From mboxrd@z Thu Jan 1 00:00:00 1970 From: guoren@kernel.org Subject: [PATCH 3/3] riscv/signal: Fixup additional syscall restarting Date: Tue, 2 Apr 2019 16:02:33 +0800 Message-ID: <1554192153-2587-3-git-send-email-guoren@kernel.org> References: <1554192153-2587-1-git-send-email-guoren@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1554192153-2587-1-git-send-email-guoren@kernel.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-riscv" Errors-To: linux-riscv-bounces+glpr-linux-riscv=m.gmane.org@lists.infradead.org To: arnd@arndb.de, palmer@sifive.com Cc: linux-arch@vger.kernel.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, ren_guo@c-sky.com List-Id: linux-arch.vger.kernel.org From: Guo Ren The function of do_notify_resume called by entry.S could be entered in loop when SIGPENDING was setted again before sret. So we must add prevent code to make syscall restart (regs->sepc -= 0x4) or it may re-execute unexpected instructions. Just like in_syscall & forget_syscall used by arm. Signed-off-by: Guo Ren Cc: Palmer Dabbelt Cc: Arnd Bergmann --- arch/riscv/kernel/signal.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/riscv/kernel/signal.c b/arch/riscv/kernel/signal.c index 837e164..804d6ee 100644 --- a/arch/riscv/kernel/signal.c +++ b/arch/riscv/kernel/signal.c @@ -234,6 +234,9 @@ static void handle_signal(struct ksignal *ksig, struct pt_regs *regs) /* Are we from a system call? */ if (regs->scause == EXC_SYSCALL) { + /* Avoid additional syscall restarting via ret_from_exception */ + regs->scause = -1UL; + /* If so, check system call restarting.. */ switch (regs->a0) { case -ERESTART_RESTARTBLOCK: @@ -272,6 +275,9 @@ static void do_signal(struct pt_regs *regs) /* Did we come from a system call? */ if (regs->scause == EXC_SYSCALL) { + /* Avoid additional syscall restarting via ret_from_exception */ + regs->scause = -1UL; + /* Restart the system call - no handlers present */ switch (regs->a0) { case -ERESTARTNOHAND: -- 2.7.4 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:41462 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725778AbfDBIDj (ORCPT ); Tue, 2 Apr 2019 04:03:39 -0400 From: guoren@kernel.org Subject: [PATCH 3/3] riscv/signal: Fixup additional syscall restarting Date: Tue, 2 Apr 2019 16:02:33 +0800 Message-ID: <1554192153-2587-3-git-send-email-guoren@kernel.org> In-Reply-To: <1554192153-2587-1-git-send-email-guoren@kernel.org> References: <1554192153-2587-1-git-send-email-guoren@kernel.org> Sender: linux-arch-owner@vger.kernel.org List-ID: To: arnd@arndb.de, palmer@sifive.com Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, ren_guo@c-sky.com, linux-riscv@lists.infradead.org Message-ID: <20190402080233.cQ6llgZqjR8J6uODoerKWEU6j7DdlxjXty62zOrVoyU@z> From: Guo Ren The function of do_notify_resume called by entry.S could be entered in loop when SIGPENDING was setted again before sret. So we must add prevent code to make syscall restart (regs->sepc -= 0x4) or it may re-execute unexpected instructions. Just like in_syscall & forget_syscall used by arm. Signed-off-by: Guo Ren Cc: Palmer Dabbelt Cc: Arnd Bergmann --- arch/riscv/kernel/signal.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/riscv/kernel/signal.c b/arch/riscv/kernel/signal.c index 837e164..804d6ee 100644 --- a/arch/riscv/kernel/signal.c +++ b/arch/riscv/kernel/signal.c @@ -234,6 +234,9 @@ static void handle_signal(struct ksignal *ksig, struct pt_regs *regs) /* Are we from a system call? */ if (regs->scause == EXC_SYSCALL) { + /* Avoid additional syscall restarting via ret_from_exception */ + regs->scause = -1UL; + /* If so, check system call restarting.. */ switch (regs->a0) { case -ERESTART_RESTARTBLOCK: @@ -272,6 +275,9 @@ static void do_signal(struct pt_regs *regs) /* Did we come from a system call? */ if (regs->scause == EXC_SYSCALL) { + /* Avoid additional syscall restarting via ret_from_exception */ + regs->scause = -1UL; + /* Restart the system call - no handlers present */ switch (regs->a0) { case -ERESTARTNOHAND: -- 2.7.4