Reset the per-CPU unique value at boot and clear it in the PCB of the

child when forking. This provides a consistent initial state.
Note that cpu_set_upcall() does not clear the per-CPU unique value as
it is followed by a call to set_mcontext(), which sets it accordingly.

3 files changed, 9 insertions, 3 deletions

diff --git a/sys/alpha/alpha/machdep.c b/sys/alpha/alpha/machdep.c
index ba40437..64148f9 100644
--- a/sys/alpha/alpha/machdep.c
+++ b/sys/alpha/alpha/machdep.c
@@ -548,6 +548,9 @@ alpha_init(pfn, ptb, bim, bip, biv)
 	alpha_pal_wrmces(alpha_pal_rdmces() &
 			 ~(ALPHA_MCES_DSC|ALPHA_MCES_DPC));
 
+	/* Clear userland thread pointer */
+	alpha_pal_wrunique(0);
+
 	/*
 	 * Find out what hardware we're on, and do basic initialization.
 	 */
@@ -2028,7 +2031,7 @@ get_mcontext(struct thread *td, mcontext_t *mcp, int clear_ret)
 		mcp->mc_regs[FRAME_SP] = alpha_pal_rdusp();
 		mcp->mc_thrptr = alpha_pal_rdunique();
 	} else
-		mcp->mc_thrptr = td->td_pcb->pcb_hw.apcb_unique;
+		mcp->mc_thrptr = 0;
 
 	mcp->mc_format = _MC_REV0_TRAPFRAME;
 	PROC_LOCK(curthread->td_proc);
@@ -2069,8 +2072,7 @@ set_mcontext(struct thread *td, const mcontext_t *mcp)
 		if (td == curthread) {
 			alpha_pal_wrusp(mcp->mc_regs[FRAME_SP]);
 			alpha_pal_wrunique(mcp->mc_thrptr);
-		} else
-			td->td_pcb->pcb_hw.apcb_unique = mcp->mc_thrptr;
+		}
 
 		/*
 		 * The context is a trapframe, so just copy it over the
diff --git a/sys/alpha/alpha/mp_machdep.c b/sys/alpha/alpha/mp_machdep.c
index 609fa85..f37d0f1 100644
--- a/sys/alpha/alpha/mp_machdep.c
+++ b/sys/alpha/alpha/mp_machdep.c
@@ -137,6 +137,9 @@ smp_init_secondary(void)
 	 */
 	alpha_pal_wrval((u_int64_t) pcpup);
 
+	/* Clear userland thread pointer. */
+	alpha_pal_wrunique(0);
+
 	/*
 	 * Point interrupt/exception vectors to our own.
 	 */
diff --git a/sys/alpha/alpha/vm_machdep.c b/sys/alpha/alpha/vm_machdep.c
index 3df1388..b0ed146 100644
--- a/sys/alpha/alpha/vm_machdep.c
+++ b/sys/alpha/alpha/vm_machdep.c
@@ -145,6 +145,7 @@ cpu_fork(td1, p2, td2, flags)
 	 */
 	bcopy(td1->td_pcb, td2->td_pcb, sizeof(struct pcb));
 	td2->td_pcb->pcb_hw.apcb_usp = alpha_pal_rdusp();
+	td2->td_pcb->pcb_hw.apcb_unique = 0;
 	td2->td_pcb->pcb_hw.apcb_flags &= ~ALPHA_PCB_FLAGS_FEN;
 
 	/*