syscalls: fix page count for mapping in sys_execve and make caller run coreutils

grubshit/caller.c

@@ -9,7 +9,7 @@ int main() {
 
     // Arguments for the new program
     // The first argument is conventionally the program name
-    char *argv[] = { "./callee", "first_arg", "second_arg", NULL };
+    char *argv[] = { "/katau/core", "--help", NULL };
 
     // Environment variables for the new program
     char *envp[] = { "CUSTOM_VAR=Hello from caller!", "ANOTHER_VAR=123", NULL };
@@ -18,7 +18,7 @@ int main() {
     // The first argument is the path to the executable
     // The second is the array of arguments
     // The third is the array of environment variables
-    execve("/katau/callee.", argv, envp);
+    execve("/katau/core.", argv, envp);
 
     // This part of the code will only be reached if execve fails
     perror("execve failed");

src/tasking/syscalls.c

@@ -323,10 +323,17 @@ int sys_execve(TrapFrame *tf) {
     for (int i = 0; i < elf_header->e_phnum; i++) {
         Elf32_Phdr *p_header = (Elf32_Phdr *)(file_buffer + elf_header->e_phoff + i * elf_header->e_phentsize);
         if (p_header->p_type == PT_LOAD) {
-            for (uint32_t vaddr = p_header->p_vaddr; vaddr < p_header->p_vaddr + p_header->p_memsz; vaddr += PAGE_SIZE) {
+            uint32_t start_addr = p_header->p_vaddr;
+            uint32_t end_addr = start_addr + p_header->p_memsz;
+
+            uint32_t start_page = start_addr & ~0xFFF;
+            uint32_t end_page = (end_addr - 1) & ~0xFFF;
+
+            for (uint32_t vaddr = start_page; vaddr <= end_page; vaddr += PAGE_SIZE) {
                 void* phys_addr = alloc_page();
-                map_page(phys_addr, (void*)(vaddr & ~0xFFF), PAGE_PRESENT | PAGE_RW | PAGE_USER);
+                map_page(phys_addr, (void*)vaddr, PAGE_PRESENT | PAGE_RW | PAGE_USER);
             }
+
             memcpy((void*)p_header->p_vaddr, file_buffer + p_header->p_offset, p_header->p_filesz);
             if (p_header->p_memsz > p_header->p_filesz) {
                 memset((void*)(p_header->p_vaddr + p_header->p_filesz), 0, p_header->p_memsz - p_header->p_filesz);