ref: ca4f815cfc673d00834b48535b9903aae3ac3961
parent: 7c1ae2ead32396761f3f08b1ec15645dc53aae0d
author: cinap_lenrek <cinap_lenrek@felloff.net>
date: Thu Aug 7 15:55:25 EDT 2014
pc64: fix wrong Ureg* argument on note handler (thanks _sl!) _sl reported crash: stats 593: suicide: sys: trap: fault write addr=0xffffffff8258d1b0 pc=0x204cc7 ; acid 593 /proc/593/text:amd64 plan 9 executable /sys/lib/acid/port /sys/lib/acid/amd64 acid: lstk() notejmp(ret=0x1,j=0x40ac90)+0x13 /sys/src/libc/amd64/notejmp.c:10 alarmed(a=0xffffffff8258d1b0,s=0x7ffffeffea58)+0x3f /sys/src/cmd/stats.c:718 notifier+0x3e /sys/src/libc/port/atnotify.c:15 acid: note how a in alarmed is a kernel address! the first Ureg* argument is passed to the note handler in the RARG (BX) register, which was not loaded when returning to userspace from syscall() thru forkret(). fix by returning thru noteret() from syscall().
--- a/sys/src/9/pc64/trap.c
+++ b/sys/src/9/pc64/trap.c
@@ -769,6 +769,7 @@
if(scallnr!=RFORK && (up->procctl || up->nnote)){splhi();
notify(ureg);
+ ((void**)&ureg)[-1] = (void*)noteret; /* loads RARG */
}
/* if we delayed sched because we held a lock, sched now */
if(up->delaysched)