From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E163EEB64DD for ; Wed, 9 Aug 2023 11:14:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233391AbjHILOs (ORCPT ); Wed, 9 Aug 2023 07:14:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51400 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233389AbjHILOr (ORCPT ); Wed, 9 Aug 2023 07:14:47 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8A5D5ED for ; Wed, 9 Aug 2023 04:14:46 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 2ABFD62457 for ; Wed, 9 Aug 2023 11:14:46 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3AD8AC433C7; Wed, 9 Aug 2023 11:14:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1691579685; bh=OTNG/ysHhnRdqsIky9K/xCdaG6fR/3rOa+a0/cLbH8s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PiEDQnvNvO8jz/4ne8DxwB1ObzATXC6s7RtJmj1TILVsu8AFBFckI0eRKCFPOy2IW N5e3CUqKPLGnYBauRCqIYIdOW3nihTEVTlwpjlk3hqeI2G6rthvuc966l6rjhmdXap 9cLHYELfkTp552wGzZ7Q0VP5/hwFAq0oQcc9wUs8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Vineet Gupta , Sasha Levin Subject: [PATCH 4.19 080/323] ARCv2: entry: comments about hardware auto-save on taken interrupts Date: Wed, 9 Aug 2023 12:38:38 +0200 Message-ID: <20230809103701.797548716@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230809103658.104386911@linuxfoundation.org> References: <20230809103658.104386911@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Vineet Gupta [ Upstream commit 45869eb0c0afd72bd5ab2437d4b00915697c044a ] Signed-off-by: Vineet Gupta Stable-dep-of: 92e2921eeafd ("ARC: define ASM_NL and __ALIGN(_STR) outside #ifdef __ASSEMBLY__ guard") Signed-off-by: Sasha Levin --- arch/arc/include/asm/entry-arcv2.h | 78 ++++++++++++++++++++++++------ 1 file changed, 62 insertions(+), 16 deletions(-) diff --git a/arch/arc/include/asm/entry-arcv2.h b/arch/arc/include/asm/entry-arcv2.h index 225e7df2d8ed8..1c3520d1fa420 100644 --- a/arch/arc/include/asm/entry-arcv2.h +++ b/arch/arc/include/asm/entry-arcv2.h @@ -7,15 +7,54 @@ #include #include /* For THREAD_SIZE */ +/* + * Interrupt/Exception stack layout (pt_regs) for ARCv2 + * (End of struct aligned to end of page [unless nested]) + * + * INTERRUPT EXCEPTION + * + * manual --------------------- manual + * | orig_r0 | + * | event/ECR | + * | bta | + * | user_r25 | + * | gp | + * | fp | + * | sp | + * | r12 | + * | r30 | + * | r58 | + * | r59 | + * hw autosave --------------------- + * optional | r0 | + * | r1 | + * ~ ~ + * | r9 | + * | r10 | + * | r11 | + * | blink | + * | lpe | + * | lps | + * | lpc | + * | ei base | + * | ldi base | + * | jli base | + * --------------------- + * hw autosave | pc / eret | + * mandatory | stat32 / erstatus | + * --------------------- + */ + /*------------------------------------------------------------------------*/ .macro INTERRUPT_PROLOGUE called_from - - ; Before jumping to Interrupt Vector, hardware micro-ops did following: + ; (A) Before jumping to Interrupt Vector, hardware micro-ops did following: ; 1. SP auto-switched to kernel mode stack - ; 2. STATUS32.Z flag set to U mode at time of interrupt (U:1, K:0) - ; 3. Auto saved: r0-r11, blink, LPE,LPS,LPC, JLI,LDI,EI, PC, STAT32 + ; 2. STATUS32.Z flag set if in U mode at time of interrupt (U:1,K:0) + ; 3. Auto save: (mandatory) Push PC and STAT32 on stack + ; hardware does even if CONFIG_ARC_IRQ_NO_AUTOSAVE + ; 4. Auto save: (optional) r0-r11, blink, LPE,LPS,LPC, JLI,LDI,EI ; - ; Now manually save: r12, sp, fp, gp, r25 + ; (B) Manually saved some regs: r12,r25,r30, sp,fp,gp, ACCL pair #ifdef CONFIG_ARC_IRQ_NO_AUTOSAVE .ifnc \called_from, exception @@ -57,14 +96,17 @@ ; - U mode: retrieve it from AUX_USER_SP ; - K mode: add the offset from current SP where H/w starts auto push ; - ; Utilize the fact that Z bit is set if Intr taken in U mode + ; 1. Utilize the fact that Z bit is set if Intr taken in U mode + ; 2. Upon entry SP is always saved (for any inspection, unwinding etc), + ; but on return, restored only if U mode + mov.nz r9, sp - add.nz r9, r9, SZ_PT_REGS - PT_sp - 4 + add.nz r9, r9, SZ_PT_REGS - PT_sp - 4 ; K mode SP bnz 1f - lr r9, [AUX_USER_SP] + lr r9, [AUX_USER_SP] ; U mode SP 1: - PUSH r9 ; SP + PUSH r9 ; SP (pt_regs->sp) PUSH fp PUSH gp @@ -85,6 +127,8 @@ /*------------------------------------------------------------------------*/ .macro INTERRUPT_EPILOGUE called_from + ; INPUT: r0 has STAT32 of calling context + ; INPUT: Z flag set if returning to K mode .ifnc \called_from, exception add sp, sp, 12 ; skip BTA/ECR/orig_r0 placeholderss .endif @@ -98,9 +142,10 @@ POP gp POP fp - ; Don't touch AUX_USER_SP if returning to K mode (Z bit set) - ; (Z bit set on K mode is inverse of INTERRUPT_PROLOGUE) - add.z sp, sp, 4 + ; Restore SP (into AUX_USER_SP) only if returning to U mode + ; - for K mode, it will be implicitly restored as stack is unwound + ; - Z flag set on K is inverse of what hardware does on interrupt entry + ; but that doesn't really matter bz 1f POPAX AUX_USER_SP @@ -145,11 +190,11 @@ /*------------------------------------------------------------------------*/ .macro EXCEPTION_PROLOGUE - ; Before jumping to Exception Vector, hardware micro-ops did following: + ; (A) Before jumping to Exception Vector, hardware micro-ops did following: ; 1. SP auto-switched to kernel mode stack - ; 2. STATUS32.Z flag set to U mode at time of interrupt (U:1,K:0) + ; 2. STATUS32.Z flag set if in U mode at time of exception (U:1,K:0) ; - ; Now manually save the complete reg file + ; (B) Manually save the complete reg file below PUSH r9 ; freeup a register: slot of erstatus @@ -195,12 +240,13 @@ PUSHAX ecr ; r9 contains ECR, expected by EV_Trap PUSH r0 ; orig_r0 + ; OUTPUT: r9 has ECR .endm /*------------------------------------------------------------------------*/ .macro EXCEPTION_EPILOGUE - ; Assumes r0 has PT_status32 + ; INPUT: r0 has STAT32 of calling context btst r0, STATUS_U_BIT ; Z flag set if K, used in INTERRUPT_EPILOGUE add sp, sp, 8 ; orig_r0/ECR don't need restoring -- 2.39.2