From b2013255aa85ae2019c2d0e245dc5323e1d8e6fc Mon Sep 17 00:00:00 2001
From: Peter Maydell <peter.maydell@linaro.org>
Date: Sat, 24 Feb 2018 17:21:00 -0500
Subject: [PATCH] user-exec: Push resume-from-signal code out to
 handle_cpu_signal()

Since the only caller of page_unprotect() which might cause it to
need to call cpu_resume_from_signal() is handle_cpu_signal() in
the user-mode code, push the longjump handling out to that function.

Since this is the only caller of cpu_resume_from_signal() which
passes a non-NULL puc argument, split the non-NULL handling into
a new cpu_exit_tb_from_sighandler() function. This allows us
to merge the softmmu and usermode implementations of the
cpu_resume_from_signal() function, which are now identical.

Backports commit f213e72f2356b77768b9cb73814a3b26ad5a0099 from qemu
---
 qemu/cpu-exec-common.c |  3 ---
 qemu/translate-all.c   | 12 ++++++++----
 qemu/translate-all.h   |  2 +-
 3 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/qemu/cpu-exec-common.c b/qemu/cpu-exec-common.c
index ef134f58..f1289f1d 100644
--- a/qemu/cpu-exec-common.c
+++ b/qemu/cpu-exec-common.c
@@ -26,11 +26,8 @@
 /* exit the current TB from a signal handler. The host registers are
    restored in a state compatible with the CPU emulator
    */
-#if defined(CONFIG_SOFTMMU)
-
 void cpu_resume_from_signal(CPUState *cpu, void *puc)
 {
-#endif
     /* XXX: restore cpu registers saved in host registers */
 
     cpu->exception_index = -1;
diff --git a/qemu/translate-all.c b/qemu/translate-all.c
index 7324174b..624554a8 100644
--- a/qemu/translate-all.c
+++ b/qemu/translate-all.c
@@ -2059,7 +2059,7 @@ static int page_check_range(target_ulong start, target_ulong len, int flags)
             /* unprotect the page if it was put read-only because it
                contains translated code */
             if (!(p->flags & PAGE_WRITE)) {
-                if (!page_unprotect(addr, 0, NULL)) {
+                if (!page_unprotect(addr, 0)) {
                     return -1;
                 }
             }
@@ -2069,8 +2069,12 @@ static int page_check_range(target_ulong start, target_ulong len, int flags)
 }
 
 /* called from signal handler: invalidate the code and unprotect the
-   page. Return TRUE if the fault was successfully handled. */
-static int page_unprotect(target_ulong address, uintptr_t pc, void *puc)
+ * page. Return 0 if the fault was not handled, 1 if it was handled,
+ * and 2 if it was handled but the caller must cause the TB to be
+ * immediately exited. (We can only return 2 if the 'pc' argument is
+ * non-zero.)
+ */
+int page_unprotect(target_ulong address, uintptr_t pc)
 {
     unsigned int prot;
     PageDesc *p;
@@ -2103,7 +2107,7 @@ static int page_unprotect(target_ulong address, uintptr_t pc, void *puc)
                the corresponding translated code. */
             if (tb_invalidate_phys_page(addr, pc)) {
                 mmap_unlock();
-                cpu_resume_from_signal(current_cpu, puc);
+                return 2;
             }
 #ifdef DEBUG_TB_CHECK
             tb_invalidate_check(addr);
diff --git a/qemu/translate-all.h b/qemu/translate-all.h
index 8d5a48ed..87d1b942 100644
--- a/qemu/translate-all.h
+++ b/qemu/translate-all.h
@@ -28,7 +28,7 @@ void tb_invalidate_phys_range(struct uc_struct *uc, tb_page_addr_t start, tb_pag
 void tb_cleanup(struct uc_struct *uc);
 
 #ifdef CONFIG_USER_ONLY
-int page_unprotect(target_ulong address, uintptr_t pc, void *puc);
+int page_unprotect(target_ulong address, uintptr_t pc);
 #endif
 
 #endif /* TRANSLATE_ALL_H */