diff mbox series

[v2,8/8] powerpc/signal64: Rewrite rt_sigreturn() to minimise uaccess switches

Message ID 20201105051701.25053-9-cmr@codefail.de (mailing list archive)
State Superseded
Headers show
Series Improve signal performance on PPC64 with KUAP | expand

Checks

Context Check Description
snowpatch_ozlabs/apply_patch warning Failed to apply on branch powerpc/merge (58b9041431fcf9f3f87c8def87ca82dd54cf80dd)
snowpatch_ozlabs/apply_patch warning Failed to apply on branch powerpc/next (3cea11cd5e3b00d91caf0b4730194039b45c5891)
snowpatch_ozlabs/apply_patch warning Failed to apply on branch linus/master (4ef8451b332662d004df269d4cdeb7d9f31419b5)
snowpatch_ozlabs/apply_patch warning Failed to apply on branch powerpc/fixes (1344a232016dbb0492be81f8517c4bf8fc1c6610)
snowpatch_ozlabs/apply_patch warning Failed to apply on branch linux-next (cf7cd542d1b538f6e9e83490bc090dd773f4266d)
snowpatch_ozlabs/apply_patch fail Failed to apply to any branch

Commit Message

Christopher M. Riedl Nov. 5, 2020, 5:17 a.m. UTC 
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 | 24 ++++++++++++++----------
 1 file changed, 14 insertions(+), 10 deletions(-)
diff mbox series

Patch

diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c
index d17f2d5436d2..82e68a508e5c 100644
--- a/arch/powerpc/kernel/signal_64.c
+++ b/arch/powerpc/kernel/signal_64.c
@@ -784,8 +784,11 @@  SYSCALL_DEFINE0(rt_sigreturn)
 	regs->msr &= ~MSR_TS_MASK;
 #endif
 
-	if (__get_user(msr, &uc->uc_mcontext.gp_regs[PT_MSR]))
+	if (!user_read_access_begin(uc, sizeof(*uc)))
 		goto badframe;
+
+	unsafe_get_user(msr, &uc->uc_mcontext.gp_regs[PT_MSR], badframe_block);
+
 	if (MSR_TM_ACTIVE(msr)) {
 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
 		/* We recheckpoint on return. */
@@ -793,10 +796,12 @@  SYSCALL_DEFINE0(rt_sigreturn)
 
 		/* Trying to start TM on non TM system */
 		if (!cpu_has_feature(CPU_FTR_TM))
-			goto badframe;
+			goto badframe_block;
+
+		unsafe_get_user(uc_transact, &uc->uc_link, badframe_block);
+
+		user_read_access_end();
 
-		if (__get_user(uc_transact, &uc->uc_link))
-			goto badframe;
 		if (restore_tm_sigcontexts(current, &uc->uc_mcontext,
 					   &uc_transact->uc_mcontext))
 			goto badframe;
@@ -815,12 +820,9 @@  SYSCALL_DEFINE0(rt_sigreturn)
 		 * causing a TM bad thing.
 		 */
 		current->thread.regs->msr &= ~MSR_TS_MASK;
-		if (!user_read_access_begin(uc, sizeof(*uc)))
-			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();
 	}
 
@@ -830,6 +832,8 @@  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);