diff mbox series

[v2,01/41] accel/tcg: Split out adjust_signal_pc

Message ID 20210918184527.408540-2-richard.henderson@linaro.org
State Superseded
Headers show
Series linux-user: Streamline handling of SIGSEGV | expand

Commit Message

Richard Henderson Sept. 18, 2021, 6:44 p.m. UTC 
Split out a function to adjust the raw signal pc into a
value that could be passed to cpu_restore_state.

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 | 10 ++++++++++
 accel/tcg/user-exec.c   | 41 +++++++++++++++++++++++++----------------
 2 files changed, 35 insertions(+), 16 deletions(-)

-- 
2.25.1
diff mbox series

Patch

diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h
index 9d5987ba04..e54f8e5d65 100644
--- a/include/exec/exec-all.h
+++ b/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
diff --git a/accel/tcg/user-exec.c b/accel/tcg/user-exec.c
index 8fed542622..cef025d001 100644
--- a/accel/tcg/user-exec.c
+++ b/accel/tcg/user-exec.c
@@ -57,18 +57,11 @@  static void QEMU_NORETURN cpu_exit_tb_from_sighandler(CPUState *cpu,
     cpu_loop_exit_noexc(cpu);
 }
 
-/* 'pc' is the host PC at which the exception was raised. 'address' is
-   the effective address of the memory exception. 'is_write' is 1 if a
-   write caused the exception and otherwise 0'. 'old_set' is the
-   signal set which should be restored */
-static inline int handle_cpu_signal(uintptr_t pc, siginfo_t *info,
-                                    int is_write, sigset_t *old_set)
+/*
+ * Adjust the pc to pass to cpu_restore_state; return the memop type.
+ */
+MMUAccessType adjust_signal_pc(uintptr_t *pc, bool is_write)
 {
-    CPUState *cpu = current_cpu;
-    CPUClass *cc;
-    unsigned long address = (unsigned long)info->si_addr;
-    MMUAccessType access_type = is_write ? MMU_DATA_STORE : MMU_DATA_LOAD;
-
     switch (helper_retaddr) {
     default:
         /*
@@ -77,7 +70,7 @@  static inline int handle_cpu_signal(uintptr_t pc, siginfo_t *info,
          * pointer into the generated code that will unwind to the
          * correct guest pc.
          */
-        pc = helper_retaddr;
+        *pc = helper_retaddr;
         break;
 
     case 0:
@@ -97,7 +90,7 @@  static inline int handle_cpu_signal(uintptr_t pc, siginfo_t *info,
          * Therefore, adjust to compensate for what will be done later
          * by cpu_restore_state_from_tb.
          */
-        pc += GETPC_ADJ;
+        *pc += GETPC_ADJ;
         break;
 
     case 1:
@@ -113,12 +106,28 @@  static inline int handle_cpu_signal(uintptr_t pc, siginfo_t *info,
          *
          * Like tb_gen_code, release the memory lock before cpu_loop_exit.
          */
-        pc = 0;
-        access_type = MMU_INST_FETCH;
         mmap_unlock();
-        break;
+        *pc = 0;
+        return MMU_INST_FETCH;
     }
 
+    return is_write ? MMU_DATA_STORE : MMU_DATA_LOAD;
+}
+
+/*
+ * 'pc' is the host PC at which the exception was raised.
+ * 'address' is the effective address of the memory exception.
+ * 'is_write' is 1 if a write caused the exception and otherwise 0.
+ * 'old_set' is the signal set which should be restored.
+ */
+static inline int handle_cpu_signal(uintptr_t pc, siginfo_t *info,
+                                    int is_write, sigset_t *old_set)
+{
+    CPUState *cpu = current_cpu;
+    CPUClass *cc;
+    unsigned long address = (unsigned long)info->si_addr;
+    MMUAccessType access_type = adjust_signal_pc(&pc, is_write);
+
     /* For synchronous signals we expect to be coming from the vCPU
      * thread (so current_cpu should be valid) and either from running
      * code or during translation which can fault as we cross pages.