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Process.cpp
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Process.cpp
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#include "types.h"
#include "Process.h"
#include "kmalloc.h"
#include "VGA.h"
#include "StdLib.h"
#include "i386.h"
#include "system.h"
#include <VirtualFileSystem/FileDescriptor.h>
#include <VirtualFileSystem/VirtualFileSystem.h>
#include <ELFLoader/ELFLoader.h>
#include "MemoryManager.h"
#include "errno.h"
#include "i8253.h"
#include "RTC.h"
#include "ProcFileSystem.h"
#include <AK/StdLib.h>
#include <LibC/signal_numbers.h>
//#define DEBUG_IO
//#define TASK_DEBUG
//#define FORK_DEBUG
//#define SCHEDULER_DEBUG
#define COOL_GLOBALS
#define MAX_PROCESS_GIDS 32
#ifdef COOL_GLOBALS
struct CoolGlobals {
dword current_pid;
};
CoolGlobals* g_cool_globals;
#endif
// FIXME: Only do a single validation for accesses that don't span multiple pages.
// FIXME: Some places pass strlen(arg1) as arg2. This doesn't seem entirely perfect..
#define VALIDATE_USER_READ(b, s) \
do { \
LinearAddress laddr((dword)(b)); \
if (!validate_user_read(laddr) || !validate_user_read(laddr.offset((s) - 1))) \
return -EFAULT; \
} while(0)
#define VALIDATE_USER_WRITE(b, s) \
do { \
LinearAddress laddr((dword)(b)); \
if (!validate_user_write(laddr) || !validate_user_write(laddr.offset((s) - 1))) \
return -EFAULT; \
} while(0)
static const DWORD defaultStackSize = 16384;
Process* current;
Process* s_kernelProcess;
static pid_t next_pid;
static InlineLinkedList<Process>* s_processes;
static InlineLinkedList<Process>* s_deadProcesses;
static String* s_hostname;
static String& hostnameStorage(InterruptDisabler&)
{
ASSERT(s_hostname);
return *s_hostname;
}
static String getHostname()
{
InterruptDisabler disabler;
return hostnameStorage(disabler).isolatedCopy();
}
static bool contextSwitch(Process*);
static void redoKernelProcessTSS()
{
if (!s_kernelProcess->selector())
s_kernelProcess->setSelector(gdt_alloc_entry());
auto& tssDescriptor = getGDTEntry(s_kernelProcess->selector());
tssDescriptor.setBase(&s_kernelProcess->tss());
tssDescriptor.setLimit(0xffff);
tssDescriptor.dpl = 0;
tssDescriptor.segment_present = 1;
tssDescriptor.granularity = 1;
tssDescriptor.zero = 0;
tssDescriptor.operation_size = 1;
tssDescriptor.descriptor_type = 0;
tssDescriptor.type = 9;
flushGDT();
}
void Process::prepForIRETToNewProcess()
{
redoKernelProcessTSS();
s_kernelProcess->tss().backlink = current->selector();
loadTaskRegister(s_kernelProcess->selector());
}
static void hlt_loop()
{
for (;;) {
asm volatile("hlt");
}
}
void Process::initialize()
{
#ifdef COOL_GLOBALS
g_cool_globals = (CoolGlobals*)0x1000;
#endif
current = nullptr;
next_pid = 0;
s_processes = new InlineLinkedList<Process>;
s_deadProcesses = new InlineLinkedList<Process>;
s_kernelProcess = Process::createKernelProcess(hlt_loop, "colonel");
s_hostname = new String("birx");
redoKernelProcessTSS();
loadTaskRegister(s_kernelProcess->selector());
}
template<typename Callback>
static void forEachProcess(Callback callback)
{
ASSERT_INTERRUPTS_DISABLED();
for (auto* process = s_processes->head(); process; process = process->next()) {
if (!callback(*process))
break;
}
}
void Process::for_each_in_pgrp(pid_t pgid, Function<void(Process&)> callback)
{
ASSERT_INTERRUPTS_DISABLED();
for (auto* process = s_processes->head(); process; process = process->next()) {
if (process->pgid() == pgid)
callback(*process);
}
}
Vector<Process*> Process::allProcesses()
{
InterruptDisabler disabler;
Vector<Process*> processes;
processes.ensureCapacity(s_processes->sizeSlow());
for (auto* process = s_processes->head(); process; process = process->next())
processes.append(process);
return processes;
}
Region* Process::allocate_region(LinearAddress laddr, size_t size, String&& name, bool is_readable, bool is_writable)
{
// FIXME: This needs sanity checks. What if this overlaps existing regions?
if (laddr.is_null()) {
laddr = m_nextRegion;
m_nextRegion = m_nextRegion.offset(size).offset(PAGE_SIZE);
}
laddr.mask(0xfffff000);
unsigned page_count = ceilDiv(size, PAGE_SIZE);
auto physical_pages = MM.allocate_physical_pages(page_count);
ASSERT(physical_pages.size() == page_count);
m_regions.append(adopt(*new Region(laddr, size, move(physical_pages), move(name), is_readable, is_writable)));
MM.mapRegion(*this, *m_regions.last());
return m_regions.last().ptr();
}
bool Process::deallocate_region(Region& region)
{
InterruptDisabler disabler;
for (size_t i = 0; i < m_regions.size(); ++i) {
if (m_regions[i].ptr() == ®ion) {
MM.unmapRegion(*this, region);
m_regions.remove(i);
return true;
}
}
return false;
}
Region* Process::regionFromRange(LinearAddress laddr, size_t size)
{
for (auto& region : m_regions) {
if (region->linearAddress == laddr && region->size == size)
return region.ptr();
}
return nullptr;
}
int Process::sys$set_mmap_name(void* addr, size_t size, const char* name)
{
VALIDATE_USER_READ(name, strlen(name));
auto* region = regionFromRange(LinearAddress((dword)addr), size);
if (!region)
return -EINVAL;
region->name = name;
return 0;
}
void* Process::sys$mmap(void* addr, size_t size)
{
InterruptDisabler disabler;
// FIXME: Implement mapping at a client-preferred address.
ASSERT(addr == nullptr);
auto* region = allocate_region(LinearAddress(), size, "mmap");
if (!region)
return (void*)-1;
MM.mapRegion(*this, *region);
return (void*)region->linearAddress.get();
}
int Process::sys$munmap(void* addr, size_t size)
{
InterruptDisabler disabler;
auto* region = regionFromRange(LinearAddress((dword)addr), size);
if (!region)
return -1;
if (!deallocate_region(*region))
return -1;
return 0;
}
int Process::sys$gethostname(char* buffer, size_t size)
{
VALIDATE_USER_WRITE(buffer, size);
auto hostname = getHostname();
if (size < (hostname.length() + 1))
return -ENAMETOOLONG;
memcpy(buffer, hostname.characters(), size);
return 0;
}
Process* Process::fork(RegisterDump& regs)
{
auto* child = new Process(String(m_name), m_uid, m_gid, m_pid, m_ring, m_cwd.copyRef(), m_executable.copyRef(), m_tty, this);
#ifdef FORK_DEBUG
dbgprintf("fork: child=%p\n", child);
#endif
#if 0
// FIXME: An honest fork() would copy these. Needs a Vector copy ctor.
child->m_arguments = m_arguments;
child->m_initialEnvironment = m_initialEnvironment;
#endif
for (auto& region : m_regions) {
#ifdef FORK_DEBUG
dbgprintf("fork: cloning Region{%p}\n", region.ptr());
#endif
auto cloned_region = region->clone();
child->m_regions.append(move(cloned_region));
MM.mapRegion(*child, *child->m_regions.last());
}
child->m_tss.eax = 0; // fork() returns 0 in the child :^)
child->m_tss.ebx = regs.ebx;
child->m_tss.ecx = regs.ecx;
child->m_tss.edx = regs.edx;
child->m_tss.ebp = regs.ebp;
child->m_tss.esp = regs.esp_if_crossRing;
child->m_tss.esi = regs.esi;
child->m_tss.edi = regs.edi;
child->m_tss.eflags = regs.eflags;
child->m_tss.eip = regs.eip;
child->m_tss.cs = regs.cs;
child->m_tss.ds = regs.ds;
child->m_tss.es = regs.es;
child->m_tss.fs = regs.fs;
child->m_tss.gs = regs.gs;
child->m_tss.ss = regs.ss_if_crossRing;
#ifdef FORK_DEBUG
dbgprintf("fork: child will begin executing at %w:%x with stack %w:%x\n", child->m_tss.cs, child->m_tss.eip, child->m_tss.ss, child->m_tss.esp);
#endif
ProcFileSystem::the().addProcess(*child);
s_processes->prepend(child);
system.nprocess++;
#ifdef TASK_DEBUG
kprintf("Process %u (%s) forked from %u @ %p\n", child->pid(), child->name().characters(), m_pid, child->m_tss.eip);
#endif
return child;
}
pid_t Process::sys$fork(RegisterDump& regs)
{
auto* child = fork(regs);
ASSERT(child);
return child->pid();
}
int Process::exec(const String& path, Vector<String>&& arguments, Vector<String>&& environment)
{
auto parts = path.split('/');
if (parts.isEmpty())
return -ENOENT;
int error;
auto descriptor = VirtualFileSystem::the().open(path, error, 0, m_cwd ? m_cwd->inode : InodeIdentifier());
if (!descriptor) {
ASSERT(error != 0);
return error;
}
if (!descriptor->metadata().mayExecute(m_euid, m_gids))
return -EACCES;
auto elfData = descriptor->readEntireFile();
if (!elfData)
return -EIO; // FIXME: Get a more detailed error from VFS.
dword entry_eip = 0;
PageDirectory* old_page_directory;
PageDirectory* new_page_directory;
{
InterruptDisabler disabler;
// Okay, here comes the sleight of hand, pay close attention..
auto old_regions = move(m_regions);
old_page_directory = m_page_directory;
new_page_directory = reinterpret_cast<PageDirectory*>(kmalloc_page_aligned(sizeof(PageDirectory)));
MM.populate_page_directory(*new_page_directory);
m_page_directory = new_page_directory;
MM.enter_process_paging_scope(*this);
ELFLoader loader(move(elfData));
loader.alloc_section_hook = [&] (LinearAddress laddr, size_t size, size_t alignment, bool is_readable, bool is_writable, const String& name) {
ASSERT(size);
size = ((size / 4096) + 1) * 4096; // FIXME: Use ceil_div?
(void) allocate_region(laddr, size, String(name), is_readable, is_writable);
return laddr.asPtr();
};
bool success = loader.load();
if (!success) {
m_page_directory = old_page_directory;
MM.enter_process_paging_scope(*this);
MM.release_page_directory(*new_page_directory);
m_regions = move(old_regions);
kprintf("sys$execve: Failure loading %s\n", path.characters());
return -ENOEXEC;
}
entry_eip = (dword)loader.symbol_ptr("_start");
if (!entry_eip) {
m_page_directory = old_page_directory;
MM.enter_process_paging_scope(*this);
MM.release_page_directory(*new_page_directory);
m_regions = move(old_regions);
return -ENOEXEC;
}
}
InterruptDisabler disabler;
if (current == this)
loadTaskRegister(s_kernelProcess->selector());
m_name = parts.takeLast();
dword old_esp0 = m_tss.esp0;
memset(&m_tss, 0, sizeof(m_tss));
m_tss.eflags = 0x0202;
m_tss.eip = entry_eip;
m_tss.cs = 0x1b;
m_tss.ds = 0x23;
m_tss.es = 0x23;
m_tss.fs = 0x23;
m_tss.gs = 0x23;
m_tss.ss = 0x23;
m_tss.cr3 = (dword)m_page_directory;
auto* stack_region = allocate_region(LinearAddress(), defaultStackSize, "stack");
ASSERT(stack_region);
m_stackTop3 = stack_region->linearAddress.offset(defaultStackSize).get() & 0xfffffff8;
m_tss.esp = m_stackTop3;
m_tss.ss0 = 0x10;
m_tss.esp0 = old_esp0;
m_tss.ss2 = m_pid;
MM.release_page_directory(*old_page_directory);
m_executable = descriptor->vnode();
m_arguments = move(arguments);
m_initialEnvironment = move(environment);
#ifdef TASK_DEBUG
kprintf("Process %u (%s) exec'd %s @ %p\n", pid(), name().characters(), filename, m_tss.eip);
#endif
if (current == this)
sched_yield();
return 0;
}
int Process::sys$execve(const char* filename, const char** argv, const char** envp)
{
VALIDATE_USER_READ(filename, strlen(filename));
if (argv) {
for (size_t i = 0; argv[i]; ++i) {
VALIDATE_USER_READ(argv[i], strlen(argv[i]));
}
}
if (envp) {
for (size_t i = 0; envp[i]; ++i) {
VALIDATE_USER_READ(envp[i], strlen(envp[i]));
}
}
String path(filename);
auto parts = path.split('/');
Vector<String> arguments;
if (argv) {
for (size_t i = 0; argv[i]; ++i) {
arguments.append(argv[i]);
}
} else {
arguments.append(parts.last());
}
Vector<String> environment;
if (envp) {
for (size_t i = 0; envp[i]; ++i) {
environment.append(envp[i]);
}
}
int rc = exec(path, move(arguments), move(environment));
ASSERT(rc < 0);
return rc;
}
pid_t Process::sys$spawn(const char* filename, const char** argv, const char** envp)
{
VALIDATE_USER_READ(filename, strlen(filename));
if (argv) {
for (size_t i = 0; argv[i]; ++i) {
VALIDATE_USER_READ(argv[i], strlen(argv[i]));
}
}
if (envp) {
for (size_t i = 0; envp[i]; ++i) {
VALIDATE_USER_READ(envp[i], strlen(envp[i]));
}
}
String path(filename);
auto parts = path.split('/');
Vector<String> arguments;
if (argv) {
for (size_t i = 0; argv[i]; ++i) {
arguments.append(argv[i]);
}
} else {
arguments.append(parts.last());
}
Vector<String> environment;
if (envp) {
for (size_t i = 0; envp[i]; ++i) {
environment.append(envp[i]);
}
}
int error;
auto* child = create_user_process(path, m_uid, m_gid, m_pid, error, move(arguments), move(environment), m_tty);
if (child)
return child->pid();
return error;
}
Process* Process::create_user_process(const String& path, uid_t uid, gid_t gid, pid_t parent_pid, int& error, Vector<String>&& arguments, Vector<String>&& environment, TTY* tty)
{
// FIXME: Don't split() the path twice (sys$spawn also does it...)
auto parts = path.split('/');
if (arguments.isEmpty()) {
arguments.append(parts.last());
}
RetainPtr<VirtualFileSystem::Node> cwd;
{
InterruptDisabler disabler;
if (auto* parent = Process::fromPID(parent_pid))
cwd = parent->m_cwd.copyRef();
}
if (!cwd)
cwd = VirtualFileSystem::the().root();
auto* process = new Process(parts.takeLast(), uid, gid, parent_pid, Ring3, move(cwd), nullptr, tty);
error = process->exec(path, move(arguments), move(environment));
if (error != 0)
return nullptr;
ProcFileSystem::the().addProcess(*process);
s_processes->prepend(process);
system.nprocess++;
#ifdef TASK_DEBUG
kprintf("Process %u (%s) spawned @ %p\n", process->pid(), process->name().characters(), process->m_tss.eip);
#endif
error = 0;
return process;
}
int Process::sys$get_environment(char*** environ)
{
auto* region = allocate_region(LinearAddress(), PAGE_SIZE, "environ");
if (!region)
return -ENOMEM;
MM.mapRegion(*this, *region);
char* envpage = (char*)region->linearAddress.get();
*environ = (char**)envpage;
char* bufptr = envpage + (sizeof(char*) * (m_initialEnvironment.size() + 1));
for (size_t i = 0; i < m_initialEnvironment.size(); ++i) {
(*environ)[i] = bufptr;
memcpy(bufptr, m_initialEnvironment[i].characters(), m_initialEnvironment[i].length());
bufptr += m_initialEnvironment[i].length();
*(bufptr++) = '\0';
}
(*environ)[m_initialEnvironment.size()] = nullptr;
return 0;
}
int Process::sys$get_arguments(int* argc, char*** argv)
{
auto* region = allocate_region(LinearAddress(), PAGE_SIZE, "argv");
if (!region)
return -ENOMEM;
MM.mapRegion(*this, *region);
char* argpage = (char*)region->linearAddress.get();
*argc = m_arguments.size();
*argv = (char**)argpage;
char* bufptr = argpage + (sizeof(char*) * m_arguments.size());
for (size_t i = 0; i < m_arguments.size(); ++i) {
(*argv)[i] = bufptr;
memcpy(bufptr, m_arguments[i].characters(), m_arguments[i].length());
bufptr += m_arguments[i].length();
*(bufptr++) = '\0';
}
return 0;
}
Process* Process::createKernelProcess(void (*e)(), String&& name)
{
auto* process = new Process(move(name), (uid_t)0, (gid_t)0, (pid_t)0, Ring0);
process->m_tss.eip = (dword)e;
if (process->pid() != 0) {
InterruptDisabler disabler;
s_processes->prepend(process);
system.nprocess++;
ProcFileSystem::the().addProcess(*process);
#ifdef TASK_DEBUG
kprintf("Kernel process %u (%s) spawned @ %p\n", process->pid(), process->name().characters(), process->m_tss.eip);
#endif
}
return process;
}
Process::Process(String&& name, uid_t uid, gid_t gid, pid_t ppid, RingLevel ring, RetainPtr<VirtualFileSystem::Node>&& cwd, RetainPtr<VirtualFileSystem::Node>&& executable, TTY* tty, Process* fork_parent)
: m_name(move(name))
, m_pid(next_pid++) // FIXME: RACE: This variable looks racy!
, m_uid(uid)
, m_gid(gid)
, m_euid(uid)
, m_egid(gid)
, m_state(Runnable)
, m_ring(ring)
, m_cwd(move(cwd))
, m_executable(move(executable))
, m_tty(tty)
, m_ppid(ppid)
{
m_gids.set(m_gid);
if (fork_parent) {
m_sid = fork_parent->m_sid;
m_pgid = fork_parent->m_pgid;
} else {
// FIXME: Use a ProcessHandle? Presumably we're executing *IN* the parent right now though..
InterruptDisabler disabler;
if (auto* parent = Process::fromPID(m_ppid)) {
m_sid = parent->m_sid;
m_pgid = parent->m_pgid;
}
}
m_page_directory = (PageDirectory*)kmalloc_page_aligned(sizeof(PageDirectory));
MM.populate_page_directory(*m_page_directory);
if (fork_parent) {
m_file_descriptors.resize(fork_parent->m_file_descriptors.size());
for (size_t i = 0; i < fork_parent->m_file_descriptors.size(); ++i) {
if (!fork_parent->m_file_descriptors[i])
continue;
#ifdef FORK_DEBUG
dbgprintf("fork: cloning fd %u... (%p) istty? %um\n", i, fork_parent->m_file_descriptors[i].ptr(), fork_parent->m_file_descriptors[i]->isTTY());
#endif
m_file_descriptors[i] = fork_parent->m_file_descriptors[i]->clone();
}
} else {
m_file_descriptors.resize(m_max_open_file_descriptors);
if (tty) {
m_file_descriptors[0] = tty->open(O_RDONLY);
m_file_descriptors[1] = tty->open(O_WRONLY);
m_file_descriptors[2] = tty->open(O_WRONLY);
}
}
if (fork_parent)
m_nextRegion = fork_parent->m_nextRegion;
else
m_nextRegion = LinearAddress(0x10000000);
if (fork_parent) {
memcpy(&m_tss, &fork_parent->m_tss, sizeof(m_tss));
} else {
memset(&m_tss, 0, sizeof(m_tss));
// Only IF is set when a process boots.
m_tss.eflags = 0x0202;
word cs, ds, ss;
if (isRing0()) {
cs = 0x08;
ds = 0x10;
ss = 0x10;
} else {
cs = 0x1b;
ds = 0x23;
ss = 0x23;
}
m_tss.ds = ds;
m_tss.es = ds;
m_tss.fs = ds;
m_tss.gs = ds;
m_tss.ss = ss;
m_tss.cs = cs;
}
m_tss.cr3 = (dword)m_page_directory;
if (isRing0()) {
// FIXME: This memory is leaked.
// But uh, there's also no kernel process termination, so I guess it's not technically leaked...
dword stackBottom = (dword)kmalloc_eternal(defaultStackSize);
m_stackTop0 = (stackBottom + defaultStackSize) & 0xffffff8;
m_tss.esp = m_stackTop0;
} else {
if (fork_parent) {
m_stackTop3 = fork_parent->m_stackTop3;
} else {
auto* region = allocate_region(LinearAddress(), defaultStackSize, "stack");
ASSERT(region);
m_stackTop3 = region->linearAddress.offset(defaultStackSize).get() & 0xfffffff8;
m_tss.esp = m_stackTop3;
}
}
if (isRing3()) {
// Ring3 processes need a separate stack for Ring0.
m_kernelStack = kmalloc(defaultStackSize);
m_stackTop0 = ((DWORD)m_kernelStack + defaultStackSize) & 0xffffff8;
m_tss.ss0 = 0x10;
m_tss.esp0 = m_stackTop0;
}
// HACK: Ring2 SS in the TSS is the current PID.
m_tss.ss2 = m_pid;
m_farPtr.offset = 0x98765432;
}
Process::~Process()
{
InterruptDisabler disabler;
ProcFileSystem::the().removeProcess(*this);
system.nprocess--;
gdt_free_entry(selector());
if (m_kernelStack) {
kfree(m_kernelStack);
m_kernelStack = nullptr;
}
MM.release_page_directory(*m_page_directory);
}
void Process::dumpRegions()
{
kprintf("Process %s(%u) regions:\n", name().characters(), pid());
kprintf("BEGIN END SIZE NAME\n");
for (auto& region : m_regions) {
kprintf("%x -- %x %x %s\n",
region->linearAddress.get(),
region->linearAddress.offset(region->size - 1).get(),
region->size,
region->name.characters());
}
}
void Process::notify_waiters(pid_t waitee, int exit_status, int signal)
{
ASSERT_INTERRUPTS_DISABLED();
for (auto* process = s_processes->head(); process; process = process->next()) {
if (process->waitee() == waitee)
process->m_waiteeStatus = (exit_status << 8) | (signal);
}
}
void Process::sys$exit(int status)
{
cli();
#ifdef TASK_DEBUG
kprintf("sys$exit: %s(%u) exit with status %d\n", name().characters(), pid(), status);
#endif
set_state(Exiting);
s_processes->remove(this);
notify_waiters(m_pid, status, 0);
if (!scheduleNewProcess()) {
kprintf("Process::sys$exit: Failed to schedule a new process :(\n");
HANG;
}
s_deadProcesses->append(this);
switchNow();
}
void Process::terminate_due_to_signal(int signal, Process* sender)
{
ASSERT_INTERRUPTS_DISABLED();
bool wasCurrent = this == current;
set_state(Exiting);
s_processes->remove(this);
notify_waiters(m_pid, 0, signal);
if (wasCurrent) {
kprintf("Current process (%u) committing suicide!\n", pid());
if (!scheduleNewProcess()) {
kprintf("Process::send_signal: Failed to schedule a new process :(\n");
HANG;
}
}
s_deadProcesses->append(this);
if (wasCurrent)
switchNow();
}
void Process::send_signal(int signal, Process* sender)
{
ASSERT_INTERRUPTS_DISABLED();
ASSERT(signal < 32);
// FIXME: Handle send_signal to self.
ASSERT(this != current);
auto& action = m_signal_action_data[signal];
// FIXME: Implement SA_SIGINFO signal handlers.
ASSERT(!(action.flags & SA_SIGINFO));
auto handler_laddr = action.handler_or_sigaction;
if (handler_laddr.is_null())
return terminate_due_to_signal(signal, sender);
word ret_cs = m_tss.cs;
dword ret_eip = m_tss.eip;
dword ret_eflags = m_tss.eflags;
if ((ret_cs & 3) == 0) {
// FIXME: Handle send_signal to process currently in kernel code.
ASSERT_NOT_REACHED();
}
ProcessPagingScope pagingScope(*this);
dword old_esp = m_tss.esp;
push_value_on_stack(ret_eip);
push_value_on_stack(ret_eflags);
push_value_on_stack(m_tss.eax);
push_value_on_stack(m_tss.ecx);
push_value_on_stack(m_tss.edx);
push_value_on_stack(m_tss.ebx);
push_value_on_stack(old_esp);
push_value_on_stack(m_tss.ebp);
push_value_on_stack(m_tss.esi);
push_value_on_stack(m_tss.edi);
m_tss.eax = (dword)signal;
m_tss.cs = 0x1b;
m_tss.eip = handler_laddr.get();
if (m_return_from_signal_trampoline.is_null()) {
auto* region = allocate_region(LinearAddress(), PAGE_SIZE, "signal_trampoline", true, true); // FIXME: Remap as read-only after setup.
m_return_from_signal_trampoline = region->linearAddress;
byte* code_ptr = m_return_from_signal_trampoline.asPtr();
*code_ptr++ = 0x61; // popa
*code_ptr++ = 0x9d; // popf
*code_ptr++ = 0xc3; // ret
*code_ptr++ = 0x0f; // ud2
*code_ptr++ = 0x0b;
}
push_value_on_stack(m_return_from_signal_trampoline.get());
dbgprintf("signal: %s(%u) sent %d to %s(%u)\n", sender->name().characters(), sender->pid(), signal, name().characters(), pid());
if (sender == this) {
sched_yield();
ASSERT_NOT_REACHED();
}
}
void Process::push_value_on_stack(dword value)
{
m_tss.esp -= 4;
dword* stack_ptr = (dword*)m_tss.esp;
*stack_ptr = value;
}
void Process::processDidCrash(Process* crashedProcess)
{
ASSERT_INTERRUPTS_DISABLED();
if (crashedProcess->state() == Crashing) {
kprintf("Double crash :(\n");
HANG;
}
crashedProcess->set_state(Crashing);
crashedProcess->dumpRegions();
s_processes->remove(crashedProcess);
notify_waiters(crashedProcess->m_pid, 0, SIGSEGV);
if (!scheduleNewProcess()) {
kprintf("Process::processDidCrash: Failed to schedule a new process :(\n");
HANG;
}
s_deadProcesses->append(crashedProcess);
switchNow();
}
void Process::doHouseKeeping()
{
if (s_deadProcesses->isEmpty())
return;
InterruptDisabler disabler;
Process* next = nullptr;
for (auto* deadProcess = s_deadProcesses->head(); deadProcess; deadProcess = next) {
next = deadProcess->next();
delete deadProcess;
}
s_deadProcesses->clear();
}
int sched_yield()
{
if (!current) {
kprintf( "PANIC: yield() with !current" );
HANG;
}
//kprintf("%s<%u> yield()\n", current->name().characters(), current->pid());
InterruptDisabler disabler;
if (!scheduleNewProcess())
return 1;
//kprintf("yield() jumping to new process: %x (%s)\n", current->farPtr().selector, current->name().characters());
switchNow();
return 0;
}
void switchNow()
{
Descriptor& descriptor = getGDTEntry(current->selector());
descriptor.type = 9;
flushGDT();
asm("sti\n"
"ljmp *(%%eax)\n"
::"a"(¤t->farPtr())
);
}
bool scheduleNewProcess()
{
ASSERT_INTERRUPTS_DISABLED();
if (!current) {
// XXX: The first ever context_switch() goes to the idle process.
// This to setup a reliable place we can return to.
return contextSwitch(Process::kernelProcess());
}
// Check and unblock processes whose wait conditions have been met.
for (auto* process = s_processes->head(); process; process = process->next()) {
if (process->state() == Process::BlockedSleep) {
if (process->wakeupTime() <= system.uptime) {
process->unblock();
continue;
}
}
if (process->state() == Process::BlockedWait) {
if (!Process::fromPID(process->waitee())) {
process->unblock();
continue;
}
}
if (process->state() == Process::BlockedRead) {
ASSERT(process->m_fdBlockedOnRead != -1);
if (process->m_file_descriptors[process->m_fdBlockedOnRead]->hasDataAvailableForRead()) {
process->unblock();
continue;
}
}
}
#ifdef SCHEDULER_DEBUG
dbgprintf("Scheduler choices:\n");
for (auto* process = s_processes->head(); process; process = process->next()) {
//if (process->state() == Process::BlockedWait || process->state() == Process::BlockedSleep)
// continue;
dbgprintf("% 12s %s(%u) @ %w:%x\n", toString(process->state()), process->name().characters(), process->pid(), process->tss().cs, process->tss().eip);
}
#endif
auto* prevHead = s_processes->head();
for (;;) {
// Move head to tail.
s_processes->append(s_processes->removeHead());
auto* process = s_processes->head();
if (process->state() == Process::Runnable || process->state() == Process::Running) {
#ifdef SCHEDULER_DEBUG
dbgprintf("switch to %s(%u) (%p vs %p)\n", process->name().characters(), process->pid(), process, current);
#endif
return contextSwitch(process);
}
if (process == prevHead) {
// Back at process_head, nothing wants to run.
kprintf("Nothing wants to run!\n");
kprintf("PID OWNER STATE NSCHED NAME\n");
for (auto* process = s_processes->head(); process; process = process->next()) {
kprintf("%w %w:%w %b %w %s\n",
process->pid(),
process->uid(),
process->gid(),
process->state(),
process->timesScheduled(),
process->name().characters());
}
kprintf("Switch to kernel process @ %w:%x\n", s_kernelProcess->tss().cs, s_kernelProcess->tss().eip);
return contextSwitch(Process::kernelProcess());
}
}
}
static bool contextSwitch(Process* t)
{
t->setTicksLeft(5);
t->didSchedule();
if (current == t)
return false;
#ifdef SCHEDULER_DEBUG
// Some sanity checking to force a crash earlier.
auto csRPL = t->tss().cs & 3;
auto ssRPL = t->tss().ss & 3;
if (csRPL != ssRPL) {
kprintf("Fuckup! Switching from %s(%u) to %s(%u) has RPL mismatch\n",
current->name().characters(), current->pid(),
t->name().characters(), t->pid()
);
kprintf("code: %w:%x\n", t->tss().cs, t->tss().eip);
kprintf(" stk: %w:%x\n", t->tss().ss, t->tss().esp);
ASSERT(csRPL == ssRPL);
}
#endif
if (current) {
// If the last process hasn't blocked (still marked as running),
// mark it as runnable for the next round.
if (current->state() == Process::Running)