[RFC Patch 8/9] Modify Ptrace to use wrapper routines to access breakpoint registers

["K.Prasad" <prasad@linux.vnet.ibm.com>]

This patch modifies the ptrace code to use the new wrapper routines around the 
debug/breakpoint registers.

Signed-off-by: K.Prasad <prasad@linux.vnet.ibm.com>
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
---
 arch/x86/kernel/ptrace.c |  101 +----------------------------------------------
 1 file changed, 4 insertions(+), 97 deletions(-)

Index: linux-bkpt-lkml-27-rc9/arch/x86/kernel/ptrace.c
===================================================================
--- linux-bkpt-lkml-27-rc9.orig/arch/x86/kernel/ptrace.c
+++ linux-bkpt-lkml-27-rc9/arch/x86/kernel/ptrace.c
@@ -462,98 +462,6 @@ static int genregs_set(struct task_struc
 	return ret;
 }
 
-/*
- * This function is trivial and will be inlined by the compiler.
- * Having it separates the implementation details of debug
- * registers from the interface details of ptrace.
- */
-static unsigned long ptrace_get_debugreg(struct task_struct *child, int n)
-{
-	switch (n) {
-	case 0:		return child->thread.debugreg0;
-	case 1:		return child->thread.debugreg1;
-	case 2:		return child->thread.debugreg2;
-	case 3:		return child->thread.debugreg3;
-	case 6:		return child->thread.debugreg6;
-	case 7:		return child->thread.debugreg7;
-	}
-	return 0;
-}
-
-static int ptrace_set_debugreg(struct task_struct *child,
-			       int n, unsigned long data)
-{
-	int i;
-
-	if (unlikely(n == 4 || n == 5))
-		return -EIO;
-
-	if (n < 4 && unlikely(data >= debugreg_addr_limit(child)))
-		return -EIO;
-
-	switch (n) {
-	case 0:		child->thread.debugreg0 = data; break;
-	case 1:		child->thread.debugreg1 = data; break;
-	case 2:		child->thread.debugreg2 = data; break;
-	case 3:		child->thread.debugreg3 = data; break;
-
-	case 6:
-		if ((data & ~0xffffffffUL) != 0)
-			return -EIO;
-		child->thread.debugreg6 = data;
-		break;
-
-	case 7:
-		/*
-		 * Sanity-check data. Take one half-byte at once with
-		 * check = (val >> (16 + 4*i)) & 0xf. It contains the
-		 * R/Wi and LENi bits; bits 0 and 1 are R/Wi, and bits
-		 * 2 and 3 are LENi. Given a list of invalid values,
-		 * we do mask |= 1 << invalid_value, so that
-		 * (mask >> check) & 1 is a correct test for invalid
-		 * values.
-		 *
-		 * R/Wi contains the type of the breakpoint /
-		 * watchpoint, LENi contains the length of the watched
-		 * data in the watchpoint case.
-		 *
-		 * The invalid values are:
-		 * - LENi == 0x10 (undefined), so mask |= 0x0f00.	[32-bit]
-		 * - R/Wi == 0x10 (break on I/O reads or writes), so
-		 *   mask |= 0x4444.
-		 * - R/Wi == 0x00 && LENi != 0x00, so we have mask |=
-		 *   0x1110.
-		 *
-		 * Finally, mask = 0x0f00 | 0x4444 | 0x1110 == 0x5f54.
-		 *
-		 * See the Intel Manual "System Programming Guide",
-		 * 15.2.4
-		 *
-		 * Note that LENi == 0x10 is defined on x86_64 in long
-		 * mode (i.e. even for 32-bit userspace software, but
-		 * 64-bit kernel), so the x86_64 mask value is 0x5454.
-		 * See the AMD manual no. 24593 (AMD64 System Programming)
-		 */
-#ifdef CONFIG_X86_32
-#define	DR7_MASK	0x5f54
-#else
-#define	DR7_MASK	0x5554
-#endif
-		data &= ~DR_CONTROL_RESERVED;
-		for (i = 0; i < 4; i++)
-			if ((DR7_MASK >> ((data >> (16 + 4*i)) & 0xf)) & 1)
-				return -EIO;
-		child->thread.debugreg7 = data;
-		if (data)
-			set_tsk_thread_flag(child, TIF_DEBUG);
-		else
-			clear_tsk_thread_flag(child, TIF_DEBUG);
-		break;
-	}
-
-	return 0;
-}
-
 #ifdef X86_BTS
 
 static int ptrace_bts_get_size(struct task_struct *child)
@@ -888,7 +796,7 @@ long arch_ptrace(struct task_struct *chi
 		else if (addr >= offsetof(struct user, u_debugreg[0]) &&
 			 addr <= offsetof(struct user, u_debugreg[7])) {
 			addr -= offsetof(struct user, u_debugreg[0]);
-			tmp = ptrace_get_debugreg(child, addr / sizeof(data));
+			tmp = thread_get_debugreg(child, addr/sizeof(data));
 		}
 		ret = put_user(tmp, datap);
 		break;
@@ -905,8 +813,7 @@ long arch_ptrace(struct task_struct *chi
 		else if (addr >= offsetof(struct user, u_debugreg[0]) &&
 			 addr <= offsetof(struct user, u_debugreg[7])) {
 			addr -= offsetof(struct user, u_debugreg[0]);
-			ret = ptrace_set_debugreg(child,
-						  addr / sizeof(data), data);
+			ret = thread_set_debugreg(child, addr/sizeof(data), data);
 		}
 		break;
 
@@ -1073,7 +980,7 @@ static int putreg32(struct task_struct *
 	case offsetof(struct user32, u_debugreg[0]) ...
 		offsetof(struct user32, u_debugreg[7]):
 		regno -= offsetof(struct user32, u_debugreg[0]);
-		return ptrace_set_debugreg(child, regno / 4, value);
+		return thread_set_debugreg(child, regno / 4, value);
 
 	default:
 		if (regno > sizeof(struct user32) || (regno & 3))
@@ -1132,7 +1039,7 @@ static int getreg32(struct task_struct *
 	case offsetof(struct user32, u_debugreg[0]) ...
 		offsetof(struct user32, u_debugreg[7]):
 		regno -= offsetof(struct user32, u_debugreg[0]);
-		*val = ptrace_get_debugreg(child, regno / 4);
+		*val = thread_get_debugreg(child, regno / 4);
 		break;
 
 	default: