| 235 | |
| 236 | namespace FEX::GCS { |
| 237 | void CheckForGCS() { |
| 238 | #ifndef PR_GET_SHADOW_STACK_STATUS |
| 239 | #define PR_GET_SHADOW_STACK_STATUS 74 |
| 240 | #endif |
| 241 | #ifndef PR_LOCK_SHADOW_STACK_STATUS |
| 242 | #define PR_LOCK_SHADOW_STACK_STATUS 76 |
| 243 | #endif |
| 244 | #ifndef PR_SHADOW_STACK_ENABLE |
| 245 | #define PR_SHADOW_STACK_ENABLE (1ULL << 0) |
| 246 | #endif |
| 247 | uint64_t ShadowStackWord {}; |
| 248 | if (prctl(PR_GET_SHADOW_STACK_STATUS, &ShadowStackWord, 0, 0, 0) == -1) { |
| 249 | return; |
| 250 | } |
| 251 | |
| 252 | // Kernel supports shadow stack. |
| 253 | if (ShadowStackWord & PR_SHADOW_STACK_ENABLE) { |
| 254 | // Welp. |
| 255 | ERROR_AND_DIE_FMT("Shadow stack is enabled which FEX is incompatible with!"); |
| 256 | } |
| 257 | |
| 258 | // Disable if we've gotten this far, to ensure guest can't try. |
| 259 | prctl(PR_LOCK_SHADOW_STACK_STATUS, ~0ULL, 0, 0, 0); |
| 260 | } |
| 261 | } // namespace FEX::GCS |
| 262 | |
| 263 | /** |