Avoid freezeing the core from LWIP under FreeRTOS (#1884)

Avoid issues with interrupts and priority inversions and other deadlocks
and use a SW based random generator for LWIP when under FreeRTOS.

This means removing any overrides for sleep_until and the two
get_rand_xx calls from the SDK, making things much saner.

Related to #1883, #1872, and other random FreeRTOS lockups.

README.md

@@ -252,14 +252,14 @@ If you want to contribute or have bugfixes, drop me a note at <earlephilhower@ya
 * [UF2CONV.PY](https://github.com/microsoft/uf2) is by Microsoft Corporation and licensed under the MIT license.
 * Networking and filesystem code taken from the [ESP8266 Arduino Core](https://github.com/esp8266/Arduino) and licensed under the LGPL.
 * DHCP server for AP host mode from the [Micropython Project](https://micropython.org), distributed under the MIT License.
-* [FreeRTOS](https://freertos.org) is Copyright Amazon.com, Inc. or its affiliates, and distributed under the MIT license.
+* [FreeRTOS](https://freertos.org) is copyright Amazon.com, Inc. or its affiliates, and distributed under the MIT license.
 * [lwIP](https://savannah.nongnu.org/projects/lwip/) is (c) the Swedish Institute of Computer Science and licenced under the BSD license.
 * [BearSSL](https://bearssl.org) library written by Thomas Pornin, is distributed under the [MIT License](https://bearssl.org/#legal-details).
 * [UZLib](https://github.com/pfalcon/uzlib) is copyright (c) 2003 Joergen Ibsen and distributed under the zlib license.
 * [LEAmDNS](https://github.com/LaborEtArs/ESP8266mDNS) is copyright multiple authors and distributed under the MIT license.
 * [http-parser](https://github.com/nodejs/http-parser) is copyright Joyent, Inc. and other Node contributors.
-* WebServer code modified from the [ESP32 WebServer](https://github.com/espressif/arduino-esp32/tree/master/libraries/WebServer) and is copyright (c) 2015 Ivan Grokhotkov and others
-
+* WebServer code modified from the [ESP32 WebServer](https://github.com/espressif/arduino-esp32/tree/master/libraries/WebServer) and is copyright (c) 2015 Ivan Grokhotkov and others.
+* [Xoshiro-cpp](https://github.com/Reputeless/Xoshiro-cpp) is copyright (c) 2020 Ryo Suzuki and distributed under the MIT license.
 
 -Earle F. Philhower, III  
  earlephilhower@yahoo.com

cores/rp2040/_freertos.cpp

@@ -60,45 +60,3 @@ SemaphoreHandle_t __get_freertos_mutex_for_ptr(mutex_t *m, bool recursive) {
     }
     return nullptr; // Need to make space for more mutex maps!
 }
-
-
-// The HW Random code needs a precise sleep_until() in order to assure it
-// grabs the ROSC bit when it wants.  Unfortunately, under FreeRTOS the
-// sleep_until() becomes imprecise and the "did I get the bit when I wanted"
-// check in the pico_rand code always fails and you get an infinite loop.
-
-// This block wraps the 2 get_rand calls to set a flag to convert
-// sleep_until() (which can do a task swap and cause bad timing) into a
-// busy wait.
-
-extern "C" {
-    static bool __inRand = false;
-
-    extern uint64_t __real_get_rand_64();
-    uint64_t __wrap_get_rand_64() {
-        if (__isFreeRTOS) {
-            rp2040.idleOtherCore();
-            __inRand = true;
-            auto r = __real_get_rand_64();
-            __inRand = false;
-            rp2040.resumeOtherCore();
-            return r;
-        } else {
-            return __real_get_rand_64();
-        }
-    }
-
-    uint32_t __wrap_get_rand_32() {
-        return (uint32_t) __wrap_get_rand_64();
-    }
-
-    extern void __real_sleep_until(absolute_time_t t);
-    void __wrap_sleep_until(absolute_time_t t) {
-        if (__inRand) {
-            busy_wait_until(t);
-        } else {
-            __real_sleep_until(t);
-        }
-    }
-
-}

cores/rp2040/lwip_wrap.cpp

@@ -29,6 +29,7 @@
 #include <pico/cyw43_arch.h>
 #include <pico/mutex.h>
 #include <sys/lock.h>
+#include "_xoshiro.h"
 
 extern void ethernet_arch_lwip_begin() __attribute__((weak));
 extern void ethernet_arch_lwip_end() __attribute__((weak));
@@ -68,11 +69,25 @@ public:
 
 extern "C" {
 
+    static XoshiroCpp::Xoshiro256PlusPlus *_lwip_rng = nullptr;
+    // Random number generator for LWIP.  Bare metal, use the HW.  FreeRTOS, use xoshiro generator to avoid needing to freeze the other core
+    unsigned long __lwip_rand() {
+        if (__isFreeRTOS) {
+            return (unsigned long)(*_lwip_rng)();
+        } else {
+            return get_rand_32();
+        }
+    }
+
+
     // Avoid calling lwip_init multiple times
     extern void __real_lwip_init();
     void __wrap_lwip_init() {
         static bool initted = false;
         if (!initted) {
+            if (__isFreeRTOS) {
+                _lwip_rng = new XoshiroCpp::Xoshiro256PlusPlus(rp2040.getCycleCount());
+            }
             __real_lwip_init();
             initted = true;
         }

include/lwipopts.h

@@ -13,8 +13,8 @@ extern void interrupts();
 #define SYS_ARCH_PROTECT(lev) noInterrupts
 #define SYS_ARCH_UNPROTECT(lev) interrupts
 
-extern unsigned long get_rand_32(void);
-#define LWIP_RAND() get_rand_32()
+extern unsigned long __lwip_rand(void);
+#define LWIP_RAND() __lwip_rand()
 
 // Common settings used in most of the pico_w examples
 // (see https://www.nongnu.org/lwip/2_1_x/group__lwip__opts.html for details)

lib/platform_wrap.txt

@@ -209,7 +209,3 @@
 -Wl,--wrap=cyw43_tcpip_link_status
 -Wl,--wrap=cyw43_cb_tcpip_init
 -Wl,--wrap=cyw43_cb_tcpip_deinit
-
--Wl,--wrap=get_rand_64
--Wl,--wrap=get_rand_32
--Wl,--wrap=sleep_until

tools/libpico/lwipopts.h

@@ -13,8 +13,8 @@ extern void interrupts();
 #define SYS_ARCH_PROTECT(lev) noInterrupts
 #define SYS_ARCH_UNPROTECT(lev) interrupts
 
-extern unsigned long get_rand_32(void);
-#define LWIP_RAND() get_rand_32()
+extern unsigned long __lwip_rand(void);
+#define LWIP_RAND() __lwip_rand()
 
 // Common settings used in most of the pico_w examples
 // (see https://www.nongnu.org/lwip/2_1_x/group__lwip__opts.html for details)