accel/tcg: Split out adjust_signal_pc

Split out a function to adjust the raw signal pc into a
value that could be passed to cpu_restore_state.

Reviewed-by: Warner Losh <imp@bsdimp.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
v2: Adjust pc in place; return MMUAccessType.

include/exec/exec-all.h

@@ -663,6 +663,16 @@ static inline tb_page_addr_t get_page_addr_code_hostp(CPUArchState *env,
     return addr;
 }
 
+/**
+ * adjust_signal_pc:
+ * @pc: raw pc from the host signal ucontext_t.
+ * @is_write: host memory operation was write, or read-modify-write.
+ *
+ * Alter @pc as required for unwinding.  Return the type of the
+ * guest memory access -- host reads may be for guest execution.
+ */
+MMUAccessType adjust_signal_pc(uintptr_t *pc, bool is_write);
+
 /**
  * cpu_signal_handler
  * @signum: host signal number