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Fix signal delivery during context switch.

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This commit is contained in:
Jonas 'Sortie' Termansen 2015-10-08 21:34:02 +02:00
parent 82775c4803
commit 12b5044bc7
3 changed files with 103 additions and 4 deletions
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101
kernel/scheduler.cpp
View file

@ -175,6 +175,86 @@ void LoadInterruptedContext(struct interrupt_context* intctx,
#endif
}
extern "C" void fake_interrupt(void);
// Pretend a particular interrupt arrived on another thread's stack. This
// assumes we're _not_ on current_thread's stack right now. This sets up the
// interrupt context such that the interrupt handler runs in that thread.
// The interrupt handler runs with premption enabled. This is used to deliver
// signals during context switches, as the signal handler needs to have
// preemption enabled.
static void FakeInterruptedContext(struct interrupt_context* intctx, int int_no)
{
#if defined(__i386__)
uintptr_t stack = current_thread->kernelstackpos +
current_thread->kernelstacksize;
stack -= sizeof(struct interrupt_context);
struct interrupt_context* fakectx = (struct interrupt_context*) stack;
memcpy(fakectx, intctx, sizeof(struct interrupt_context));
fakectx->int_no = int_no;
fakectx->err_code = 0;
stack -= 4;
stack &= 0xFFFFFFF0;
intctx->signal_pending = intctx->signal_pending;
intctx->kerrno = 0;
intctx->cr2 = 0;
intctx->ds = KDS | KRPL;
intctx->edi = intctx->edi;
intctx->esi = intctx->esi;
intctx->ebp = intctx->signal_pending;
intctx->not_esp = intctx->not_esp;
intctx->ebx = (uintptr_t) fakectx;
intctx->edx = intctx->edx;
intctx->ecx = intctx->ecx;
intctx->eax = intctx->eax;
intctx->int_no = intctx->int_no;
intctx->err_code = intctx->err_code;
intctx->eip = (uintptr_t) fake_interrupt;
intctx->cs = KCS | KRPL;
intctx->eflags = FLAGS_RESERVED1 | FLAGS_INTERRUPT | FLAGS_ID;
intctx->esp = stack;
intctx->ss = KDS | KRPL;
#elif defined(__x86_64__)
uintptr_t stack = current_thread->kernelstackpos +
current_thread->kernelstacksize;
stack -= sizeof(struct interrupt_context);
struct interrupt_context* fakectx = (struct interrupt_context*) stack;
memcpy(fakectx, intctx, sizeof(struct interrupt_context));
fakectx->int_no = int_no;
fakectx->err_code = 0;
stack &= 0xFFFFFFFFFFFFFFF0;
intctx->signal_pending = intctx->signal_pending;
intctx->kerrno = 0;
intctx->cr2 = 0;
intctx->ds = KDS | KRPL;
intctx->rdi = (uintptr_t) fakectx;
intctx->rsi = intctx->rsi;
intctx->rbp = intctx->signal_pending;
intctx->not_rsp = intctx->not_rsp;
intctx->rbx = (uintptr_t) fakectx;
intctx->rdx = intctx->rdx;
intctx->rcx = intctx->rcx;
intctx->rax = intctx->rax;
intctx->r8 = intctx->r8;
intctx->r9 = intctx->r9;
intctx->r10 = intctx->r10;
intctx->r11 = intctx->r11;
intctx->r12 = intctx->r12;
intctx->r13 = intctx->r13;
intctx->r14 = intctx->r14;
intctx->r15 = intctx->r15;
intctx->int_no = intctx->int_no;
intctx->err_code = intctx->err_code;
intctx->rip = (uintptr_t) fake_interrupt;
intctx->cs = KCS | KRPL;
intctx->rflags = FLAGS_RESERVED1 | FLAGS_INTERRUPT | FLAGS_ID;
intctx->rsp = stack;
intctx->ss = KDS | KRPL;
#else
#warning "You need to implement faking an interrupt"
#endif
}
static
void SwitchThread(struct interrupt_context* intctx, Thread* prev, Thread* next)
{
@ -237,12 +317,25 @@ static Thread* PopNextThread(bool yielded)
static void RealSwitch(struct interrupt_context* intctx, bool yielded)
{
SwitchThread(intctx, CurrentThread(), PopNextThread(yielded));
Thread* old_thread = CurrentThread();
Thread* new_thread = PopNextThread(yielded);
SwitchThread(intctx, old_thread, new_thread);
if ( intctx->signal_pending && InUserspace(intctx) )
{
Interrupt::Enable();
Signal::DispatchHandler(intctx, NULL);
// Become the thread for real and run the signal handler.
if ( old_thread == new_thread )
{
// We're already this thread, so run the signal handler.
Interrupt::Enable();
Signal::DispatchHandler(intctx, NULL);
}
else
{
// We need to transfer execution to the correct stack. We know the
// the thread is in user-space and isn't using its kernel stack, and
// we know we're not using the stack right now.
FakeInterruptedContext(intctx, 130);
}
}
}

3
kernel/x64/interrupt.S
View file

@ -388,6 +388,9 @@ interrupt_handler_prepare:
movq %rsp, %rdi
movq %rsp, %rbx
andq $0xFFFFFFFFFFFFFFF0, %rsp
.global fake_interrupt
.type fake_interrupt, @function
fake_interrupt:
call interrupt_handler
movq %rbx, %rsp

3
kernel/x86/interrupt.S
View file

@ -385,6 +385,9 @@ fixup_relocate_stack_complete:
movl %esp, %ebx
subl $4, %esp
andl $0xFFFFFFF0, %esp
.global fake_interrupt
.type fake_interrupt, @function
fake_interrupt:
movl %ebx, (%esp)
call interrupt_handler
movl %ebx, %esp