pc, pc64: park application processors in rebootcode with mmu off

instead of having application processors spin in mpshutdown()
with mmu on, and be subject to reboot() overriding kernel text
and modifying page tables, park the application processors in
rebootcode idle loop with the mmu off.

4 files changed, 88 insertions, 46 deletions

diff --git a/sys/src/9/pc/main.c b/sys/src/9/pc/main.c
index b60329776..61db6f113 100644
--- a/sys/src/9/pc/main.c
+++ b/sys/src/9/pc/main.c
@@ -701,34 +701,13 @@ procsave(Proc *p)
 	mmuflushtlb(PADDR(m->pdb));
 }
 
-void
-reboot(void *entry, void *code, ulong size)
+static void
+rebootjump(uintptr entry, uintptr code, ulong size)
 {
-	void (*f)(ulong, ulong, ulong);
+	void (*f)(uintptr, uintptr, ulong);
 	ulong *pdb;
 
-	writeconf();
-	vmxshutdown();
-
-	/*
-	 * the boot processor is cpu0.  execute this function on it
-	 * so that the new kernel has the same cpu0.  this only matters
-	 * because the hardware has a notion of which processor was the
-	 * boot processor and we look at it at start up.
-	 */
-	if (m->machno != 0) {
-		procwired(up, 0);
-		sched();
-	}
-	cpushutdown();
-
 	splhi();
-
-	/* turn off buffered serial console */
-	serialoq = nil;
-
-	/* shutdown devices */
-	chandevshutdown();
 	arch->introff();
 
 	/*
@@ -745,7 +724,8 @@ reboot(void *entry, void *code, ulong size)
 
 	/* off we go - never to return */
 	coherence();
-	(*f)((ulong)entry & ~0xF0000000UL, PADDR(code), size);
+	(*f)(entry, code, size);
+	for(;;);
 }
 
 
@@ -753,5 +733,36 @@ void
 exit(int)
 {
 	cpushutdown();
+	if(m->machno)
+		rebootjump(0, 0, 0);
 	arch->reset();
 }
+
+void
+reboot(void *entry, void *code, ulong size)
+{
+	writeconf();
+	vmxshutdown();
+
+	/*
+	 * the boot processor is cpu0.  execute this function on it
+	 * so that the new kernel has the same cpu0.  this only matters
+	 * because the hardware has a notion of which processor was the
+	 * boot processor and we look at it at start up.
+	 */
+	if (m->machno != 0) {
+		procwired(up, 0);
+		sched();
+	}
+	cpushutdown();
+	delay(1000);
+	splhi();
+
+	/* turn off buffered serial console */
+	serialoq = nil;
+
+	/* shutdown devices */
+	chandevshutdown();
+
+	rebootjump((ulong)entry & ~0xF0000000UL, PADDR(code), size);
+}
diff --git a/sys/src/9/pc/rebootcode.s b/sys/src/9/pc/rebootcode.s
index c7d0b1991..0b4a28481 100644
--- a/sys/src/9/pc/rebootcode.s
+++ b/sys/src/9/pc/rebootcode.s
@@ -20,6 +20,13 @@ TEXT	main(SB),$0
 	MOVL	$0, DX
 	MOVL	DX, CR3
 
+	/* stack below entry point */
+	MOVL	AX, SP
+
+	/* park cpu for zero entry point */
+	ORL	AX, AX
+	JZ	_idle
+
 /*
  * the source and destination may overlap.
  * determine whether to copy forward or backwards
@@ -52,3 +59,7 @@ _back:
 _startkernel:
 	ORL	AX, AX		/* NOP: avoid link bug */
 	JMP*	AX
+
+_idle:
+	HLT
+	JMP	_idle
diff --git a/sys/src/9/pc64/main.c b/sys/src/9/pc64/main.c
index fc1bfeb92..dd9e2d8f2 100644
--- a/sys/src/9/pc64/main.c
+++ b/sys/src/9/pc64/main.c
@@ -336,18 +336,45 @@ main()
 	schedinit();
 }
 
+static void
+rebootjump(uintptr entry, uintptr code, ulong size)
+{
+	void (*f)(uintptr, uintptr, ulong);
+
+	splhi();
+	arch->introff();
+
+	/*
+	 * This allows the reboot code to turn off the page mapping
+	 */
+	*mmuwalk(m->pml4, 0, 3, 0) = *mmuwalk(m->pml4, KZERO, 3, 0);
+	*mmuwalk(m->pml4, 0, 2, 0) = *mmuwalk(m->pml4, KZERO, 2, 0);
+	mmuflushtlb();
+
+	/* setup reboot trampoline function */
+	f = (void*)REBOOTADDR;
+	memmove(f, rebootcode, sizeof(rebootcode));
+
+	/* off we go - never to return */
+	coherence();
+	(*f)(entry, code, size);
+
+	for(;;);
+}
+
+
 void
 exit(int)
 {
 	cpushutdown();
+	if(m->machno)
+		rebootjump(0, 0, 0);
 	arch->reset();
 }
 
 void
 reboot(void *entry, void *code, ulong size)
 {
-	void (*f)(uintptr, uintptr, ulong);
-
 	writeconf();
 	vmxshutdown();
 
@@ -362,7 +389,7 @@ reboot(void *entry, void *code, ulong size)
 		sched();
 	}
 	cpushutdown();
-
+	delay(1000);
 	splhi();
 
 	/* turn off buffered serial console */
@@ -370,22 +397,8 @@ reboot(void *entry, void *code, ulong size)
 
 	/* shutdown devices */
 	chandevshutdown();
-	arch->introff();
-
-	/*
-	 * This allows the reboot code to turn off the page mapping
-	 */
-	*mmuwalk(m->pml4, 0, 3, 0) = *mmuwalk(m->pml4, KZERO, 3, 0);
-	*mmuwalk(m->pml4, 0, 2, 0) = *mmuwalk(m->pml4, KZERO, 2, 0);
-	mmuflushtlb();
-
-	/* setup reboot trampoline function */
-	f = (void*)REBOOTADDR;
-	memmove(f, rebootcode, sizeof(rebootcode));
 
-	/* off we go - never to return */
-	coherence();
-	(*f)((uintptr)entry & ~0xF0000000UL, (uintptr)PADDR(code), size);
+	rebootjump((uintptr)entry & ~0xF0000000UL, PADDR(code), size);
 }
 
 /*
diff --git a/sys/src/9/pc64/rebootcode.s b/sys/src/9/pc64/rebootcode.s
index 7b6d150f1..91c3c788d 100644
--- a/sys/src/9/pc64/rebootcode.s
+++ b/sys/src/9/pc64/rebootcode.s
@@ -20,9 +20,6 @@ TEXT	main(SB), 1, $-4
 	MOVL	$_gdtptr64p<>(SB), AX
 	MOVL	(AX), GDTR
 
-	/* move stack below destination */
-	MOVL	DI, SP
-
 	/* load CS with 32bit code segment */
 	PUSHQ	$SELECTOR(3, SELGDT, 0)
 	PUSHQ	$_warp32<>(SB)
@@ -61,6 +58,12 @@ TEXT	_warp32<>(SB), 1, $-4
 
 	MOVL	BX, CX			/* byte count */
 	MOVL	DI, AX			/* save entry point */
+	MOVL	AX, SP			/* move stack below entry */
+
+	/* park cpu for zero entry point */
+	ORL	AX, AX
+	JZ	_idle
+
 
 /*
  * the source and destination may overlap.
@@ -90,6 +93,10 @@ _back:
 	REP;	MOVSB
 	JMP	_startkernel
 
+_idle:
+	HLT
+	JMP	_idle
+
 TEXT _gdt<>(SB), 1, $-4
 	/* null descriptor */
 	LONG	$0