diff options
Diffstat (limited to 'include/exec')
| -rw-r--r-- | include/exec/cpu_ldst.h | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/include/exec/cpu_ldst.h b/include/exec/cpu_ldst.h index 71009f84f5..dac12bd8eb 100644 --- a/include/exec/cpu_ldst.h +++ b/include/exec/cpu_ldst.h @@ -379,4 +379,38 @@ void *tlb_vaddr_to_host(CPUArchState *env, abi_ptr addr, MMUAccessType access_type, int mmu_idx); #endif +/* + * For user-only, helpers that use guest to host address translation + * must protect the actual host memory access by recording 'retaddr' + * for the signal handler. This is required for a race condition in + * which another thread unmaps the page between a probe and the + * actual access. + */ +#ifdef CONFIG_USER_ONLY +extern __thread uintptr_t helper_retaddr; + +static inline void set_helper_retaddr(uintptr_t ra) +{ + helper_retaddr = ra; + /* + * Ensure that this write is visible to the SIGSEGV handler that + * may be invoked due to a subsequent invalid memory operation. + */ + signal_barrier(); +} + +static inline void clear_helper_retaddr(void) +{ + /* + * Ensure that previous memory operations have succeeded before + * removing the data visible to the signal handler. + */ + signal_barrier(); + helper_retaddr = 0; +} +#else +#define set_helper_retaddr(ra) do { } while (0) +#define clear_helper_retaddr() do { } while (0) +#endif + #endif /* CPU_LDST_H */ |