[PATCH -mm 2/2] x86_64: semi-rewrite of PTRACE_PEEKUSR, PTRACE_POKEUSR

[Alexey Dobriyan <adobriyan@sw.ru>]

Refactor x86_64 PTRACE_PEEKUSR, PTRACE_POKEUSR implementations through
regset code.

Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
---

 arch/x86_64/kernel/ptrace.c |  203 +++++++++++++++++++++++---------------------
 1 file changed, 110 insertions(+), 93 deletions(-)

--- a/arch/x86_64/kernel/ptrace.c
+++ b/arch/x86_64/kernel/ptrace.c
@@ -305,9 +305,114 @@ static unsigned long getreg(struct task_struct *child, unsigned long regno)
 
 }
 
+static struct regset x86_64_gp_regset = {
+	.getreg	= getreg,
+	.setreg	= putreg,
+};
+
+static unsigned long x86_64_db_getreg(struct task_struct *tsk, unsigned long addr)
+{
+	switch (addr) {
+	case offsetof(struct user, u_debugreg[0]):
+		return tsk->thread.debugreg0;
+	case offsetof(struct user, u_debugreg[1]):
+		return tsk->thread.debugreg1;
+	case offsetof(struct user, u_debugreg[2]):
+		return tsk->thread.debugreg2;
+	case offsetof(struct user, u_debugreg[3]):
+		return tsk->thread.debugreg3;
+	case offsetof(struct user, u_debugreg[6]):
+		return tsk->thread.debugreg6;
+	case offsetof(struct user, u_debugreg[7]):
+		return tsk->thread.debugreg7;
+	default:
+		return 0;
+	}
+}
+
+static int x86_64_db_setreg(struct task_struct *tsk, unsigned long addr, unsigned long val)
+{
+	int i, dsize = test_tsk_thread_flag(tsk, TIF_IA32) ? 3 : 7;
+
+	switch (addr) {
+	case offsetof(struct user, u_debugreg[4]):
+	case offsetof(struct user, u_debugreg[5]):
+		return -EIO;
+	/* Disallows to set a breakpoint into the vsyscall */
+	case offsetof(struct user, u_debugreg[0]):
+		if (val >= TASK_SIZE_OF(tsk) - dsize)
+			return -EIO;
+		tsk->thread.debugreg0 = val;
+		return 0;
+	case offsetof(struct user, u_debugreg[1]):
+		if (val >= TASK_SIZE_OF(tsk) - dsize)
+			return -EIO;
+		tsk->thread.debugreg1 = val;
+		return 0;
+	case offsetof(struct user, u_debugreg[2]):
+		if (val >= TASK_SIZE_OF(tsk) - dsize)
+			return -EIO;
+		tsk->thread.debugreg2 = val;
+		return 0;
+	case offsetof(struct user, u_debugreg[3]):
+		if (val >= TASK_SIZE_OF(tsk) - dsize)
+			return -EIO;
+		tsk->thread.debugreg3 = val;
+		return 0;
+	case offsetof(struct user, u_debugreg[6]):
+		if (val >> 32)
+			return -EIO;
+		tsk->thread.debugreg6 = val;
+		return 0;
+	case offsetof(struct user, u_debugreg[7]):
+		/*
+		 * See arch/i386/kernel/ptrace.c for an explanation of this
+		 * awkward check.
+		 */
+		val &= ~DR_CONTROL_RESERVED;
+		for (i = 0; i < 4; i++)
+			if ((0x5554 >> ((val >> (16 + 4 * i)) & 0xf)) & 1)
+				return -EIO;
+		tsk->thread.debugreg7 = val;
+		if (val)
+			set_tsk_thread_flag(tsk, TIF_DEBUG);
+		else
+			clear_tsk_thread_flag(tsk, TIF_DEBUG);
+		return 0;
+	default:
+		BUG();
+	}
+}
+
+static struct regset x86_64_db_regset = {
+	.getreg	= x86_64_db_getreg,
+	.setreg	= x86_64_db_setreg,
+};
+
+static struct ptrace_usr_area x86_64_usr_area[] = {
+	{
+		.start	= 0,
+		.end	= sizeof(struct user_regs_struct),
+		.regset	= &x86_64_gp_regset,
+	}, {
+		.start	= sizeof(struct user_regs_struct),
+		.end	= offsetof(struct user, u_debugreg[0]),
+		.hole	= 1,
+	}, {
+		.start	= offsetof(struct user, u_debugreg[0]),
+		.end	= offsetof(struct user, u_debugreg[8]),
+		.regset	= &x86_64_db_regset,
+	}, {
+		.start	= offsetof(struct user, u_debugreg[8]),
+		.end	= sizeof(struct user),
+		.hole	= 1,
+	},
+	{}
+};
+
 long arch_ptrace(struct task_struct *child, long request, long addr, long data)
 {
-	long i, ret;
+	long ret;
 	unsigned ui;
 
 	switch (request) {
@@ -318,43 +423,9 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data)
 		break;
 
 	/* read the word at location addr in the USER area. */
-	case PTRACE_PEEKUSR: {
-		unsigned long tmp;
-
-		ret = -EIO;
-		if ((addr & 7) ||
-		    addr > sizeof(struct user) - 7)
-			break;
-
-		switch (addr) { 
-		case 0 ... sizeof(struct user_regs_struct) - sizeof(long):
-			tmp = getreg(child, addr);
-			break;
-		case offsetof(struct user, u_debugreg[0]):
-			tmp = child->thread.debugreg0;
-			break;
-		case offsetof(struct user, u_debugreg[1]):
-			tmp = child->thread.debugreg1;
-			break;
-		case offsetof(struct user, u_debugreg[2]):
-			tmp = child->thread.debugreg2;
-			break;
-		case offsetof(struct user, u_debugreg[3]):
-			tmp = child->thread.debugreg3;
-			break;
-		case offsetof(struct user, u_debugreg[6]):
-			tmp = child->thread.debugreg6;
-			break;
-		case offsetof(struct user, u_debugreg[7]):
-			tmp = child->thread.debugreg7;
-			break;
-		default:
-			tmp = 0;
-			break;
-		}
-		ret = put_user(tmp,(unsigned long __user *) data);
+	case PTRACE_PEEKUSR:
+		ret = ptrace_peekusr(child, x86_64_usr_area, addr, data);
 		break;
-	}
 
 	/* when I and D space are separate, this will have to be fixed. */
 	case PTRACE_POKETEXT: /* write the word at location addr. */
@@ -363,63 +434,9 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data)
 		break;
 
 	case PTRACE_POKEUSR: /* write the word at location addr in the USER area */
-	{
-		int dsize = test_tsk_thread_flag(child, TIF_IA32) ? 3 : 7;
-		ret = -EIO;
-		if ((addr & 7) ||
-		    addr > sizeof(struct user) - 7)
-			break;
-
-		switch (addr) { 
-		case 0 ... sizeof(struct user_regs_struct) - sizeof(long):
-			ret = putreg(child, addr, data);
-			break;
-		/* Disallows to set a breakpoint into the vsyscall */
-		case offsetof(struct user, u_debugreg[0]):
-			if (data >= TASK_SIZE_OF(child) - dsize) break;
-			child->thread.debugreg0 = data;
-			ret = 0;
-			break;
-		case offsetof(struct user, u_debugreg[1]):
-			if (data >= TASK_SIZE_OF(child) - dsize) break;
-			child->thread.debugreg1 = data;
-			ret = 0;
-			break;
-		case offsetof(struct user, u_debugreg[2]):
-			if (data >= TASK_SIZE_OF(child) - dsize) break;
-			child->thread.debugreg2 = data;
-			ret = 0;
-			break;
-		case offsetof(struct user, u_debugreg[3]):
-			if (data >= TASK_SIZE_OF(child) - dsize) break;
-			child->thread.debugreg3 = data;
-			ret = 0;
-			break;
-		case offsetof(struct user, u_debugreg[6]):
-				  if (data >> 32)
-				break; 
-			child->thread.debugreg6 = data;
-			ret = 0;
-			break;
-		case offsetof(struct user, u_debugreg[7]):
-			/* See arch/i386/kernel/ptrace.c for an explanation of
-			 * this awkward check.*/
-			data &= ~DR_CONTROL_RESERVED;
-			for(i=0; i<4; i++)
-				if ((0x5554 >> ((data >> (16 + 4*i)) & 0xf)) & 1)
-					break;
-			if (i == 4) {
-			  child->thread.debugreg7 = data;
-			  if (data)
-			  	set_tsk_thread_flag(child, TIF_DEBUG);
-			  else
-			  	clear_tsk_thread_flag(child, TIF_DEBUG);
-			  ret = 0;
-		  	}
-		  break;
-		}
+		ret = ptrace_pokeusr(child, x86_64_usr_area, addr, data);
 		break;
-	}
+
 	case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
 	case PTRACE_CONT:    /* restart after signal. */