Update the callframe structure to leave space for the frame pointer

and saved link register as per the ABI call sequence. Update code
that uses this (fork_trampoline etc) to use the correct genassym'd
offsets.

 This fixes the 'invalid LR' message when backtracing kernel
threads in DDB.

6 files changed, 16 insertions, 2 deletions

diff --git a/sys/powerpc/aim/swtch.S b/sys/powerpc/aim/swtch.S
index 6e3bfdd..12bb488 100644
--- a/sys/powerpc/aim/swtch.S
+++ b/sys/powerpc/aim/swtch.S
@@ -147,5 +147,8 @@ ENTRY(fork_trampoline)
 	lwz	%r4,CF_ARG0(%r1)
 	lwz	%r5,CF_ARG1(%r1)
 	bl	fork_exit
-	addi	%r1,%r1,4
+	addi	%r1,%r1,CF_SIZE-FSP	/* Allow 8 bytes in front of
+					   trapframe to simulate FRAME_SETUP
+					   does when allocating space for
+					   a frame pointer/saved LR */
 	b	trapexit
diff --git a/sys/powerpc/aim/vm_machdep.c b/sys/powerpc/aim/vm_machdep.c
index 4e8c803..3b19213 100644
--- a/sys/powerpc/aim/vm_machdep.c
+++ b/sys/powerpc/aim/vm_machdep.c
@@ -146,6 +146,7 @@ cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags)
 	td2->td_frame = tf;
 
 	cf = (struct callframe *)tf - 1;
+	memset(cf, 0, sizeof(struct callframe));
 	cf->cf_func = (register_t)fork_return;
 	cf->cf_arg0 = (register_t)td2;
 	cf->cf_arg1 = (register_t)tf;
@@ -321,6 +322,7 @@ cpu_set_upcall(struct thread *td, struct thread *td0)
 
 	/* Set registers for trampoline to user mode. */
 	cf = (struct callframe *)tf - 1;
+	memset(cf, 0, sizeof(struct callframe));
 	cf->cf_func = (register_t)fork_return;
 	cf->cf_arg0 = (register_t)td;
 	cf->cf_arg1 = (register_t)tf;
diff --git a/sys/powerpc/include/frame.h b/sys/powerpc/include/frame.h
index 6b75e46..ae0103b 100644
--- a/sys/powerpc/include/frame.h
+++ b/sys/powerpc/include/frame.h
@@ -85,6 +85,8 @@ struct clockframe {
  * Call frame for PowerPC used during fork.
  */
 struct callframe {
+	register_t	cf_dummy_fp;	/* dummy frame pointer */
+	register_t	cf_lr;		/* space for link register save */
 	register_t	cf_func;
 	register_t	cf_arg0;
 	register_t	cf_arg1;
diff --git a/sys/powerpc/powerpc/genassym.c b/sys/powerpc/powerpc/genassym.c
index 38de0c2b..1aa26ef 100644
--- a/sys/powerpc/powerpc/genassym.c
+++ b/sys/powerpc/powerpc/genassym.c
@@ -79,6 +79,7 @@ ASSYM(PM_KERNELSR, offsetof(struct pmap, pm_sr[KERNEL_SR]));
 ASSYM(PM_USRSR, offsetof(struct pmap, pm_sr[USER_SR]));
 ASSYM(PM_SR, offsetof(struct pmap, pm_sr));
 
+ASSYM(FSP, 8);
 ASSYM(FRAMELEN, FRAMELEN);
 ASSYM(FRAME_0, offsetof(struct trapframe, fixreg[0]));
 ASSYM(FRAME_1, offsetof(struct trapframe, fixreg[1]));
@@ -164,6 +165,7 @@ ASSYM(SPFRAME_R0, offsetof(struct spillframe, r0));
 ASSYM(CF_FUNC, offsetof(struct callframe, cf_func));
 ASSYM(CF_ARG0, offsetof(struct callframe, cf_arg0));
 ASSYM(CF_ARG1, offsetof(struct callframe, cf_arg1));
+ASSYM(CF_SIZE, sizeof(struct callframe));
 
 ASSYM(PCB_CONTEXT, offsetof(struct pcb, pcb_context));
 ASSYM(PCB_CR, offsetof(struct pcb, pcb_cr));
diff --git a/sys/powerpc/powerpc/swtch.S b/sys/powerpc/powerpc/swtch.S
index 6e3bfdd..12bb488 100644
--- a/sys/powerpc/powerpc/swtch.S
+++ b/sys/powerpc/powerpc/swtch.S
@@ -147,5 +147,8 @@ ENTRY(fork_trampoline)
 	lwz	%r4,CF_ARG0(%r1)
 	lwz	%r5,CF_ARG1(%r1)
 	bl	fork_exit
-	addi	%r1,%r1,4
+	addi	%r1,%r1,CF_SIZE-FSP	/* Allow 8 bytes in front of
+					   trapframe to simulate FRAME_SETUP
+					   does when allocating space for
+					   a frame pointer/saved LR */
 	b	trapexit
diff --git a/sys/powerpc/powerpc/vm_machdep.c b/sys/powerpc/powerpc/vm_machdep.c
index 4e8c803..3b19213 100644
--- a/sys/powerpc/powerpc/vm_machdep.c
+++ b/sys/powerpc/powerpc/vm_machdep.c
@@ -146,6 +146,7 @@ cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags)
 	td2->td_frame = tf;
 
 	cf = (struct callframe *)tf - 1;
+	memset(cf, 0, sizeof(struct callframe));
 	cf->cf_func = (register_t)fork_return;
 	cf->cf_arg0 = (register_t)td2;
 	cf->cf_arg1 = (register_t)tf;
@@ -321,6 +322,7 @@ cpu_set_upcall(struct thread *td, struct thread *td0)
 
 	/* Set registers for trampoline to user mode. */
 	cf = (struct callframe *)tf - 1;
+	memset(cf, 0, sizeof(struct callframe));
 	cf->cf_func = (register_t)fork_return;
 	cf->cf_arg0 = (register_t)td;
 	cf->cf_arg1 = (register_t)tf;