diff mbox series

[v6,08/10] powerpc/signal64: Rewrite handle_rt_signal64() to minimise uaccess switches

Message ID 20210221012401.22328-9-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State Superseded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 (626a6c3d2e20da80aaa710104f34ea6037b28b33)
snowpatch_ozlabs/apply_patch warning Failed to apply on branch powerpc/next (6895c5ba7bdcc55eacad03cf309ab23be63b9cac)
snowpatch_ozlabs/apply_patch warning Failed to apply on branch linus/master (92bf22614b21a2706f4993b278017e437f7785b3)
snowpatch_ozlabs/apply_patch warning Failed to apply on branch powerpc/fixes (24321ac668e452a4942598533d267805f291fdc9)
snowpatch_ozlabs/apply_patch warning Failed to apply on branch linux-next (1e0d27fce010b0a4a9e595506b6ede75934c31be)
snowpatch_ozlabs/apply_patch fail Failed to apply to any branch

Commit Message

Christopher M. Riedl Feb. 21, 2021, 1:23 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.

There is no 'unsafe' version of copy_siginfo_to_user, so move it
slightly to allow for a "longer" uaccess block.

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 | 56 ++++++++++++++++++++-------------
 1 file changed, 35 insertions(+), 21 deletions(-)
diff mbox series

Patch

diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c
index 76b525261f61..4bf73731533f 100644
--- a/arch/powerpc/kernel/signal_64.c
+++ b/arch/powerpc/kernel/signal_64.c
@@ -853,45 +853,52 @@  int handle_rt_signal64(struct ksignal *ksig, sigset_t *set,
 	unsigned long msr = regs->msr;
 
 	frame = get_sigframe(ksig, tsk, sizeof(*frame), 0);
-	if (!access_ok(frame, sizeof(*frame)))
-		goto badframe;
 
-	err |= __put_user(&frame->info, &frame->pinfo);
-	err |= __put_user(&frame->uc, &frame->puc);
-	err |= copy_siginfo_to_user(&frame->info, &ksig->info);
-	if (err)
+	/* This only applies when calling unsafe_setup_sigcontext() and must be
+	 * called before opening the uaccess window.
+	 */
+	if (!MSR_TM_ACTIVE(msr))
+		prepare_setup_sigcontext(tsk);
+
+	if (!user_write_access_begin(frame, sizeof(*frame)))
 		goto badframe;
 
+	unsafe_put_user(&frame->info, &frame->pinfo, badframe_block);
+	unsafe_put_user(&frame->uc, &frame->puc, badframe_block);
+
 	/* Create the ucontext.  */
-	err |= __put_user(0, &frame->uc.uc_flags);
-	err |= __save_altstack(&frame->uc.uc_stack, regs->gpr[1]);
+	unsafe_put_user(0, &frame->uc.uc_flags, badframe_block);
+	unsafe_save_altstack(&frame->uc.uc_stack, regs->gpr[1], badframe_block);
 
 	if (MSR_TM_ACTIVE(msr)) {
 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
 		/* The ucontext_t passed to userland points to the second
 		 * ucontext_t (for transactional state) with its uc_link ptr.
 		 */
-		err |= __put_user(&frame->uc_transact, &frame->uc.uc_link);
+		unsafe_put_user(&frame->uc_transact, &frame->uc.uc_link, badframe_block);
+
+		user_write_access_end();
+
 		err |= setup_tm_sigcontexts(&frame->uc.uc_mcontext,
 					    &frame->uc_transact.uc_mcontext,
 					    tsk, ksig->sig, NULL,
 					    (unsigned long)ksig->ka.sa.sa_handler,
 					    msr);
+
+		if (!user_write_access_begin(&frame->uc.uc_sigmask,
+					     sizeof(frame->uc.uc_sigmask)))
+			goto badframe;
+
 #endif
 	} else {
-		err |= __put_user(0, &frame->uc.uc_link);
-		prepare_setup_sigcontext(tsk);
-		if (!user_write_access_begin(&frame->uc.uc_mcontext,
-					     sizeof(frame->uc.uc_mcontext)))
-			return -EFAULT;
-		err |= __unsafe_setup_sigcontext(&frame->uc.uc_mcontext, tsk,
-						ksig->sig, NULL,
-						(unsigned long)ksig->ka.sa.sa_handler, 1);
-		user_write_access_end();
+		unsafe_put_user(0, &frame->uc.uc_link, badframe_block);
+		unsafe_setup_sigcontext(&frame->uc.uc_mcontext, tsk, ksig->sig,
+					NULL, (unsigned long)ksig->ka.sa.sa_handler,
+					1, badframe_block);
 	}
-	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
-	if (err)
-		goto badframe;
+
+	unsafe_copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set), badframe_block);
+	user_write_access_end();
 
 	/* Make sure signal handler doesn't get spurious FP exceptions */
 	tsk->thread.fp_state.fpscr = 0;
@@ -906,6 +913,11 @@  int handle_rt_signal64(struct ksignal *ksig, sigset_t *set,
 		regs->nip = (unsigned long) &frame->tramp[0];
 	}
 
+
+	/* Save the siginfo outside of the unsafe block. */
+	if (copy_siginfo_to_user(&frame->info, &ksig->info))
+		goto badframe;
+
 	/* Allocate a dummy caller frame for the signal handler. */
 	newsp = ((unsigned long)frame) - __SIGNAL_FRAMESIZE;
 	err |= put_user(regs->gpr[1], (unsigned long __user *)newsp);
@@ -945,6 +957,8 @@  int handle_rt_signal64(struct ksignal *ksig, sigset_t *set,
 
 	return 0;
 
+badframe_block:
+	user_write_access_end();
 badframe:
 	signal_fault(current, regs, "handle_rt_signal64", frame);