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Turn the syscall interrupt into a trap (by switching the gate type.)

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This leaves interrupts enabled while we're in the kernel, which is
precisely what we want.

This uncovered a horrendous problem with kernel tasks silently
overflowing their stacks. For now I've simply increased the stack size
but I need a more MMU-y solution for this eventually.
This commit is contained in:
Andreas Kling 2018-10-19 11:28:43 +02:00
parent 2d1d01661b
commit 46ff281695
6 changed files with 116 additions and 25 deletions
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65
Kernel/i386.cpp
View file

@ -68,6 +68,67 @@ asm( \
" iret\n" \
);
#define EH_ENTRY_NO_CODE(ec) \
extern "C" void exception_ ## ec ## _handler(); \
extern "C" void exception_ ## ec ## _entry(); \
asm( \
".globl exception_" # ec "_entry\n" \
"exception_" # ec "_entry: \n" \
" pusha\n" \
" pushw %ds\n" \
" pushw %es\n" \
" pushw %fs\n" \
" pushw %gs\n" \
" pushw %ss\n" \
" pushw %ss\n" \
" pushw %ss\n" \
" pushw %ss\n" \
" popw %ds\n" \
" popw %es\n" \
" popw %fs\n" \
" popw %gs\n" \
" mov %esp, exception_state_dump\n" \
" call exception_" # ec "_handler\n" \
" popw %gs\n" \
" popw %fs\n" \
" popw %es\n" \
" popw %ds\n" \
" popa\n" \
" iret\n" \
);
// 6: Invalid Opcode
EH_ENTRY_NO_CODE(6);
void exception_6_handler()
{
auto& regs = *reinterpret_cast<RegisterDump*>(exception_state_dump);
kprintf("%s invalid opcode: %u(%s)\n", current->isRing0() ? "Kernel" : "Process", current->pid(), current->name().characters());
word ss;
dword esp;
if (current->isRing0()) {
ss = regs.ds;
esp = regs.esp;
} else {
ss = regs.ss_if_crossRing;
esp = regs.esp_if_crossRing;
}
kprintf("exception code: %w\n", exception_code);
kprintf("pc=%w:%x ds=%w es=%w fs=%w gs=%w\n", regs.cs, regs.eip, regs.ds, regs.es, regs.fs, regs.gs);
kprintf("eax=%x ebx=%x ecx=%x edx=%x\n", regs.eax, regs.ebx, regs.ecx, regs.edx);
kprintf("ebp=%x esp=%x esi=%x edi=%x\n", regs.ebp, esp, regs.esi, regs.edi);
if (current->isRing0()) {
kprintf("Oh shit, we've crashed in ring 0 :(\n");
HANG;
}
HANG;
// NOTE: This will schedule a new task.
Task::taskDidCrash(current);
}
// 13: General Protection Fault
EH_ENTRY(13);
void exception_13_handler()
@ -239,7 +300,7 @@ void registerInterruptHandler(BYTE index, void (*f)())
void registerUserCallableInterruptHandler(BYTE index, void (*f)())
{
s_idt[index].low = 0x00080000 | LSW((f));
s_idt[index].high = ((DWORD)(f) & 0xffff0000) | 0xee00;
s_idt[index].high = ((DWORD)(f) & 0xffff0000) | 0xef00;
flushIDT();
}
@ -276,7 +337,7 @@ void idt_init()
registerInterruptHandler(0x03, _exception3);
registerInterruptHandler(0x04, _exception4);
registerInterruptHandler(0x05, _exception5);
registerInterruptHandler(0x06, _exception6);
registerInterruptHandler(0x06, exception_6_entry);
registerInterruptHandler(0x07, _exception7);
registerInterruptHandler(0x08, _exception8);
registerInterruptHandler(0x09, _exception9);