Expand BSSL stack (#6819)

earlephilhower · web-flow · commit ebae47c13aef · 2019-11-20T18:05:38.000-07:00
Fixes #6811 which found an issue where connecting to scripts.google.com would *occasionally* cause a crash. On inspection, it was found that up to 5828 bytes of stack were used once in a while, so expand the stack to 5900 bytes to cover this case plus a little extra.
diff --git a/cores/esp8266/StackThunk.cpp b/cores/esp8266/StackThunk.cpp
@@ -36,7 +36,8 @@ uint32_t *stack_thunk_top = NULL;
 uint32_t *stack_thunk_save = NULL;  /* Saved A1 while in BearSSL */
 uint32_t stack_thunk_refcnt = 0;
 
-#define _stackSize (5748/4)
+/* Largest stack usage seen in the wild at scripts.google.com at 5828 */
+#define _stackSize (5900/4)
 #define _stackPaint 0xdeadbeef
 
 /* Add a reference, and allocate the stack if necessary */
diff --git a/libraries/ESP8266WiFi/examples/BearSSL_Validation/BearSSL_Validation.ino b/libraries/ESP8266WiFi/examples/BearSSL_Validation/BearSSL_Validation.ino
@@ -6,6 +6,7 @@
 
 #include <ESP8266WiFi.h>
 #include <WiFiClientSecure.h>
+#include <StackThunk.h>
 #include <time.h>
 
 #ifndef STASSID
@@ -81,7 +82,8 @@ void fetchURL(BearSSL::WiFiClientSecure *client, const char *host, const uint16_
   }
   client->stop();
   uint32_t freeStackEnd = ESP.getFreeContStack();
-  Serial.printf("\nCONT stack used: %d\n-------\n\n", freeStackStart - freeStackEnd);
+  Serial.printf("\nCONT stack used: %d\n", freeStackStart - freeStackEnd);
+  Serial.printf("BSSL stack used: %d\n-------\n\n", stack_thunk_get_max_usage());
 }
 
 void fetchNoConfig() {

Original file line number	Diff line number	Diff line change
`@@ -6,6 +6,7 @@`
`6`	`6`
`7`	`7`	`#include <ESP8266WiFi.h>`
`8`	`8`	`#include <WiFiClientSecure.h>`
	`9`	`+#include <StackThunk.h>`
`9`	`10`	`#include <time.h>`
`10`	`11`
`11`	`12`	`#ifndef STASSID`
`@@ -81,7 +82,8 @@ void fetchURL(BearSSL::WiFiClientSecure client, const char host, const uint16_`
`81`	`82`	`}`
`82`	`83`	`client->stop();`
`83`	`84`	`uint32_t freeStackEnd = ESP.getFreeContStack();`
`84`		`- Serial.printf("\nCONT stack used: %d\n-------\n\n", freeStackStart - freeStackEnd);`
	`85`	`+ Serial.printf("\nCONT stack used: %d\n", freeStackStart - freeStackEnd);`
	`86`	`+ Serial.printf("BSSL stack used: %d\n-------\n\n", stack_thunk_get_max_usage());`
`85`	`87`	`}`
`86`	`88`
`87`	`89`	`void fetchNoConfig() {`