arm64: add support for machine check error safe

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5GB28
CVE: NA

-------------------------------

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: NTong Tiangen <tongtiangen@huawei.com>

arch/arm64/Kconfig

@@ -11,6 +11,7 @@ config ARM64
 	select ACPI_PPTT if ACPI
 	select ARCH_HAS_DEBUG_WX
 	select ARCH_BINFMT_ELF_STATE
+	select ARCH_HAS_COPY_MC if ACPI_APEI_GHES
 	select ARCH_HAS_DEBUG_VIRTUAL
 	select ARCH_HAS_DEBUG_VM_PGTABLE
 	select ARCH_HAS_DEVMEM_IS_ALLOWED
@@ -22,6 +23,7 @@ config ARM64
 	select ARCH_HAS_GIGANTIC_PAGE
 	select ARCH_HAS_KCOV
 	select ARCH_HAS_KEEPINITRD
+	select ARCH_HAS_MC_EXTABLE if ARCH_HAS_COPY_MC
 	select ARCH_HAS_MEMBARRIER_SYNC_CORE
 	select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
 	select ARCH_HAS_PTE_DEVMAP

arch/arm64/include/asm/extable.h

@@ -44,4 +44,5 @@ int arm64_bpf_fixup_exception(const struct exception_table_entry *ex,
 #endif /* !CONFIG_BPF_JIT */
 
 extern int fixup_exception(struct pt_regs *regs);
+extern int fixup_exception_mc(struct pt_regs *regs);
 #endif

arch/arm64/mm/extable.c

@@ -20,3 +20,15 @@ int fixup_exception(struct pt_regs *regs)
 	regs->pc = (unsigned long)&fixup->fixup + fixup->fixup;
 	return 1;
 }
+
+int fixup_exception_mc(struct pt_regs *regs)
+{
+	const struct exception_table_entry *fixup;
+
+	fixup = search_mc_exception_tables(instruction_pointer(regs));
+	if (!fixup)
+		return 0;
+
+	regs->pc = (unsigned long)&fixup->fixup + fixup->fixup;
+	return 1;
+}

arch/arm64/mm/fault.c

@@ -634,6 +634,31 @@ static int do_bad(unsigned long addr, unsigned int esr, struct pt_regs *regs)
 	return 1; /* "fault" */
 }
 
+static bool arm64_do_kernel_sea(void __user *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))
+		return false;
+
+	if (apei_claim_sea(regs) < 0)
+		return false;
+
+	if (!fixup_exception_mc(regs))
+		return false;
+
+	if (current->flags & PF_KTHREAD)
+		return true;
+
+	set_thread_esr(0, esr);
+	arm64_force_sig_fault(sig, code, addr,
+		"Uncorrected memory error on access to user memory\n");
+
+	return true;
+}
+
 static int do_sea(unsigned long addr, unsigned int esr, struct pt_regs *regs)
 {
 	const struct fault_info *inf;
@@ -653,7 +678,9 @@ static int do_sea(unsigned long addr, unsigned int esr, struct pt_regs *regs)
 		siaddr = NULL;
 	else
 		siaddr  = (void __user *)addr;
-	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;
 }