arch/arm/kernel/spectre.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 #include <linux/bpf.h>
   3 #include <linux/cpu.h>
   4 #include <linux/device.h>
   5
   6 #include <asm/spectre.h>
   7
   8 static bool _unprivileged_ebpf_enabled(void)
   9 {
  10 #ifdef CONFIG_BPF_SYSCALL
  11         return !sysctl_unprivileged_bpf_disabled;
  12 #else
  13         return false;
  14 #endif
  15 }
  16
  17 ssize_t cpu_show_spectre_v1(struct device *dev, struct device_attribute *attr,
  18                             char *buf)
  19 {
  20         return sprintf(buf, "Mitigation: __user pointer sanitization\n");
  21 }
  22
  23 static unsigned int spectre_v2_state;
  24 static unsigned int spectre_v2_methods;
  25
  26 void spectre_v2_update_state(unsigned int state, unsigned int method)
  27 {
  28         if (state > spectre_v2_state)
  29                 spectre_v2_state = state;
  30         spectre_v2_methods |= method;
  31 }
  32
  33 ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr,
  34                             char *buf)
  35 {
  36         const char *method;
  37
  38         if (spectre_v2_state == SPECTRE_UNAFFECTED)
  39                 return sprintf(buf, "%s\n", "Not affected");
  40
  41         if (spectre_v2_state != SPECTRE_MITIGATED)
  42                 return sprintf(buf, "%s\n", "Vulnerable");
  43
  44         if (_unprivileged_ebpf_enabled())
  45                 return sprintf(buf, "Vulnerable: Unprivileged eBPF enabled\n");
  46
  47         switch (spectre_v2_methods) {
  48         case SPECTRE_V2_METHOD_BPIALL:
  49                 method = "Branch predictor hardening";
  50                 break;
  51
  52         case SPECTRE_V2_METHOD_ICIALLU:
  53                 method = "I-cache invalidation";
  54                 break;
  55
  56         case SPECTRE_V2_METHOD_SMC:
  57         case SPECTRE_V2_METHOD_HVC:
  58                 method = "Firmware call";
  59                 break;
  60
  61         case SPECTRE_V2_METHOD_LOOP8:
  62                 method = "History overwrite";
  63                 break;
  64
  65         default:
  66                 method = "Multiple mitigations";
  67                 break;
  68         }
  69
  70         return sprintf(buf, "Mitigation: %s\n", method);
  71 }