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Kernel+LibELF: Expose ELF Auxiliary Vector to Userspace

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The AT_* entries are placed after the environment variables, so that
they can be found by iterating until the end of the envp array, and then
going even further beyond :^)
This commit is contained in:
Andrew Kaster 2020-07-04 17:37:36 -06:00 • committed by Andreas Kling
parent 8b76a1e548
commit f96b827990
5 changed files with 200 additions and 28 deletions
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32
Kernel/Thread.cpp
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@ -185,18 +185,18 @@ void Thread::die_if_needed()
ScopedCritical critical;
set_state(Thread::State::Dying);
// Flag a context switch. Because we're in a critical section,
// Scheduler::yield will actually only mark a pending scontext switch
// Simply leaving the critical section would not necessarily trigger
// a switch.
Scheduler::yield();
// Now leave the critical section so that we can also trigger the
// actual context switch
u32 prev_flags;
Processor::current().clear_critical(prev_flags, false);
dbg() << "die_if_needed returned form clear_critical!!! in irq: " << Processor::current().in_irq();
dbg() << "die_if_needed returned form clear_critical!!! in irq: " << Processor::current().in_irq();
// We should never get here, but the scoped scheduler lock
// will be released by Scheduler::context_switch again
ASSERT_NOT_REACHED();
@ -640,7 +640,7 @@ RegisterState& Thread::get_register_dump_from_stack()
return *(RegisterState*)(kernel_stack_top() - sizeof(RegisterState));
}
u32 Thread::make_userspace_stack_for_main_thread(Vector<String> arguments, Vector<String> environment)
u32 Thread::make_userspace_stack_for_main_thread(Vector<String> arguments, Vector<String> environment, Vector<AuxiliaryValue> auxv)
{
auto* region = m_process.allocate_region(VirtualAddress(), default_userspace_stack_size, "Stack (Main thread)", PROT_READ | PROT_WRITE, false);
ASSERT(region);
@ -654,7 +654,8 @@ u32 Thread::make_userspace_stack_for_main_thread(Vector<String> arguments, Vecto
int argc = arguments.size();
char** argv = (char**)stack_base;
char** env = argv + arguments.size() + 1;
char* bufptr = stack_base + (sizeof(char*) * (arguments.size() + 1)) + (sizeof(char*) * (environment.size() + 1));
auxv_t* auxvp = (auxv_t*)((char*)(env + environment.size() + 1));
char* bufptr = stack_base + (sizeof(char*) * (arguments.size() + 1)) + (sizeof(char*) * (environment.size() + 1) + (sizeof(auxv_t) * auxv.size()));
SmapDisabler disabler;
@ -674,6 +675,17 @@ u32 Thread::make_userspace_stack_for_main_thread(Vector<String> arguments, Vecto
}
env[environment.size()] = nullptr;
for (size_t i = 0; i < auxv.size(); ++i) {
*auxvp = auxv[i].auxv;
if (!auxv[i].optional_string.is_empty()) {
auxvp->a_un.a_ptr = bufptr;
memcpy(bufptr, auxv[i].optional_string.characters(), auxv[i].optional_string.length());
bufptr += auxv[i].optional_string.length();
*(bufptr++) = '\0';
}
++auxvp;
}
auto push_on_new_stack = [&new_esp](u32 value) {
new_esp -= 4;
u32* stack_ptr = (u32*)new_esp;
@ -685,6 +697,9 @@ u32 Thread::make_userspace_stack_for_main_thread(Vector<String> arguments, Vecto
push_on_new_stack((FlatPtr)argv);
push_on_new_stack((FlatPtr)argc);
push_on_new_stack(0);
ASSERT((FlatPtr)new_esp % 16 == 0);
return new_esp;
}
@ -802,7 +817,7 @@ String Thread::backtrace_impl()
if (!process.validate_read_from_kernel(VirtualAddress(stack_ptr), sizeof(void*) * 2))
break;
FlatPtr retaddr;
if (is_user_range(VirtualAddress(stack_ptr), sizeof(FlatPtr) * 2)) {
copy_from_user(&retaddr, &((FlatPtr*)stack_ptr)[1]);
recognized_symbols.append({ retaddr, symbolicate_kernel_address(retaddr) });
@ -890,7 +905,6 @@ Thread::BlockResult Thread::wait_on(WaitQueue& queue, const char* reason, timeva
set_state(State::Queued);
m_wait_reason = reason;
if (timeout) {
timer_id = TimerQueue::the().add_timer(*timeout, [&]() {
ScopedSpinLock sched_lock(g_scheduler_lock);
@ -928,9 +942,9 @@ Thread::BlockResult Thread::wait_on(WaitQueue& queue, const char* reason, timeva
// To be able to look at m_wait_queue_node we once again need the
// scheduler lock, which is held when we insert into the queue
ScopedSpinLock sched_lock(g_scheduler_lock);
result = m_wait_queue_node.is_in_list() ? BlockResult::InterruptedByTimeout : BlockResult::WokeNormally;
// Make sure we cancel the timer if woke normally.
if (timeout && result == BlockResult::WokeNormally)
TimerQueue::the().cancel_timer(timer_id);