powerpc/ptrace: Convert gpr32_set_common_user() to scoped user access

Commit 861574d51bbd ("powerpc/uaccess: Implement masked user access")
provides optimised user access by avoiding the cost of access_ok().

Convert gpr32_set_common_user() to scoped user access to benefit
from masked user access.

Scoped user access also make the code simpler.

Also changes label from Efault to efault to avoid checkpatch
complaining about CamelCase.

Signed-off-by: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/2409643daab08b4bc07004c2b88f42085d1ef45a.1773136838.git.chleroy@kernel.org

1 files changed, 31 insertions, 33 deletions

diff --git a/arch/powerpc/kernel/ptrace/ptrace-view.c b/arch/powerpc/kernel/ptrace/ptrace-view.c
index 0310f9097e39..eb5f2091bb59 100644
--- a/arch/powerpc/kernel/ptrace/ptrace-view.c
+++ b/arch/powerpc/kernel/ptrace/ptrace-view.c
@@ -758,38 +758,37 @@ static int gpr32_set_common_user(struct task_struct *target,
 	const void *kbuf = NULL;
 	compat_ulong_t reg;
 
-	if (!user_read_access_begin(u, count))
-		return -EFAULT;
-
-	pos /= sizeof(reg);
-	count /= sizeof(reg);
-
-	for (; count > 0 && pos < PT_MSR; --count) {
-		unsafe_get_user(reg, u++, Efault);
-		regs[pos++] = reg;
-	}
-
-	if (count > 0 && pos == PT_MSR) {
-		unsafe_get_user(reg, u++, Efault);
-		set_user_msr(target, reg);
-		++pos;
-		--count;
-	}
-
-	for (; count > 0 && pos <= PT_MAX_PUT_REG; --count) {
-		unsafe_get_user(reg, u++, Efault);
-		regs[pos++] = reg;
-	}
-	for (; count > 0 && pos < PT_TRAP; --count, ++pos)
-		unsafe_get_user(reg, u++, Efault);
-
-	if (count > 0 && pos == PT_TRAP) {
-		unsafe_get_user(reg, u++, Efault);
-		set_user_trap(target, reg);
-		++pos;
-		--count;
+	scoped_user_read_access_size(ubuf, count, efault) {
+		u = ubuf;
+		pos /= sizeof(reg);
+		count /= sizeof(reg);
+
+		for (; count > 0 && pos < PT_MSR; --count) {
+			unsafe_get_user(reg, u++, efault);
+			regs[pos++] = reg;
+		}
+
+		if (count > 0 && pos == PT_MSR) {
+			unsafe_get_user(reg, u++, efault);
+			set_user_msr(target, reg);
+			++pos;
+			--count;
+		}
+
+		for (; count > 0 && pos <= PT_MAX_PUT_REG; --count) {
+			unsafe_get_user(reg, u++, efault);
+			regs[pos++] = reg;
+		}
+		for (; count > 0 && pos < PT_TRAP; --count, ++pos)
+			unsafe_get_user(reg, u++, efault);
+
+		if (count > 0 && pos == PT_TRAP) {
+			unsafe_get_user(reg, u++, efault);
+			set_user_trap(target, reg);
+			++pos;
+			--count;
+		}
 	}
-	user_read_access_end();
 
 	ubuf = u;
 	pos *= sizeof(reg);
@@ -798,8 +797,7 @@ static int gpr32_set_common_user(struct task_struct *target,
 				  (PT_TRAP + 1) * sizeof(reg), -1);
 	return 0;
 
-Efault:
-	user_read_access_end();
+efault:
 	return -EFAULT;
 }