Author: kib
Date: Mon Jun 25 09:41:47 2012
New Revision: 237559
URL: http://svn.freebsd.org/changeset/base/237559
Log:
MFC r237243:
Adjust the fix in r236953, by not generating the signal manually, but
performing the return to usermode using full return path.
Modified:
stable/9/sys/amd64/amd64/trap.c
Directory Properties:
stable/9/sys/ (props changed)
Modified: stable/9/sys/amd64/amd64/trap.c
==============================================================================
--- stable/9/sys/amd64/amd64/trap.c Mon Jun 25 08:34:14 2012
(r237558)
+++ stable/9/sys/amd64/amd64/trap.c Mon Jun 25 09:41:47 2012
(r237559)
@@ -982,16 +982,10 @@ amd64_syscall(struct thread *td, int tra
* If the user-supplied value of %rip is not a canonical
* address, then some CPUs will trigger a ring 0 #GP during
* the sysret instruction. However, the fault handler would
- * execute with the user's %gs and %rsp in ring 0 which would
- * not be safe. Instead, preemptively kill the thread with a
- * SIGBUS.
+ * execute in ring 0 with the user's %gs and %rsp which would
+ * not be safe. Instead, use the full return path which
+ * catches the problem safely.
*/
- if (td->td_frame->tf_rip >= VM_MAXUSER_ADDRESS) {
- ksiginfo_init_trap(&ksi);
- ksi.ksi_signo = SIGBUS;
- ksi.ksi_code = BUS_OBJERR;
- ksi.ksi_trapno = T_PROTFLT;
- ksi.ksi_addr = (void *)td->td_frame->tf_rip;
- trapsignal(td, &ksi);
- }
+ if (td->td_frame->tf_rip >= VM_MAXUSER_ADDRESS)
+ set_pcb_flags(td->td_pcb, PCB_FULL_IRET);
}
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