[PATCH 2.6.10-rc3-mm1] m32r: Update ptrace.c for multithreaddebugging

[Hirokazu Takata]

Hello,

This patch updates ptrace.c to support multithread debugging.
So far, only one breakpoint's location was kept by kernel, however,
in the multithreaded application's debug, it is required to kept 
multi-point breakpoint locations by kernel.

In this implementation, maximum number of MAX_TRAPS(=10 (by default))
breakpoint's information will be kept in the "debug_trap" member
of the thread_struct for each thread.

	* include/asm-m32r/processor.h: 
	  Modify debug_trap struct to keep multipoint breakpoint locations
	  for multithread debugging.

	* arch/m32r/kernel/ptrace.c:
	- Update to support multithread debugging.
	- Remove unused functions, withdraw_debug_trap_for_signal() and
	  embed_debug_trap_for_signal().

Regards,

Signed-off-by: Kei Sakamoto <ksakamot@xxxxxxxxxxxxxx>
Signed-off-by: Hirokazu Takata <takata@xxxxxxxxxxxxxx>
---

 arch/m32r/kernel/ptrace.c    |   89 ++++++++++++++-----------------------------
 include/asm-m32r/processor.h |    6 +-
 2 files changed, 34 insertions(+), 61 deletions(-)


diff -ruNp a/include/asm-m32r/processor.h b/include/asm-m32r/processor.h
--- a/include/asm-m32r/processor.h	2004-12-15 18:36:49.000000000 +0900
+++ b/include/asm-m32r/processor.h	2004-12-15 18:37:29.000000000 +0900
@@ -70,10 +70,12 @@ typedef struct {
 	unsigned long seg;
 } mm_segment_t;
 
+#define MAX_TRAPS 10
+
 struct debug_trap {
 	int nr_trap;
-	unsigned long	addr;
-	unsigned long	insn;
+	unsigned long	addr[MAX_TRAPS];
+	unsigned long	insn[MAX_TRAPS];
 };
 
 struct thread_struct {
diff -ruNp a/arch/m32r/kernel/ptrace.c b/arch/m32r/kernel/ptrace.c
--- a/arch/m32r/kernel/ptrace.c	2004-12-15 18:36:49.000000000 +0900
+++ b/arch/m32r/kernel/ptrace.c	2004-12-15 18:37:47.000000000 +0900
@@ -2,7 +2,7 @@
  * linux/arch/m32r/kernel/ptrace.c
  *
  * Copyright (C) 2002  Hirokazu Takata, Takeo Takahashi
- * Copyright (C) 2004  Hirokazu Takata <takata at linux-m32r.org>
+ * Copyright (C) 2004  Hirokazu Takata, Kei Sakamoto
  *
  * Original x86 implementation:
  *	By Ross Biro 1/23/92
@@ -450,13 +450,13 @@ register_debug_trap(struct task_struct *
 	struct debug_trap *p = &child->thread.debug_trap;
 	unsigned long addr = next_pc & ~3;
 
-	if (p->nr_trap != 0) {
+	if (p->nr_trap == MAX_TRAPS) {
 		printk("kernel BUG at %s %d: p->nr_trap = %d\n",
 					__FILE__, __LINE__, p->nr_trap);
 		return -1;
 	}
-	p->addr = addr;
-	p->insn = next_insn;
+	p->addr[p->nr_trap] = addr;
+	p->insn[p->nr_trap] = next_insn;
 	p->nr_trap++;
 	if (next_pc & 3) {
 		*code = (next_insn & 0xffff0000) | 0x10f1;
@@ -473,35 +473,34 @@ register_debug_trap(struct task_struct *
 	return 0;
 }
 
-int withdraw_debug_trap_for_signal(struct task_struct *child)
-{
-	struct debug_trap *p = &child->thread.debug_trap;
-	int nr_trap = p->nr_trap;
-
-	if (nr_trap) {
-		access_process_vm(child, p->addr, &p->insn, sizeof(p->insn), 1);
-		p->nr_trap = 0;
-		p->addr = 0;
-		p->insn = 0;
-	}
-	return nr_trap;
-}
-
 static int
 unregister_debug_trap(struct task_struct *child, unsigned long addr,
 		      unsigned long *code)
 {
 	struct debug_trap *p = &child->thread.debug_trap;
+        int i;
 
-	if (p->nr_trap != 1 || p->addr != addr) {
+	/* Search debug trap entry. */
+	for (i = 0; i < p->nr_trap; i++) {
+		if (p->addr[i] == addr)
+			break;
+	}
+	if (i >= p->nr_trap) {
 		/* The trap may be requested from debugger.
 		 * ptrace should do nothing in this case.
 		 */
 		return 0;
 	}
-	*code = p->insn;
-	p->insn = 0;
-	p->addr = 0;
+
+	/* Recover orignal instruction code. */
+	*code = p->insn[i];
+
+	/* Shift debug trap entries. */
+	while (i < p->nr_trap - 1) {
+		p->insn[i] = p->insn[i + 1];
+		p->addr[i] = p->addr[i + 1];
+		i++;
+	}
 	p->nr_trap--;
 	return 1;
 }
@@ -510,13 +509,11 @@ static void
 unregister_all_debug_traps(struct task_struct *child)
 {
 	struct debug_trap *p = &child->thread.debug_trap;
+	int i;
 
-	if (p->nr_trap) {
-		access_process_vm(child, p->addr, &p->insn, sizeof(p->insn), 1);
-		p->addr = 0;
-		p->insn = 0;
-		p->nr_trap = 0;
-	}
+	for (i = 0; i < p->nr_trap; i++)
+		access_process_vm(child, p->addr[i], &p->insn[i], sizeof(p->insn[i]), 1);
+	p->nr_trap = 0;
 }
 
 static inline void
@@ -576,34 +573,6 @@ embed_debug_trap(struct task_struct *chi
 }
 
 void
-embed_debug_trap_for_signal(struct task_struct *child)
-{
-	unsigned long next_pc;
-	unsigned long pc, insn;
-	int ret;
-
-	pc = get_stack_long(child, PT_BPC);
-	ret = access_process_vm(child, pc&~3, &insn, sizeof(insn), 0);
-	if (ret != sizeof(insn)) {
-		printk("kernel BUG at %s %d: access_process_vm returns %d\n",
-		       __FILE__, __LINE__, ret);
-		return;
-	}
-	compute_next_pc(insn, pc, &next_pc, child);
-	if (next_pc & 0x80000000) {
-		printk("kernel BUG at %s %d: next_pc = 0x%08x\n",
-		       __FILE__, __LINE__, (int)next_pc);
-		return;
-	}
-	if (embed_debug_trap(child, next_pc)) {
-		printk("kernel BUG at %s %d: embed_debug_trap error\n",
-		       __FILE__, __LINE__);
-		return;
-	}
-	invalidate_cache();
-}
-
-void
 withdraw_debug_trap(struct pt_regs *regs)
 {
 	unsigned long addr;
@@ -621,9 +590,12 @@ static void
 init_debug_traps(struct task_struct *child)
 {
 	struct debug_trap *p = &child->thread.debug_trap;
+	int i;
 	p->nr_trap = 0;
-	p->addr = 0;
-	p->insn = 0;
+	for (i = 0; i < MAX_TRAPS; i++) {
+		p->addr[i] = 0;
+		p->insn[i] = 0;
+	}
 }
 
 
@@ -855,4 +827,3 @@ void do_syscall_trace(void)
 		current->exit_code = 0;
 	}
 }
-

--
Hirokazu Takata <takata@xxxxxxxxxxxxxx>
Linux/M32R Project:  http://www.linux-m32r.org/
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