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Adjust the fix in r236953, by not generating the signal manually, but

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performing the return to usermode using full return path.  This
consolidates the handling of exceptional situations in less number of
places, and is less code as well.

Reviewed by:   jhb
MFC after:     1 week
This commit is contained in:
kib 2012-06-18 21:08:48 +00:00
parent 545343a302
commit 4eede7506a
1 changed files with 5 additions and 11 deletions
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16
sys/amd64/amd64/trap.c
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@ -977,16 +977,10 @@ amd64_syscall(struct thread *td, int traced)
* 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);
}