microblaze_v8: ptrace support

Reviewed-by: Ingo Molnar <mingo@elte.hu>
Acked-by: John Linn <john.linn@xilinx.com>
Acked-by: Stephen Neuendorffer <stephen.neuendorffer@xilinx.com>
Acked-by: John Williams <john.williams@petalogix.com>
Signed-off-by: Michal Simek <monstr@monstr.eu>

1 files changed, 182 insertions, 0 deletions

diff --git a/arch/microblaze/kernel/ptrace.c b/arch/microblaze/kernel/ptrace.c
new file mode 100644
index 0000000..3171e39
--- /dev/null
+++ b/arch/microblaze/kernel/ptrace.c
@@ -0,0 +1,182 @@
+/*
+ * `ptrace' system call
+ *
+ * Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu>
+ * Copyright (C) 2007-2009 PetaLogix
+ * Copyright (C) 2004-2007 John Williams <john.williams@petalogix.com>
+ *
+ * derived from arch/v850/kernel/ptrace.c
+ *
+ * Copyright (C) 2002,03 NEC Electronics Corporation
+ * Copyright (C) 2002,03 Miles Bader <miles@gnu.org>
+ *
+ * Derived from arch/mips/kernel/ptrace.c:
+ *
+ * Copyright (C) 1992 Ross Biro
+ * Copyright (C) Linus Torvalds
+ * Copyright (C) 1994, 95, 96, 97, 98, 2000 Ralf Baechle
+ * Copyright (C) 1996 David S. Miller
+ * Kevin D. Kissell, kevink@mips.com and Carsten Langgaard, carstenl@mips.com
+ * Copyright (C) 1999 MIPS Technologies, Inc.
+ *
+ * This file is subject to the terms and conditions of the GNU General
+ * Public License. See the file COPYING in the main directory of this
+ * archive for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/sched.h>
+#include <linux/smp_lock.h>
+#include <linux/ptrace.h>
+#include <linux/signal.h>
+
+#include <linux/errno.h>
+#include <linux/ptrace.h>
+#include <asm/processor.h>
+#include <linux/uaccess.h>
+#include <asm/asm-offsets.h>
+
+/* Returns the address where the register at REG_OFFS in P is stashed away. */
+static microblaze_reg_t *reg_save_addr(unsigned reg_offs,
+					struct task_struct *t)
+{
+	struct pt_regs *regs;
+
+	/*
+	 * Three basic cases:
+	 *
+	 * (1)	A register normally saved before calling the scheduler, is
+	 *	available in the kernel entry pt_regs structure at the top
+	 *	of the kernel stack. The kernel trap/irq exit path takes
+	 *	care to save/restore almost all registers for ptrace'd
+	 *	processes.
+	 *
+	 * (2)	A call-clobbered register, where the process P entered the
+	 *	kernel via [syscall] trap, is not stored anywhere; that's
+	 *	OK, because such registers are not expected to be preserved
+	 *	when the trap returns anyway (so we don't actually bother to
+	 *	test for this case).
+	 *
+	 * (3)	A few registers not used at all by the kernel, and so
+	 *	normally never saved except by context-switches, are in the
+	 *	context switch state.
+	 */
+
+	/* Register saved during kernel entry (or not available). */
+	regs = task_pt_regs(t);
+
+	return (microblaze_reg_t *)((char *)regs + reg_offs);
+}
+
+long arch_ptrace(struct task_struct *child, long request, long addr, long data)
+{
+	int rval;
+	unsigned long val = 0;
+	unsigned long copied;
+
+	switch (request) {
+	case PTRACE_PEEKTEXT: /* read word at location addr. */
+	case PTRACE_PEEKDATA:
+		pr_debug("PEEKTEXT/PEEKDATA at %08lX\n", addr);
+		copied = access_process_vm(child, addr, &val, sizeof(val), 0);
+		rval = -EIO;
+		if (copied != sizeof(val))
+			break;
+		rval = put_user(val, (unsigned long *)data);
+		break;
+
+	case PTRACE_POKETEXT: /* write the word at location addr. */
+	case PTRACE_POKEDATA:
+		pr_debug("POKETEXT/POKEDATA to %08lX\n", addr);
+		rval = 0;
+		if (access_process_vm(child, addr, &data, sizeof(data), 1)
+		    == sizeof(data))
+			break;
+		rval = -EIO;
+		break;
+
+	/* Read/write the word at location ADDR in the registers. */
+	case PTRACE_PEEKUSR:
+	case PTRACE_POKEUSR:
+		pr_debug("PEEKUSR/POKEUSR : 0x%08lx\n", addr);
+		rval = 0;
+		if (addr >= PT_SIZE && request == PTRACE_PEEKUSR) {
+			/*
+			 * Special requests that don't actually correspond
+			 * to offsets in struct pt_regs.
+			 */
+			if (addr == PT_TEXT_ADDR) {
+				val = child->mm->start_code;
+			} else if (addr == PT_DATA_ADDR) {
+				val = child->mm->start_data;
+			} else if (addr == PT_TEXT_LEN) {
+				val = child->mm->end_code
+					- child->mm->start_code;
+			} else {
+				rval = -EIO;
+			}
+		} else if (addr >= 0 && addr < PT_SIZE && (addr & 0x3) == 0) {
+			microblaze_reg_t *reg_addr = reg_save_addr(addr, child);
+			if (request == PTRACE_PEEKUSR)
+				val = *reg_addr;
+			else
+				*reg_addr = data;
+		} else
+			rval = -EIO;
+
+		if (rval == 0 && request == PTRACE_PEEKUSR)
+			rval = put_user(val, (unsigned long *)data);
+		break;
+	/* Continue and stop at next (return from) syscall */
+	case PTRACE_SYSCALL:
+		pr_debug("PTRACE_SYSCALL\n");
+	case PTRACE_SINGLESTEP:
+		pr_debug("PTRACE_SINGLESTEP\n");
+	/* Restart after a signal.  */
+	case PTRACE_CONT:
+		pr_debug("PTRACE_CONT\n");
+		rval = -EIO;
+		if (!valid_signal(data))
+			break;
+
+		if (request == PTRACE_SYSCALL)
+			set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
+		else
+			clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
+
+		child->exit_code = data;
+		pr_debug("wakeup_process\n");
+		wake_up_process(child);
+		rval = 0;
+		break;
+
+	/*
+	 * make the child exit.  Best I can do is send it a sigkill.
+	 * perhaps it should be put in the status that it wants to
+	 * exit.
+	 */
+	case PTRACE_KILL:
+		pr_debug("PTRACE_KILL\n");
+		rval = 0;
+		if (child->exit_state == EXIT_ZOMBIE)	/* already dead */
+			break;
+		child->exit_code = SIGKILL;
+		wake_up_process(child);
+		break;
+
+	case PTRACE_DETACH: /* detach a process that was attached. */
+		pr_debug("PTRACE_DETACH\n");
+		rval = ptrace_detach(child, data);
+		break;
+	default:
+		/* rval = ptrace_request(child, request, addr, data); noMMU */
+		rval = -EIO;
+	}
+	return rval;
+}
+
+void ptrace_disable(struct task_struct *child)
+{
+	/* nothing to do */
+}