powerpc/ptrace: Create ptrace_get_fpr() and ptrace_put_fpr()

On the same model as ptrace_get_reg() and ptrace_put_reg(),
create ptrace_get_fpr() and ptrace_put_fpr() to get/set
the floating points registers.

We move the boundary checkings in them.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/24a1baedea7f7ae7b6bf27be98bab6d01b5ca2c1.1597770847.git.christophe.leroy@csgroup.eu

arch/powerpc/kernel/ptrace/Makefile

@@ -6,6 +6,7 @@
 CFLAGS_ptrace-view.o		+= -DUTS_MACHINE='"$(UTS_MACHINE)"'
 
 obj-y				+= ptrace.o ptrace-view.o
+obj-y				+= ptrace-fpu.o
 obj-$(CONFIG_COMPAT)		+= ptrace32.o
 obj-$(CONFIG_VSX)		+= ptrace-vsx.o
 ifneq ($(CONFIG_VSX),y)

arch/powerpc/kernel/ptrace/ptrace-decl.h

@@ -164,6 +164,10 @@ int ptrace_put_reg(struct task_struct *task, int regno, unsigned long data);
 
 extern const struct user_regset_view user_ppc_native_view;
 
+/* ptrace-fpu */
+int ptrace_get_fpr(struct task_struct *child, int index, unsigned long *data);
+int ptrace_put_fpr(struct task_struct *child, int index, unsigned long data);
+
 /* ptrace-(no)adv */
 void ppc_gethwdinfo(struct ppc_debug_info *dbginfo);
 int ptrace_get_debugreg(struct task_struct *child, unsigned long addr,

arch/powerpc/kernel/ptrace/ptrace-fpu.c

@@ -0,0 +1,40 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <linux/regset.h>
+
+#include <asm/switch_to.h>
+
+#include "ptrace-decl.h"
+
+int ptrace_get_fpr(struct task_struct *child, int index, unsigned long *data)
+{
+	unsigned int fpidx = index - PT_FPR0;
+
+	if (index > PT_FPSCR)
+		return -EIO;
+
+	flush_fp_to_thread(child);
+	if (fpidx < (PT_FPSCR - PT_FPR0))
+		memcpy(data, &child->thread.TS_FPR(fpidx), sizeof(long));
+	else
+		*data = child->thread.fp_state.fpscr;
+
+	return 0;
+}
+
+int ptrace_put_fpr(struct task_struct *child, int index, unsigned long data)
+{
+	unsigned int fpidx = index - PT_FPR0;
+
+	if (index > PT_FPSCR)
+		return -EIO;
+
+	flush_fp_to_thread(child);
+	if (fpidx < (PT_FPSCR - PT_FPR0))
+		memcpy(&child->thread.TS_FPR(fpidx), &data, sizeof(long));
+	else
+		child->thread.fp_state.fpscr = data;
+
+	return 0;
+}
+

arch/powerpc/kernel/ptrace/ptrace.c

@@ -56,25 +56,17 @@ long arch_ptrace(struct task_struct *child, long request,
 		ret = -EIO;
 		/* convert to index and check */
 		index = addr / sizeof(long);
-		if ((addr & (sizeof(long) - 1)) || (index > PT_FPSCR)
-		    || (child->thread.regs == NULL))
+		if ((addr & (sizeof(long) - 1)) || !child->thread.regs)
 			break;
 
 		CHECK_FULL_REGS(child->thread.regs);
-		if (index < PT_FPR0) {
+		if (index < PT_FPR0)
 			ret = ptrace_get_reg(child, (int) index, &tmp);
-			if (ret)
-				break;
-		} else {
-			unsigned int fpidx = index - PT_FPR0;
+		else
+			ret = ptrace_get_fpr(child, index, &tmp);
 
-			flush_fp_to_thread(child);
-			if (fpidx < (PT_FPSCR - PT_FPR0))
-				memcpy(&tmp, &child->thread.TS_FPR(fpidx),
-				       sizeof(long));
-			else
-				tmp = child->thread.fp_state.fpscr;
-		}
+		if (ret)
+			break;
 		ret = put_user(tmp, datalp);
 		break;
 	}
@@ -86,24 +78,14 @@ long arch_ptrace(struct task_struct *child, long request,
 		ret = -EIO;
 		/* convert to index and check */
 		index = addr / sizeof(long);
-		if ((addr & (sizeof(long) - 1)) || (index > PT_FPSCR)
-		    || (child->thread.regs == NULL))
+		if ((addr & (sizeof(long) - 1)) || !child->thread.regs)
 			break;
 
 		CHECK_FULL_REGS(child->thread.regs);
-		if (index < PT_FPR0) {
+		if (index < PT_FPR0)
 			ret = ptrace_put_reg(child, index, data);
-		} else {
-			unsigned int fpidx = index - PT_FPR0;
-
-			flush_fp_to_thread(child);
-			if (fpidx < (PT_FPSCR - PT_FPR0))
-				memcpy(&child->thread.TS_FPR(fpidx), &data,
-				       sizeof(long));
-			else
-				child->thread.fp_state.fpscr = data;
-			ret = 0;
-		}
+		else
+			ret = ptrace_put_fpr(child, index, data);
 		break;
 	}