signal: ucontext and a fix

kernel-src/include/kernel/signal.h

@@ -161,7 +161,7 @@ void signal_signalthread(struct thread_t *thread, int signal, bool urgent);
 void signal_pending(struct thread_t *, sigset_t *sigset);
 void signal_suspend(sigset_t *sigset);
 int signal_wait(sigset_t *sigset, timespec_t *timeout, siginfo_t *siginfo, int *signum);
-bool signal_check(struct thread_t *thread, context_t *context, bool syscall, uint64_t syscallret, uint64_t syscallerrno);
+bool signal_check(struct thread_t *thread, context_t *context, bool syscall, uint64_t syscallret, uint64_t syscallerrno, bool *need_context_switch);
 extern int signal_defaultactions[NSIG];
 
 #endif

kernel-src/include/x86-64/arch/signal.h

@@ -9,13 +9,89 @@
 
 #define ARCH_SIGNAL_GETFROMRETURN(x) 
 
+#define MCONTEXT_REG_R8 0
+#define MCONTEXT_REG_R9 1
+#define MCONTEXT_REG_R10 2
+#define MCONTEXT_REG_R11 3
+#define MCONTEXT_REG_R12 4
+#define MCONTEXT_REG_R13 5
+#define MCONTEXT_REG_R14 6
+#define MCONTEXT_REG_R15 7
+#define MCONTEXT_REG_RDI 8
+#define MCONTEXT_REG_RSI 9
+#define MCONTEXT_REG_RBP 10
+#define MCONTEXT_REG_RBX 11
+#define MCONTEXT_REG_RDX 12
+#define MCONTEXT_REG_RAX 13
+#define MCONTEXT_REG_RCX 14
+#define MCONTEXT_REG_RSP 15
+#define MCONTEXT_REG_RIP 16
+#define MCONTEXT_REG_EFL 17
+#define MCONTEXT_REG_CSGSFS 18
+#define MCONTEXT_REG_ERR 19
+#define MCONTEXT_REG_TRAPNO 20
+#define MCONTEXT_REG_OLDMASK 21
+#define MCONTEXT_REG_CR2 22
+#define MCONTEXT_NGREG 23
+
 typedef struct {
-	void *restorer;
+	unsigned long gregs[MCONTEXT_NGREG];
+	uint8_t fpu_state[512];
+	unsigned long __reserved1[8];
+} mcontext_t;
+
+// this structure should have a part of it matching the ucontext from the abi
+// which then gets its address returned by the ARCH_SIGFRAME_GET_UCONTEXT_POINTER macro
+typedef struct {
+	void *restorer; // for return from signal
+
+	// ucontext starts here
+	unsigned long uc_flags; // can be zero
+	void *uc_link; // unused for signals
 	stack_t oldstack;
+	mcontext_t mcontext;
 	sigset_t oldmask;
+
+	// astral bits
 	context_t context;
 	extracontext_t extracontext;
 	siginfo_t siginfo;
 } sigframe_t;
 
+#define ARCH_SIGFRAME_GET_UCONTEXT_POINTER(x) (&(x)->uc_flags)
+
+static inline void arch_sigframe_prepare_mcontext(sigframe_t *sigframe) {
+	context_t *context = &sigframe->context;
+	extracontext_t *extracontext = &sigframe->extracontext;
+	unsigned long *gregs = sigframe->mcontext.gregs;
+	uint8_t *fpu_state = sigframe->mcontext.fpu_state;
+
+	gregs[MCONTEXT_REG_R8] = context->r8;
+	gregs[MCONTEXT_REG_R9] = context->r9;
+	gregs[MCONTEXT_REG_R10] = context->r10;
+	gregs[MCONTEXT_REG_R11] = context->r11;
+	gregs[MCONTEXT_REG_R12] = context->r12;
+	gregs[MCONTEXT_REG_R13] = context->r13;
+	gregs[MCONTEXT_REG_R14] = context->r14;
+	gregs[MCONTEXT_REG_R15] = context->r15;
+	gregs[MCONTEXT_REG_RDI] = context->rdi;
+	gregs[MCONTEXT_REG_RSI] = context->rsi;
+	gregs[MCONTEXT_REG_RBP] = context->rbp;
+	gregs[MCONTEXT_REG_RBX] = context->rbx;
+	gregs[MCONTEXT_REG_RDX] = context->rdx;
+	gregs[MCONTEXT_REG_RAX] = context->rax;
+	gregs[MCONTEXT_REG_RCX] = context->rcx;
+	gregs[MCONTEXT_REG_RSP] = context->rsp;
+	gregs[MCONTEXT_REG_RIP] = context->rip;
+	gregs[MCONTEXT_REG_EFL] = context->rflags;
+	gregs[MCONTEXT_REG_CSGSFS] = 0;
+	gregs[MCONTEXT_REG_ERR] = context->error;
+	gregs[MCONTEXT_REG_TRAPNO] = 0;
+	gregs[MCONTEXT_REG_OLDMASK] = 0;
+	gregs[MCONTEXT_REG_CR2] = context->cr2;
+
+	memcpy(fpu_state, extracontext->fx, 512);
+}
+
+
 #endif

kernel-src/sys/scheduler/scheduler.c

@@ -162,7 +162,7 @@ typedef struct {
 } checkargs_t;
 
 // SHOULD NOT BE CALLED WITH THE SCHEDULER STACK
-static void userspacecheck(void *_args) {
+static bool userspacecheck(void *_args) {
 	checkargs_t *args = _args;
 	thread_t *thread = current_thread();
 
@@ -171,7 +171,10 @@ static void userspacecheck(void *_args) {
 		sched_threadexit();
 	}
 
-	while (signal_check(thread, args->context, args->syscall, args->syscallret, args->syscallerrno)) ;
+	bool need_context_switch = false;
+
+	while (signal_check(thread, args->context, args->syscall, args->syscallret, args->syscallerrno, &need_context_switch)) ;
+	return need_context_switch;
 }
 
 static void checktrampoline(context_t *context, void *_args) {
@@ -203,7 +206,10 @@ __attribute__((no_caller_saved_registers)) void sched_userspacecheck(context_t *
 	if (&args < (checkargs_t *)current_cpu()->schedulerstack && &args >= (checkargs_t *)((uintptr_t)current_cpu()->schedulerstack - SCHEDULER_STACK_SIZE)) {
 		arch_context_saveandcall(checktrampoline, current_thread()->kernelstacktop, &args);
 	} else {
-		userspacecheck(&args);
+		if (userspacecheck(&args)) {
+			// need context switch
+			arch_context_switch(context);
+		}
 	}
 
 	current_cpu()->intstatus = intstatus;

kernel-src/sys/signal.c

@@ -423,7 +423,7 @@ void signal_signalproc(struct proc_t *proc, int signal) {
 }
 
 // returns true if should retry check
-bool signal_check(struct thread_t *thread, context_t *context, bool syscall, uint64_t syscallret, uint64_t syscallerrno) {
+bool signal_check(struct thread_t *thread, context_t *context, bool syscall, uint64_t syscallret, uint64_t syscallerrno, bool *need_context_switch) {
 	bool retry = false;
 	proc_t *proc = thread->proc;
 
@@ -563,6 +563,7 @@ bool signal_check(struct thread_t *thread, context_t *context, bool syscall, uin
 		}
 		memcpy(&sigframe.context, context, sizeof(context_t));
 		memcpy(&sigframe.extracontext, &thread->extracontext, sizeof(extracontext_t));
+		arch_sigframe_prepare_mcontext(&sigframe);
 		// TODO siginfo
 
 		if (usercopy_touser(stack, &sigframe, sizeof(sigframe_t))) {
@@ -591,11 +592,13 @@ bool signal_check(struct thread_t *thread, context_t *context, bool syscall, uin
 		CTX_SP(context) = (uint64_t)stack;
 		CTX_ARG0(context) = signal;
 		CTX_ARG1(context) = 0; // TODO pass siginfo
-		CTX_ARG2(context) = 0; // TODO ucontext
+		CTX_ARG2(context) = (uint64_t)ARCH_SIGFRAME_GET_UCONTEXT_POINTER((sigframe_t*)stack);
 
 		// reset handler if asked for
 		if (action->flags & SA_RESETHAND)
 			memset(action, 0, sizeof(sigaction_t));
+
+		*need_context_switch = true;
 	}
 
 	leave: