137 lines
3.8 KiB
C++
137 lines
3.8 KiB
C++
#define MODULE "exec"
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#include "errno.h"
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#include "interrupts/Interrupts.h"
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#include "kassert.h"
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#include "memory/MemoryManager.h"
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#include "memory/PMM.h"
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#include "memory/VMM.h"
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#include "std/stdlib.h"
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#include "std/string.h"
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#include "sys/Syscall.h"
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#include "sys/elf/ELFLoader.h"
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#include "thread/Scheduler.h"
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#include "utils/Addresses.h"
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void sys_fork(Context* context) // FIXME: Even though both processes's address spaces are the same in content, writing
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// to one should not affect the other.
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{
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kinfoln("fork(): attempting fork");
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Task* parent = Scheduler::current_task();
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Task* child = Scheduler::create_user_task();
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memcpy(&child->regs, &parent->regs, sizeof(Context));
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if (parent->floating_saved)
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{
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memcpy(child->floating_region, parent->floating_region, sizeof(parent->floating_region));
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child->floating_saved = true;
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}
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for (int i = 0; i < TASK_MAX_FDS; i++) { child->files[i] = parent->files[i]; }
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size_t stack_bytes = get_top_of_stack(parent->allocated_stack, TASK_PAGES_IN_STACK) - parent->regs.rsp;
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child->regs.rsp -= stack_bytes;
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memcpy((void*)child->regs.rsp, (void*)parent->regs.rsp, stack_bytes);
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child->address_space = parent->address_space.clone();
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child->regs.rax = 0;
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context->rax = child->id;
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kinfoln("fork(): forked parent %d into child %d", parent->id, child->id);
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return;
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}
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void sys_exec(Context* context, const char* pathname)
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{
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char* kpathname = Syscall::strdup_from_user(pathname);
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if (!kpathname)
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{
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context->rax = -EFAULT;
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return;
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}
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kinfoln("exec(): executing %s", kpathname);
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VFS::Node* program = VFS::resolve_path(kpathname);
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if (!program)
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{
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kfree(kpathname);
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context->rax = -ENOENT;
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return;
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}
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if (program->type == VFS_DIRECTORY)
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{
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kfree(kpathname);
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context->rax = -EISDIR;
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return;
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}
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long memusage;
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if ((memusage = ELFLoader::check_elf_image(program)) < 0)
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{
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kfree(kpathname);
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context->rax = -ENOEXEC;
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return;
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}
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uint64_t allocated_stack = (uint64_t)MemoryManager::get_pages(TASK_PAGES_IN_STACK, MAP_READ_WRITE | MAP_USER);
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if (!allocated_stack)
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{
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kfree(kpathname);
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context->rax = -ENOMEM;
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return;
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}
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uint64_t allocated_stack_phys = VMM::get_physical(allocated_stack);
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if ((uint64_t)memusage > PMM::get_free())
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{
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kfree(kpathname);
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MemoryManager::release_pages((void*)allocated_stack, TASK_PAGES_IN_STACK);
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context->rax = -ENOMEM;
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return;
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}
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Interrupts::disable();
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ASSERT(!Interrupts::are_enabled()); // This part is pretty sensitive.
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Task* task = Scheduler::current_task();
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ASSERT(task);
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if (task->address_space.is_cloned())
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{
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kdbgln("Detaching cloned address space, %p, %s", (void*)task->address_space.get_pml4(),
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task->address_space.is_cloned() ? "is cloned" : "is not cloned");
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task->address_space.detach();
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VMM::switch_to_user_address_space(task->address_space);
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kdbgln("Detached cloned address space, %p, %s", (void*)task->address_space.get_pml4(),
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task->address_space.is_cloned() ? "is cloned" : "is not cloned");
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}
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// At this point, pretty much nothing can fail.
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ELFImage* image = ELFLoader::load_elf_from_vfs(program);
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ASSERT(image); // If check_elf_image succeeded, load_elf_from_vfs MUST succeed, unless something has gone terribly
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// wrong.
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task->allocated_stack = allocated_stack;
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for (uint64_t i = 0; i < TASK_PAGES_IN_STACK; i++)
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{
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VMM::map(allocated_stack + (i * PAGE_SIZE), allocated_stack_phys + (i * PAGE_SIZE), MAP_READ_WRITE | MAP_USER);
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}
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Scheduler::reset_task(task, image);
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set_context_from_task(*task, context);
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kfree(kpathname);
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return;
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} |