From babc58fd749a5bef05f6861e9ae3b86ed01c8bf7 Mon Sep 17 00:00:00 2001 From: Peter Wemm Date: Mon, 2 Jun 2003 21:56:08 +0000 Subject: [PATCH] Fix restarted syscalls. When we rewind %rip, we also need to restore all the argument registers etc since we have almost certainly have trashed them by now. Take particular car of %r10 since it held the original value of %rcx (which we saved in tf_rcx on entry and doreti doesn't know this). --- sys/amd64/amd64/trap.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/sys/amd64/amd64/trap.c b/sys/amd64/amd64/trap.c index 72ba59037804..c4e7f16e991b 100644 --- a/sys/amd64/amd64/trap.c +++ b/sys/amd64/amd64/trap.c @@ -751,10 +751,14 @@ syscall(frame) case ERESTART: /* - * Reconstruct pc, assuming lcall $X,y is 7 bytes, - * int 0x80 is 2 bytes. We saved this in tf_err. + * Reconstruct pc, we know that 'syscall' is 2 bytes. + * We have to do a full context restore so that %r10 + * (which was holding the value of %rcx) is restored for + * the next iteration. */ frame.tf_rip -= frame.tf_err; + frame.tf_r10 = frame.tf_rcx; + td->td_pcb->pcb_flags |= PCB_FULLCTX; break; case EJUSTRETURN: