Merge remote-tracking branch 'remotes/rth/tags/pull-tcg-20200228' into staging

Fix race in cpu_exec_step_atomic.
Work around compile failure with -fno-inine.
Expand tcg/arm epilogue inline.
Adjustments to the default code gen buffer size.

# gpg: Signature made Sat 29 Feb 2020 02:13:43 GMT
# gpg:                using RSA key 7A481E78868B4DB6A85A05C064DF38E8AF7E215F
# gpg:                issuer "richard.henderson@linaro.org"
# gpg: Good signature from "Richard Henderson <richard.henderson@linaro.org>" [full]
# Primary key fingerprint: 7A48 1E78 868B 4DB6 A85A  05C0 64DF 38E8 AF7E 215F

* remotes/rth/tags/pull-tcg-20200228:
  accel/tcg: increase default code gen buffer size for 64 bit
  accel/tcg: only USE_STATIC_CODE_GEN_BUFFER on 32 bit hosts
  accel/tcg: remove link between guest ram and TCG cache size
  accel/tcg: use units.h for defining code gen buffer sizes
  tcg/arm: Expand epilogue inline
  tcg/arm: Split out tcg_out_epilogue
  compiler.h: Don't use compile-time assert when __NO_INLINE__ is defined
  accel/tcg: fix race in cpu_exec_step_atomic (bug 1863025)

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 11 insertions, 10 deletions

diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c
index 2560c90eec..d95c4848a4 100644
--- a/accel/tcg/cpu-exec.c
+++ b/accel/tcg/cpu-exec.c
@@ -240,6 +240,8 @@ void cpu_exec_step_atomic(CPUState *cpu)
     uint32_t cf_mask = cflags & CF_HASH_MASK;
 
     if (sigsetjmp(cpu->jmp_env, 0) == 0) {
+        start_exclusive();
+
         tb = tb_lookup__cpu_state(cpu, &pc, &cs_base, &flags, cf_mask);
         if (tb == NULL) {
             mmap_lock();
@@ -247,8 +249,6 @@ void cpu_exec_step_atomic(CPUState *cpu)
             mmap_unlock();
         }
 
-        start_exclusive();
-
         /* Since we got here, we know that parallel_cpus must be true.  */
         parallel_cpus = false;
         cc->cpu_exec_enter(cpu);
@@ -271,14 +271,15 @@ void cpu_exec_step_atomic(CPUState *cpu)
         qemu_plugin_disable_mem_helpers(cpu);
     }
 
-    if (cpu_in_exclusive_context(cpu)) {
-        /* We might longjump out of either the codegen or the
-         * execution, so must make sure we only end the exclusive
-         * region if we started it.
-         */
-        parallel_cpus = true;
-        end_exclusive();
-    }
+
+    /*
+     * As we start the exclusive region before codegen we must still
+     * be in the region if we longjump out of either the codegen or
+     * the execution.
+     */
+    g_assert(cpu_in_exclusive_context(cpu));
+    parallel_cpus = true;
+    end_exclusive();
 }
 
 struct tb_desc {