linux-kernel - [RFC PATCH 1/2] powerpc/signal: Clean up pt

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Message-ID: <20250129132148.301937-2-npiggin@gmail.com>
Date: Wed, 29 Jan 2025 23:21:42 +1000
From: Nicholas Piggin <npiggin@...il.com>
To: "Dmitry V. Levin" <ldv@...ace.io>
Cc: Nicholas Piggin <npiggin@...il.com>,
	Oleg Nesterov <oleg@...hat.com>,
	Eugene Syromyatnikov <evgsyr@...il.com>,
	Mike Frysinger <vapier@...too.org>,
	Renzo Davoli <renzo@...unibo.it>,
	Davide Berardi <berardi.dav@...il.com>,
	strace-devel@...ts.strace.io,
	Madhavan Srinivasan <maddy@...ux.ibm.com>,
	Christophe Leroy <christophe.leroy@...roup.eu>,
	linuxppc-dev@...ts.ozlabs.org,
	linux-kernel@...r.kernel.org
Subject: [RFC PATCH 1/2] powerpc/signal: Clean up pt_regs access

There are places in signal code that are made more readable by using a
'regs' local variable instead of finding it from the task.

Signed-off-by: Nicholas Piggin <npiggin@...il.com>
---
 arch/powerpc/kernel/signal.c    | 11 ++++++-----
 arch/powerpc/kernel/signal_64.c |  5 +++--
 2 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/arch/powerpc/kernel/signal.c b/arch/powerpc/kernel/signal.c
index aa17e62f3754..193211b04805 100644
--- a/arch/powerpc/kernel/signal.c
+++ b/arch/powerpc/kernel/signal.c
@@ -242,6 +242,7 @@ static void check_syscall_restart(struct pt_regs *regs, struct k_sigaction *ka,
 
 static void do_signal(struct task_struct *tsk)
 {
+	struct pt_regs *regs = tsk->thread.regs;
 	sigset_t *oldset = sigmask_to_save();
 	struct ksignal ksig = { .sig = 0 };
 	int ret;
@@ -251,12 +252,12 @@ static void do_signal(struct task_struct *tsk)
 	get_signal(&ksig);
 
 	/* Is there any syscall restart business here ? */
-	check_syscall_restart(tsk->thread.regs, &ksig.ka, ksig.sig > 0);
+	check_syscall_restart(regs, &ksig.ka, ksig.sig > 0);
 
 	if (ksig.sig <= 0) {
 		/* No signal to deliver -- put the saved sigmask back */
 		restore_saved_sigmask();
-		set_trap_norestart(tsk->thread.regs);
+		set_trap_norestart(regs);
 		return;               /* no signals delivered */
 	}
 
@@ -275,9 +276,9 @@ static void do_signal(struct task_struct *tsk)
 	}
 
 	/* Re-enable the breakpoints for the signal stack */
-	thread_change_pc(tsk, tsk->thread.regs);
+	thread_change_pc(tsk, regs);
 
-	rseq_signal_deliver(&ksig, tsk->thread.regs);
+	rseq_signal_deliver(&ksig, regs);
 
 	if (is_32bit_task()) {
         	if (ksig.ka.sa.sa_flags & SA_SIGINFO)
@@ -288,7 +289,7 @@ static void do_signal(struct task_struct *tsk)
 		ret = handle_rt_signal64(&ksig, oldset, tsk);
 	}
 
-	set_trap_norestart(tsk->thread.regs);
+	set_trap_norestart(regs);
 	signal_setup_done(ret, &ksig, test_thread_flag(TIF_SINGLESTEP));
 }
 
diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c
index 86bb5bb4c143..1f0c43baeff2 100644
--- a/arch/powerpc/kernel/signal_64.c
+++ b/arch/powerpc/kernel/signal_64.c
@@ -748,6 +748,8 @@ SYSCALL_DEFINE0(rt_sigreturn)
 	sigset_t set;
 	unsigned long msr;
 
+	BUG_ON(regs != current->thread.regs);
+
 	/* Always make any pending restarted system calls return -EINTR */
 	current->restart_block.fn = do_no_restart_syscall;
 
@@ -827,8 +829,7 @@ SYSCALL_DEFINE0(rt_sigreturn)
 		 * MSR[TS] set, but without CPU in the proper state,
 		 * causing a TM bad thing.
 		 */
-		regs_set_return_msr(current->thread.regs,
-				current->thread.regs->msr & ~MSR_TS_MASK);
+		regs_set_return_msr(regs, regs->msr & ~MSR_TS_MASK);
 		if (!user_read_access_begin(&uc->uc_mcontext, sizeof(uc->uc_mcontext)))
 			goto badframe;
 
-- 
2.47.1