git: a5b0b2a7d421 - main - C runtime: add kernel version guards on exterrctl

The branch main has been updated by brooks:

URL: https://cgit.FreeBSD.org/src/commit/?id=a5b0b2a7d4219ae86f152433b6fcecd9e8c767d6

commit a5b0b2a7d4219ae86f152433b6fcecd9e8c767d6
Author:     Brooks Davis <brooks@FreeBSD.org>
AuthorDate: 2025-06-04 17:58:03 +0000
Commit:     Brooks Davis <brooks@FreeBSD.org>
CommitDate: 2025-06-04 18:09:19 +0000

    C runtime: add kernel version guards on exterrctl
    
    This allows userspace to run on a (somewhat) out of date kernel.
    
    Avoid a __FreeBSD_version bump and use the bump from a02180cf60a6 which
    has occured since exterrctl was added.
    
    Reviewed by:    kevans
    Fixes:          b9c8a07d4dd9 ("C runtime: enable extended error reporting from kernel")
    Sponsored by:   DARPA, AFRL
    Differential Revision:  https://reviews.freebsd.org/D50687
---
 lib/libc/gen/uexterr_gettext.c | 8 ++++++--
 lib/libthr/thread/thr_create.c | 6 +++++-
 lib/libthr/thread/thr_init.c   | 5 ++++-
 sys/sys/param.h                | 1 +
 4 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/lib/libc/gen/uexterr_gettext.c b/lib/libc/gen/uexterr_gettext.c
index b4bb93cfdb50..5b8a5cd17a48 100644
--- a/lib/libc/gen/uexterr_gettext.c
+++ b/lib/libc/gen/uexterr_gettext.c
@@ -8,7 +8,8 @@
  * under sponsorship from the FreeBSD Foundation.
  */
 
-#include <sys/types.h>
+#define	_WANT_P_OSREL
+#include <sys/param.h>
 #include <sys/exterrvar.h>
 #include <exterr.h>
 #include <string.h>
@@ -18,11 +19,14 @@ static struct uexterror uexterr = {
 	.ver = UEXTERROR_VER,
 };
 
+int __getosreldate(void);
+
 static void uexterr_ctr(void) __attribute__((constructor));
 static void
 uexterr_ctr(void)
 {
-	exterrctl(EXTERRCTL_ENABLE, 0, &uexterr);
+	if (__getosreldate() >= P_OSREL_EXTERRCTL)
+		exterrctl(EXTERRCTL_ENABLE, 0, &uexterr);
 }
 
 int
diff --git a/lib/libthr/thread/thr_create.c b/lib/libthr/thread/thr_create.c
index ba2575d461e5..c66a5bb3bd21 100644
--- a/lib/libthr/thread/thr_create.c
+++ b/lib/libthr/thread/thr_create.c
@@ -27,6 +27,7 @@
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+#define _WANT_P_OSREL
 #include "namespace.h"
 #include <sys/types.h>
 #include <sys/rtprio.h>
@@ -44,6 +45,8 @@
 #include "libc_private.h"
 #include "thr_private.h"
 
+int __getosreldate(void);
+
 static int  create_stack(struct pthread_attr *pattr);
 static void thread_start(struct pthread *curthread);
 
@@ -287,7 +290,8 @@ thread_start(struct pthread *curthread)
 #endif
 
 	curthread->uexterr.ver = UEXTERROR_VER;
-	exterrctl(EXTERRCTL_ENABLE, 0, &curthread->uexterr);
+	if (__getosreldate() >= P_OSREL_EXTERRCTL)
+		exterrctl(EXTERRCTL_ENABLE, 0, &curthread->uexterr);
 
 	/* Run the current thread's start routine with argument: */
 	_pthread_exit(curthread->start_routine(curthread->arg));
diff --git a/lib/libthr/thread/thr_init.c b/lib/libthr/thread/thr_init.c
index aef2281c5f22..bd1474a7c6e8 100644
--- a/lib/libthr/thread/thr_init.c
+++ b/lib/libthr/thread/thr_init.c
@@ -33,6 +33,7 @@
  * SUCH DAMAGE.
  */
 
+#define _WANT_P_OSREL
 #include "namespace.h"
 #include <sys/param.h>
 #include <sys/auxv.h>
@@ -59,6 +60,7 @@
 #include "libc_private.h"
 #include "thr_private.h"
 
+int		__getosreldate(void);
 char		*_usrstack;
 struct pthread	*_thr_initial;
 int		_libthr_debug;
@@ -434,7 +436,8 @@ init_main_thread(struct pthread *thread)
 #endif
 
 	thread->uexterr.ver = UEXTERROR_VER;
-	exterrctl(EXTERRCTL_ENABLE, EXTERRCTLF_FORCE, &thread->uexterr);
+	if (__getosreldate() >= P_OSREL_EXTERRCTL)
+		exterrctl(EXTERRCTL_ENABLE, EXTERRCTLF_FORCE, &thread->uexterr);
 
 	/* Others cleared to zero by thr_alloc() */
 }
diff --git a/sys/sys/param.h b/sys/sys/param.h
index 98fb0aeacef0..da2089918323 100644
--- a/sys/sys/param.h
+++ b/sys/sys/param.h
@@ -107,6 +107,7 @@
 #define	P_OSREL_TIDPID			1400079
 #define	P_OSREL_ARM64_SPSR		1400084
 #define	P_OSREL_TLSBASE			1500044
+#define	P_OSREL_EXTERRCTL		1500045
 
 #define	P_OSREL_MAJOR(x)		((x) / 100000)
 #endif