git: 16ce7f1a3603 - main - amd64: set PCB_TLSBASE pcb flag only for new C runtime threads

The branch main has been updated by kib:

URL: https://cgit.FreeBSD.org/src/commit/?id=16ce7f1a3603fce5262cf0656a01c4177c75fa50

commit 16ce7f1a3603fce5262cf0656a01c4177c75fa50
Author:     Konstantin Belousov <kib@FreeBSD.org>
AuthorDate: 2025-05-30 11:25:50 +0000
Commit:     Konstantin Belousov <kib@FreeBSD.org>
CommitDate: 2025-05-31 14:55:24 +0000

    amd64: set PCB_TLSBASE pcb flag only for new C runtime threads
    
    where the runtime does want the pcb_tlsbase to be set in fsbase in
    signal handlers.  This way, other runtimes that are not aware of
    pcb_tlsbase get the old behavior of preserving fsbase on calling signal
    handler.
    
    For instance, this fixes Go runtime that wants to handle fsbase in its
    own way.
    
    Reported by:    Herbert J. Skuhra <herbert@gojira.at>
    Sponsored by:   The FreeBSD Foundation
    MFC after:      1 week
---
 sys/amd64/amd64/vm_machdep.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/sys/amd64/amd64/vm_machdep.c b/sys/amd64/amd64/vm_machdep.c
index 275ab1a54e52..c763ff58680e 100644
--- a/sys/amd64/amd64/vm_machdep.c
+++ b/sys/amd64/amd64/vm_machdep.c
@@ -60,6 +60,7 @@
 #include <sys/smp.h>
 #include <sys/sysctl.h>
 #include <sys/sysent.h>
+#include <sys/thr.h>
 #include <sys/unistd.h>
 #include <sys/vnode.h>
 #include <sys/vmmeter.h>
@@ -164,6 +165,7 @@ copy_thread(struct thread *td1, struct thread *td2)
 		MPASS((pcb2->pcb_flags & (PCB_KERNFPU | PCB_KERNFPU_THR)) == 0);
 		bcopy(get_pcb_user_save_td(td1), get_pcb_user_save_pcb(pcb2),
 		    cpu_max_ext_state_size);
+		clear_pcb_flags(pcb2, PCB_TLSBASE);
 	}
 
 	td2->td_frame = (struct trapframe *)td2->td_md.md_stack_base - 1;
@@ -663,7 +665,8 @@ cpu_set_user_tls(struct thread *td, void *tls_base, int thr_flags)
 		return (EINVAL);
 
 	pcb = td->td_pcb;
-	set_pcb_flags(pcb, PCB_FULL_IRET | PCB_TLSBASE);
+	set_pcb_flags(pcb, PCB_FULL_IRET | ((thr_flags &
+	    THR_C_RUNTIME) != 0 ? PCB_TLSBASE : 0));
 #ifdef COMPAT_FREEBSD32
 	if (SV_PROC_FLAG(td->td_proc, SV_ILP32)) {
 		pcb->pcb_gsbase = (register_t)tls_base;