From 9981bb227093373649acd019d378dfccb54189c8 Mon Sep 17 00:00:00 2001
From: Robert Morris <rtm@csail.mit.edu>
Date: Wed, 10 Jul 2019 08:57:51 -0400
Subject: tweak some comments.

---
 kernel/trap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'kernel/trap.c')

diff --git a/kernel/trap.c b/kernel/trap.c
index 018b7db..27cfd32 100644
--- a/kernel/trap.c
+++ b/kernel/trap.c
@@ -100,7 +100,7 @@ usertrapret(void)
   p->tf->kernel_satp = r_satp();
   p->tf->kernel_sp = (uint64)p->kstack + PGSIZE;
   p->tf->kernel_trap = (uint64)usertrap;
-  p->tf->hartid = r_tp();
+  p->tf->kernel_hartid = r_tp();
 
   // set up the registers that trampoline.S's sret will use
   // to get to user space.
-- 
cgit v1.2.3


From 5eb1685700a7665814f1bcf63fc26f5dbf0f719a Mon Sep 17 00:00:00 2001
From: Robert Morris <rtm@csail.mit.edu>
Date: Wed, 10 Jul 2019 09:24:50 -0400
Subject: have kill() lock before looking at p->pid document wait()'s use of
 np->parent w/o holding lock.

---
 kernel/trap.c | 3 +++
 1 file changed, 3 insertions(+)

(limited to 'kernel/trap.c')

diff --git a/kernel/trap.c b/kernel/trap.c
index 27cfd32..eb7f6cf 100644
--- a/kernel/trap.c
+++ b/kernel/trap.c
@@ -53,6 +53,9 @@ usertrap(void)
   if(r_scause() == 8){
     // system call
 
+    if(p->killed)
+      exit();
+
     // sepc points to the ecall instruction,
     // but we want to return to the next instruction.
     p->tf->epc += 4;
-- 
cgit v1.2.3


From 6bbc2b2245c5b006824eb42ef33d5b296158a693 Mon Sep 17 00:00:00 2001
From: Robert Morris <rtm@csail.mit.edu>
Date: Thu, 11 Jul 2019 10:38:56 -0400
Subject: cosmetic changes

---
 kernel/trap.c | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

(limited to 'kernel/trap.c')

diff --git a/kernel/trap.c b/kernel/trap.c
index eb7f6cf..ea5799f 100644
--- a/kernel/trap.c
+++ b/kernel/trap.c
@@ -158,6 +158,15 @@ kerneltrap()
   w_sstatus(sstatus);
 }
 
+void
+clockintr()
+{
+  acquire(&tickslock);
+  ticks++;
+  wakeup(&ticks);
+  release(&tickslock);
+}
+
 // check if it's an external interrupt or software interrupt,
 // and handle it.
 // returns 2 if timer interrupt,
@@ -182,16 +191,15 @@ devintr()
     plic_complete(irq);
     return 1;
   } else if(scause == 0x8000000000000001){
-    // software interrupt from a machine-mode timer interrupt.
+    // software interrupt from a machine-mode timer interrupt,
+    // forwarded by machinevec in kernelvec.S.
 
     if(cpuid() == 0){
-      acquire(&tickslock);
-      ticks++;
-      wakeup(&ticks);
-      release(&tickslock);
+      clockintr();
     }
     
-    // acknowledge.
+    // acknowledge the software interrupt by clearing
+    // the SSIP bit in sip.
     w_sip(r_sip() & ~2);
 
     return 2;
-- 
cgit v1.2.3