1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
|
/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <Kernel/Debug.h>
#include <Kernel/FileSystem/Custody.h>
#include <Kernel/Memory/Region.h>
#include <Kernel/PerformanceManager.h>
#include <Kernel/Process.h>
#include <Kernel/Scheduler.h>
namespace Kernel {
ErrorOr<FlatPtr> Process::sys$fork(RegisterState& regs)
{
VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this);
TRY(require_promise(Pledge::proc));
LockRefPtr<Thread> child_first_thread;
ArmedScopeGuard thread_finalizer_guard = [&child_first_thread]() {
SpinlockLocker lock(g_scheduler_lock);
if (child_first_thread) {
child_first_thread->detach();
child_first_thread->set_state(Thread::State::Dying);
}
};
auto child_name = TRY(m_name->try_clone());
auto credentials = this->credentials();
auto child = TRY(Process::try_create(child_first_thread, move(child_name), credentials->uid(), credentials->gid(), pid(), m_is_kernel_process, current_directory(), executable(), m_tty, this));
// NOTE: All user processes have a leaked ref on them. It's balanced by Thread::WaitBlockerSet::finalize().
child->ref();
TRY(m_unveil_data.with([&](auto& parent_unveil_data) -> ErrorOr<void> {
return child->m_unveil_data.with([&](auto& child_unveil_data) -> ErrorOr<void> {
child_unveil_data.state = parent_unveil_data.state;
child_unveil_data.paths = TRY(parent_unveil_data.paths.deep_copy());
return {};
});
}));
// Note: We take the spinlock of Process::all_instances list because we need
// to ensure that when we take the jail spinlock of two processes that we don't
// run into a deadlock situation because both processes compete over each other Jail's
// spinlock. Such pattern of taking 3 spinlocks in the same order happens in
// Process::for_each* methods.
TRY(Process::all_instances().with([&](auto const&) -> ErrorOr<void> {
TRY(m_attached_jail.with([&](auto& parent_jail) -> ErrorOr<void> {
return child->m_attached_jail.with([&](auto& child_jail) -> ErrorOr<void> {
child_jail = parent_jail;
if (child_jail) {
child_jail->attach_count().with([&](auto& attach_count) {
attach_count++;
});
}
return {};
});
}));
return {};
}));
TRY(child->m_fds.with_exclusive([&](auto& child_fds) {
return m_fds.with_exclusive([&](auto& parent_fds) {
return child_fds.try_clone(parent_fds);
});
}));
child->m_pg = m_pg;
with_protected_data([&](auto& my_protected_data) {
child->with_mutable_protected_data([&](auto& child_protected_data) {
child_protected_data.promises = my_protected_data.promises.load();
child_protected_data.execpromises = my_protected_data.execpromises.load();
child_protected_data.has_promises = my_protected_data.has_promises.load();
child_protected_data.has_execpromises = my_protected_data.has_execpromises.load();
child_protected_data.sid = my_protected_data.sid;
child_protected_data.credentials = my_protected_data.credentials;
child_protected_data.umask = my_protected_data.umask;
child_protected_data.signal_trampoline = my_protected_data.signal_trampoline;
child_protected_data.dumpable = my_protected_data.dumpable;
});
});
dbgln_if(FORK_DEBUG, "fork: child={}", child);
// A child created via fork(2) inherits a copy of its parent's signal mask
child_first_thread->update_signal_mask(Thread::current()->signal_mask());
// A child process created via fork(2) inherits a copy of its parent's alternate signal stack settings.
child_first_thread->m_alternative_signal_stack = Thread::current()->m_alternative_signal_stack;
child_first_thread->m_alternative_signal_stack_size = Thread::current()->m_alternative_signal_stack_size;
#if ARCH(I386)
auto& child_regs = child_first_thread->m_regs;
child_regs.eax = 0; // fork() returns 0 in the child :^)
child_regs.ebx = regs.ebx;
child_regs.ecx = regs.ecx;
child_regs.edx = regs.edx;
child_regs.ebp = regs.ebp;
child_regs.esp = regs.userspace_esp;
child_regs.esi = regs.esi;
child_regs.edi = regs.edi;
child_regs.eflags = regs.eflags;
child_regs.eip = regs.eip;
child_regs.cs = regs.cs;
child_regs.ds = regs.ds;
child_regs.es = regs.es;
child_regs.fs = regs.fs;
child_regs.gs = regs.gs;
child_regs.ss = regs.userspace_ss;
dbgln_if(FORK_DEBUG, "fork: child will begin executing at {:#04x}:{:p} with stack {:#04x}:{:p}, kstack {:#04x}:{:p}",
child_regs.cs, child_regs.eip, child_regs.ss, child_regs.esp, child_regs.ss0, child_regs.esp0);
#elif ARCH(X86_64)
auto& child_regs = child_first_thread->m_regs;
child_regs.rax = 0; // fork() returns 0 in the child :^)
child_regs.rbx = regs.rbx;
child_regs.rcx = regs.rcx;
child_regs.rdx = regs.rdx;
child_regs.rbp = regs.rbp;
child_regs.rsp = regs.userspace_rsp;
child_regs.rsi = regs.rsi;
child_regs.rdi = regs.rdi;
child_regs.r8 = regs.r8;
child_regs.r9 = regs.r9;
child_regs.r10 = regs.r10;
child_regs.r11 = regs.r11;
child_regs.r12 = regs.r12;
child_regs.r13 = regs.r13;
child_regs.r14 = regs.r14;
child_regs.r15 = regs.r15;
child_regs.rflags = regs.rflags;
child_regs.rip = regs.rip;
child_regs.cs = regs.cs;
dbgln_if(FORK_DEBUG, "fork: child will begin executing at {:#04x}:{:p} with stack {:p}, kstack {:p}",
child_regs.cs, child_regs.rip, child_regs.rsp, child_regs.rsp0);
#else
# error Unknown architecture
#endif
TRY(address_space().with([&](auto& parent_space) {
return child->address_space().with([&](auto& child_space) -> ErrorOr<void> {
child_space->set_enforces_syscall_regions(parent_space->enforces_syscall_regions());
for (auto& region : parent_space->region_tree().regions()) {
dbgln_if(FORK_DEBUG, "fork: cloning Region '{}' @ {}", region.name(), region.vaddr());
auto region_clone = TRY(region.try_clone());
TRY(region_clone->map(child_space->page_directory(), Memory::ShouldFlushTLB::No));
TRY(child_space->region_tree().place_specifically(*region_clone, region.range()));
auto* child_region = region_clone.leak_ptr();
if (®ion == m_master_tls_region.unsafe_ptr())
child->m_master_tls_region = TRY(child_region->try_make_weak_ptr());
}
return {};
});
}));
thread_finalizer_guard.disarm();
Process::register_new(*child);
PerformanceManager::add_process_created_event(*child);
SpinlockLocker lock(g_scheduler_lock);
child_first_thread->set_affinity(Thread::current()->affinity());
child_first_thread->set_state(Thread::State::Runnable);
auto child_pid = child->pid().value();
return child_pid;
}
}
|
