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Implement fork()!

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This is quite cool! The syscall entry point plumbs the register dump
down to sys$fork(), which uses it to set up the child process's TSS
in order to resume execution right after the int 0x80 fork() call. :^)

This works pretty well, although there is some problem with the kernel
alias mappings used to clone the parent process's regions. If I disable
the MM::release_page_directory() code, there's no problem. Probably there's
a premature freeing of a physical page somehow.
This commit is contained in:
Andreas Kling 2018-11-02 20:41:58 +01:00
parent 10b666f69a
commit 8accc92c3c
16 changed files with 228 additions and 78 deletions
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7
Kernel/Process.h
View file

@ -119,6 +119,7 @@ public:
int sys$uname(utsname*);
int sys$readlink(const char*, char*, size_t);
int sys$ttyname_r(int fd, char*, size_t);
pid_t sys$fork(RegisterDump&);
static void initialize();
@ -155,11 +156,13 @@ public:
void send_signal(int signal, Process* sender);
Process* fork(RegisterDump&);
private:
friend class MemoryManager;
friend bool scheduleNewProcess();
Process(String&& name, uid_t, gid_t, pid_t parentPID, RingLevel, RetainPtr<VirtualFileSystem::Node>&& cwd = nullptr, RetainPtr<VirtualFileSystem::Node>&& executable = nullptr, TTY* = nullptr);
Process(String&& name, uid_t, gid_t, pid_t parentPID, RingLevel, RetainPtr<VirtualFileSystem::Node>&& cwd = nullptr, RetainPtr<VirtualFileSystem::Node>&& executable = nullptr, TTY* = nullptr, Process* fork_parent = nullptr);
void allocateLDT();
@ -183,8 +186,6 @@ private:
State m_state { Invalid };
DWORD m_wakeupTime { 0 };
TSS32 m_tss;
word m_ldt_selector { 0 };
Descriptor* m_ldtEntries { nullptr };
Vector<OwnPtr<FileHandle>> m_file_descriptors;
RingLevel m_ring { Ring0 };
int m_error { 0 };