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More work on per-process page directories. It basically works now!

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I spent some time stuck on a problem where processes would clobber each
other's stacks. Took me a moment to figure out that their stacks
were allocated in the sub-4MB linear address range which is shared
between all processes. Oops!
This commit is contained in:
Andreas Kling 2018-11-01 11:30:48 +01:00
parent 1da0a7c949
commit c45f166c63
5 changed files with 147 additions and 61 deletions
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43
Kernel/Task.cpp
View file

@ -228,6 +228,11 @@ int Task::sys$spawn(const char* path, const char** args)
return error;
}
struct KernelPagingScope {
KernelPagingScope() { MM.enter_kernel_paging_scope(); }
~KernelPagingScope() { MM.enter_task_paging_scope(*current); }
};
Task* Task::createUserTask(const String& path, uid_t uid, gid_t gid, pid_t parentPID, int& error, const char** args, TTY* tty)
{
auto parts = path.split('/');
@ -276,6 +281,7 @@ Task* Task::createUserTask(const String& path, uid_t uid, gid_t gid, pid_t paren
taskEnvironment.append("HOME=/");
InterruptDisabler disabler; // FIXME: Get rid of this, jesus christ. This "critical" section is HUGE.
KernelPagingScope kernelScope;
Task* t = new Task(parts.takeLast(), uid, gid, parentPID, Ring3, move(cwd), handle->vnode(), tty);
t->m_arguments = move(taskArguments);
@ -283,20 +289,21 @@ Task* Task::createUserTask(const String& path, uid_t uid, gid_t gid, pid_t paren
ExecSpace space;
Region* region = nullptr;
byte* region_alias = nullptr;
space.hookableAlloc = [&] (const String& name, size_t size) {
if (!size)
return (void*)nullptr;
size = ((size / 4096) + 1) * 4096;
size = ((size / 4096) + 1) * 4096; // FIXME: Use ceil_div?
region = t->allocateRegion(size, String(name));
ASSERT(region);
MM.mapRegion(*t, *region);
return (void*)region->linearAddress.asPtr();
region_alias = MM.create_kernel_alias_for_region(*region);
return (void*)region_alias;
};
bool success = space.loadELF(move(elfData));
if (!success) {
// FIXME: This is ugly. If we need to do this, it should be at a different level.
MM.unmapRegionsForTask(*t);
MM.mapRegionsForTask(*current);
MM.remove_kernel_alias_for_region(*region, region_alias);
delete t;
kprintf("Failure loading ELF %s\n", path.characters());
error = -ENOEXEC;
@ -321,16 +328,15 @@ Task* Task::createUserTask(const String& path, uid_t uid, gid_t gid, pid_t paren
t->m_tss.eip = (dword)space.symbolPtr("_start");
if (!t->m_tss.eip) {
// FIXME: This is ugly. If we need to do this, it should be at a different level.
MM.unmapRegionsForTask(*t);
MM.mapRegionsForTask(*current);
MM.remove_kernel_alias_for_region(*region, region_alias);
delete t;
error = -ENOEXEC;
return nullptr;
}
// FIXME: This is ugly. If we need to do this, it should be at a different level.
MM.unmapRegionsForTask(*t);
MM.mapRegionsForTask(*current);
MM.remove_kernel_alias_for_region(*region, region_alias);
MM.mapRegionsForTask(*t);
s_tasks->prepend(t);
system.nprocess++;
@ -409,7 +415,7 @@ Task::Task(String&& name, uid_t uid, gid_t gid, pid_t parentPID, RingLevel ring,
, m_parentPID(parentPID)
{
m_pageDirectory = (dword*)kmalloc_page_aligned(4096);
MM.populatePageDirectory(*this);
MM.populate_page_directory(*this);
if (tty) {
m_fileHandles.append(tty->open(O_RDONLY)); // stdin
@ -421,7 +427,7 @@ Task::Task(String&& name, uid_t uid, gid_t gid, pid_t parentPID, RingLevel ring,
m_fileHandles.append(nullptr); // stderr
}
m_nextRegion = LinearAddress(0x600000);
m_nextRegion = LinearAddress(0x10000000);
memset(&m_tss, 0, sizeof(m_tss));
@ -539,8 +545,6 @@ void Task::sys$exit(int status)
setState(Exiting);
MM.unmapRegionsForTask(*this);
s_tasks->remove(this);
notify_waiters(m_pid, status, 0);
@ -566,7 +570,6 @@ void Task::murder(int signal)
if (wasCurrent) {
kprintf("Current task committing suicide!\n");
MM.unmapRegionsForTask(*this);
if (!scheduleNewTask()) {
kprintf("Task::murder: Failed to schedule a new task :(\n");
HANG;
@ -593,8 +596,6 @@ void Task::taskDidCrash(Task* crashedTask)
notify_waiters(crashedTask->m_pid, 0, SIGSEGV);
MM.unmapRegionsForTask(*crashedTask);
if (!scheduleNewTask()) {
kprintf("Task::taskDidCrash: Failed to schedule a new task :(\n");
HANG;
@ -750,14 +751,8 @@ static bool contextSwitch(Task* t)
// mark it as runnable for the next round.
if (current->state() == Task::Running)
current->setState(Task::Runnable);
bool success = MM.unmapRegionsForTask(*current);
ASSERT(success);
}
bool success = MM.mapRegionsForTask(*t);
ASSERT(success);
current = t;
t->setState(Task::Running);