Toggle IBT off during amd64 hibernate before dropping to real mode.

Hibernate on IBT-capable MP systems broke when trying to quiesce
cpus. Instead of finding the locations of endbr64 in the asm indirect
jumps in acpi_wakecode.S, simply disable CR4.CET beforehand and
re-enable on resume.

This will also disable shadowstack, but there are no plans to use it.

"this approach is fine" deraadt@

diff --git a/sys/arch/amd64/amd64/acpi_machdep.c b/sys/arch/amd64/amd64/acpi_machdep.c
index 502bd70..23ca827 100644 (file)
--- a/sys/arch/amd64/amd64/acpi_machdep.c
+++ b/sys/arch/amd64/amd64/acpi_machdep.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: acpi_machdep.c,v 1.106 2022/11/08 17:34:12 cheloha Exp $      */
+/*     $OpenBSD: acpi_machdep.c,v 1.107 2023/04/24 09:04:03 dv Exp $   */
 /*
  * Copyright (c) 2005 Thorsten Lockert <tholo@sigmasoft.com>
  *
@@ -434,6 +434,8 @@ acpi_sleep_cpu(struct acpi_softc *sc, int state)
                return (ECANCELED);
        }
        /* Resume path */
+       if (curcpu()->ci_feature_sefflags_edx & SEFF0EDX_IBT)
+               lcr4(rcr4() | CR4_CET);
        fpureset();
 
        /* Reset the vectors */

diff --git a/sys/arch/amd64/amd64/cpu.c b/sys/arch/amd64/amd64/cpu.c
index 75d4eee..ab5013e 100644 (file)
--- a/sys/arch/amd64/amd64/cpu.c
+++ b/sys/arch/amd64/amd64/cpu.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: cpu.c,v 1.167 2023/04/22 18:27:28 guenther Exp $      */
+/*     $OpenBSD: cpu.c,v 1.168 2023/04/24 09:04:03 dv Exp $    */
 /* $NetBSD: cpu.c,v 1.1 2003/04/26 18:39:26 fvdl Exp $ */
 
 /*-
@@ -989,6 +989,8 @@ cpu_hatch(void *v)
                delay(10);
 #ifdef HIBERNATE
        if ((ci->ci_flags & CPUF_PARK) != 0) {
+               if (ci->ci_feature_sefflags_edx & SEFF0EDX_IBT)
+                       lcr4(rcr4() & ~CR4_CET);
                atomic_clearbits_int(&ci->ci_flags, CPUF_PARK);
                hibernate_drop_to_real_mode();
        }

diff --git a/sys/arch/amd64/amd64/hibernate_machdep.c b/sys/arch/amd64/amd64/hibernate_machdep.c
index 961d430..19fe8e8 100644 (file)
--- a/sys/arch/amd64/amd64/hibernate_machdep.c
+++ b/sys/arch/amd64/amd64/hibernate_machdep.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: hibernate_machdep.c,v 1.49 2022/09/02 09:02:37 mlarkin Exp $  */
+/*     $OpenBSD: hibernate_machdep.c,v 1.50 2023/04/24 09:04:03 dv Exp $       */
 
 /*
  * Copyright (c) 2012 Mike Larkin <mlarkin@openbsd.org>
@@ -468,6 +468,9 @@ hibernate_quiesce_cpus(void)
        pmap_kenter_pa(ACPI_TRAMP_DATA, ACPI_TRAMP_DATA,
                PROT_READ | PROT_WRITE);
 
+       if (curcpu()->ci_feature_sefflags_edx & SEFF0EDX_IBT)
+               lcr4(rcr4() & ~CR4_CET);
+
        for (i = 0; i < MAXCPUS; i++) {
                ci = cpu_info[i];
                if (ci == NULL)