From nobody Sun Feb 8 13:20:58 2026 Received: from mail-lf1-f46.google.com (mail-lf1-f46.google.com [209.85.167.46]) (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 D9E7F208990 for ; Tue, 29 Oct 2024 10:53:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.46 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730199206; cv=none; b=BLHh2aI05Y6UH6sm99iqfUaNuit7ao6V92Tu9GN+n53PNu1xSFXmPHohXBBVwTRGnHJqp1fn+KUTnM8xlt/tI8oXMEGkz2fCyCHPSJWC1iseqwV4lLywoHxfAFPoSfWS2Hc0vl1Us7+1amUTBNr65ploPTOQnB/SJmiLnoiISoQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730199206; c=relaxed/simple; bh=U7+/gc2e2KuWRZx3ryccMQNU5ZCqQa+rXx8yeFy3Nh8=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=NjRCI0kWhaG3bHX3CS04ibwwv6NV6qznBHNUIg8QledDbEI7Dzr1HJrzG0e3Zu6Fw/jH/N4y4b9hNClQ4gT0ZAeXnq0NrGGCENX+uwesj0hqlgNU/1yL4DCPdicG44MFlgz9YorAEYvih5aC/lsZeE2kTtnsvJT0g0qrjxasLtw= 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=wqeYGmZh; arc=none smtp.client-ip=209.85.167.46 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="wqeYGmZh" Received: by mail-lf1-f46.google.com with SMTP id 2adb3069b0e04-539f0f9ee49so5633242e87.1 for ; Tue, 29 Oct 2024 03:53:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1730199203; x=1730804003; 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=hWWOf9VRKfs2/tqyRJcdO75r8/gLb8BcoV6DE9Ay3YY=; b=wqeYGmZhkBmx+JKiBU/6fwO2+uOEUnY1Wglfg860BHfqB4FAB+FTdrvr7mVLdA9mFM kKQtTBF3kj35Sd31qLKKpfDGm2FRBTTdG0bAUvPLo9n3+3U6NnnS447NKOhAmuODb3qR xHNKd4WS1aicOLm16LEl4viXxHTddIgPGjsP9WphwHtHYKAizldAi8j9xRtxLkcD6OT9 oDFJpgpADLytklgN04/oRtwhSeGQHtPnKRkfnXzqtIXQPVWQlaf2fpdJ4uZmoR+ld/fE YGL+gLOsePMX2MKnEJ4klFVOmCg8QZzVNb2Gf6Cgv94yIVfjhXLsI0adaOW88tVCOUkl 0xog== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1730199203; x=1730804003; 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=hWWOf9VRKfs2/tqyRJcdO75r8/gLb8BcoV6DE9Ay3YY=; b=kGZzKUFOlqto9hqwrxUeNdDnqLHrLVAv5yJaTzNm4w+Db8lNBfT97Ss7mKqW3bhSFG 8ebvr3EWW9kdAhF66sCCVezn4zz1v07+Gmf2xRoOWosOybFmzKxRB19wouUJNYQi+pzp VAdomGYqUWX8f4oHpNVchrSEX89ErMd3vwqD3o++j6HaAQQVJVP1fdQTCRnzMkoaMjso osvZFRr1HzJnse71e9uOz+K/d9nAru6uCYkzwc3rbzjNhj+6oQ1DfjucwwWfYUImUAIn mZCXdBwUm9ZQfEXf0oLXMA08e3BcwFqhKcxwQhfv4tKJWciiNSssdCFAFR4ZxgrRL/7e AsqQ== X-Forwarded-Encrypted: i=1; AJvYcCWq26kbOcC+IjkzdQSUPdFNd9o1YBzJHvwzxlgAorzk/YMQYnHlSlFqvw/qdB0bhH86YoTmNzLWpCoGDac=@vger.kernel.org X-Gm-Message-State: AOJu0Yx7eeICny75YQj0YKAwRHESIcDVPjz/oZBn6ZDUpd6LMtgzglqb B6BZghJ5xY/Povu/qZ05lnZc1rNvoqnmntG7HXiK71LwDELuKbXOqJdj6E+5RPA= X-Google-Smtp-Source: AGHT+IGYokcfvTEQUjshtOgXGdmRS2U3eH+gIN/8bmikMfR0LXUeM0vzogR0GFUwOUcsWs1HgXxhYQ== X-Received: by 2002:a05:6512:3084:b0:539:fed8:321 with SMTP id 2adb3069b0e04-53b34a31cdbmr4939668e87.51.1730199202995; Tue, 29 Oct 2024 03:53:22 -0700 (PDT) Received: from lino.lan ([85.235.12.238]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-53b2e12452fsm1351307e87.73.2024.10.29.03.53.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 29 Oct 2024 03:53:21 -0700 (PDT) From: Linus Walleij Date: Tue, 29 Oct 2024 11:53:00 +0100 Subject: [PATCH RFC v2 20/28] ARM: entry: Untangle ret_fast_syscall/to_user 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-v2-20-573519abef38@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 return to userspace is a bit hard to follow. To prepare the ground for further refactorings we rewrite the functions to ret_fast_syscall and ret_to_user are mostly stand-alone symbols. Signed-off-by: Linus Walleij --- arch/arm/kernel/entry-common.S | 25 +++++++++++++++---------- 1 file changed, 15 insertions(+), 10 deletions(-) diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S index d27e34d7e97a..ece921571714 100644 --- a/arch/arm/kernel/entry-common.S +++ b/arch/arm/kernel/entry-common.S @@ -44,20 +44,23 @@ ret_fast_syscall: bl syscall_exit_to_user_mode ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing movs r1, r1, lsl #16 - beq no_work_pending - UNWIND(.fnend ) -ENDPROC(ret_fast_syscall) - - /* Slower path - fall through to work_pending */ + beq 2f =20 tst r1, #_TIF_SYSCALL_WORK - beq slow_work_pending + beq 1f + b ret_to_user =20 -slow_work_pending: - mov r0, sp @ 'regs' +1: mov r0, sp @ 'regs' bl do_work_pending - b no_work_pending + +2: asm_irqentry_exit_to_user_mode + +#ifdef CONFIG_GCC_PLUGIN_STACKLEAK + bl stackleak_erase_on_task_stack +#endif + restore_user_regs + UNWIND(.fnend ) ENDPROC(ret_fast_syscall) =20 /* @@ -74,7 +77,9 @@ ENTRY(ret_to_user) ENTRY(ret_to_user_from_irq) ldr r1, [tsk, #TI_FLAGS] movs r1, r1, lsl #16 - bne slow_work_pending + beq no_work_pending + mov r0, sp @ 'regs' + bl do_work_pending no_work_pending: asm_irqentry_exit_to_user_mode =20 --=20 2.46.2