, data, and bss into memory, and updates the 
-entry point value in the current process structure.
-*/
+struct elf_header {
+	char ident[16];
+	uint16_t type;
+	uint16_t machine;
+	uint32_t version;
+	uint32_t entry;
+	uint32_t program_offset;
+	uint32_t section_offset;
+	uint32_t flags;
+	uint16_t header_size;
+	uint16_t phentsize;
+	uint16_t phnum;
+	uint16_t shentsize;
+	uint16_t shnum;
+	uint16_t shstrndx;
+};
+
+#define ELF_HEADER_TYPE_NONE         0
+#define ELF_HEADER_TYPE_OBJECT       1
+#define ELF_HEADER_TYPE_EXECUTABLE   2
+#define ELF_HEADER_TYPE_DYNAMIC      3
+#define ELF_HEADER_TYPE_CORE         4
+
+#define ELF_HEADER_MACHINE_I386   3
+#define ELF_HEADER_MACHINE_ARM    40
+#define ELF_HEADER_MACHINE_X86_64 62
+
+#define ELF_HEADER_VERSION     1
+
+struct elf_program {
+	uint32_t type;
+	uint32_t offset;
+	uint32_t vaddr;
+	uint32_t paddr;
+	uint32_t file_size;
+	uint32_t memory_size;
+	uint32_t flags;
+	uint32_t align;
+};
+
+#define ELF_PROGRAM_TYPE_NULL 0
+#define ELF_PROGRAM_TYPE_LOADABLE 1
+#define ELF_PROGRAM_TYPE_DYNAMIC 2
+#define ELF_PROGRAM_TYPE_INTERPRETER 3
+#define ELF_PROGRAM_TYPE_NOTE 4
+#define ELF_PROGRAM_TYPE_SHARED_LIBRARY 5
+#define ELF_PROGRAM_TYPE_PROGRAM_HEADER 6
+#define ELF_PROGRAM_TYPE_THREAD_LOCAL 7
+#define ELF_PROGRAM_TYPE_GNU_EH_FRAME 0x6474e550
+#define ELF_PROGRAM_TYPE_GNU_STACK 0x6474e551
+#define ELF_PROGRAM_TYPE_GNU_RELRO 0x6474e552
+
+#define ELF_PROGRAM_FLAGS_EXEC  1
+#define ELF_PROGRAM_FLAGS_WRITE 2
+#define ELF_PROGRAM_FLAGS_READ  4
+
+struct elf_section {
+	uint32_t name;
+	uint32_t type;
+	uint32_t flags;
+	uint32_t address;
+	uint32_t offset;
+	uint32_t size;
+	uint32_t link;
+	uint32_t info;
+	uint32_t alignment;
+	uint32_t entry_size;
+};
+
+#define ELF_SECTION_TYPE_NULL         0
+#define ELF_SECTION_TYPE_PROGRAM      1
+#define ELF_SECTION_TYPE_SYMBOL_TABLE 2
+#define ELF_SECTION_TYPE_STRING_TABLE 3
+#define ELF_SECTION_TYPE_RELA         4
+#define ELF_SECTION_TYPE_HASH         5
+#define ELF_SECTION_TYPE_DYNAMIC      6
+#define ELF_SECTION_TYPE_NOTE         7
+#define ELF_SECTION_TYPE_BSS          8
 
-int elf_load(struct process *p, struct fs_dirent *d, addr_t * entry);
+#define ELF_SECTION_FLAGS_WRITE    1
+#define ELF_SECTION_FLAGS_MEMORY   2
+#define ELF_SECTION_FLAGS_EXEC     8
+#define ELF_SECTION_FLAGS_MERGE    16
+#define ELF_SECTION_FLAGS_STRINGS  32
+#define ELF_SECTION_FLAGS_INFO_LINK 64
+#define ELF_SECTION_FLAGS_LINK_ORDER 128
+#define ELF_SECTION_FLAGS_NONSTANDARD 256
+#define ELF_SECTION_FLAGS_GROUP 512
+#define ELF_SECTION_FLAGS_TLS 1024
 
 #endif
diff --git a/kernel/elf.c b/kernel/loader.c
similarity index 57%
rename from kernel/elf.c
rename to kernel/loader.c
index 5c591e26..53e21134 100644
--- a/kernel/elf.c
+++ b/kernel/loader.c
@@ -1,9 +1,10 @@
 /*
-Copyright (C) 2015-2019 The University of Notre Dame
+Copyright (C) 2015-2025 The University of Notre Dame
 This software is distributed under the GNU General Public License.
 See the file LICENSE for details.
 */
 
+#include "loader.h"
 #include "elf.h"
 #include "fs.h"
 #include "string.h"
@@ -12,99 +13,9 @@ See the file LICENSE for details.
 #include "kernel/syscall.h"
 #include "memorylayout.h"
 
-struct elf_header {
-	char ident[16];
-	uint16_t type;
-	uint16_t machine;
-	uint32_t version;
-	uint32_t entry;
-	uint32_t program_offset;
-	uint32_t section_offset;
-	uint32_t flags;
-	uint16_t header_size;
-	uint16_t phentsize;
-	uint16_t phnum;
-	uint16_t shentsize;
-	uint16_t shnum;
-	uint16_t shstrndx;
-};
-
-#define ELF_HEADER_TYPE_NONE         0
-#define ELF_HEADER_TYPE_OBJECT       1
-#define ELF_HEADER_TYPE_EXECUTABLE   2
-#define ELF_HEADER_TYPE_DYNAMIC      3
-#define ELF_HEADER_TYPE_CORE         4
-
-#define ELF_HEADER_MACHINE_I386   3
-#define ELF_HEADER_MACHINE_ARM    40
-#define ELF_HEADER_MACHINE_X86_64 62
-
-#define ELF_HEADER_VERSION     1
-
-struct elf_program {
-	uint32_t type;
-	uint32_t offset;
-	uint32_t vaddr;
-	uint32_t paddr;
-	uint32_t file_size;
-	uint32_t memory_size;
-	uint32_t flags;
-	uint32_t align;
-};
-
-#define ELF_PROGRAM_TYPE_NULL 0
-#define ELF_PROGRAM_TYPE_LOADABLE 1
-#define ELF_PROGRAM_TYPE_DYNAMIC 2
-#define ELF_PROGRAM_TYPE_INTERPRETER 3
-#define ELF_PROGRAM_TYPE_NOTE 4
-#define ELF_PROGRAM_TYPE_SHARED_LIBRARY 5
-#define ELF_PROGRAM_TYPE_PROGRAM_HEADER 6
-#define ELF_PROGRAM_TYPE_THREAD_LOCAL 7
-#define ELF_PROGRAM_TYPE_GNU_EH_FRAME 0x6474e550
-#define ELF_PROGRAM_TYPE_GNU_STACK 0x6474e551
-#define ELF_PROGRAM_TYPE_GNU_RELRO 0x6474e552
-
-#define ELF_PROGRAM_FLAGS_EXEC  1
-#define ELF_PROGRAM_FLAGS_WRITE 2
-#define ELF_PROGRAM_FLAGS_READ  4
-
-struct elf_section {
-	uint32_t name;
-	uint32_t type;
-	uint32_t flags;
-	uint32_t address;
-	uint32_t offset;
-	uint32_t size;
-	uint32_t link;
-	uint32_t info;
-	uint32_t alignment;
-	uint32_t entry_size;
-};
-
-#define ELF_SECTION_TYPE_NULL         0
-#define ELF_SECTION_TYPE_PROGRAM      1
-#define ELF_SECTION_TYPE_SYMBOL_TABLE 2
-#define ELF_SECTION_TYPE_STRING_TABLE 3
-#define ELF_SECTION_TYPE_RELA         4
-#define ELF_SECTION_TYPE_HASH         5
-#define ELF_SECTION_TYPE_DYNAMIC      6
-#define ELF_SECTION_TYPE_NOTE         7
-#define ELF_SECTION_TYPE_BSS          8
-
-#define ELF_SECTION_FLAGS_WRITE    1
-#define ELF_SECTION_FLAGS_MEMORY   2
-#define ELF_SECTION_FLAGS_EXEC     8
-#define ELF_SECTION_FLAGS_MERGE    16
-#define ELF_SECTION_FLAGS_STRINGS  32
-#define ELF_SECTION_FLAGS_INFO_LINK 64
-#define ELF_SECTION_FLAGS_LINK_ORDER 128
-#define ELF_SECTION_FLAGS_NONSTANDARD 256
-#define ELF_SECTION_FLAGS_GROUP 512
-#define ELF_SECTION_FLAGS_TLS 1024
-
 /* Ensure that the current process has address space up to this value. */
 
-static int elf_ensure_address_space( struct process *p, uint32_t addr )
+static int loader_ensure_address_space( struct process *p, uint32_t addr )
 {
 	/* Size of user data area, ignoring start addr */
 	uint32_t limit = addr - PROCESS_ENTRY_POINT;
@@ -125,7 +36,7 @@ static int elf_ensure_address_space( struct process *p, uint32_t addr )
 
 /* Load an ELF executable into user space. */
 
-int elf_load(struct process *p, struct fs_dirent *d, addr_t * entry)
+int loader_load_process(struct process *p, struct fs_dirent *d, addr_t * entry)
 {
 	struct elf_header header;
 	struct elf_program program;
@@ -174,7 +85,7 @@ int elf_load(struct process *p, struct fs_dirent *d, addr_t * entry)
 
 
 		/* Expand the user address space if needed for this segment. */
-		if(elf_ensure_address_space(p,program.vaddr + program.memory_size)!=0) {
+		if(loader_ensure_address_space(p,program.vaddr + program.memory_size)!=0) {
 			printf("elf: unable to allocate memory for segment %d vaddr %x size %x\n",i,program.vaddr,program.memory_size);
 			return KERROR_OUT_OF_MEMORY;
 		}
diff --git a/kernel/loader.h b/kernel/loader.h
new file mode 100644
index 00000000..45d5cd08
--- /dev/null
+++ b/kernel/loader.h
@@ -0,0 +1,23 @@
+/*
+Copyright (C) 2015-2025 The University of Notre Dame
+This software is distributed under the GNU General Public License.
+See the file LICENSE for details.
+*/
+
+#ifndef LOADER_H
+#define LOADER_H
+
+#include "process.h"
+#include "fs.h"
+
+/*
+loader_load_process reads the given file object,
+and if it contains a valid ELF executable, loads
+the segments of the executable into the process
+address space, returning the executable entry point
+in the argument "entry".
+*/
+
+int loader_load_process(struct process *p, struct fs_dirent *d, addr_t * entry);
+
+#endif
diff --git a/kernel/syscall_handler.c b/kernel/syscall_handler.c
index f1bda5e6..ee6793eb 100644
--- a/kernel/syscall_handler.c
+++ b/kernel/syscall_handler.c
@@ -21,7 +21,7 @@ See the file LICENSE for details.
 #include "pagetable.h"
 #include "clock.h"
 #include "rtc.h"
-#include "elf.h"
+#include "loader.h"
 #include "kmalloc.h"
 #include "page.h"
 #include "ata.h"
@@ -119,7 +119,7 @@ int sys_process_run( int fd, int argc, const char **argv)
 
 	/* Attempt to load the program image. */
 	addr_t entry;
-	int r = elf_load(p, k->data.file, &entry);
+	int r = loader_load_process(p, k->data.file, &entry);
 	if(r >= 0) {
 		/* If load succeeded, reset stack and pass arguments */
 		process_stack_reset(p, PAGE_SIZE);
@@ -168,7 +168,7 @@ int sys_process_wrun( int fd, int argc, const char **argv, int *fds, int fd_len)
 
 	/* Attempt to load the program image. */
 	addr_t entry;
-	int r = elf_load(p, k->data.file, &entry);
+	int r = loader_load_process(p, k->data.file, &entry);
 	if(r >= 0) {
 		/* If load succeeded, reset stack and pass arguments */
 		process_stack_reset(p, PAGE_SIZE);
@@ -207,7 +207,7 @@ int sys_process_exec( int fd, int argc, const char **argv)
 	char **copy_argv = argv_copy(argc, argv);
 
 	/* Attempt to load the program image into this process. */
-	int r = elf_load(current, k->data.file, &entry);
+	int r = loader_load_process(current, k->data.file, &entry);
 
 	/* On failure, return only if our address space is not corrupted. */
 	if(r < 0) {