kernel: pass more information to user on interrupt

This is meant to facilitate a syscall for returning from interrupts, which
will actually work in the general case as opposed to the current hack, which
only works if the interrupt occured during a syscall (which is correct... for
now).

1 files changed, 61 insertions, 12 deletions

diff --git a/src/kernel/proc.c b/src/kernel/proc.c
index a22f632..350f3ee 100644
--- a/src/kernel/proc.c
+++ b/src/kernel/proc.c
@@ -259,6 +259,11 @@ void proc_kill(Proc *p, int ret) {
 			it = sibling;
 		}
 
+		if (p->queuedintr) {
+			kfree(p->queuedintr);
+			p->queuedintr = NULL;
+		}
+
 		if (p->execbuf.buf) {
 			kfree(p->execbuf.buf);
 			p->execbuf.buf = NULL;
@@ -352,14 +357,12 @@ void proc_tryreap(Proc *dead) {
 	}
 }
 
-void proc_tryintr(Proc *p) {
-	if (p->state == PS_WAITS4TIMER) {
-		timer_deschedule(p);
-	}
-}
-
 void proc_intr(Proc *p, const char *buf, size_t len) {
-	assert(buf != NULL || len == 0);
+	/* ignore attempts to interrupt with no string. they sometimes occur due
+	 * to e.g. fopen trying to truncate the /intr file */
+	// TODO check callsites
+	if (len == 0) return;
+	assert(buf != NULL);
 
 	if (4 <= len && memcmp(buf, "kill", 4) == 0) {
 		proc_kill(p, EINTR);
@@ -367,18 +370,63 @@ void proc_intr(Proc *p, const char *buf, size_t len) {
 	}
 
 	if (!p->intr_fn) return;
-	proc_tryintr(p);
+	if (p->state == PS_WAITS4TIMER) {
+		timer_deschedule(p);
+	}
 
-	/* save old rsp,rip */
+	if (p->queuedintr != NULL) {
+		// TODO multiple queued interrupts. should be easy
+		panic_unimplemented();
+	}
+	p->queuedintr = kmalloc(sizeof(Intr) + len, TagIntr);
+	p->queuedintr->len = len;
+	memcpy(p->queuedintr->buf, buf, len);
+}
+
+static void proc_intr_deliver(Proc *p) {
+	assert(p->state == PS_RUNNING);
+	Intr *intr = p->queuedintr;
+
+	/* interrupts are held off until a handler is registered */
+	if (intr == NULL || p->intr_fn == NULL) {
+		return;
+	}
+
+	/* save old registers */
+	// TODO separate types for normal registers and sse?
+	// then i could reuse the normal register type here
 	struct intr_data d;
-	void __user *sp = p->regs.rsp - 128 - sizeof(d);
-	d.ip = (void __user *)p->regs.rip;
-	d.sp = p->regs.rsp;
+	d.r15 = p->regs.r15;
+	d.r14 = p->regs.r14;
+	d.r13 = p->regs.r13;
+	d.r12 = p->regs.r12;
+	d.r11 = p->regs.r11;
+	d.r10 = p->regs.r10;
+	d.r9  = p->regs.r9;
+	d.r8  = p->regs.r8;
+	d.rdi = p->regs.rdi;
+	d.rsi = p->regs.rsi;
+	d.rbp = p->regs.rbp;
+	d.rsp = p->regs.rsp;
+	d.rbx = p->regs.rbx;
+	d.rdx = p->regs.rdx;
+	d.rcx = p->regs.rcx;
+	d.rax = p->regs.rax;
+	d.rip = p->regs.rip;
+
+	// one more because the buffer itself isn't NUL terminated
+	// TODO ensure NUL termination
+	void __user *sp = p->regs.rsp - 128 - sizeof(d) - intr->len - 1;
 	pcpy_to(p, sp, &d, sizeof(d));
+	pcpy_to(p, sp + sizeof(d), intr->buf, intr->len);
+	pcpy_to(p, sp + sizeof(d) + intr->len, "", 1);
 
 	/* switch to intr handler */
 	p->regs.rip = (uint64_t)p->intr_fn;
 	p->regs.rsp = sp;
+
+	kfree(p->queuedintr);
+	p->queuedintr = NULL;
 }
 
 static void proc_prune_leaves(void) {
@@ -432,6 +480,7 @@ _Noreturn void proc_switch_any(void) {
 		if (p) {
 			assert(p->state == PS_RUNNING);
 			proc_cur = p;
+			proc_intr_deliver(p);
 			pagedir_switch(p->pages);
 			if (p->execbuf.buf) {
 				execbuf_run(p);