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Kernel: Dispatch handle-able signals instead of crashing if possible

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This matches the behaviour of the other *nixs and allows processes to
try and recover from such signals in userland.
This commit is contained in:
Idan Horowitz 2021-11-30 01:07:59 +02:00
parent f415218afe
commit 40f64d7379
5 changed files with 23 additions and 10 deletions
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2
Kernel/Arch/x86/CPU.h
View file

@ -36,7 +36,7 @@ inline u32 get_iopl_from_eflags(u32 eflags)
const DescriptorTablePointer& get_gdtr();
const DescriptorTablePointer& get_idtr();
[[noreturn]] void handle_crash(RegisterState const&, char const* description, int signal, bool out_of_memory = false);
void handle_crash(RegisterState const&, char const* description, int signal, bool out_of_memory = false);
#define LSW(x) ((u32)(x)&0xFFFF)
#define MSW(x) (((u32)(x) >> 16) & 0xFFFF)

16
Kernel/Arch/x86/common/Interrupts.cpp
View file

@ -215,10 +215,16 @@ static void dump(const RegisterState& regs)
void handle_crash(RegisterState const& regs, char const* description, int signal, bool out_of_memory)
{
if (!Process::has_current())
PANIC("{} with !current", description);
auto* current_thread = Thread::current();
if (!current_thread)
PANIC("{} with !Thread::current()", description);
auto& process = Process::current();
if (!current_thread->should_ignore_signal(signal) && !current_thread->is_signal_masked(signal)) {
current_thread->send_urgent_signal_to_self(signal);
return;
}
auto& process = current_thread->process();
// If a process crashed while inspecting another process,
// make sure we switch back to the right page tables.
@ -316,7 +322,7 @@ void page_fault_handler(TrapFrame* trap)
VirtualAddress userspace_sp = VirtualAddress { regs.userspace_sp() };
if (!faulted_in_kernel && !MM.validate_user_stack(current_thread->process().address_space(), userspace_sp)) {
dbgln("Invalid stack pointer: {}", userspace_sp);
handle_crash(regs, "Bad stack on page fault", SIGSEGV);
return handle_crash(regs, "Bad stack on page fault", SIGSEGV);
}
if (fault_address >= (FlatPtr)&start_of_ro_after_init && fault_address < (FlatPtr)&end_of_ro_after_init) {
@ -417,7 +423,7 @@ void page_fault_handler(TrapFrame* trap)
}
}
handle_crash(regs, "Page Fault", SIGSEGV, response == PageFaultResponse::OutOfMemory);
return handle_crash(regs, "Page Fault", SIGSEGV, response == PageFaultResponse::OutOfMemory);
} else if (response == PageFaultResponse::Continue) {
dbgln_if(PAGE_FAULT_DEBUG, "Continuing after resolved page fault");
} else {

8
Kernel/Memory/MemoryManager.cpp
View file

@ -654,7 +654,7 @@ void MemoryManager::validate_syscall_preconditions(AddressSpace& space, Register
VirtualAddress userspace_sp = VirtualAddress { regs.userspace_sp() };
if (!MM.validate_user_stack_no_lock(space, userspace_sp)) {
dbgln("Invalid stack pointer: {}", userspace_sp);
unlock_and_handle_crash("Bad stack on syscall entry", SIGSEGV);
return unlock_and_handle_crash("Bad stack on syscall entry", SIGSEGV);
}
}
@ -663,17 +663,17 @@ void MemoryManager::validate_syscall_preconditions(AddressSpace& space, Register
auto* calling_region = MM.find_user_region_from_vaddr_no_lock(space, ip);
if (!calling_region) {
dbgln("Syscall from {:p} which has no associated region", ip);
unlock_and_handle_crash("Syscall from unknown region", SIGSEGV);
return unlock_and_handle_crash("Syscall from unknown region", SIGSEGV);
}
if (calling_region->is_writable()) {
dbgln("Syscall from writable memory at {:p}", ip);
unlock_and_handle_crash("Syscall from writable memory", SIGSEGV);
return unlock_and_handle_crash("Syscall from writable memory", SIGSEGV);
}
if (space.enforces_syscall_regions() && !calling_region->is_syscall_region()) {
dbgln("Syscall from non-syscall region");
unlock_and_handle_crash("Syscall from non-syscall region", SIGSEGV);
return unlock_and_handle_crash("Syscall from non-syscall region", SIGSEGV);
}
}
}

6
Kernel/Thread.cpp
View file

@ -802,6 +802,12 @@ bool Thread::has_signal_handler(u8 signal) const
return !action.handler_or_sigaction.is_null();
}
bool Thread::is_signal_masked(u8 signal) const
{
VERIFY(signal < 32);
return (1 << (signal - 1)) & m_signal_mask;
}
bool Thread::has_alternative_signal_stack() const
{
return m_alternative_signal_stack_size != 0;

1
Kernel/Thread.h
View file

@ -1023,6 +1023,7 @@ public:
[[nodiscard]] bool has_unmasked_pending_signals() const { return m_have_any_unmasked_pending_signals.load(AK::memory_order_consume); }
[[nodiscard]] bool should_ignore_signal(u8 signal) const;
[[nodiscard]] bool has_signal_handler(u8 signal) const;
[[nodiscard]] bool is_signal_masked(u8 signal) const;
u32 pending_signals() const;
u32 pending_signals_for_state() const;