LoongArch: Show CPU vulnerabilites correctly

Most LoongArch processors are vulnerable to Spectre-V1 Proof-of-Concept
(PoC). And the generic mechanism, __user pointer sanitization, can be
used as a mitigation. This means to use array_index_nospec() to prevent
out of boundry access in syscall and other critical paths.

Implement the arch-specific cpu_show_spectre_v1() to show CPU Spectre-V1
vulnerabilites correctly.

Cc: stable@vger.kernel.org
Link: https://cc-sw.com/chinese-loongarch-architecture-evaluation-part-3-of-3/
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

diff --git a/arch/loongarch/kernel/cpu-probe.c b/arch/loongarch/kernel/cpu-probe.c
index 657bbae6c1c7ea2d43d32d85fe1eeb3b9e407501..82cf426faafda56ec3da14313e4e7eff44251330 100644 (file)
--- a/arch/loongarch/kernel/cpu-probe.c
+++ b/arch/loongarch/kernel/cpu-probe.c
@@ -7,6 +7,7 @@
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/ptrace.h>
+#include <linux/cpu.h>
 #include <linux/smp.h>
 #include <linux/stddef.h>
 #include <linux/export.h>
@@ -402,3 +403,9 @@ void cpu_probe(void)
 
        cpu_report();
 }
+
+ssize_t cpu_show_spectre_v1(struct device *dev,
+                           struct device_attribute *attr, char *buf)
+{
+       return sysfs_emit(buf, "Mitigation: __user pointer sanitization\n");
+}