1 files changed, 356 insertions, 0 deletions

diff --git a/arch/avr32/kernel/ptrace.c b/arch/avr32/kernel/ptrace.c
new file mode 100644
index 000000000..4aedcab7c
--- /dev/null
+++ b/arch/avr32/kernel/ptrace.c
@@ -0,0 +1,356 @@
+/*
+ * Copyright (C) 2004-2006 Atmel Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#undef DEBUG
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <linux/ptrace.h>
+#include <linux/errno.h>
+#include <linux/user.h>
+#include <linux/security.h>
+#include <linux/unistd.h>
+#include <linux/notifier.h>
+
+#include <asm/traps.h>
+#include <asm/uaccess.h>
+#include <asm/ocd.h>
+#include <asm/mmu_context.h>
+#include <linux/kdebug.h>
+
+static struct pt_regs *get_user_regs(struct task_struct *tsk)
+{
+	return (struct pt_regs *)((unsigned long)task_stack_page(tsk) +
+				  THREAD_SIZE - sizeof(struct pt_regs));
+}
+
+void user_enable_single_step(struct task_struct *tsk)
+{
+	pr_debug("user_enable_single_step: pid=%u, PC=0x%08lx, SR=0x%08lx\n",
+		 tsk->pid, task_pt_regs(tsk)->pc, task_pt_regs(tsk)->sr);
+
+	/*
+	 * We can't schedule in Debug mode, so when TIF_BREAKPOINT is
+	 * set, the system call or exception handler will do a
+	 * breakpoint to enter monitor mode before returning to
+	 * userspace.
+	 *
+	 * The monitor code will then notice that TIF_SINGLE_STEP is
+	 * set and return to userspace with single stepping enabled.
+	 * The CPU will then enter monitor mode again after exactly
+	 * one instruction has been executed, and the monitor code
+	 * will then send a SIGTRAP to the process.
+	 */
+	set_tsk_thread_flag(tsk, TIF_BREAKPOINT);
+	set_tsk_thread_flag(tsk, TIF_SINGLE_STEP);
+}
+
+void user_disable_single_step(struct task_struct *child)
+{
+	/* XXX(hch): a no-op here seems wrong.. */
+}
+
+/*
+ * Called by kernel/ptrace.c when detaching
+ *
+ * Make sure any single step bits, etc. are not set
+ */
+void ptrace_disable(struct task_struct *child)
+{
+	clear_tsk_thread_flag(child, TIF_SINGLE_STEP);
+	clear_tsk_thread_flag(child, TIF_BREAKPOINT);
+	ocd_disable(child);
+}
+
+/*
+ * Read the word at offset "offset" into the task's "struct user". We
+ * actually access the pt_regs struct stored on the kernel stack.
+ */
+static int ptrace_read_user(struct task_struct *tsk, unsigned long offset,
+			    unsigned long __user *data)
+{
+	unsigned long *regs;
+	unsigned long value;
+
+	if (offset & 3 || offset >= sizeof(struct user)) {
+		printk("ptrace_read_user: invalid offset 0x%08lx\n", offset);
+		return -EIO;
+	}
+
+	regs = (unsigned long *)get_user_regs(tsk);
+
+	value = 0;
+	if (offset < sizeof(struct pt_regs))
+		value = regs[offset / sizeof(regs[0])];
+
+	pr_debug("ptrace_read_user(%s[%u], %#lx, %p) -> %#lx\n",
+		 tsk->comm, tsk->pid, offset, data, value);
+
+	return put_user(value, data);
+}
+
+/*
+ * Write the word "value" to offset "offset" into the task's "struct
+ * user". We actually access the pt_regs struct stored on the kernel
+ * stack.
+ */
+static int ptrace_write_user(struct task_struct *tsk, unsigned long offset,
+			     unsigned long value)
+{
+	unsigned long *regs;
+
+	pr_debug("ptrace_write_user(%s[%u], %#lx, %#lx)\n",
+			tsk->comm, tsk->pid, offset, value);
+
+	if (offset & 3 || offset >= sizeof(struct user)) {
+		pr_debug("  invalid offset 0x%08lx\n", offset);
+		return -EIO;
+	}
+
+	if (offset >= sizeof(struct pt_regs))
+		return 0;
+
+	regs = (unsigned long *)get_user_regs(tsk);
+	regs[offset / sizeof(regs[0])] = value;
+
+	return 0;
+}
+
+static int ptrace_getregs(struct task_struct *tsk, void __user *uregs)
+{
+	struct pt_regs *regs = get_user_regs(tsk);
+
+	return copy_to_user(uregs, regs, sizeof(*regs)) ? -EFAULT : 0;
+}
+
+static int ptrace_setregs(struct task_struct *tsk, const void __user *uregs)
+{
+	struct pt_regs newregs;
+	int ret;
+
+	ret = -EFAULT;
+	if (copy_from_user(&newregs, uregs, sizeof(newregs)) == 0) {
+		struct pt_regs *regs = get_user_regs(tsk);
+
+		ret = -EINVAL;
+		if (valid_user_regs(&newregs)) {
+			*regs = newregs;
+			ret = 0;
+		}
+	}
+
+	return ret;
+}
+
+long arch_ptrace(struct task_struct *child, long request,
+		 unsigned long addr, unsigned long data)
+{
+	int ret;
+	void __user *datap = (void __user *) data;
+
+	switch (request) {
+	/* Read the word at location addr in the child process */
+	case PTRACE_PEEKTEXT:
+	case PTRACE_PEEKDATA:
+		ret = generic_ptrace_peekdata(child, addr, data);
+		break;
+
+	case PTRACE_PEEKUSR:
+		ret = ptrace_read_user(child, addr, datap);
+		break;
+
+	/* Write the word in data at location addr */
+	case PTRACE_POKETEXT:
+	case PTRACE_POKEDATA:
+		ret = generic_ptrace_pokedata(child, addr, data);
+		break;
+
+	case PTRACE_POKEUSR:
+		ret = ptrace_write_user(child, addr, data);
+		break;
+
+	case PTRACE_GETREGS:
+		ret = ptrace_getregs(child, datap);
+		break;
+
+	case PTRACE_SETREGS:
+		ret = ptrace_setregs(child, datap);
+		break;
+
+	default:
+		ret = ptrace_request(child, request, addr, data);
+		break;
+	}
+
+	return ret;
+}
+
+asmlinkage void syscall_trace(void)
+{
+	if (!test_thread_flag(TIF_SYSCALL_TRACE))
+		return;
+	if (!(current->ptrace & PT_PTRACED))
+		return;
+
+	/* The 0x80 provides a way for the tracing parent to
+	 * distinguish between a syscall stop and SIGTRAP delivery */
+	ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
+				 ? 0x80 : 0));
+
+	/*
+	 * this isn't the same as continuing with a signal, but it
+	 * will do for normal use.  strace only continues with a
+	 * signal if the stopping signal is not SIGTRAP.  -brl
+	 */
+	if (current->exit_code) {
+		pr_debug("syscall_trace: sending signal %d to PID %u\n",
+			 current->exit_code, current->pid);
+		send_sig(current->exit_code, current, 1);
+		current->exit_code = 0;
+	}
+}
+
+/*
+ * debug_trampoline() is an assembly stub which will store all user
+ * registers on the stack and execute a breakpoint instruction.
+ *
+ * If we single-step into an exception handler which runs with
+ * interrupts disabled the whole time so it doesn't have to check for
+ * pending work, its return address will be modified so that it ends
+ * up returning to debug_trampoline.
+ *
+ * If the exception handler decides to store the user context and
+ * enable interrupts after all, it will restore the original return
+ * address and status register value. Before it returns, it will
+ * notice that TIF_BREAKPOINT is set and execute a breakpoint
+ * instruction.
+ */
+extern void debug_trampoline(void);
+
+asmlinkage struct pt_regs *do_debug(struct pt_regs *regs)
+{
+	struct thread_info	*ti;
+	unsigned long		trampoline_addr;
+	u32			status;
+	u32			ctrl;
+	int			code;
+
+	status = ocd_read(DS);
+	ti = current_thread_info();
+	code = TRAP_BRKPT;
+
+	pr_debug("do_debug: status=0x%08x PC=0x%08lx SR=0x%08lx tif=0x%08lx\n",
+			status, regs->pc, regs->sr, ti->flags);
+
+	if (!user_mode(regs)) {
+		unsigned long	die_val = DIE_BREAKPOINT;
+
+		if (status & (1 << OCD_DS_SSS_BIT))
+			die_val = DIE_SSTEP;
+
+		if (notify_die(die_val, "ptrace", regs, 0, 0, SIGTRAP)
+				== NOTIFY_STOP)
+			return regs;
+
+		if ((status & (1 << OCD_DS_SWB_BIT))
+				&& test_and_clear_ti_thread_flag(
+					ti, TIF_BREAKPOINT)) {
+			/*
+			 * Explicit breakpoint from trampoline or
+			 * exception/syscall/interrupt handler.
+			 *
+			 * The real saved regs are on the stack right
+			 * after the ones we saved on entry.
+			 */
+			regs++;
+			pr_debug("  -> TIF_BREAKPOINT done, adjusted regs:"
+					"PC=0x%08lx SR=0x%08lx\n",
+					regs->pc, regs->sr);
+			BUG_ON(!user_mode(regs));
+
+			if (test_thread_flag(TIF_SINGLE_STEP)) {
+				pr_debug("Going to do single step...\n");
+				return regs;
+			}
+
+			/*
+			 * No TIF_SINGLE_STEP means we're done
+			 * stepping over a syscall. Do the trap now.
+			 */
+			code = TRAP_TRACE;
+		} else if ((status & (1 << OCD_DS_SSS_BIT))
+				&& test_ti_thread_flag(ti, TIF_SINGLE_STEP)) {
+
+			pr_debug("Stepped into something, "
+					"setting TIF_BREAKPOINT...\n");
+			set_ti_thread_flag(ti, TIF_BREAKPOINT);
+
+			/*
+			 * We stepped into an exception, interrupt or
+			 * syscall handler. Some exception handlers
+			 * don't check for pending work, so we need to
+			 * set up a trampoline just in case.
+			 *
+			 * The exception entry code will undo the
+			 * trampoline stuff if it does a full context
+			 * save (which also means that it'll check for
+			 * pending work later.)
+			 */
+			if ((regs->sr & MODE_MASK) == MODE_EXCEPTION) {
+				trampoline_addr
+					= (unsigned long)&debug_trampoline;
+
+				pr_debug("Setting up trampoline...\n");
+				ti->rar_saved = sysreg_read(RAR_EX);
+				ti->rsr_saved = sysreg_read(RSR_EX);
+				sysreg_write(RAR_EX, trampoline_addr);
+				sysreg_write(RSR_EX, (MODE_EXCEPTION
+							| SR_EM | SR_GM));
+				BUG_ON(ti->rsr_saved & MODE_MASK);
+			}
+
+			/*
+			 * If we stepped into a system call, we
+			 * shouldn't do a single step after we return
+			 * since the return address is right after the
+			 * "scall" instruction we were told to step
+			 * over.
+			 */
+			if ((regs->sr & MODE_MASK) == MODE_SUPERVISOR) {
+				pr_debug("Supervisor; no single step\n");
+				clear_ti_thread_flag(ti, TIF_SINGLE_STEP);
+			}
+
+			ctrl = ocd_read(DC);
+			ctrl &= ~(1 << OCD_DC_SS_BIT);
+			ocd_write(DC, ctrl);
+
+			return regs;
+		} else {
+			printk(KERN_ERR "Unexpected OCD_DS value: 0x%08x\n",
+					status);
+			printk(KERN_ERR "Thread flags: 0x%08lx\n", ti->flags);
+			die("Unhandled debug trap in kernel mode",
+					regs, SIGTRAP);
+		}
+	} else if (status & (1 << OCD_DS_SSS_BIT)) {
+		/* Single step in user mode */
+		code = TRAP_TRACE;
+
+		ctrl = ocd_read(DC);
+		ctrl &= ~(1 << OCD_DC_SS_BIT);
+		ocd_write(DC, ctrl);
+	}
+
+	pr_debug("Sending SIGTRAP: code=%d PC=0x%08lx SR=0x%08lx\n",
+			code, regs->pc, regs->sr);
+
+	clear_thread_flag(TIF_SINGLE_STEP);
+	_exception(SIGTRAP, regs, code, instruction_pointer(regs));
+
+	return regs;
+}