Make Book-E debug register state part of the PCB context.

Previously, DBCR0 flags were set "globally", but this leads to problems
because Book-E fine grained debug settings work only in conjuction with the
debug master enable bit in MSR: in scenarios when the DBCR0 was set with
intention to debug one process, but another one with MSR[DE] set got
scheduled, the latter would immediately cause debug exceptions to occur upon
execution of its own code instructions (and not the one intended for
debugging).

To avoid such problems and properly handle debugging context, DBCR0 state
should be managed individually per process.

Submitted by:	Grzegorz Bernacki gjb ! semihalf dot com
Reviewed by:	marcel

4 files changed, 14 insertions, 5 deletions

diff --git a/sys/powerpc/booke/machdep.c b/sys/powerpc/booke/machdep.c
index 1803ef2..e42aa8c 100644
--- a/sys/powerpc/booke/machdep.c
+++ b/sys/powerpc/booke/machdep.c
@@ -806,14 +806,10 @@ int
 ptrace_single_step(struct thread *td)
 {
 	struct trapframe *tf;
-	u_int reg;
-
-	reg = mfspr(SPR_DBCR0);
-	reg |= DBCR0_IC | DBCR0_IDM;
-	mtspr(SPR_DBCR0, reg);
 
 	tf = td->td_frame;
 	tf->srr1 |= PSL_DE;
+	tf->cpu.booke.dbcr0 |= (DBCR0_IDM | DBCR0_IC);
 	return (0);
 }
 
@@ -824,6 +820,7 @@ ptrace_clear_single_step(struct thread *td)
 
 	tf = td->td_frame;
 	tf->srr1 &= ~PSL_DE;
+	tf->cpu.booke.dbcr0 &= ~(DBCR0_IDM | DBCR0_IC);
 	return (0);
 }
 
diff --git a/sys/powerpc/booke/swtch.S b/sys/powerpc/booke/swtch.S
index 80bf2b3..bfd7dd2 100644
--- a/sys/powerpc/booke/swtch.S
+++ b/sys/powerpc/booke/swtch.S
@@ -66,6 +66,7 @@
 #include <machine/param.h>
 #include <machine/psl.h>
 #include <machine/asm.h>
+#include <machine/spr.h>
 
 /*
  * void cpu_switch(struct thread *old, struct thread *new)
@@ -87,6 +88,8 @@ ENTRY(cpu_switch)
 	stw	%r16, PCB_BOOKE_CTR(%r5)
 	mfxer	%r16
 	stw	%r16, PCB_BOOKE_XER(%r5)
+	mfspr	%r16, SPR_DBCR0
+	stw	%r16, PCB_BOOKE_DBCR0(%r5)
 
 	stw	%r1, PCB_SP(%r5)	/* Save the stack pointer */
 
@@ -114,6 +117,8 @@ ENTRY(cpu_switch)
 	mtctr	%r5
 	lwz	%r5, PCB_BOOKE_XER(%r3)
 	mtxer	%r5
+	lwz	%r5, PCB_BOOKE_DBCR0(%r3)
+	mtspr	SPR_DBCR0, %r5
 
 	lwz	%r1, PCB_SP(%r3)	/* Load the stack pointer */
 	blr
diff --git a/sys/powerpc/booke/trap.c b/sys/powerpc/booke/trap.c
index 88a0a51..0e746f4 100644
--- a/sys/powerpc/booke/trap.c
+++ b/sys/powerpc/booke/trap.c
@@ -187,6 +187,7 @@ trap(struct trapframe *frame)
 		case EXC_DEBUG:	/* Single stepping */
 			mtspr(SPR_DBSR, mfspr(SPR_DBSR));
 			frame->srr1 &= ~PSL_DE;
+			frame->cpu.booke.dbcr0 &= ~(DBCR0_IDM || DBCR0_IC);
 			sig = SIGTRAP;
 			break;
 
diff --git a/sys/powerpc/booke/trap_subr.S b/sys/powerpc/booke/trap_subr.S
index f7a54a6..2a5820d 100644
--- a/sys/powerpc/booke/trap_subr.S
+++ b/sys/powerpc/booke/trap_subr.S
@@ -207,6 +207,9 @@
 	stw	%r4, FRAME_CTR+8(1);					\
 	li	%r5, exc;						\
 	stw	%r5, FRAME_EXC+8(1);					\
+	/* save DBCR0 */						\
+	mfspr	%r3, SPR_DBCR0;						\
+	stw	%r3, FRAME_BOOKE_DBCR0+8(1);				\
 	/* save xSSR0-1 */						\
 	lwz	%r30, (savearea+CPUSAVE_SRR0)(%r2);			\
 	lwz	%r31, (savearea+CPUSAVE_SRR1)(%r2);			\
@@ -231,6 +234,9 @@
 	mtxer	%r5;							\
 	mtlr	%r6;							\
 	mtcr	%r7;							\
+	/* restore DBCR0 */						\
+	lwz	%r4, FRAME_BOOKE_DBCR0+8(%r1);				\
+	mtspr	SPR_DBCR0, %r4;						\
 	/* restore xSRR0-1 */						\
 	lwz	%r30, FRAME_SRR0+8(%r1);				\
 	lwz	%r31, FRAME_SRR1+8(%r1);				\