[xen stable-4.17] x86: re-run exception-from-stub recovery selftests with CET-SS enabled

[patchbot@xxxxxxx]

commit 79f83106f92777bc21ca57bccde45af29308b813
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Thu Jul 4 14:17:03 2024 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Jul 4 14:17:03 2024 +0200

    x86: re-run exception-from-stub recovery selftests with CET-SS enabled
    
    On the BSP, shadow stacks are enabled only relatively late in the
    booting process. They in particular aren't active yet when initcalls are
    run. Keep the testing there, but invoke that testing a 2nd time when
    shadow stacks are active, to make sure we won't regress that case after
    addressing XSA-451.
    
    While touching this code, switch the guard from NDEBUG to CONFIG_DEBUG,
    such that IS_ENABLED() can validly be used at the new call site.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    master commit: cfe3ad67127b86e1b1c06993b86422673a51b050
    master date: 2024-02-27 13:49:52 +0100
---
 xen/arch/x86/extable.c           | 8 +++++---
 xen/arch/x86/include/asm/setup.h | 2 ++
 xen/arch/x86/setup.c             | 4 ++++
 3 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/xen/arch/x86/extable.c b/xen/arch/x86/extable.c
index dd9583f2a5..f05c16def6 100644
--- a/xen/arch/x86/extable.c
+++ b/xen/arch/x86/extable.c
@@ -128,10 +128,11 @@ search_exception_table(const struct cpu_user_regs *regs, 
unsigned long *stub_ra)
     return 0;
 }
 
-#ifndef NDEBUG
+#ifdef CONFIG_DEBUG
+#include <asm/setup.h>
 #include <asm/traps.h>
 
-static int __init cf_check stub_selftest(void)
+int __init cf_check stub_selftest(void)
 {
     static const struct {
         uint8_t opc[8];
@@ -155,7 +156,8 @@ static int __init cf_check stub_selftest(void)
     unsigned int i;
     bool fail = false;
 
-    printk("Running stub recovery selftests...\n");
+    printk("%s stub recovery selftests...\n",
+           system_state < SYS_STATE_active ? "Running" : "Re-running");
 
     for ( i = 0; i < ARRAY_SIZE(tests); ++i )
     {
diff --git a/xen/arch/x86/include/asm/setup.h b/xen/arch/x86/include/asm/setup.h
index 21037b7f31..a870c61b3f 100644
--- a/xen/arch/x86/include/asm/setup.h
+++ b/xen/arch/x86/include/asm/setup.h
@@ -48,6 +48,8 @@ int xen_in_range(unsigned long mfn);
 void microcode_grab_module(
     unsigned long *, const multiboot_info_t *);
 
+int cf_check stub_selftest(void);
+
 extern uint8_t kbd_shift_flags;
 
 #ifdef NDEBUG
diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
index d47f156711..2d2eb791e4 100644
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -622,6 +622,10 @@ static void noreturn init_done(void)
 
     system_state = SYS_STATE_active;
 
+    /* Re-run stub recovery self-tests with CET-SS active. */
+    if ( IS_ENABLED(CONFIG_DEBUG) && cpu_has_xen_shstk )
+        stub_selftest();
+
     domain_unpause_by_systemcontroller(dom0);
 
     /* MUST be done prior to removing .init data. */
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.17