Merge branch 'sverk/safe-purging/OTP-13122'

* sverk/safe-purging/OTP-13122:
  erts: Ignore unexpected messages to erts_code_purger
  erts: Optimize erlang:check_process_code
  erts: Refactor check_process_code/3
  erts: Make copy_literals more fail safe
  erts: Move copy_literals/2 from erlang to erts_internal
  erts: Make erlang:purge_module/1 safe
  erts: Refactor code:purge/1 and code:soft_purge/1
  erts: Introduce erts_code_purger

6 files changed, 90 insertions, 65 deletions

diff --git a/erts/emulator/Makefile.in b/erts/emulator/Makefile.in
index 8cf435905b..f4b806fae9 100644
--- a/erts/emulator/Makefile.in
+++ b/erts/emulator/Makefile.in
@@ -591,6 +591,7 @@ ifeq ($(TARGET),win32)
 PRELOAD_OBJ = $(OBJDIR)/beams.$(RES_EXT)
 PRELOAD_SRC = $(TARGET)/beams.rc
 $(PRELOAD_SRC): $(ERL_TOP)/erts/preloaded/ebin/otp_ring0.beam \
+			$(ERL_TOP)/erts/preloaded/ebin/erts_code_purger.beam \
 			$(ERL_TOP)/erts/preloaded/ebin/init.beam \
 			$(ERL_TOP)/erts/preloaded/ebin/prim_eval.beam \
 			$(ERL_TOP)/erts/preloaded/ebin/prim_inet.beam \
@@ -600,11 +601,13 @@ $(PRELOAD_SRC): $(ERL_TOP)/erts/preloaded/ebin/otp_ring0.beam \
 			$(ERL_TOP)/erts/preloaded/ebin/erl_prim_loader.beam \
 			$(ERL_TOP)/erts/preloaded/ebin/erlang.beam \
 			$(ERL_TOP)/erts/preloaded/ebin/erts_internal.beam
+
 	$(gen_verbose)LANG=C $(PERL) utils/make_preload $(MAKE_PRELOAD_EXTRA) -rc $^ > $@
 else
 PRELOAD_OBJ = $(OBJDIR)/preload.o
 PRELOAD_SRC = $(TARGET)/preload.c
 $(PRELOAD_SRC): $(ERL_TOP)/erts/preloaded/ebin/otp_ring0.beam \
+			$(ERL_TOP)/erts/preloaded/ebin/erts_code_purger.beam \
 			$(ERL_TOP)/erts/preloaded/ebin/init.beam \
 			$(ERL_TOP)/erts/preloaded/ebin/prim_eval.beam \
 			$(ERL_TOP)/erts/preloaded/ebin/prim_inet.beam \
diff --git a/erts/emulator/beam/beam_bif_load.c b/erts/emulator/beam/beam_bif_load.c
index 6bb70cc5a7..a000935388 100644
--- a/erts/emulator/beam/beam_bif_load.c
+++ b/erts/emulator/beam/beam_bif_load.c
@@ -38,7 +38,7 @@
 #include "erl_thr_progress.h"
 
 static void set_default_trace_pattern(Eterm module);
-static Eterm check_process_code(Process* rp, Module* modp, int allow_gc, int *redsp);
+static Eterm check_process_code(Process* rp, Module* modp, Uint flags, int *redsp);
 static void delete_code(Module* modp);
 static void decrement_refc(BeamCodeHeader*);
 static int any_heap_ref_ptrs(Eterm* start, Eterm* end, char* mod_start, Uint mod_size);
@@ -426,7 +426,7 @@ check_old_code_1(BIF_ALIST_1)
 }
 
 Eterm
-erts_check_process_code(Process *c_p, Eterm module, int allow_gc, int *redsp)
+erts_check_process_code(Process *c_p, Eterm module, Uint flags, int *redsp)
 {
     Module* modp;
     Eterm res;
@@ -441,7 +441,8 @@ erts_check_process_code(Process *c_p, Eterm module, int allow_gc, int *redsp)
     if (!modp)
 	return am_false;
     erts_rlock_old_code(code_ix);
-    res = modp->old.code_hdr ? check_process_code(c_p, modp, allow_gc, redsp) : am_false;
+    res = (!modp->old.code_hdr ? am_false :
+           check_process_code(c_p, modp, flags, redsp));
     erts_runlock_old_code(code_ix);
 
     return res;
@@ -450,49 +451,21 @@ erts_check_process_code(Process *c_p, Eterm module, int allow_gc, int *redsp)
 BIF_RETTYPE erts_internal_check_process_code_2(BIF_ALIST_2)
 {
     int reds = 0;
+    Uint flags;
     Eterm res;
-    Eterm olist = BIF_ARG_2;
-    int allow_gc = 1;
 
     if (is_not_atom(BIF_ARG_1))
 	goto badarg;
 
-    while (is_list(olist)) {
-	Eterm *lp = list_val(olist);
-	Eterm opt = CAR(lp);
-	if (is_tuple(opt)) {
-	    Eterm* tp = tuple_val(opt);
-	    switch (arityval(tp[0])) {
-	    case 2:
-		switch (tp[1]) {
-		case am_allow_gc:
-		    switch (tp[2]) {
-		    case am_false:
-			allow_gc = 0;
-			break;
-		    case am_true:
-			allow_gc = 1;
-			break;
-		    default:
-			goto badarg;
-		    }
-		    break;
-		default:
-		    goto badarg;
-		}
-		break;
-	    default:
-		goto badarg;
-	    }
-	}
-	else
-	    goto badarg;
-	olist = CDR(lp);
+    if (is_not_small(BIF_ARG_2))
+        goto badarg;
+
+    flags = unsigned_val(BIF_ARG_2);
+    if (flags & ~ERTS_CPC_ALL) {
+        goto badarg;
     }
-    if (is_not_nil(olist))
-	goto badarg;
 
-    res = erts_check_process_code(BIF_P, BIF_ARG_1, allow_gc, &reds);
+    res = erts_check_process_code(BIF_P, BIF_ARG_1, flags, &reds);
 
     ASSERT(is_value(res));
 
@@ -739,7 +712,7 @@ check_mod_funs(Process *p, ErlOffHeap *off_heap, char *area, size_t area_size)
 
 
 static Eterm
-check_process_code(Process* rp, Module* modp, int allow_gc, int *redsp)
+check_process_code(Process* rp, Module* modp, Uint flags, int *redsp)
 {
     BeamInstr* start;
     char* literals;
@@ -852,6 +825,12 @@ check_process_code(Process* rp, Module* modp, int allow_gc, int *redsp)
 	/* Check heap, stack etc... */
 	if (check_mod_funs(rp, &rp->off_heap, mod_start, mod_size))
 	    goto try_gc;
+        if (!(flags & ERTS_CPC_COPY_LITERALS)) {
+            /* Process ok. May contain old literals but we will be called
+             * again before module is purged.
+             */
+            return am_false;
+        }
 	if (any_heap_ref_ptrs(&rp->fvalue, &rp->fvalue+1, literals, lit_bsize)) {
 	    rp->freason = EXC_NULL;
 	    rp->fvalue = NIL;
@@ -919,7 +898,7 @@ check_process_code(Process* rp, Module* modp, int allow_gc, int *redsp)
 	if ((done_gc & need_gc) == need_gc)
 	    return am_true;
 
-	if (!allow_gc)
+	if (!(flags & ERTS_CPC_ALLOW_GC))
 	    return am_aborted;
 
 	need_gc &= ~done_gc;
@@ -1013,7 +992,7 @@ any_heap_refs(Eterm* start, Eterm* end, char* mod_start, Uint mod_size)
 static void copy_literals_commit(void*);
 #endif
 
-copy_literals_t erts_clrange = {NULL, 0};
+copy_literals_t erts_clrange = {NULL, 0, THE_NON_VALUE};
 
 /* copy literals
  *
@@ -1031,9 +1010,8 @@ copy_literals_t erts_clrange = {NULL, 0};
  */
 
 
-BIF_RETTYPE copy_literals_2(BIF_ALIST_2)
+BIF_RETTYPE erts_internal_copy_literals_2(BIF_ALIST_2)
 {
-    Module* modp;
     ErtsCodeIndex code_ix;
     Eterm res = am_true;
 
@@ -1042,26 +1020,34 @@ BIF_RETTYPE copy_literals_2(BIF_ALIST_2)
     }
 
     if (!erts_try_seize_code_write_permission(BIF_P)) {
-	ERTS_BIF_YIELD2(bif_export[BIF_copy_literals_2], BIF_P, BIF_ARG_1, BIF_ARG_2);
+	ERTS_BIF_YIELD2(bif_export[BIF_erts_internal_copy_literals_2],
+                        BIF_P, BIF_ARG_1, BIF_ARG_2);
     }
 
     code_ix = erts_active_code_ix();
 
-    if ((modp = erts_get_module(BIF_ARG_1, code_ix)) == NULL || !modp->old.code_hdr) {
-        res = am_false;
-        goto done;
-    }
-
     if (BIF_ARG_2 == am_true) {
-        if (erts_clrange.ptr != NULL) {
+        Module* modp = erts_get_module(BIF_ARG_1, code_ix);
+        if (!modp || !modp->old.code_hdr) {
+            res = am_false;
+            goto done;
+        }
+        if (erts_clrange.ptr != NULL
+            && !(BIF_P->static_flags & ERTS_STC_FLG_SYSTEM_PROC)) {
             res = am_aborted;
             goto done;
-       }
-        erts_clrange.ptr = (Eterm*) modp->old.code_hdr->literals_start;
-        erts_clrange.sz  = (Eterm*) modp->old.code_hdr->literals_end - erts_clrange.ptr;
+        }
+        erts_clrange.ptr = modp->old.code_hdr->literals_start;
+        erts_clrange.sz  = modp->old.code_hdr->literals_end - erts_clrange.ptr;
+        erts_clrange.pid = BIF_P->common.id;
     } else if (BIF_ARG_2 == am_false) {
+        if (erts_clrange.pid != BIF_P->common.id) {
+            res = am_false;
+            goto done;
+        }
         erts_clrange.ptr = NULL;
         erts_clrange.sz  = 0;
+        erts_clrange.pid = THE_NON_VALUE;
     }
 
 #ifdef ERTS_SMP
@@ -1094,7 +1080,12 @@ static void copy_literals_commit(void* null) {
 #endif /* ERTS_SMP */
 
 
-BIF_RETTYPE purge_module_1(BIF_ALIST_1)
+/* Do the actualy module purging and return:
+ * true for success
+ * false if no such old module
+ * BADARG if not an atom
+ */
+BIF_RETTYPE erts_internal_purge_module_1(BIF_ALIST_1)
 {
     ErtsCodeIndex code_ix;
     BeamInstr* code;
@@ -1108,7 +1099,8 @@ BIF_RETTYPE purge_module_1(BIF_ALIST_1)
     }
 
     if (!erts_try_seize_code_write_permission(BIF_P)) {
-	ERTS_BIF_YIELD1(bif_export[BIF_purge_module_1], BIF_P, BIF_ARG_1);
+	ERTS_BIF_YIELD1(bif_export[BIF_erts_internal_purge_module_1],
+                        BIF_P, BIF_ARG_1);
     }
 
     code_ix = erts_active_code_ix();
@@ -1118,7 +1110,7 @@ BIF_RETTYPE purge_module_1(BIF_ALIST_1)
      */
 
     if ((modp = erts_get_module(BIF_ARG_1, code_ix)) == NULL) {
-	ERTS_BIF_PREP_ERROR(ret, BIF_P, BADARG);
+        ERTS_BIF_PREP_RET(ret, am_false);
     }
     else {
 	erts_rwlock_old_code(code_ix);
@@ -1127,7 +1119,7 @@ BIF_RETTYPE purge_module_1(BIF_ALIST_1)
 	 * Any code to purge?
 	 */
 	if (!modp->old.code_hdr) {
-	    ERTS_BIF_PREP_ERROR(ret, BIF_P, BADARG);
+            ERTS_BIF_PREP_RET(ret, am_false);
 	}
 	else {
 	    /*
diff --git a/erts/emulator/beam/bif.tab b/erts/emulator/beam/bif.tab
index 0aee8681c6..1b8ae8cef5 100644
--- a/erts/emulator/beam/bif.tab
+++ b/erts/emulator/beam/bif.tab
@@ -125,7 +125,6 @@ bif erlang:process_flag/3
 bif erlang:process_info/1
 bif erlang:process_info/2
 bif erlang:processes/0
-bif erlang:purge_module/1
 bif erlang:put/2
 bif erlang:register/2
 bif erlang:registered/0
@@ -642,7 +641,8 @@ bif erts_debug:map_info/1
 # New in 19.0
 #
 
-bif erlang:copy_literals/2
+bif erts_internal:copy_literals/2
+bif erts_internal:purge_module/1
 bif binary:split/2
 bif binary:split/3
 bif erts_debug:size_shared/1
diff --git a/erts/emulator/beam/erl_init.c b/erts/emulator/beam/erl_init.c
index 58ef09662c..42aca726bf 100644
--- a/erts/emulator/beam/erl_init.c
+++ b/erts/emulator/beam/erl_init.c
@@ -439,6 +439,29 @@ erl_first_process_otp(char* modname, void* code, unsigned size, int argc, char**
     return res;
 }
 
+static Eterm
+erl_system_process_otp(Eterm parent_pid, char* modname)
+{
+    Eterm start_mod;
+    Process* parent;
+    ErlSpawnOpts so;
+    Eterm res;
+
+    start_mod = erts_atom_put((byte *) modname, sys_strlen(modname), ERTS_ATOM_ENC_LATIN1, 1);
+    if (erts_find_function(start_mod, am_start, 0,
+			   erts_active_code_ix()) == NULL) {
+	erl_exit(5, "No function %s:start/0\n", modname);
+    }
+
+    parent = erts_pid2proc(NULL, 0, parent_pid, ERTS_PROC_LOCK_MAIN);
+
+    so.flags = erts_default_spo_flags|SPO_SYSTEM_PROC;
+    res = erl_create_process(parent, start_mod, am_start, NIL, &so);
+    erts_smp_proc_unlock(parent, ERTS_PROC_LOCK_MAIN);
+    return res;
+}
+
+
 Eterm
 erts_preloaded(Process* p)
 {
@@ -1234,6 +1257,7 @@ erl_start(int argc, char **argv)
     ErtsTimeWarpMode time_warp_mode;
     int node_tab_delete_delay = ERTS_NODE_TAB_DELAY_GC_DEFAULT;
     ErtsDbSpinCount db_spin_count = ERTS_DB_SPNCNT_NORMAL;
+    Eterm otp_ring0_pid;
 
     set_default_time_adj(&time_correction,
 			 &time_warp_mode);
@@ -2183,8 +2207,10 @@ erl_start(int argc, char **argv)
 
     erts_initialized = 1;
 
-    (void) erl_first_process_otp("otp_ring0", NULL, 0,
-				 boot_argc, boot_argv);
+    otp_ring0_pid = erl_first_process_otp("otp_ring0", NULL, 0,
+					  boot_argc, boot_argv);
+
+    (void) erl_system_process_otp(otp_ring0_pid, "erts_code_purger");
 
 #ifdef ERTS_SMP
     erts_start_schedulers();
diff --git a/erts/emulator/beam/erl_process.c b/erts/emulator/beam/erl_process.c
index 2cdb98b2aa..9431bf98ec 100644
--- a/erts/emulator/beam/erl_process.c
+++ b/erts/emulator/beam/erl_process.c
@@ -10052,7 +10052,7 @@ execute_sys_tasks(Process *c_p, erts_aint32_t *statep, int in_reds)
 	case ERTS_PSTT_CPC:
 	    st_res = erts_check_process_code(c_p,
 					     st->arg[0],
-					     st->arg[1] == am_true,
+                                             unsigned_val(st->arg[1]),
 					     &reds);
 	    if (is_non_value(st_res)) {
 		/* Needed gc, but gc was disabled */
@@ -10216,7 +10216,7 @@ erts_internal_request_system_task_3(BIF_ALIST_3)
     case am_check_process_code:
 	if (is_not_atom(st->arg[0]))
 	    goto badarg;
-	if (st->arg[1] != am_true && st->arg[1] != am_false)
+	if (is_not_small(st->arg[1]) || (unsigned_val(st->arg[1]) & ~ERTS_CPC_ALL))
 	    goto badarg;
 	noproc_res = am_false;
 	st->type = ERTS_PSTT_CPC;
diff --git a/erts/emulator/beam/global.h b/erts/emulator/beam/global.h
index 0bf5988244..3f5925765d 100644
--- a/erts/emulator/beam/global.h
+++ b/erts/emulator/beam/global.h
@@ -985,11 +985,15 @@ Eterm erl_send(Process *p, Eterm to, Eterm msg);
 Eterm erl_is_function(Process* p, Eterm arg1, Eterm arg2);
 
 /* beam_bif_load.c */
-Eterm erts_check_process_code(Process *c_p, Eterm module, int allow_gc, int *redsp);
+#define ERTS_CPC_ALLOW_GC      (1 << 0)
+#define ERTS_CPC_COPY_LITERALS (1 << 1)
+#define ERTS_CPC_ALL           (ERTS_CPC_ALLOW_GC | ERTS_CPC_COPY_LITERALS)
+Eterm erts_check_process_code(Process *c_p, Eterm module, Uint flags, int *redsp);
 
 typedef struct {
     Eterm *ptr;
     Uint   sz;
+    Eterm pid;
 } copy_literals_t;
 
 extern copy_literals_t erts_clrange;