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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 9B581C3DA4A for ; Tue, 20 Aug 2024 02:12:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:CC:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=/DoRg/+8Dn3+bI1w+7qf3TaYz2OSUFBpCMro8E+cGTw=; b=vD7j43nCckjKKjSY7Me0urgK84 bQC+isCIrdUiRdxivYwcNltwzU3gFGTphgbQNNCqxucLy1uO9Votib9408+0xR8PqZPVq7uGBNCP6 grgPQoVseorsYvBAPQBZyWSNrni9tZDNTbvVFq0bKToQ5LP2xaQJKKAUuMyg0lVGVDkTaMIAHuMSx UDmcGiZVLeFFzuuhBCORslmmEmP5Hldh575nLN8qI955RHYtpjh2VGT2Q6Se/AJS/BSYzqWCp2aEW Bf9cOm/0zUaYrmMykvzq1DUIvT/SAD11qd5yIDv79yh8h1Hx2Fc9DNbJUvk70rv7IPqbWzQS83XTI LII3kjPA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sgEMT-00000003WP6-319e; Tue, 20 Aug 2024 02:12:41 +0000 Received: from szxga02-in.huawei.com ([45.249.212.188]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1sgELm-00000003WHd-2kCB for linux-arm-kernel@lists.infradead.org; Tue, 20 Aug 2024 02:12:00 +0000 Received: from mail.maildlp.com (unknown [172.19.88.194]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4WntGL6b8rzpTPR; Tue, 20 Aug 2024 10:10:18 +0800 (CST) Received: from kwepemm600017.china.huawei.com (unknown [7.193.23.234]) by mail.maildlp.com (Postfix) with ESMTPS id 38859140133; Tue, 20 Aug 2024 10:11:48 +0800 (CST) Received: from [10.174.179.234] (10.174.179.234) by kwepemm600017.china.huawei.com (7.193.23.234) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.39; Tue, 20 Aug 2024 10:11:46 +0800 Message-ID: <4436d172-c474-8ecd-b5e4-4c21088baf49@huawei.com> Date: Tue, 20 Aug 2024 10:11:45 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 Subject: Re: [PATCH v12 2/6] arm64: add support for ARCH_HAS_COPY_MC To: Mark Rutland CC: Catalin Marinas , Will Deacon , Andrew Morton , James Morse , Robin Murphy , Andrey Konovalov , Dmitry Vyukov , Vincenzo Frascino , Michael Ellerman , Nicholas Piggin , Andrey Ryabinin , Alexander Potapenko , Christophe Leroy , Aneesh Kumar K.V , "Naveen N. Rao" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , , "H. Peter Anvin" , , , , , , Guohanjun References: <20240528085915.1955987-1-tongtiangen@huawei.com> <20240528085915.1955987-3-tongtiangen@huawei.com> From: Tong Tiangen In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.179.234] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To kwepemm600017.china.huawei.com (7.193.23.234) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240819_191159_232557_159893FA X-CRM114-Status: GOOD ( 39.43 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 在 2024/8/20 1:29, Mark Rutland 写道: > Hi Tong, > > On Tue, May 28, 2024 at 04:59:11PM +0800, Tong Tiangen wrote: >> For the arm64 kernel, when it processes hardware memory errors for >> synchronize notifications(do_sea()), if the errors is consumed within the >> kernel, the current processing is panic. However, it is not optimal. >> >> Take copy_from/to_user for example, If ld* triggers a memory error, even in >> kernel mode, only the associated process is affected. Killing the user >> process and isolating the corrupt page is a better choice. >> >> New fixup type EX_TYPE_KACCESS_ERR_ZERO_ME_SAFE is added to identify insn >> that can recover from memory errors triggered by access to kernel memory. >> >> Signed-off-by: Tong Tiangen > > Generally this looks ok, but I have a couple of comments below. > >> --- >> arch/arm64/Kconfig | 1 + >> arch/arm64/include/asm/asm-extable.h | 31 +++++++++++++++++++++++----- >> arch/arm64/include/asm/asm-uaccess.h | 4 ++++ >> arch/arm64/include/asm/extable.h | 1 + >> arch/arm64/lib/copy_to_user.S | 10 ++++----- >> arch/arm64/mm/extable.c | 19 +++++++++++++++++ >> arch/arm64/mm/fault.c | 27 +++++++++++++++++------- >> 7 files changed, 75 insertions(+), 18 deletions(-) >> >> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig >> index 5d91259ee7b5..13ca06ddf3dd 100644 >> --- a/arch/arm64/Kconfig >> +++ b/arch/arm64/Kconfig >> @@ -20,6 +20,7 @@ config ARM64 >> select ARCH_ENABLE_SPLIT_PMD_PTLOCK if PGTABLE_LEVELS > 2 >> select ARCH_ENABLE_THP_MIGRATION if TRANSPARENT_HUGEPAGE >> select ARCH_HAS_CACHE_LINE_SIZE >> + select ARCH_HAS_COPY_MC if ACPI_APEI_GHES >> select ARCH_HAS_CURRENT_STACK_POINTER >> select ARCH_HAS_DEBUG_VIRTUAL >> select ARCH_HAS_DEBUG_VM_PGTABLE >> diff --git a/arch/arm64/include/asm/asm-extable.h b/arch/arm64/include/asm/asm-extable.h >> index 980d1dd8e1a3..9c0664fe1eb1 100644 >> --- a/arch/arm64/include/asm/asm-extable.h >> +++ b/arch/arm64/include/asm/asm-extable.h >> @@ -5,11 +5,13 @@ >> #include >> #include >> >> -#define EX_TYPE_NONE 0 >> -#define EX_TYPE_BPF 1 >> -#define EX_TYPE_UACCESS_ERR_ZERO 2 >> -#define EX_TYPE_KACCESS_ERR_ZERO 3 >> -#define EX_TYPE_LOAD_UNALIGNED_ZEROPAD 4 >> +#define EX_TYPE_NONE 0 >> +#define EX_TYPE_BPF 1 >> +#define EX_TYPE_UACCESS_ERR_ZERO 2 >> +#define EX_TYPE_KACCESS_ERR_ZERO 3 >> +#define EX_TYPE_LOAD_UNALIGNED_ZEROPAD 4 >> +/* kernel access memory error safe */ >> +#define EX_TYPE_KACCESS_ERR_ZERO_ME_SAFE 5 > > Could we please use 'MEM_ERR', and likewise for the macros below? That's > more obvious than 'ME_SAFE', and we wouldn't need the comment here. > Likewise elsewhere in this patch and the series. > > To Jonathan's comment, I do prefer these numbers are aligned, so aside > from the naming, the diff above looks good. OK, I also modified other locations to use 'MEM_ERR'. > >> >> /* Data fields for EX_TYPE_UACCESS_ERR_ZERO */ >> #define EX_DATA_REG_ERR_SHIFT 0 >> @@ -51,6 +53,17 @@ >> #define _ASM_EXTABLE_UACCESS(insn, fixup) \ >> _ASM_EXTABLE_UACCESS_ERR_ZERO(insn, fixup, wzr, wzr) >> >> +#define _ASM_EXTABLE_KACCESS_ERR_ZERO_ME_SAFE(insn, fixup, err, zero) \ >> + __ASM_EXTABLE_RAW(insn, fixup, \ >> + EX_TYPE_KACCESS_ERR_ZERO_ME_SAFE, \ >> + ( \ >> + EX_DATA_REG(ERR, err) | \ >> + EX_DATA_REG(ZERO, zero) \ >> + )) >> + >> +#define _ASM_EXTABLE_KACCESS_ME_SAFE(insn, fixup) \ >> + _ASM_EXTABLE_KACCESS_ERR_ZERO_ME_SAFE(insn, fixup, wzr, wzr) >> + >> /* >> * Create an exception table entry for uaccess `insn`, which will branch to `fixup` >> * when an unhandled fault is taken. >> @@ -69,6 +82,14 @@ >> .endif >> .endm >> >> +/* >> + * Create an exception table entry for kaccess me(memory error) safe `insn`, which >> + * will branch to `fixup` when an unhandled fault is taken. >> + */ >> + .macro _asm_extable_kaccess_me_safe, insn, fixup >> + _ASM_EXTABLE_KACCESS_ME_SAFE(\insn, \fixup) >> + .endm >> + > > With the naming above, I think this can be: > > | /* > | * Create an exception table entry for kaccess `insn`, which will branch to > | * `fixup` when a memory error is taken > | */ > | .macro _asm_extable_kaccess_mem_err, insn, fixup > | _ASM_EXTABLE_KACCESS_MEM_ERR(\insn, \fixup) > | .endm > OK, will be fixed next version. >> #else /* __ASSEMBLY__ */ >> >> #include >> diff --git a/arch/arm64/include/asm/asm-uaccess.h b/arch/arm64/include/asm/asm-uaccess.h >> index 5b6efe8abeeb..7bbebfa5b710 100644 >> --- a/arch/arm64/include/asm/asm-uaccess.h >> +++ b/arch/arm64/include/asm/asm-uaccess.h >> @@ -57,6 +57,10 @@ alternative_else_nop_endif >> .endm >> #endif >> >> +#define KERNEL_ME_SAFE(l, x...) \ >> +9999: x; \ >> + _asm_extable_kaccess_me_safe 9999b, l >> + >> #define USER(l, x...) \ >> 9999: x; \ >> _asm_extable_uaccess 9999b, l >> diff --git a/arch/arm64/include/asm/extable.h b/arch/arm64/include/asm/extable.h >> index 72b0e71cc3de..bc49443bc502 100644 >> --- a/arch/arm64/include/asm/extable.h >> +++ b/arch/arm64/include/asm/extable.h >> @@ -46,4 +46,5 @@ bool ex_handler_bpf(const struct exception_table_entry *ex, >> #endif /* !CONFIG_BPF_JIT */ >> >> bool fixup_exception(struct pt_regs *regs); >> +bool fixup_exception_me(struct pt_regs *regs); >> #endif >> diff --git a/arch/arm64/lib/copy_to_user.S b/arch/arm64/lib/copy_to_user.S >> index 802231772608..2ac716c0d6d8 100644 >> --- a/arch/arm64/lib/copy_to_user.S >> +++ b/arch/arm64/lib/copy_to_user.S >> @@ -20,7 +20,7 @@ >> * x0 - bytes not copied >> */ >> .macro ldrb1 reg, ptr, val >> - ldrb \reg, [\ptr], \val >> + KERNEL_ME_SAFE(9998f, ldrb \reg, [\ptr], \val) >> .endm >> >> .macro strb1 reg, ptr, val >> @@ -28,7 +28,7 @@ >> .endm >> >> .macro ldrh1 reg, ptr, val >> - ldrh \reg, [\ptr], \val >> + KERNEL_ME_SAFE(9998f, ldrh \reg, [\ptr], \val) >> .endm >> >> .macro strh1 reg, ptr, val >> @@ -36,7 +36,7 @@ >> .endm >> >> .macro ldr1 reg, ptr, val >> - ldr \reg, [\ptr], \val >> + KERNEL_ME_SAFE(9998f, ldr \reg, [\ptr], \val) >> .endm >> >> .macro str1 reg, ptr, val >> @@ -44,7 +44,7 @@ >> .endm >> >> .macro ldp1 reg1, reg2, ptr, val >> - ldp \reg1, \reg2, [\ptr], \val >> + KERNEL_ME_SAFE(9998f, ldp \reg1, \reg2, [\ptr], \val) >> .endm >> >> .macro stp1 reg1, reg2, ptr, val > > These changes mean that regular copy_to_user() will handle kernel memory > errors, rather than only doing that in copy_mc_to_user(). If that's > intentional, please call that out explicitly in the commit message. Yes. This is the purpose of the modification. If the copy_to_user() function encounters a memory error, this uaccess affects only the current process. and only need to kill the current process instead of the entire kernel panic. Do not add copy_mc_to_user() so that copy_to_user() can process memory errors. I'll add a description in the commit msg next version. > >> @@ -64,7 +64,7 @@ SYM_FUNC_START(__arch_copy_to_user) >> 9997: cmp dst, dstin >> b.ne 9998f >> // Before being absolutely sure we couldn't copy anything, try harder >> - ldrb tmp1w, [srcin] >> +KERNEL_ME_SAFE(9998f, ldrb tmp1w, [srcin]) >> USER(9998f, sttrb tmp1w, [dst]) >> add dst, dst, #1 >> 9998: sub x0, end, dst // bytes not copied > > Same comment as above. > >> diff --git a/arch/arm64/mm/extable.c b/arch/arm64/mm/extable.c >> index 228d681a8715..8c690ae61944 100644 >> --- a/arch/arm64/mm/extable.c >> +++ b/arch/arm64/mm/extable.c >> @@ -72,7 +72,26 @@ bool fixup_exception(struct pt_regs *regs) >> return ex_handler_uaccess_err_zero(ex, regs); >> case EX_TYPE_LOAD_UNALIGNED_ZEROPAD: >> return ex_handler_load_unaligned_zeropad(ex, regs); >> + case EX_TYPE_KACCESS_ERR_ZERO_ME_SAFE: >> + return false; >> } >> >> BUG(); >> } >> + >> +bool fixup_exception_me(struct pt_regs *regs) >> +{ >> + const struct exception_table_entry *ex; >> + >> + ex = search_exception_tables(instruction_pointer(regs)); >> + if (!ex) >> + return false; >> + >> + switch (ex->type) { >> + case EX_TYPE_UACCESS_ERR_ZERO: >> + case EX_TYPE_KACCESS_ERR_ZERO_ME_SAFE: >> + return ex_handler_uaccess_err_zero(ex, regs); >> + } >> + >> + return false; >> +} >> diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c >> index 451ba7cbd5ad..2dc65f99d389 100644 >> --- a/arch/arm64/mm/fault.c >> +++ b/arch/arm64/mm/fault.c >> @@ -708,21 +708,32 @@ static int do_bad(unsigned long far, unsigned long esr, struct pt_regs *regs) >> return 1; /* "fault" */ >> } >> >> +/* >> + * APEI claimed this as a firmware-first notification. >> + * Some processing deferred to task_work before ret_to_user(). >> + */ >> +static bool do_apei_claim_sea(struct pt_regs *regs) >> +{ >> + if (user_mode(regs)) { >> + if (!apei_claim_sea(regs)) >> + return true; >> + } else if (IS_ENABLED(CONFIG_ARCH_HAS_COPY_MC)) { >> + if (fixup_exception_me(regs) && !apei_claim_sea(regs)) >> + return true; >> + } >> + >> + return false; >> +} > > Hmm... that'll fixup the exception even if we don't manage to claim a > the SEA. I suspect this should probably be: > > static bool do_apei_claim_sea(struct pt_regs *regs) > { > if (apei_claim_sea(regs)) > return false; > if (user_mode(regs)) > return true; > if (IS_ENABLED(CONFIG_ARCH_HAS_COPY_MC)) > return !fixup_excepton_mem_err(regs); > > return false; > } > > ... unless we *don't* want to claim the SEA in the case we don't have a > fixup? > > Mark. > Yes. My original meaning here is that if not have fixup, panic is performed in do_sea() according to the original logic, and claim sea is not required. Thanks, Tong. >> + >> static int do_sea(unsigned long far, unsigned long esr, struct pt_regs *regs) >> { >> const struct fault_info *inf; >> unsigned long siaddr; >> >> - inf = esr_to_fault_info(esr); >> - >> - if (user_mode(regs) && apei_claim_sea(regs) == 0) { >> - /* >> - * APEI claimed this as a firmware-first notification. >> - * Some processing deferred to task_work before ret_to_user(). >> - */ >> + if (do_apei_claim_sea(regs)) >> return 0; >> - } >> >> + inf = esr_to_fault_info(esr); >> if (esr & ESR_ELx_FnV) { >> siaddr = 0; >> } else { >> -- >> 2.25.1 >> >> > > .