Date: Mon, 18 Jun 2012 21:08:48 +0000 (UTC) From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r237243 - head/sys/amd64/amd64 Message-ID: <201206182108.q5IL8mWK001009@svn.freebsd.org>
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Author: kib Date: Mon Jun 18 21:08:48 2012 New Revision: 237243 URL: http://svn.freebsd.org/changeset/base/237243 Log: Adjust the fix in r236953, by not generating the signal manually, but 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 Modified: head/sys/amd64/amd64/trap.c Modified: head/sys/amd64/amd64/trap.c ============================================================================== --- head/sys/amd64/amd64/trap.c Mon Jun 18 21:00:54 2012 (r237242) +++ head/sys/amd64/amd64/trap.c Mon Jun 18 21:08:48 2012 (r237243) @@ -977,16 +977,10 @@ 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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