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Implement sending signals to blocked-in-kernel processes.

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This is dirty but pretty cool! If we have a pending, unmasked signal for
a process that's blocked inside the kernel, we set up alternate stacks
for that process and unblock it to execute the signal handler.

A slightly different return trampoline is used here: since we need to
get back into the kernel, a dedicated syscall is used (sys$sigreturn.)

This restores the TSS contents of the process to the state it was in
while we were originally blocking in the kernel.

NOTE: There's currently only one "kernel resume TSS" so signal nesting
definitely won't work.
This commit is contained in:
Andreas Kling 2018-11-07 21:19:47 +01:00
parent c8b308910e
commit 03a8357e84
10 changed files with 190 additions and 27 deletions
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18
Kernel/Process.h
View file

@ -51,6 +51,13 @@ public:
bool isRing0() const { return m_ring == Ring0; }
bool isRing3() const { return m_ring == Ring3; }
bool is_blocked() const
{
return m_state == BlockedSleep || m_state == BlockedWait || m_state == BlockedRead;
}
bool in_kernel() const { return (m_tss.cs & 0x03) == 0; }
static Process* fromPID(pid_t);
static Process* kernelProcess();
@ -115,6 +122,7 @@ public:
int sys$kill(pid_t pid, int sig);
int sys$geterror() { return m_error; }
void sys$exit(int status);
void sys$sigreturn();
pid_t sys$spawn(const char* path, const char** args, const char** envp);
pid_t sys$waitpid(pid_t, int* wstatus, int options);
void* sys$mmap(void*, size_t size);
@ -212,6 +220,7 @@ private:
State m_state { Invalid };
DWORD m_wakeupTime { 0 };
TSS32 m_tss;
TSS32 m_tss_to_resume_kernel;
Vector<RetainPtr<FileDescriptor>> m_file_descriptors;
RingLevel m_ring { Ring0 };
int m_error { 0 };
@ -243,16 +252,23 @@ private:
// FIXME: Implement some kind of ASLR?
LinearAddress m_nextRegion;
LinearAddress m_return_from_signal_trampoline;
LinearAddress m_return_to_ring3_from_signal_trampoline;
LinearAddress m_return_to_ring0_from_signal_trampoline;
pid_t m_ppid { 0 };
mode_t m_umask { 022 };
bool m_was_interrupted_while_blocked { false };
static void notify_waiters(pid_t waitee, int exit_status, int signal);
Vector<String> m_arguments;
Vector<String> m_initialEnvironment;
HashTable<gid_t> m_gids;
Region* m_stack_region { nullptr };
Region* m_signal_stack_user_region { nullptr };
Region* m_signal_stack_kernel_region { nullptr };
};
class ProcessInspectionScope {