Merge remote-tracking branch 'remotes/bonzini/tags/for-upstream' into staging

* Support for jemalloc
* qemu_mutex_lock_iothread "No such process" fix
* cutils: qemu_strto* wrappers
* iohandler.c simplification
* Many other fixes and misc patches.

And some MTTCG work (with Emilio's fixes squashed):
* Signal-free TCG kick
* Removing spinlock in favor of QemuMutex
* User-mode emulation multi-threading fixes/docs

# gpg: Signature made Thu 10 Sep 2015 09:03:07 BST using RSA key ID 78C7AE83
# gpg: Good signature from "Paolo Bonzini <bonzini@gnu.org>"
# gpg:                 aka "Paolo Bonzini <pbonzini@redhat.com>"

* remotes/bonzini/tags/for-upstream: (44 commits)
  cutils: work around platform differences in strto{l,ul,ll,ull}
  cpu-exec: fix lock hierarchy for user-mode emulation
  exec: make mmap_lock/mmap_unlock globally available
  tcg: comment on which functions have to be called with mmap_lock held
  tcg: add memory barriers in page_find_alloc accesses
  remove unused spinlock.
  replace spinlock by QemuMutex.
  cpus: remove tcg_halt_cond and tcg_cpu_thread globals
  cpus: protect work list with work_mutex
  scripts/dump-guest-memory.py: fix after RAMBlock change
  configure: Add support for jemalloc
  add macro file for coccinelle
  configure: factor out adding disas configure
  vhost-scsi: fix wrong vhost-scsi firmware path
  checkpatch: remove tests that are not relevant outside the kernel
  checkpatch: adapt some tests to QEMU
  CODING_STYLE: update mixed declaration rules
  qmp: Add example usage of strto*l() qemu wrapper
  cutils: Add qemu_strtoull() wrapper
  cutils: Add qemu_strtoll() wrapper
  ...

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

1 files changed, 70 insertions, 49 deletions

diff --git a/cpu-exec.c b/cpu-exec.c
index 6b6942de69..89455339ea 100644
--- a/cpu-exec.c
+++ b/cpu-exec.c
@@ -258,10 +258,10 @@ static void cpu_exec_nocache(CPUState *cpu, int max_cycles,
     tb_free(tb);
 }
 
-static TranslationBlock *tb_find_slow(CPUState *cpu,
-                                      target_ulong pc,
-                                      target_ulong cs_base,
-                                      uint64_t flags)
+static TranslationBlock *tb_find_physical(CPUState *cpu,
+                                          target_ulong pc,
+                                          target_ulong cs_base,
+                                          uint64_t flags)
 {
     CPUArchState *env = (CPUArchState *)cpu->env_ptr;
     TranslationBlock *tb, **ptb1;
@@ -278,8 +278,9 @@ static TranslationBlock *tb_find_slow(CPUState *cpu,
     ptb1 = &tcg_ctx.tb_ctx.tb_phys_hash[h];
     for(;;) {
         tb = *ptb1;
-        if (!tb)
-            goto not_found;
+        if (!tb) {
+            return NULL;
+        }
         if (tb->pc == pc &&
             tb->page_addr[0] == phys_page1 &&
             tb->cs_base == cs_base &&
@@ -291,25 +292,59 @@ static TranslationBlock *tb_find_slow(CPUState *cpu,
                 virt_page2 = (pc & TARGET_PAGE_MASK) +
                     TARGET_PAGE_SIZE;
                 phys_page2 = get_page_addr_code(env, virt_page2);
-                if (tb->page_addr[1] == phys_page2)
-                    goto found;
+                if (tb->page_addr[1] == phys_page2) {
+                    break;
+                }
             } else {
-                goto found;
+                break;
             }
         }
         ptb1 = &tb->phys_hash_next;
     }
- not_found:
-   /* if no translated code available, then translate it now */
-    tb = tb_gen_code(cpu, pc, cs_base, flags, 0);
 
- found:
-    /* Move the last found TB to the head of the list */
-    if (likely(*ptb1)) {
-        *ptb1 = tb->phys_hash_next;
-        tb->phys_hash_next = tcg_ctx.tb_ctx.tb_phys_hash[h];
-        tcg_ctx.tb_ctx.tb_phys_hash[h] = tb;
+    /* Move the TB to the head of the list */
+    *ptb1 = tb->phys_hash_next;
+    tb->phys_hash_next = tcg_ctx.tb_ctx.tb_phys_hash[h];
+    tcg_ctx.tb_ctx.tb_phys_hash[h] = tb;
+    return tb;
+}
+
+static TranslationBlock *tb_find_slow(CPUState *cpu,
+                                      target_ulong pc,
+                                      target_ulong cs_base,
+                                      uint64_t flags)
+{
+    TranslationBlock *tb;
+
+    tb = tb_find_physical(cpu, pc, cs_base, flags);
+    if (tb) {
+        goto found;
+    }
+
+#ifdef CONFIG_USER_ONLY
+    /* mmap_lock is needed by tb_gen_code, and mmap_lock must be
+     * taken outside tb_lock.  Since we're momentarily dropping
+     * tb_lock, there's a chance that our desired tb has been
+     * translated.
+     */
+    tb_unlock();
+    mmap_lock();
+    tb_lock();
+    tb = tb_find_physical(cpu, pc, cs_base, flags);
+    if (tb) {
+        mmap_unlock();
+        goto found;
     }
+#endif
+
+    /* if no translated code available, then translate it now */
+    tb = tb_gen_code(cpu, pc, cs_base, flags, 0);
+
+#ifdef CONFIG_USER_ONLY
+    mmap_unlock();
+#endif
+
+found:
     /* we add the TB in the virtual pc hash table */
     cpu->tb_jmp_cache[tb_jmp_cache_hash_func(pc)] = tb;
     return tb;
@@ -350,7 +385,8 @@ static void cpu_handle_debug_exception(CPUState *cpu)
 
 /* main execution loop */
 
-volatile sig_atomic_t exit_request;
+bool exit_request;
+CPUState *tcg_current_cpu;
 
 int cpu_exec(CPUState *cpu)
 {
@@ -365,9 +401,6 @@ int cpu_exec(CPUState *cpu)
     uintptr_t next_tb;
     SyncClocks sc;
 
-    /* This must be volatile so it is not trashed by longjmp() */
-    volatile bool have_tb_lock = false;
-
     if (cpu->halted) {
         if (!cpu_has_work(cpu)) {
             return EXCP_HALTED;
@@ -377,18 +410,10 @@ int cpu_exec(CPUState *cpu)
     }
 
     current_cpu = cpu;
-
-    /* As long as current_cpu is null, up to the assignment just above,
-     * requests by other threads to exit the execution loop are expected to
-     * be issued using the exit_request global. We must make sure that our
-     * evaluation of the global value is performed past the current_cpu
-     * value transition point, which requires a memory barrier as well as
-     * an instruction scheduling constraint on modern architectures.  */
-    smp_mb();
-
+    atomic_mb_set(&tcg_current_cpu, cpu);
     rcu_read_lock();
 
-    if (unlikely(exit_request)) {
+    if (unlikely(atomic_mb_read(&exit_request))) {
         cpu->exit_request = 1;
     }
 
@@ -484,8 +509,7 @@ int cpu_exec(CPUState *cpu)
                     cpu->exception_index = EXCP_INTERRUPT;
                     cpu_loop_exit(cpu);
                 }
-                spin_lock(&tcg_ctx.tb_ctx.tb_lock);
-                have_tb_lock = true;
+                tb_lock();
                 tb = tb_find_fast(cpu);
                 /* Note: we do it here to avoid a gcc bug on Mac OS X when
                    doing it in tb_find_slow */
@@ -507,20 +531,14 @@ int cpu_exec(CPUState *cpu)
                     tb_add_jump((TranslationBlock *)(next_tb & ~TB_EXIT_MASK),
                                 next_tb & TB_EXIT_MASK, tb);
                 }
-                have_tb_lock = false;
-                spin_unlock(&tcg_ctx.tb_ctx.tb_lock);
-
-                /* cpu_interrupt might be called while translating the
-                   TB, but before it is linked into a potentially
-                   infinite loop and becomes env->current_tb. Avoid
-                   starting execution if there is a pending interrupt. */
-                cpu->current_tb = tb;
-                barrier();
+                tb_unlock();
                 if (likely(!cpu->exit_request)) {
                     trace_exec_tb(tb, tb->pc);
                     tc_ptr = tb->tc_ptr;
                     /* execute the generated code */
+                    cpu->current_tb = tb;
                     next_tb = cpu_tb_exec(cpu, tc_ptr);
+                    cpu->current_tb = NULL;
                     switch (next_tb & TB_EXIT_MASK) {
                     case TB_EXIT_REQUESTED:
                         /* Something asked us to stop executing
@@ -528,8 +546,12 @@ int cpu_exec(CPUState *cpu)
                          * loop. Whatever requested the exit will also
                          * have set something else (eg exit_request or
                          * interrupt_request) which we will handle
-                         * next time around the loop.
+                         * next time around the loop.  But we need to
+                         * ensure the tcg_exit_req read in generated code
+                         * comes before the next read of cpu->exit_request
+                         * or cpu->interrupt_request.
                          */
+                        smp_rmb();
                         next_tb = 0;
                         break;
                     case TB_EXIT_ICOUNT_EXPIRED:
@@ -559,7 +581,6 @@ int cpu_exec(CPUState *cpu)
                         break;
                     }
                 }
-                cpu->current_tb = NULL;
                 /* Try to align the host and virtual clocks
                    if the guest is in advance */
                 align_clocks(&sc, cpu);
@@ -576,10 +597,7 @@ int cpu_exec(CPUState *cpu)
             x86_cpu = X86_CPU(cpu);
             env = &x86_cpu->env;
 #endif
-            if (have_tb_lock) {
-                spin_unlock(&tcg_ctx.tb_ctx.tb_lock);
-                have_tb_lock = false;
-            }
+            tb_lock_reset();
         }
     } /* for(;;) */
 
@@ -588,5 +606,8 @@ int cpu_exec(CPUState *cpu)
 
     /* fail safe : never use current_cpu outside cpu_exec() */
     current_cpu = NULL;
+
+    /* Does not need atomic_mb_set because a spurious wakeup is okay.  */
+    atomic_set(&tcg_current_cpu, NULL);
     return ret;
 }