Implement makectx(). The makectx() function is used by KDB to create

a PCB from a trapframe for purposes of unwinding the stack. The PCB
is used as the thread context and all but the thread that entered the
debugger has a valid PCB.
This function can also be used to create a context for the threads
running on the CPUs that have been stopped when the debugger got
entered. This however is not done at the time of this commit.

sys/alpha/alpha/machdep.c

@@ -1989,6 +1989,29 @@ alpha_pa_access(vm_offset_t pa)
 #endif
 }
 
+/*
+ * Construct a PCB from a trapframe. This is called from kdb_trap() where
+ * we want to start a backtrace from the function that caused us to enter
+ * the debugger. We have the context in the trapframe, but base the trace
+ * on the PCB. The PCB doesn't have to be perfect, as long as it contains
+ * enough for a backtrace.
+ */
+void
+makectx(struct trapframe *tf, struct pcb *pcb)
+{
+
+	pcb->pcb_context[0] = tf->tf_regs[FRAME_S0];
+	pcb->pcb_context[1] = tf->tf_regs[FRAME_S1];
+	pcb->pcb_context[2] = tf->tf_regs[FRAME_S2];
+	pcb->pcb_context[3] = tf->tf_regs[FRAME_S3];
+	pcb->pcb_context[4] = tf->tf_regs[FRAME_S4];
+	pcb->pcb_context[5] = tf->tf_regs[FRAME_S5];
+	pcb->pcb_context[6] = tf->tf_regs[FRAME_S6];
+	pcb->pcb_context[7] = tf->tf_regs[FRAME_PC];
+	pcb->pcb_context[8] = tf->tf_regs[FRAME_PS];
+	pcb->pcb_hw.apcb_ksp = tf->tf_regs[FRAME_SP];
+}
+
 int
 fill_regs(td, regs)
 	struct thread *td;

sys/alpha/include/pcb.h

@@ -58,6 +58,7 @@ struct pcb {
 };
 
 #ifdef _KERNEL
+void	makectx(struct trapframe *, struct pcb *);
 void	savectx(struct pcb *);
 #endif
 

sys/amd64/amd64/machdep.c

@@ -1265,6 +1265,27 @@ cpu_pcpu_init(struct pcpu *pcpu, int cpuid, size_t size)
 	pcpu->pc_acpi_id = 0xffffffff;
 }
 
+/*
+ * Construct a PCB from a trapframe. This is called from kdb_trap() where
+ * we want to start a backtrace from the function that caused us to enter
+ * the debugger. We have the context in the trapframe, but base the trace
+ * on the PCB. The PCB doesn't have to be perfect, as long as it contains
+ * enough for a backtrace.
+ */
+void
+makectx(struct trapframe *tf, struct pcb *pcb)
+{
+
+	pcb->pcb_r12 = tf->tf_r12;
+	pcb->pcb_r13 = tf->tf_r13;
+	pcb->pcb_r14 = tf->tf_r14;
+	pcb->pcb_r15 = tf->tf_r15;
+	pcb->pcb_rbp = tf->tf_rbp;
+	pcb->pcb_rbx = tf->tf_rbx;
+	pcb->pcb_rip = tf->tf_rip;
+	pcb->pcb_rsp = (ISPL(tf->tf_cs)) ? tf->tf_rsp : (long)(tf + 1) - 8;
+}
+
 int
 ptrace_set_pc(struct thread *td, unsigned long addr)
 {

sys/amd64/include/pcb.h

@@ -78,6 +78,9 @@ struct pcb {
 };
 
 #ifdef _KERNEL
+struct trapframe;
+
+void	makectx(struct trapframe *, struct pcb *);
 void	savectx(struct pcb *);
 #endif
 

sys/i386/i386/machdep.c

@@ -2206,6 +2206,25 @@ f00f_hack(void *unused)
 }
 #endif /* defined(I586_CPU) && !NO_F00F_HACK */
 
+/*
+ * Construct a PCB from a trapframe. This is called from kdb_trap() where
+ * we want to start a backtrace from the function that caused us to enter
+ * the debugger. We have the context in the trapframe, but base the trace
+ * on the PCB. The PCB doesn't have to be perfect, as long as it contains
+ * enough for a backtrace.
+ */
+void
+makectx(struct trapframe *tf, struct pcb *pcb)
+{
+
+	pcb->pcb_edi = tf->tf_edi;
+	pcb->pcb_esi = tf->tf_esi;
+	pcb->pcb_ebp = tf->tf_ebp;
+	pcb->pcb_ebx = tf->tf_ebx;
+	pcb->pcb_eip = tf->tf_eip;
+	pcb->pcb_esp = (ISPL(tf->tf_cs)) ? tf->tf_esp : (int)(tf + 1) - 8;
+}
+
 int
 ptrace_set_pc(struct thread *td, u_long addr)
 {

sys/i386/include/pcb.h

@@ -74,6 +74,9 @@ struct pcb {
 };
 
 #ifdef _KERNEL
+struct trapframe;
+
+void	makectx(struct trapframe *, struct pcb *);
 void	savectx(struct pcb *);
 #endif
 

sys/ia64/ia64/machdep.c

@@ -1017,6 +1017,23 @@ freebsd4_sigreturn(struct thread *td, struct freebsd4_sigreturn_args *uap)
 }
 #endif
 
+/*
+ * Construct a PCB from a trapframe. This is called from kdb_trap() where
+ * we want to start a backtrace from the function that caused us to enter
+ * the debugger. We have the context in the trapframe, but base the trace
+ * on the PCB. The PCB doesn't have to be perfect, as long as it contains
+ * enough for a backtrace.
+ */
+void
+makectx(struct trapframe *tf, struct pcb *pcb)
+{
+
+	pcb->pcb_special = tf->tf_special;
+	pcb->pcb_special.__spare = ~0UL;	/* XXX see unwind.c */
+	save_callee_saved(&pcb->pcb_preserved);
+	save_callee_saved_fp(&pcb->pcb_preserved_fp);
+}
+
 int
 get_mcontext(struct thread *td, mcontext_t *mc, int flags)
 {

sys/ia64/include/pcb.h

@@ -1,5 +1,5 @@
 /*-
- * Copyright (c) 2003 Doug Rabson
+ * Copyright (c) 2003,2004 Marcel Moolenaar
  * Copyright (c) 2000 Doug Rabson
  * All rights reserved.
  *
@@ -59,6 +59,10 @@ struct pcb {
 #ifdef _KERNEL
 
 #define	savectx(p)	swapctx(p, NULL)
+
+struct trapframe;
+
+void makectx(struct trapframe *, struct pcb *);
 void restorectx(struct pcb *) __dead2;
 int swapctx(struct pcb *old, struct pcb *new);
 

sys/sparc64/include/pcb.h

@@ -49,6 +49,7 @@ struct pcb {
 } __aligned(64);
 
 #ifdef _KERNEL
+void	makectx(struct trapframe *, struct pcb *);
 int	savectx(struct pcb *pcb);
 #endif
 

sys/sparc64/sparc64/machdep.c

@@ -564,6 +564,21 @@ freebsd4_sigreturn(struct thread *td, struct freebsd4_sigreturn_args *uap)
 }
 #endif
 
+/*
+ * Construct a PCB from a trapframe. This is called from kdb_trap() where
+ * we want to start a backtrace from the function that caused us to enter
+ * the debugger. We have the context in the trapframe, but base the trace
+ * on the PCB. The PCB doesn't have to be perfect, as long as it contains
+ * enough for a backtrace.
+ */
+void
+makectx(struct trapframe *tf, struct pcb *pcb)
+{
+
+	pcb->pcb_pc = tf->tf_tpc;
+	pcb->pcb_sp = tf->tf_sp;
+}
+
 int
 get_mcontext(struct thread *td, mcontext_t *mc, int flags)
 {