From nobody Sat Feb 7 04:05:58 2026 Received: from mail-lf1-f51.google.com (mail-lf1-f51.google.com [209.85.167.51]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 60A3D206E82 for ; Tue, 29 Oct 2024 10:52:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.51 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730199179; cv=none; b=eKKH/N9w10Tc/0EMNBjTrrXoupwCTE6iHmCla0OsUFefFp9ljuicg8nGzo+ktcI55RJg8b90wiM0hHprfBYxsW6OFxYqOovR+Oi3hF76Xt1gaFWe7VJMyTEOwRsipdjIcd+fE+XrtFg0J80PPq0kHO5g44H+0jTWmmnX0c21ctg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730199179; c=relaxed/simple; bh=TXjj9xFMQ8ObJncCvfOXEQyxyh4pdr8dOD7N4vVAW1Y=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=XMOFadXQn6caGKAKf+Zi5ZU7cxGEGg6nnRa+1zETh0YFnINLoCwe1xGj0edBAPsVLFBM1AfnPR0OVN5xeM7dahoXp7CJ0lwrXIIE//SdLiX3Zhkbi9mTkxw9rt4LNlsr7FctOTk0zjfwXkYJKvUIVjtmwCQZY4VndJ3vHa5MZXA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linaro.org; spf=pass smtp.mailfrom=linaro.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b=O1/ihUO6; arc=none smtp.client-ip=209.85.167.51 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linaro.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linaro.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="O1/ihUO6" Received: by mail-lf1-f51.google.com with SMTP id 2adb3069b0e04-539eb97f26aso5435641e87.2 for ; Tue, 29 Oct 2024 03:52:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1730199175; x=1730803975; darn=vger.kernel.org; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:from:to:cc:subject:date:message-id :reply-to; bh=FhwutFaJAhBwzUvxWfpVZxdfXLNUR2eiL6c/Y41YU9M=; b=O1/ihUO6X0FWsjLTrki5Kiv/jiGQdCAP7+sNVXn3o/AwONpV9JqIE1LRsqIIUfS0gB V4duyfBIwosraTXNEpByRia434Hez7wf60AnnI/hy1eNOlX2QVgcpXIhb6vfuCJkP7/W I17ZhBXp54Y/wbXzz8tqyZi2BRj+wn7LQ1MAb8/gojnvdZFRN0j37KLjmj9vKg6kvRHY /TEvVMorexZRiamtNfZQ+H6q8Di0/NSI4ygrJ4pieVFvbwEkPXp5kmGKFlwJ8zV/I6Ha Llz3F3xjiroRSpEfGn+ehS3Oyron1CqVpOR6lnjreAsfAIRMV8dUn3S9DyCTLtBXYDHa wlBw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1730199175; x=1730803975; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=FhwutFaJAhBwzUvxWfpVZxdfXLNUR2eiL6c/Y41YU9M=; b=I3FPJCpH8XMuQ5cmWJNy0hHYQcEloZpHegBPgG7fmmhUz1yiyloseaoAbvg9alEZq7 JqTqF0lyI9L4iDk3dMP5zn7AGsg9/xN1j09lUdF3BS7Ek5xkVHHXhJlPVkuhhBemWmiv 0aiNLLd3l1fPjN2qMDqGn7VL1HhXz4TJKjyycV9p89Q2FnyzFlQ4v/GD367dzyDjOg6R UR4X1bb97GWgHj3Pyu7hAPbGVxkNE8Kx01vKtZv954HNy4V9tXZWehAZN6uixK/MpgRq mo6TBY7j2CUo4ExPqJTbqQn+7BkhKGz2MHwiumhlFk/9F9idvyo6DogfvtI39Tt8e5Ih nCJw== X-Forwarded-Encrypted: i=1; AJvYcCVkkdy1wp5Ex5MhiaLoeUlE95Cja5SII7ncxN6cgu6to8ObwKqX9ZZs8TL7ABO+6PNT6iamynoPx+sac+g=@vger.kernel.org X-Gm-Message-State: AOJu0Yw2MbGPOUbwLFc2AkBY8YyvXooPmhcMN9MmONP7INUeAvY12ROj usOl1cJHaD/AkybDUCBE4/BBamI9yjldMvppv9VcVF6JmNWpgBrWCCfKVWQbDRo= X-Google-Smtp-Source: AGHT+IE7TBLGcMxKsC7a30pUEcJoXeIzSiYTepdqh334Y6u9VYfbvLHbrLSewuIIAuux0bNQMqTTNA== X-Received: by 2002:a05:6512:3b2b:b0:539:e1ea:c298 with SMTP id 2adb3069b0e04-53b348cbb37mr5497449e87.22.1730199175441; Tue, 29 Oct 2024 03:52:55 -0700 (PDT) Received: from lino.lan ([85.235.12.238]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-53b2e12452fsm1351307e87.73.2024.10.29.03.52.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 29 Oct 2024 03:52:54 -0700 (PDT) From: Linus Walleij Date: Tue, 29 Oct 2024 11:52:45 +0100 Subject: [PATCH RFC v2 05/28] ARM: process: Remove local restart Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20241029-arm-generic-entry-v2-5-573519abef38@linaro.org> References: <20241029-arm-generic-entry-v2-0-573519abef38@linaro.org> In-Reply-To: <20241029-arm-generic-entry-v2-0-573519abef38@linaro.org> To: Oleg Nesterov , Russell King , Kees Cook , Andy Lutomirski , Will Drewry , Frederic Weisbecker , "Paul E. McKenney" , Jinjie Ruan , Arnd Bergmann , Ard Biesheuvel , Al Viro Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Linus Walleij X-Mailer: b4 0.14.0 The ARM kernel contains a quirk to handle syscall restarts inside the kernel without exiting to userspace. The generic entry cannot handle this. Rename do_signal() to arch_do_signal_or_restart() to fit with the upcoming generic entry conversion. This is essentially a revert of commit 81783786d5cf "ARM: 7473/1: deal with handlerless restarts without leaving the kernel" from 2012. Other solutions may be possible, such as checking the PC after do_work_pending and assume it is a local restart if that address is inside the kernel, or modifying the generic entry code to track local restarts like ARM does and pass that information back. Signed-off-by: Linus Walleij --- arch/arm/include/asm/signal.h | 3 +-- arch/arm/kernel/entry-common.S | 9 +-------- arch/arm/kernel/signal.c | 28 +++++++++------------------- 3 files changed, 11 insertions(+), 29 deletions(-) diff --git a/arch/arm/include/asm/signal.h b/arch/arm/include/asm/signal.h index 8b84092d1518..7acccc96840c 100644 --- a/arch/arm/include/asm/signal.h +++ b/arch/arm/include/asm/signal.h @@ -24,7 +24,6 @@ typedef struct { #include =20 void do_rseq_syscall(struct pt_regs *regs); -int do_work_pending(struct pt_regs *regs, unsigned int thread_flags, - int syscall); +void do_work_pending(struct pt_regs *regs, unsigned int thread_flags); =20 #endif diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S index df6961a1006b..da5c2d4b62e5 100644 --- a/arch/arm/kernel/entry-common.S +++ b/arch/arm/kernel/entry-common.S @@ -86,14 +86,8 @@ ENDPROC(ret_fast_syscall) bne __sys_trace_return_nosave slow_work_pending: mov r0, sp @ 'regs' - mov r2, why @ 'syscall' bl do_work_pending - cmp r0, #0 - beq no_work_pending - movlt scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE) - str scno, [tsk, #TI_ABI_SYSCALL] @ make sure tracers see update - ldmia sp, {r0 - r6} @ have to reload r0 - r6 - b local_restart @ ... and off we go + b no_work_pending ENDPROC(ret_fast_syscall) =20 /* @@ -266,7 +260,6 @@ ENTRY(vector_swi) */ TRACE( ldmia sp, {r0 - r3} ) =20 -local_restart: ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing stmdb sp!, {r4, r5} @ push fifth and sixth args =20 diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c index 79a6730fa0eb..7b1a16e86b23 100644 --- a/arch/arm/kernel/signal.c +++ b/arch/arm/kernel/signal.c @@ -18,6 +18,7 @@ #include #include #include +#include #include =20 #include "signal.h" @@ -534,9 +535,10 @@ static void handle_signal(struct ksignal *ksig, struct= pt_regs *regs) * the kernel can handle, and then we build all the user-level signal hand= ling * stack-frames in one go after that. */ -static int do_signal(struct pt_regs *regs, int syscall) +static void arch_do_signal_or_restart(struct pt_regs *regs) { unsigned int retval =3D 0, continue_addr =3D 0, restart_addr =3D 0; + bool syscall =3D (syscall_get_nr(current, regs) !=3D -1); struct ksignal ksig; int restart =3D 0; =20 @@ -590,16 +592,14 @@ static int do_signal(struct pt_regs *regs, int syscal= l) } else { /* no handler */ restore_saved_sigmask(); - if (unlikely(restart) && regs->ARM_pc =3D=3D restart_addr) { + if (unlikely(restart) && regs->ARM_pc =3D=3D restart_addr) regs->ARM_pc =3D continue_addr; - return restart; - } } - return 0; + return; } =20 -asmlinkage int -do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int sysca= ll) +asmlinkage void +do_work_pending(struct pt_regs *regs, unsigned int thread_flags) { /* * The assembly code enters us with IRQs off, but it hasn't @@ -612,19 +612,10 @@ do_work_pending(struct pt_regs *regs, unsigned int th= read_flags, int syscall) schedule(); } else { if (unlikely(!user_mode(regs))) - return 0; + return; local_irq_enable(); if (thread_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL)) { - int restart =3D do_signal(regs, syscall); - if (unlikely(restart)) { - /* - * Restart without handlers. - * Deal with it without leaving - * the kernel space. - */ - return restart; - } - syscall =3D 0; + arch_do_signal_or_restart(regs); } else if (thread_flags & _TIF_UPROBE) { uprobe_notify_resume(regs); } else { @@ -634,7 +625,6 @@ do_work_pending(struct pt_regs *regs, unsigned int thre= ad_flags, int syscall) local_irq_disable(); thread_flags =3D read_thread_flags(); } while (thread_flags & _TIF_WORK_MASK); - return 0; } =20 struct page *get_signal_page(void) --=20 2.46.2