Use of these in helpers goes hand-in-hand with tlb_vaddr_to_host
and other probing functions.
Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
---
accel/tcg/user-retaddr.h | 28 ----------------------------
include/exec/cpu_ldst.h | 34 ++++++++++++++++++++++++++++++++++
accel/tcg/cpu-exec.c | 3 ---
accel/tcg/user-exec.c | 1 -
4 files changed, 34 insertions(+), 32 deletions(-)
delete mode 100644 accel/tcg/user-retaddr.h
diff --git a/accel/tcg/user-retaddr.h b/accel/tcg/user-retaddr.h
deleted file mode 100644
index e0f57e1994..0000000000
--- a/accel/tcg/user-retaddr.h
+++ /dev/null
@@ -1,28 +0,0 @@
-#ifndef ACCEL_TCG_USER_RETADDR_H
-#define ACCEL_TCG_USER_RETADDR_H
-
-#include "qemu/atomic.h"
-
-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;
-}
-
-#endif
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 */
diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c
index 6711b58e0b..0aa42591bf 100644
--- a/accel/tcg/cpu-exec.c
+++ b/accel/tcg/cpu-exec.c
@@ -41,9 +41,6 @@
#include "tb-context.h"
#include "internal-common.h"
#include "internal-target.h"
-#if defined(CONFIG_USER_ONLY)
-#include "user-retaddr.h"
-#endif
/* -icount align implementation. */
diff --git a/accel/tcg/user-exec.c b/accel/tcg/user-exec.c
index 80d24540ed..7ddc47b0ba 100644
--- a/accel/tcg/user-exec.c
+++ b/accel/tcg/user-exec.c
@@ -33,7 +33,6 @@
#include "tcg/tcg-ldst.h"
#include "internal-common.h"
#include "internal-target.h"
-#include "user-retaddr.h"
__thread uintptr_t helper_retaddr;
--
2.43.0
