From 7133e3848040a1e3c82b348e0169fb891c2d326c Mon Sep 17 00:00:00 2001
From: Alex Stratford <alexander3.stratford@live.uwe.ac.uk>
Date: Sat, 30 Nov 2019 01:32:02 +0000
Subject: [PATCH] Renamed esp to initialStackPointer to explain its usage
better Added functionality to populate_stack.c - Added populate_stack()
- Added move_stack_pointer()
---
userprog/populate_stack.c | 44 +++++++++++++++++++++++++++++++++++++--
userprog/process.c | 24 ++++++++++-----------
2 files changed, 54 insertions(+), 14 deletions(-)
diff --git a/userprog/populate_stack.c b/userprog/populate_stack.c
index 6a7bb2e..00092b3 100644
--- a/userprog/populate_stack.c
+++ b/userprog/populate_stack.c
@@ -1,6 +1,46 @@
#include "userprog/argument_parsing.h"
-void populate_stack(void* esp, int argc, char** argv) {
- #warning "Implement me"
+void populate_stack(void* stackPointer, int argc, char** argv) {
+ *stackPointer = PHYS_BASE;
+ int i = argc;
+
+ // this array holds reference to differences arguments in the stack
+ uint32_t * arr[argc];
+
+ while (--i >= 0)
+ {
+ *stackPointer = *stackPointer - (strlen(argv[i]) + 1) * sizeof(char);
+
+ arr[i] = (uint32_t *)*stackPointer;
+
+ memcpy(*stackPointer, argv[i], strlen(argv[i]) + 1);
+ }
+
+ *stackPointer = move_stack_pointer(*stackPointer, -4); //Moves the stack pointer back 4
+
+ (*(int *)(*stackPointer)) = 0;//sentinel
+ i = argc;
+
+ while (--i >= 0)
+ {
+ *stackPointer = move_stack_pointer(*stackPointer, -4); //32bit Moves the stack pointer back 4
+
+ (*(uint32_t **)(*stackPointer)) = arr[i];
+ }
+
+ *stackPointer = move_stack_pointer(*stackPointer, -4);
+
+ (*(uintptr_t **)(*stackPointer)) = *stackPointer = move_stack_pointer(*stackPointer, 4); //Moves the stack pointer forwards 4
+ *stackPointer = move_stack_pointer(*stackPointer, -4); //Moves the stack pointer back 4
+
+ *(int *)(*stackPointer) = argc;
+ *stackPointer = move_stack_pointer(*stackPointer, -4); //Moves the stack pointer back 4
+
+ (*(int *)(*stackPointer)) = 0;
}
+
+int move_stack_pointer(void* stackPointer, int moveValue) {
+ *stackPointer = *stackPointer + moveValue;
+ return *stackPointer;
+}
\ No newline at end of file
diff --git a/userprog/process.c b/userprog/process.c
index 7aa1581..d44ae7a 100644
--- a/userprog/process.c
+++ b/userprog/process.c
@@ -19,7 +19,7 @@
#include "threads/vaddr.h"
static thread_func start_process NO_RETURN;
-static bool load (const char *cmdline, void (**eip) (void), void **esp);
+static bool load (const char *cmdline, void (**eip) (void), void **initialStackPointer);
/* Starts a new thread running a user program loaded by parsing
COMMAND. The new thread may be scheduled (and may even exit)
@@ -68,7 +68,7 @@ start_process (void *file_name_)
if_.cs = SEL_UCSEG;
if_.eflags = FLAG_IF | FLAG_MBS;
- success = load (file_name, &if_.eip, &if_.esp);
+ success = load (file_name, &if_.eip, &if_.initialStackPointer);
/* If load failed, quit. */
palloc_free_page (file_name);
@@ -79,9 +79,9 @@ start_process (void *file_name_)
interrupt, implemented by intr_exit (in
threads/intr-stubs.S). Because intr_exit takes all of its
arguments on the stack in the form of a `struct intr_frame',
- we just point the stack pointer (%esp) to our stack frame
+ we just point the stack pointer (%initialStackPointer) to our stack frame
and jump to it. */
- asm volatile ("movl %0, %%esp; jmp intr_exit" : : "g" (&if_) : "memory");
+ asm volatile ("movl %0, %%initialStackPointer; jmp intr_exit" : : "g" (&if_) : "memory");
NOT_REACHED ();
}
@@ -212,7 +212,7 @@ struct Elf32_Phdr
#define PF_W 2 /* Writable. */
#define PF_R 4 /* Readable. */
-static bool setup_stack (void **esp);
+static bool setup_stack(void **initialStackPointer, char **argv, int argc)
static bool validate_segment (const struct Elf32_Phdr *, struct file *);
static bool load_segment (struct file *file, off_t ofs, uint8_t *upage,
uint32_t read_bytes, uint32_t zero_bytes,
@@ -220,15 +220,15 @@ static bool load_segment (struct file *file, off_t ofs, uint8_t *upage,
/* Loads an ELF executable from FILE_NAME into the current thread.
Stores the executable's entry point into *EIP
- and its initial stack pointer into *ESP.
+ and its initial stack pointer into *initialStackPointer.
Returns true if successful, false otherwise. */
bool
-load (const char *file_name, void (**eip) (void), void **esp)
+load (const char *file_name, void (**eip) (void), void **initialStackPointer)
{
struct thread *t = thread_current ();
struct Elf32_Ehdr ehdr;
- struct file *file = NULL;
- off_t file_ofs;
+ struct file * = NULL;
+ off_t file_ofs;file
bool success = false;
int i;
@@ -320,7 +320,7 @@ load (const char *file_name, void (**eip) (void), void **esp)
}
/* Set up stack. */
- if (!setup_stack (esp))
+ if (!setup_stack (initialStackPointer))
goto done;
/* Start address. */
@@ -445,7 +445,7 @@ load_segment (struct file *file, off_t ofs, uint8_t *upage,
/* Create a minimal stack by mapping a zeroed page at the top of
user virtual memory. */
static bool
-setup_stack (void **esp)
+setup_stack (void **initialStackPointer, char **argv, int argc)
{
uint8_t *kpage;
bool success = false;
@@ -455,7 +455,7 @@ setup_stack (void **esp)
{
success = install_page (((uint8_t *) PHYS_BASE) - PGSIZE, kpage, true);
if (success) {
- *esp = PHYS_BASE - 12;
+ *initialStackPointer = PHYS_BASE - 12;
} else
palloc_free_page (kpage);
}
--
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