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 F1B89C433FE for ; Tue, 11 Jan 2022 11:11:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238441AbiAKLLb (ORCPT ); Tue, 11 Jan 2022 06:11:31 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39158 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238050AbiAKLLa (ORCPT ); Tue, 11 Jan 2022 06:11:30 -0500 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F2249C06173F for ; Tue, 11 Jan 2022 03:11:29 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=RDA47QM+2pERloyeRR1YQ4763c2uWo7jObsPU122iPw=; b=Oqk20XY2o6SZQT2gu4wvCwu3wT IcivEEyKNwLx4WHL2l54KAx62rW1ozZxikYFLoQ6XijBZ/Mdtr7I7qcWQ5jCA4atvRhpcM2eI/PMw 5O3BPNDRumv7aNb3ECX05P5vyUR43QCkCXCTa+/D4/Bg5mqOS3qfUDwHFfScCnYjc6Jec8gkC8Sap lE6M/PPJQxnCuIwc1/4D1XsGgtLEuegvTI5BPPWqeJhyDUqM9vOvyFsaqi814OiHQc7kK2UH/HOjh wEPu2nFi16HZCL2P5gr3lD+Uu1rKmjNfy0zCvy78ckA6ftR+8tz3qr/HKn13vq4SULhRq5e9Yby19 KDHQrHIQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1n7F3c-000b4n-Lc; Tue, 11 Jan 2022 11:11:16 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 74FE3300079; Tue, 11 Jan 2022 12:11:14 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 1CBF120280BD8; Tue, 11 Jan 2022 12:11:14 +0100 (CET) Date: Tue, 11 Jan 2022 12:11:14 +0100 From: Peter Zijlstra To: kernel test robot Cc: Josh Poimboeuf , LKML , x86@kernel.org, lkp@lists.01.org, lkp@intel.com Subject: Re: [x86/entry_32] aa93e2ad74: BUG:soft_lockup-CPU##stuck_for#s![systemd-logind:#] Message-ID: References: <20220106083523.GB32167@xsang-OptiPlex-9020> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220106083523.GB32167@xsang-OptiPlex-9020> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 06, 2022 at 04:35:23PM +0800, kernel test robot wrote: > > > Greeting, > > FYI, we noticed the following commit (built with clang-14): > > commit: aa93e2ad7464ffb90155a5ffdde963816f86d5dc ("x86/entry_32: Remove .fixup usage") > https://git.kernel.org/cgit/linux/kernel/git/tip/tip.git x86/core > > in testcase: kernel-selftests > version: > with following parameters: > > group: x86 > It would be very useful if this thing would also say which of the many x86 selftests fails... it appears to be: ldt_gdt_32. The below fixes it, but I'm still not entirely sure what the actual problem is, although Andy did find a bug in that the exception handler should do: *(ss:esp) = 0, adding ss-base (using insn_get_seg_base()) doesn't seem to cure things. The below simply emulates the pop instruction and relies on the nested RESTORE_REGS to actually set the segment register. The testcase now successfully completes again. --- arch/x86/entry/entry_32.S | 13 +++++++++---- arch/x86/include/asm/extable_fixup_types.h | 5 ++++- arch/x86/lib/insn-eval.c | 5 +++++ arch/x86/mm/extable.c | 17 +++-------------- 4 files changed, 21 insertions(+), 19 deletions(-) diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S index e0a95d8a6553..fff7f2a08ff5 100644 --- a/arch/x86/entry/entry_32.S +++ b/arch/x86/entry/entry_32.S @@ -268,11 +268,16 @@ 1: popl %ds 2: popl %es 3: popl %fs - addl $(4 + \pop), %esp /* pop the unused "gs" slot */ +4: addl $(4 + \pop), %esp /* pop the unused "gs" slot */ IRET_FRAME - _ASM_EXTABLE_TYPE(1b, 1b, EX_TYPE_POP_ZERO) - _ASM_EXTABLE_TYPE(2b, 2b, EX_TYPE_POP_ZERO) - _ASM_EXTABLE_TYPE(3b, 3b, EX_TYPE_POP_ZERO) + + /* + * There is no _ASM_EXTABLE_TYPE_REG() for ASM, however since this is + * ASM the registers are known and we can trivially hard-code them. + */ + _ASM_EXTABLE_TYPE(1b, 2b, EX_TYPE_POP_ZERO|EX_DATA_REG(8)) + _ASM_EXTABLE_TYPE(2b, 3b, EX_TYPE_POP_ZERO|EX_DATA_REG(9)) + _ASM_EXTABLE_TYPE(3b, 4b, EX_TYPE_POP_ZERO|EX_DATA_REG(10)) .endm .macro RESTORE_ALL_NMI cr3_reg:req pop=0 diff --git a/arch/x86/include/asm/extable_fixup_types.h b/arch/x86/include/asm/extable_fixup_types.h index b5ab333e064a..81eedabc1ea1 100644 --- a/arch/x86/include/asm/extable_fixup_types.h +++ b/arch/x86/include/asm/extable_fixup_types.h @@ -16,6 +16,7 @@ #define EX_DATA_FLAG_SHIFT 12 #define EX_DATA_IMM_SHIFT 16 +#define EX_DATA_REG(reg) ((reg) << EX_DATA_REG_SHIFT) #define EX_DATA_FLAG(flag) ((flag) << EX_DATA_FLAG_SHIFT) #define EX_DATA_IMM(imm) ((imm) << EX_DATA_IMM_SHIFT) @@ -41,7 +42,9 @@ #define EX_TYPE_RDMSR_IN_MCE 13 #define EX_TYPE_DEFAULT_MCE_SAFE 14 #define EX_TYPE_FAULT_MCE_SAFE 15 -#define EX_TYPE_POP_ZERO 16 + +#define EX_TYPE_POP_REG 16 /* reg := (long)imm */ +#define EX_TYPE_POP_ZERO (EX_TYPE_POP_REG | EX_DATA_IMM(0)) #define EX_TYPE_IMM_REG 17 /* reg := (long)imm */ #define EX_TYPE_EFAULT_REG (EX_TYPE_IMM_REG | EX_DATA_IMM(-EFAULT)) diff --git a/arch/x86/lib/insn-eval.c b/arch/x86/lib/insn-eval.c index 666b9c5672a2..b781d324211b 100644 --- a/arch/x86/lib/insn-eval.c +++ b/arch/x86/lib/insn-eval.c @@ -428,6 +428,11 @@ static const int pt_regoff[] = { offsetof(struct pt_regs, r13), offsetof(struct pt_regs, r14), offsetof(struct pt_regs, r15), +#else + offsetof(struct pt_regs, ds), + offsetof(struct pt_regs, es), + offsetof(struct pt_regs, fs), + offsetof(struct pt_regs, gs), #endif }; diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c index 41eaa648349e..dba2197c05c3 100644 --- a/arch/x86/mm/extable.c +++ b/arch/x86/mm/extable.c @@ -126,18 +126,6 @@ static bool ex_handler_clear_fs(const struct exception_table_entry *fixup, return ex_handler_default(fixup, regs); } -static bool ex_handler_pop_zero(const struct exception_table_entry *fixup, - struct pt_regs *regs) -{ - /* - * Typically used for when "pop %seg" traps, in which case we'll clear - * the stack slot and re-try the instruction, which will then succeed - * to pop zero. - */ - *((unsigned long *)regs->sp) = 0; - return ex_handler_default(fixup, regs); -} - static bool ex_handler_imm_reg(const struct exception_table_entry *fixup, struct pt_regs *regs, int reg, int imm) { @@ -218,8 +206,9 @@ int fixup_exception(struct pt_regs *regs, int trapnr, unsigned long error_code, case EX_TYPE_RDMSR_IN_MCE: ex_handler_msr_mce(regs, false); break; - case EX_TYPE_POP_ZERO: - return ex_handler_pop_zero(e, regs); + case EX_TYPE_POP_REG: + regs->sp += sizeof(long); + fallthrough; case EX_TYPE_IMM_REG: return ex_handler_imm_reg(e, regs, reg, imm); case EX_TYPE_FAULT_SGX: