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Peter Anvin" , linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Kefeng Wang , Xie XiuQi , Guohanjun Subject: Re: [PATCH -next v5 6/8] arm64: add support for machine check error safe Message-ID: References: <20220528065056.1034168-1-tongtiangen@huawei.com> <20220528065056.1034168-7-tongtiangen@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220528065056.1034168-7-tongtiangen@huawei.com> ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1655456127; a=rsa-sha256; cv=none; b=FmdRe7KlND1mC5NSfObI3q+40obCPLF+0u4Kw3R7BCDkY5zw+9ql87eHYdcUZJqxLomeWh 6g47i3kOq/nsReeYR7AdOPLGYBhxC7zGXj9X3tCksp7mV8ZUEIHZewxZVBBtfIkZC5kbsa UsHzNf6RnazscuOnEHJg/D2iQe+0bIw= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1655456127; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=tKWWEewl5P/Ivh0wuOm71uPCSApDPyoHuC3s9fVM4z4=; b=BAs6hwjKJDnrwwp+yqbeQNEamWFy54C7frrH+H6KpaIzUYUDwXhctske33u4FdGDEfIt2W iGbfkxu5uwiUGkUabTZZLwcl6okEA2/QQIvVmauUxpja7nu/pCRPB9jA56VmqwexQ6pN9+ osQIBuUSL3e7e+J/8a2PzLszAcVpWSk= ARC-Authentication-Results: i=1; imf24.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf24.hostedemail.com: domain of mark.rutland@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=mark.rutland@arm.com Authentication-Results: imf24.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf24.hostedemail.com: domain of mark.rutland@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=mark.rutland@arm.com X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 8FC5A18007A X-Stat-Signature: rjnjnufu9ohud7eobzsywf9hig1kaqyj X-HE-Tag: 1655456127-519379 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sat, May 28, 2022 at 06:50:54AM +0000, Tong Tiangen wrote: > During the processing of arm64 kernel hardware memory errors(do_sea()), if > the errors is consumed in the kernel, the current processing is panic. > However, it is not optimal. > > Take uaccess for example, if the uaccess operation fails due to memory > error, only the user process will be affected, kill the user process > and isolate the user page with hardware memory errors is a better choice. > > This patch only enable machine error check framework, it add exception > fixup before kernel panic in do_sea() and only limit the consumption of > hardware memory errors in kernel mode triggered by user mode processes. > If fixup successful, panic can be avoided. > > Signed-off-by: Tong Tiangen > --- > arch/arm64/Kconfig | 1 + > arch/arm64/include/asm/extable.h | 1 + > arch/arm64/mm/extable.c | 17 +++++++++++++++++ > arch/arm64/mm/fault.c | 27 ++++++++++++++++++++++++++- > 4 files changed, 45 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index aaeb70358979..a3b12ff0cd7f 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -19,6 +19,7 @@ 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/extable.h b/arch/arm64/include/asm/extable.h > index 72b0e71cc3de..f80ebd0addfd 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_mc(struct pt_regs *regs); > #endif > diff --git a/arch/arm64/mm/extable.c b/arch/arm64/mm/extable.c > index 228d681a8715..c301dcf6335f 100644 > --- a/arch/arm64/mm/extable.c > +++ b/arch/arm64/mm/extable.c > @@ -9,6 +9,7 @@ > > #include > #include > +#include > > static inline unsigned long > get_ex_fixup(const struct exception_table_entry *ex) > @@ -76,3 +77,19 @@ bool fixup_exception(struct pt_regs *regs) > > BUG(); > } > + > +bool fixup_exception_mc(struct pt_regs *regs) > +{ > + const struct exception_table_entry *ex; > + > + ex = search_exception_tables(instruction_pointer(regs)); > + if (!ex) > + return false; > + > + /* > + * This is not complete, More Machine check safe extable type can > + * be processed here. > + */ > + > + return false; > +} > diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c > index c5e11768e5c1..b262bd282a89 100644 > --- a/arch/arm64/mm/fault.c > +++ b/arch/arm64/mm/fault.c > @@ -696,6 +696,29 @@ static int do_bad(unsigned long far, unsigned long esr, struct pt_regs *regs) > return 1; /* "fault" */ > } > > +static bool arm64_do_kernel_sea(unsigned long addr, unsigned int esr, > + struct pt_regs *regs, int sig, int code) > +{ > + if (!IS_ENABLED(CONFIG_ARCH_HAS_COPY_MC)) > + return false; > + > + if (user_mode(regs) || !current->mm) > + return false; What's the `!current->mm` check for? > + > + if (apei_claim_sea(regs) < 0) > + return false; > + > + if (!fixup_exception_mc(regs)) > + return false; I thought we still wanted to signal the task in this case? Or do you expect to add that into `fixup_exception_mc()` ? > + > + set_thread_esr(0, esr); Why are we not setting the address? Is that deliberate, or an oversight? > + > + arm64_force_sig_fault(sig, code, addr, > + "Uncorrected hardware memory error in kernel-access\n"); I think the wording here is misleading since we don't expect to recover from accesses to kernel memory, and would be better as something like: "Uncorrected memory error on access to user memory\n" Thanks, Mark. > + > + return true; > +} > + > static int do_sea(unsigned long far, unsigned long esr, struct pt_regs *regs) > { > const struct fault_info *inf; > @@ -721,7 +744,9 @@ static int do_sea(unsigned long far, unsigned long esr, struct pt_regs *regs) > */ > siaddr = untagged_addr(far); > } > - arm64_notify_die(inf->name, regs, inf->sig, inf->code, siaddr, esr); > + > + if (!arm64_do_kernel_sea(siaddr, esr, regs, inf->sig, inf->code)) > + arm64_notify_die(inf->name, regs, inf->sig, inf->code, siaddr, esr); > > return 0; > } > -- > 2.25.1 >