[PATCH 1/3] MIPS: Add vulnerabilities infrastructure

[Jiaxun Yang]

Add infrastructure to display CPU vulnerabilities.
As most MIPS CPU vendors are dead today and we can't confirm
vulnerabilities states with them, we'll display vulnerabilities
as "Unknown" by default and override them in cpu-probe.c

Signed-off-by: Jiaxun Yang <jiaxun.yang@xxxxxxxxxxx>
---
 arch/mips/Kconfig                |  1 +
 arch/mips/include/asm/cpu-info.h |  5 ++++
 arch/mips/include/asm/cpu.h      |  7 +++++
 arch/mips/kernel/Makefile        |  2 +-
 arch/mips/kernel/vulnbl.c        | 46 ++++++++++++++++++++++++++++++++
 5 files changed, 60 insertions(+), 1 deletion(-)
 create mode 100644 arch/mips/kernel/vulnbl.c

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index ef5b2a177b1b..524053b8f769 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -24,6 +24,7 @@ config MIPS
 	select GENERIC_CLOCKEVENTS
 	select GENERIC_CMOS_UPDATE
 	select GENERIC_CPU_AUTOPROBE
+	select GENERIC_CPU_VULNERABILITIES
 	select GENERIC_GETTIMEOFDAY
 	select GENERIC_IOMAP
 	select GENERIC_IRQ_PROBE
diff --git a/arch/mips/include/asm/cpu-info.h b/arch/mips/include/asm/cpu-info.h
index a600670d00e9..1a964dbfc0a8 100644
--- a/arch/mips/include/asm/cpu-info.h
+++ b/arch/mips/include/asm/cpu-info.h
@@ -106,6 +106,11 @@ struct cpuinfo_mips {
 	unsigned int		guestid_mask;
 	unsigned int		guestid_cache;
 
+	/* Vulnerabilities */
+	unsigned int		vulnerabilities; /* Vulnerabilities states that we known */
+	unsigned int		vulnerable; /* Vulnerabilities affated */
+	unsigned int		mitigations; /* Mitigations */
+
 #ifdef CONFIG_CPU_LOONGSON3_CPUCFG_EMULATION
 	/* CPUCFG data for this CPU, synthesized at probe time.
 	 *
diff --git a/arch/mips/include/asm/cpu.h b/arch/mips/include/asm/cpu.h
index f5b04e8f6061..3414c9f5464e 100644
--- a/arch/mips/include/asm/cpu.h
+++ b/arch/mips/include/asm/cpu.h
@@ -447,4 +447,11 @@ enum cpu_type_enum {
 #define MIPS_ASE_LOONGSON_EXT	0x00002000 /* Loongson EXTensions */
 #define MIPS_ASE_LOONGSON_EXT2	0x00004000 /* Loongson EXTensions R2 */
 
+/*
+ * CPU security vulnerabilities
+ */
+#define MIPS_VULNBL_MELTDOWN	BIT(0)
+#define MIPS_VULNBL_SPECTRE_V1	BIT(1)
+#define MIPS_VULNBL_SPECTRE_V2	BIT(2)
+
 #endif /* _ASM_CPU_H */
diff --git a/arch/mips/kernel/Makefile b/arch/mips/kernel/Makefile
index 13a26d254829..39abc8ead5e0 100644
--- a/arch/mips/kernel/Makefile
+++ b/arch/mips/kernel/Makefile
@@ -8,7 +8,7 @@ extra-y		:= head.o vmlinux.lds
 obj-y		+= cmpxchg.o cpu-probe.o branch.o elf.o entry.o genex.o idle.o irq.o \
 		   process.o prom.o ptrace.o reset.o setup.o signal.o \
 		   syscall.o time.o topology.o traps.o unaligned.o watch.o \
-		   vdso.o cacheinfo.o
+		   vdso.o cacheinfo.o vulnbl.o
 
 ifdef CONFIG_FUNCTION_TRACER
 CFLAGS_REMOVE_ftrace.o = -pg
diff --git a/arch/mips/kernel/vulnbl.c b/arch/mips/kernel/vulnbl.c
new file mode 100644
index 000000000000..fc73da6214fe
--- /dev/null
+++ b/arch/mips/kernel/vulnbl.c
@@ -0,0 +1,46 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  Copyright (C) 2020, Jiaxun Yang <jiaxun.yang@xxxxxxxxxxx>
+ *  MIPS CPU vulnerabilities
+ */
+
+#include <linux/device.h>
+
+#include <asm/cpu-info.h>
+#include <asm/cpu.h>
+
+ssize_t cpu_show_meltdown(struct device *dev,
+			  struct device_attribute *attr, char *buf)
+{
+	if (!(boot_cpu_data.vulnerabilities & MIPS_VULNBL_MELTDOWN))
+		return sprintf(buf, "Unknown\n");
+
+	if (!(boot_cpu_data.vulnerable & MIPS_VULNBL_MELTDOWN))
+		return sprintf(buf, "Not affected\n");
+
+	return sprintf(buf, "Affected\n");
+}
+
+ssize_t cpu_show_spectre_v1(struct device *dev,
+			    struct device_attribute *attr, char *buf)
+{
+	if (!(boot_cpu_data.vulnerabilities & MIPS_VULNBL_SPECTRE_V1))
+		return sprintf(buf, "Unknown\n");
+
+	if (!(boot_cpu_data.vulnerable & MIPS_VULNBL_SPECTRE_V1))
+		return sprintf(buf, "Not affected\n");
+
+	return sprintf(buf, "Affected\n");
+}
+
+ssize_t cpu_show_spectre_v2(struct device *dev,
+				   struct device_attribute *attr, char *buf)
+{
+	if (!(boot_cpu_data.vulnerabilities & MIPS_VULNBL_SPECTRE_V2))
+		return sprintf(buf, "Unknown\n");
+
+	if (!(boot_cpu_data.vulnerable & MIPS_VULNBL_SPECTRE_V2))
+		return sprintf(buf, "Not affected\n");
+
+	return sprintf(buf, "Affected\n");
+}
-- 
2.30.0