Message-ID: <1504770316-4327-2-git-send-email-xiexiuqi@huawei.com>
Date:   Thu, 7 Sep 2017 15:45:14 +0800
From:   Xie XiuQi <xiexiuqi@...wei.com>
To:     <catalin.marinas@....com>, <will.deacon@....com>,
        <mingo@...hat.com>, <mark.rutland@....com>,
        <ard.biesheuvel@...aro.org>, <james.morse@....com>,
        <Dave.Martin@....com>, <takahiro.akashi@...aro.org>,
        <tbaicar@...eaurora.org>, <stephen.boyd@...aro.org>, <bp@...e.de>,
        <julien.thierry@....com>, <shiju.jose@...wei.com>,
        <zjzhang@...eaurora.org>
CC:     <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <linux-acpi@...r.kernel.org>,
        <xiexiuqi@...wei.com>, <wangxiongfeng2@...wei.com>,
        <zhengqiang10@...wei.com>, <gengdongjiu@...wei.com>,
        <huawei.libin@...wei.com>, <wangkefeng.wang@...wei.com>,
        <lijinyue@...wei.com>, <guohanjun@...wei.com>,
        <cj.chengjian@...wei.com>
Subject: [PATCH v3 1/3] arm64/ras: support sea error recovery

With ARM v8.2 RAS Extension, SEA are usually triggered when memory errors
are consumed. In some cases, if the error address is in a clean page or a
read-only page, there is a chance to recover. Such as error occurs in a
instruction page, we can reread this page from disk instead of killing
process.

Because memory_failure() may sleep, we can not call it directly in SEA
exception context. So we saved faulting physical address associated with
a process in the ghes handler and set __TIF_SEA_NOTIFY. When we return
from SEA exception context and get into do_notify_resume() before the
process running, we could check it and call memory_failure() to do
recovery. It's safe, because we are in process context.

Signed-off-by: Xie XiuQi <xiexiuqi@...wei.com>
Signed-off-by: Wang Xiongfeng <wangxiongfeng2@...wei.com>
---
 arch/arm64/Kconfig                   |  11 +++
 arch/arm64/include/asm/ras.h         |  36 +++++++++
 arch/arm64/include/asm/thread_info.h |   4 +-
 arch/arm64/kernel/Makefile           |   1 +
 arch/arm64/kernel/ras.c              | 141 +++++++++++++++++++++++++++++++++++
 arch/arm64/kernel/signal.c           |   8 ++
 arch/arm64/mm/fault.c                |  27 +++++--
 drivers/acpi/apei/ghes.c             |   4 +-
 8 files changed, 221 insertions(+), 11 deletions(-)
 create mode 100644 arch/arm64/include/asm/ras.h
 create mode 100644 arch/arm64/kernel/ras.c

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index dfd9086..7d44589 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -640,6 +640,17 @@ config HOTPLUG_CPU
 	  Say Y here to experiment with turning CPUs off and on.  CPUs
 	  can be controlled through /sys/devices/system/cpu.
 
+config ARM64_ERR_RECOV
+	bool "Support arm64 RAS error recovery"
+	depends on ACPI_APEI_SEA && MEMORY_FAILURE
+	help
+	  With ARM v8.2 RAS Extension, SEA are usually triggered when memory errors
+	  are consumed. In some cases, if the error address is in a clean page or a
+	  read-only page, there is a chance to recover. Such as error occurs in a
+	  instruction page, we can reread this page from disk instead of killing process.
+
+	  Say Y if unsure.
+
 # Common NUMA Features
 config NUMA
 	bool "Numa Memory Allocation and Scheduler Support"
diff --git a/arch/arm64/include/asm/ras.h b/arch/arm64/include/asm/ras.h
new file mode 100644
index 0000000..e174f95
--- /dev/null
+++ b/arch/arm64/include/asm/ras.h
@@ -0,0 +1,36 @@
+/*
+ * ARM64 SEA error recoery support
+ *
+ * Copyright 2017 Huawei Technologies Co., Ltd.
+ *   Author: Xie XiuQi <xiexiuqi@...wei.com>
+ *   Author: Wang Xiongfeng <wangxiongfeng2@...wei.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version
+ * 2 as published by the Free Software Foundation;
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef _ASM_RAS_H
+#define _ASM_RAS_H
+
+#include <linux/cper.h>
+#include <linux/ras.h>
+#include <acpi/ghes.h>
+
+extern void sea_notify_process(void);
+
+#ifdef CONFIG_ARM64_ERR_RECOV
+extern void arm_process_error(struct ghes *ghes, struct cper_sec_proc_arm *err);
+#else
+static inline void arm_process_error(struct ghes *ghes, struct cper_sec_proc_arm *err)
+{
+	log_arm_hw_error(err);
+}
+#endif /* CONFIG_ARM64_ERR_RECOV */
+
+#endif /*_ASM_RAS_H*/
diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
index 46c3b93..4b10131 100644
--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h
@@ -86,6 +86,7 @@ struct thread_info {
 #define TIF_NOTIFY_RESUME	2	/* callback before returning to user */
 #define TIF_FOREIGN_FPSTATE	3	/* CPU's FP state is not current's */
 #define TIF_UPROBE		4	/* uprobe breakpoint or singlestep */
+#define TIF_SEA_NOTIFY          5       /* notify to do an error recovery */
 #define TIF_NOHZ		7
 #define TIF_SYSCALL_TRACE	8
 #define TIF_SYSCALL_AUDIT	9
@@ -102,6 +103,7 @@ struct thread_info {
 #define _TIF_NOTIFY_RESUME	(1 << TIF_NOTIFY_RESUME)
 #define _TIF_FOREIGN_FPSTATE	(1 << TIF_FOREIGN_FPSTATE)
 #define _TIF_NOHZ		(1 << TIF_NOHZ)
+#define _TIF_SEA_NOTIFY         (1 << TIF_SEA_NOTIFY)
 #define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)
 #define _TIF_SYSCALL_AUDIT	(1 << TIF_SYSCALL_AUDIT)
 #define _TIF_SYSCALL_TRACEPOINT	(1 << TIF_SYSCALL_TRACEPOINT)
@@ -111,7 +113,7 @@ struct thread_info {
 
 #define _TIF_WORK_MASK		(_TIF_NEED_RESCHED | _TIF_SIGPENDING | \
 				 _TIF_NOTIFY_RESUME | _TIF_FOREIGN_FPSTATE | \
-				 _TIF_UPROBE)
+				 _TIF_UPROBE|_TIF_SEA_NOTIFY)
 
 #define _TIF_SYSCALL_WORK	(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
 				 _TIF_SYSCALL_TRACEPOINT | _TIF_SECCOMP | \
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index f2b4e81..ba3abf8 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -43,6 +43,7 @@ arm64-obj-$(CONFIG_EFI)			+= efi.o efi-entry.stub.o
 arm64-obj-$(CONFIG_PCI)			+= pci.o
 arm64-obj-$(CONFIG_ARMV8_DEPRECATED)	+= armv8_deprecated.o
 arm64-obj-$(CONFIG_ACPI)		+= acpi.o
+arm64-obj-$(CONFIG_ARM64_ERR_RECOV)	+= ras.o
 arm64-obj-$(CONFIG_ACPI_NUMA)		+= acpi_numa.o
 arm64-obj-$(CONFIG_ARM64_ACPI_PARKING_PROTOCOL)	+= acpi_parking_protocol.o
 arm64-obj-$(CONFIG_PARAVIRT)		+= paravirt.o
diff --git a/arch/arm64/kernel/ras.c b/arch/arm64/kernel/ras.c
new file mode 100644
index 0000000..797722d
--- /dev/null
+++ b/arch/arm64/kernel/ras.c
@@ -0,0 +1,141 @@
+/*
+ * ARM64 SEA error recoery support
+ *
+ * Copyright 2017 Huawei Technologies Co., Ltd.
+ *   Author: Xie XiuQi <xiexiuqi@...wei.com>
+ *   Author: Wang Xiongfeng <wangxiongfeng2@...wei.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version
+ * 2 as published by the Free Software Foundation;
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/cper.h>
+#include <linux/mm.h>
+#include <linux/preempt.h>
+#include <linux/acpi.h>
+#include <linux/sched/signal.h>
+#include <linux/ras.h>
+
+#include <acpi/actbl1.h>
+#include <acpi/ghes.h>
+#include <acpi/apei.h>
+
+#include <asm/thread_info.h>
+#include <asm/atomic.h>
+#include <asm/ras.h>
+
+/*
+ * Need to save faulting physical address associated with a process
+ * in the sea ghes handler some place where we can grab it back
+ * later in sea_notify_process()
+ */
+#define SEA_INFO_MAX    16
+
+struct sea_info {
+	atomic_t                inuse;
+	struct task_struct      *t;
+	__u64                   paddr;
+} sea_info[SEA_INFO_MAX];
+
+static bool sea_save_info(__u64 addr)
+{
+	struct sea_info *si;
+
+	for (si = sea_info; si < &sea_info[SEA_INFO_MAX]; si++) {
+		if (atomic_cmpxchg(&si->inuse, 0, 1) == 0) {
+			si->t = current;
+			si->paddr = addr;
+			return true;
+		}
+	}
+
+	pr_err("Too many concurrent recoverable errors\n");
+	return false;
+}
+
+static struct sea_info *sea_find_info(void)
+{
+	struct sea_info *si;
+
+	for (si = sea_info; si < &sea_info[SEA_INFO_MAX]; si++)
+		if (atomic_read(&si->inuse) && si->t == current)
+			return si;
+	return NULL;
+}
+
+static void sea_clear_info(struct sea_info *si)
+{
+	atomic_set(&si->inuse, 0);
+}
+
+/*
+ * Called in process context that interrupted by SEA and marked with
+ * TIF_SEA_NOTIFY, just before returning to erroneous userland.
+ * This code is allowed to sleep.
+ * Attempt possible recovery such as calling the high level VM handler to
+ * process any corrupted pages, and kill/signal current process if required.
+ * Action required errors are handled here.
+ */
+void sea_notify_process(void)
+{
+	unsigned long pfn;
+	int fail = 0, flags = MF_ACTION_REQUIRED;
+	struct sea_info *si = sea_find_info();
+
+	if (!si)
+		panic("Lost physical address for consumed uncorrectable error");
+
+	clear_thread_flag(TIF_SEA_NOTIFY);
+	do {
+		pfn = si->paddr >> PAGE_SHIFT;
+
+
+		pr_err("Uncorrected hardware memory error in user-access at %llx\n",
+			si->paddr);
+		/*
+		 * We must call memory_failure() here even if the current process is
+		 * doomed. We still need to mark the page as poisoned and alert any
+		 * other users of the page.
+		 */
+		if (memory_failure(pfn, 0, flags) < 0)
+			fail++;
+
+		sea_clear_info(si);
+
+		si = sea_find_info();
+	} while (si);
+
+	if (fail) {
+		pr_err("Memory error not recovered\n");
+		force_sig(SIGBUS, current);
+	}
+}
+
+void arm_process_error(struct ghes *ghes, struct cper_sec_proc_arm *err)
+{
+	int i;
+	bool info_saved = false;
+	struct cper_arm_err_info *err_info;
+
+	log_arm_hw_error(err);
+
+	if ((ghes->generic->notify.type != ACPI_HEST_NOTIFY_SEA) ||
+	    (ghes->estatus->error_severity != CPER_SEV_RECOVERABLE))
+		return;
+
+	err_info = (struct cper_arm_err_info *)(err + 1);
+	for (i = 0; i < err->err_info_num; i++, err_info++) {
+		if (err_info->validation_bits & CPER_ARM_INFO_VALID_PHYSICAL_ADDR)
+			info_saved |= sea_save_info(err_info->physical_fault_addr);
+	}
+
+	if (info_saved)
+		set_thread_flag(TIF_SEA_NOTIFY);
+}
diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index 089c3747..71e314e 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -38,6 +38,7 @@
 #include <asm/fpsimd.h>
 #include <asm/signal32.h>
 #include <asm/vdso.h>
+#include <asm/ras.h>
 
 /*
  * Do a signal return; undo the signal stack. These are aligned to 128-bit.
@@ -749,6 +750,13 @@ asmlinkage void do_notify_resume(struct pt_regs *regs,
 	 * Update the trace code with the current status.
 	 */
 	trace_hardirqs_off();
+
+#ifdef CONFIG_ARM64_ERR_RECOV
+		/* notify userspace of pending SEAs */
+		if (thread_flags & _TIF_SEA_NOTIFY)
+			sea_notify_process();
+#endif /* CONFIG_ARM64_ERR_RECOV */
+
 	do {
 		if (thread_flags & _TIF_NEED_RESCHED) {
 			schedule();
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 1f22a41..b38476d 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -594,14 +594,25 @@ static int do_sea(unsigned long addr, unsigned int esr, struct pt_regs *regs)
 			nmi_exit();
 	}
 
-	info.si_signo = SIGBUS;
-	info.si_errno = 0;
-	info.si_code  = 0;
-	if (esr & ESR_ELx_FnV)
-		info.si_addr = NULL;
-	else
-		info.si_addr  = (void __user *)addr;
-	arm64_notify_die("", regs, &info, esr);
+	if (user_mode(regs)) {
+		if (test_thread_flag(TIF_SEA_NOTIFY))
+			return ret;
+
+		info.si_signo = SIGBUS;
+		info.si_errno = 0;
+		info.si_code  = 0;
+		if (esr & ESR_ELx_FnV)
+			info.si_addr = NULL;
+		else
+			info.si_addr  = (void __user *)addr;
+
+		current->thread.fault_address = 0;
+		current->thread.fault_code = esr;
+		force_sig_info(info.si_signo, &info, current);
+	} else {
+		die("Uncorrected hardware memory error in kernel-access\n",
+		    regs, esr);
+	}
 
 	return ret;
 }
diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index d661d45..502335c 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -46,12 +46,12 @@
 #include <linux/nmi.h>
 #include <linux/sched/clock.h>
 #include <linux/uuid.h>
-#include <linux/ras.h>
 
 #include <acpi/actbl1.h>
 #include <acpi/ghes.h>
 #include <acpi/apei.h>
 #include <asm/tlbflush.h>
+#include <asm/ras.h>
 #include <ras/ras_event.h>
 
 #include "apei-internal.h"
@@ -520,7 +520,7 @@ static void ghes_do_proc(struct ghes *ghes,
 		else if (guid_equal(sec_type, &CPER_SEC_PROC_ARM)) {
 			struct cper_sec_proc_arm *err = acpi_hest_get_payload(gdata);
 
-			log_arm_hw_error(err);
+			arm_process_error(ghes, err);
 		} else {
 			void *err = acpi_hest_get_payload(gdata);
 
-- 
1.8.3.1

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