Emulate ptrace(PT_STEP in software.

More or less directly from FreeBSD.

4 files changed, 245 insertions, 19 deletions

diff --git a/sys/arch/alpha/alpha/process_machdep.c b/sys/arch/alpha/alpha/process_machdep.c
index 2427271486e..4e15522218f 100644
--- a/sys/arch/alpha/alpha/process_machdep.c
+++ b/sys/arch/alpha/alpha/process_machdep.c
@@ -1,6 +1,31 @@
-/*	$OpenBSD: process_machdep.c,v 1.5 2000/11/08 16:01:03 art Exp $	*/
+/*	$OpenBSD: process_machdep.c,v 1.6 2002/03/12 11:58:14 art Exp $	*/
 /*	$NetBSD: process_machdep.c,v 1.7 1996/07/11 20:14:21 cgd Exp $	*/
 
+/*-
+ * Copyright (c) 1998 Doug Rabson
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
 /*
  * Copyright (c) 1994 Christopher G. Demetriou
  * All rights reserved.
@@ -63,6 +88,9 @@
 #include <machine/reg.h>
 #include <machine/frame.h>
 
+#include <alpha/alpha/db_instruction.h>
+#include <miscfs/procfs/procfs.h>
+
 #define	process_frame(p)	((p)->p_md.md_tf)
 #define	process_pcb(p)		(&(p)->p_addr->u_pcb)
 #define	process_fpframe(p)	(&(process_pcb(p)->pcb_fp))
@@ -92,18 +120,6 @@ process_write_regs(p, regs)
 }
 
 int
-process_sstep(p, sstep)
-	struct proc *p;
-	int sstep;
-{
-
-	if (sstep)
-		return (EINVAL);
-
-	return (0);
-}
-
-int
 process_set_pc(p, addr)
 	struct proc *p;
 	caddr_t addr;
@@ -142,3 +158,193 @@ process_write_fpregs(p, regs)
 	bcopy(regs, process_fpframe(p), sizeof(struct fpreg));
 	return (0);
 }
+
+/*
+ * Single stepping infrastructure.
+ */
+int ptrace_set_bpt(struct proc *p, struct mdbpt *bpt);
+int ptrace_clear_bpt(struct proc *p, struct mdbpt *bpt);
+int ptrace_read_int(struct proc *, vaddr_t, u_int32_t *);
+int ptrace_write_int(struct proc *, vaddr_t, u_int32_t);
+u_int64_t ptrace_read_register(struct proc *p, int regno);
+
+int
+ptrace_read_int(struct proc *p, vaddr_t addr, u_int32_t *v)
+{
+	struct iovec iov;
+	struct uio uio;
+
+	iov.iov_base = (caddr_t) v;
+	iov.iov_len = sizeof(u_int32_t);
+	uio.uio_iov = &iov;
+	uio.uio_iovcnt = 1;
+	uio.uio_offset = (off_t)addr;
+	uio.uio_resid = sizeof(u_int32_t);
+	uio.uio_segflg = UIO_SYSSPACE;
+	uio.uio_rw = UIO_READ;
+	uio.uio_procp = p;
+	return procfs_domem(curproc, p, NULL, &uio);
+}
+
+int
+ptrace_write_int(struct proc *p, vaddr_t addr, u_int32_t v)
+{
+	struct iovec iov;
+	struct uio uio;
+
+	iov.iov_base = (caddr_t) &v;
+	iov.iov_len = sizeof(u_int32_t);
+	uio.uio_iov = &iov;
+	uio.uio_iovcnt = 1;
+	uio.uio_offset = (off_t)addr;
+	uio.uio_resid = sizeof(u_int32_t);
+	uio.uio_segflg = UIO_SYSSPACE;
+	uio.uio_rw = UIO_WRITE;
+	uio.uio_procp = p;
+	return procfs_domem(curproc, p, NULL, &uio);
+}
+
+u_int64_t
+ptrace_read_register(struct proc *p, int regno)
+{
+	static int reg_to_frame[32] = {
+		FRAME_V0,
+		FRAME_T0,
+		FRAME_T1,
+		FRAME_T2,
+		FRAME_T3,
+		FRAME_T4,
+		FRAME_T5,
+		FRAME_T6,
+		FRAME_T7,
+
+		FRAME_S0,
+		FRAME_S1,
+		FRAME_S2,
+		FRAME_S3,
+		FRAME_S4,
+		FRAME_S5,
+		FRAME_S6,
+
+		FRAME_A0,
+		FRAME_A1,
+		FRAME_A2,
+		FRAME_A3,
+		FRAME_A4,
+		FRAME_A5,
+
+		FRAME_T8,
+		FRAME_T9,
+		FRAME_T10,
+		FRAME_T11,
+		FRAME_RA,
+		FRAME_T12,
+		FRAME_AT,
+		FRAME_GP,
+		FRAME_SP,
+		-1,		/* zero */
+	};
+
+	if (regno == R_ZERO)
+		return 0;
+
+	return p->p_md.md_tf->tf_regs[reg_to_frame[regno]];
+}
+
+int
+ptrace_clear_bpt(struct proc *p, struct mdbpt *bpt)
+{
+	return ptrace_write_int(p, bpt->addr, bpt->contents);
+}
+
+int
+ptrace_set_bpt(struct proc *p, struct mdbpt *bpt)
+{
+	int error;
+	u_int32_t bpins = 0x00000080;
+	error = ptrace_read_int(p, bpt->addr, &bpt->contents);
+	if (error)
+		return error;
+	return ptrace_write_int(p, bpt->addr, bpins);
+}
+
+int
+process_sstep(struct proc *p, int sstep)
+{
+	int error;
+	vaddr_t pc = p->p_md.md_tf->tf_regs[FRAME_PC];
+	alpha_instruction ins;
+	vaddr_t addr[2];
+	int count = 0;
+
+	if (sstep == 0) {
+		/* clearing the breakpoint */
+		if (p->p_md.md_flags & MDP_STEP2) {
+			ptrace_clear_bpt(p, &p->p_md.md_sstep[1]);
+			ptrace_clear_bpt(p, &p->p_md.md_sstep[0]);
+			p->p_md.md_flags &= ~MDP_STEP2;
+		} else if (p->p_md.md_flags & MDP_STEP1) {
+			ptrace_clear_bpt(p, &p->p_md.md_sstep[0]);
+			p->p_md.md_flags &= ~MDP_STEP1;
+		}
+		return (0);
+	}
+#ifdef DIAGNOSTIC
+	if (p->p_md.md_flags & (MDP_STEP1|MDP_STEP2))
+		panic("process_sstep: step breakpoints not removed");
+#endif
+	error = ptrace_read_int(p, pc, &ins.bits);
+	if (error)
+		return (error);
+
+	switch (ins.branch_format.opcode) {
+	case op_j:
+		/* Jump: target is register value */
+		addr[0] = ptrace_read_register(p, ins.jump_format.rb) & ~3;
+		count = 1;
+		break;
+
+	case op_br:
+	case op_fbeq:
+	case op_fblt:
+	case op_fble:
+	case op_bsr:
+	case op_fbne:
+	case op_fbge:
+	case op_fbgt:
+	case op_blbc:
+	case op_beq:
+	case op_blt:
+	case op_ble:
+	case op_blbs:
+	case op_bne:
+	case op_bge:
+	case op_bgt:
+		/* Branch: target is pc+4+4*displacement */
+		addr[0] = pc + 4;
+		addr[1] = pc + 4 + 4 * ins.branch_format.displacement;
+		count = 2;
+		break;
+
+	default:
+		addr[0] = pc + 4;
+		count = 1;
+	}
+
+	p->p_md.md_sstep[0].addr = addr[0];
+	error = ptrace_set_bpt(p, &p->p_md.md_sstep[0]);
+	if (error)
+		return (error);
+	if (count == 2) {
+		p->p_md.md_sstep[1].addr = addr[1];
+		error = ptrace_set_bpt(p, &p->p_md.md_sstep[1]);
+		if (error) {
+			ptrace_clear_bpt(p, &p->p_md.md_sstep[0]);
+			return (error);
+		}
+		p->p_md.md_flags |= MDP_STEP2;
+	} else
+		p->p_md.md_flags |= MDP_STEP1;
+
+	return (0);
+}
diff --git a/sys/arch/alpha/alpha/trap.c b/sys/arch/alpha/alpha/trap.c
index 1adc97860b9..fdc15020ce5 100644
--- a/sys/arch/alpha/alpha/trap.c
+++ b/sys/arch/alpha/alpha/trap.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: trap.c,v 1.29 2001/11/28 16:13:27 art Exp $ */
+/* $OpenBSD: trap.c,v 1.30 2002/03/12 11:58:14 art Exp $ */
 /* $NetBSD: trap.c,v 1.52 2000/05/24 16:48:33 thorpej Exp $ */
 
 /*-
@@ -105,6 +105,7 @@
 #ifdef KTRACE
 #include <sys/ktrace.h>
 #endif
+#include <sys/ptrace.h>
 
 #include <uvm/uvm_extern.h>
 
@@ -384,6 +385,10 @@ trap(a0, a1, a2, entry, framep)
 			/* FALLTHROUTH */
 		case ALPHA_IF_CODE_BPT:
 		case ALPHA_IF_CODE_BUGCHK:
+			if (p->p_md.md_flags & (MDP_STEP1|MDP_STEP2)) {
+				process_sstep(p, 0);
+				p->p_md.md_tf->tf_regs[FRAME_PC] -= 4;
+			}
 			ucode = a0;		/* trap type */
 			i = SIGTRAP;
 			break;
diff --git a/sys/arch/alpha/include/proc.h b/sys/arch/alpha/include/proc.h
index 22ceefe5803..8caaad0c739 100644
--- a/sys/arch/alpha/include/proc.h
+++ b/sys/arch/alpha/include/proc.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: proc.h,v 1.5 2000/11/08 16:01:13 art Exp $	*/
+/*	$OpenBSD: proc.h,v 1.6 2002/03/12 11:58:14 art Exp $	*/
 /*	$NetBSD: proc.h,v 1.2 1995/03/24 15:01:36 cgd Exp $	*/
 
 /*
@@ -33,13 +33,21 @@
  * Machine-dependent part of the proc struct for the Alpha.
  */
 
+struct mdbpt {
+	vaddr_t	addr;
+	u_int32_t contents;
+};
+
 struct mdproc {
-	u_long	md_flags;
-	struct	trapframe *md_tf;	/* trap/syscall registers */
+	u_long md_flags;
+	struct trapframe *md_tf;	/* trap/syscall registers */
 	struct pcb *md_pcbpaddr;	/* phys addr of the pcb */
+	struct mdbpt md_sstep[2];	/* two breakpoints for sstep */
 };
 
 #define	MDP_FPUSED	0x0001		/* Process used the FPU */
+#define MDP_STEP1	0x0002		/* Single step normal */
+#define MDP_STEP2	0x0003		/* Single step branch */
 
 #ifdef _KERNEL
 void switch_exit __P((struct proc *));
diff --git a/sys/arch/alpha/include/ptrace.h b/sys/arch/alpha/include/ptrace.h
index a38169df9d0..81040c1cbf1 100644
--- a/sys/arch/alpha/include/ptrace.h
+++ b/sys/arch/alpha/include/ptrace.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ptrace.h,v 1.3 1996/10/30 22:39:24 niklas Exp $	*/
+/*	$OpenBSD: ptrace.h,v 1.4 2002/03/12 11:58:14 art Exp $	*/
 /*	$NetBSD: ptrace.h,v 1.1 1995/02/13 23:07:51 cgd Exp $	*/
 
 /*
@@ -31,11 +31,18 @@
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+#ifndef __MACHINE_PTRACE_H__
+#define __MACHINE_PTRACE_H__
+
 /*
  * Alpha-dependent ptrace definitions.
- * Note that PT_STEP is _not_ supported.
  */
 #define PT_GETREGS      (PT_FIRSTMACH + 0)
 #define PT_SETREGS      (PT_FIRSTMACH + 1)
 #define PT_GETFPREGS    (PT_FIRSTMACH + 2)
 #define PT_SETFPREGS    (PT_FIRSTMACH + 3)
+#define PT_STEP		(PT_FIRSTMACH + 4)
+
+#define FIX_SSTEP(p)	process_sstep(p, 0)
+
+#endif