[PATCH v7 09/10] powerpc/signal64: Rewrite rt_sigreturn() to minimise uaccess switches

["Christopher M. Riedl" <cmr@codefail.de>]

From: Daniel Axtens <dja@axtens.net>

Add uaccess blocks and use the 'unsafe' versions of functions doing user
access where possible to reduce the number of times uaccess has to be
opened/closed.

Signed-off-by: Daniel Axtens <dja@axtens.net>
Co-developed-by: Christopher M. Riedl <cmr@codefail.de>
Signed-off-by: Christopher M. Riedl <cmr@codefail.de>
---
 arch/powerpc/kernel/signal_64.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c
index 788854734b9a..00c907022707 100644
--- a/arch/powerpc/kernel/signal_64.c
+++ b/arch/powerpc/kernel/signal_64.c
@@ -822,11 +822,11 @@ SYSCALL_DEFINE0(rt_sigreturn)
 		 */
 		current->thread.regs->msr &= ~MSR_TS_MASK;
 		if (!user_read_access_begin(&uc->uc_mcontext, sizeof(uc->uc_mcontext)))
-			return -EFAULT;
-		if (__unsafe_restore_sigcontext(current, NULL, 1, &uc->uc_mcontext)) {
-			user_read_access_end();
 			goto badframe;
-		}
+
+		unsafe_restore_sigcontext(current, NULL, 1, &uc->uc_mcontext,
+					  badframe_block);
+
 		user_read_access_end();
 	}
 
@@ -836,6 +836,8 @@ SYSCALL_DEFINE0(rt_sigreturn)
 	set_thread_flag(TIF_RESTOREALL);
 	return 0;
 
+badframe_block:
+	user_read_access_end();
 badframe:
 	signal_fault(current, regs, "rt_sigreturn", uc);
 
-- 
2.26.1