Move continuation stack from .bss onto sys stack (#4622)

cores/esp8266/cont_util.c

@@ -20,12 +20,15 @@
 
 #include "cont.h"
 #include <stddef.h>
+#include <string.h>
 #include "ets_sys.h"
 
 
 #define CONT_STACKGUARD 0xfeefeffe
 
 void cont_init(cont_t* cont) {
+    memset(cont, 0, sizeof(cont_t));
+    
     cont->stack_guard1 = CONT_STACKGUARD;
     cont->stack_guard2 = CONT_STACKGUARD;
     cont->stack_end = cont->stack + (sizeof(cont->stack) / 4);

cores/esp8266/core_esp8266_main.cpp

@@ -37,11 +37,30 @@ extern "C" {
 
 #define LOOP_TASK_PRIORITY 1
 #define LOOP_QUEUE_SIZE    1
-
 #define OPTIMISTIC_YIELD_TIME_US 16000
 
+extern "C" void call_user_start();
+extern void loop();
+extern void setup();
+extern void (*__init_array_start)(void);
+extern void (*__init_array_end)(void);
+
+/* Not static, used in Esp.cpp */
 struct rst_info resetInfo;
 
+/* Not static, used in core_esp8266_postmortem.c.
+ * Placed into noinit section because we assign value to this variable
+ * before .bss is zero-filled, and need to preserve the value.
+ */
+cont_t* g_pcont __attribute__((section(".noinit")));
+
+/* Event queue used by the main (arduino) task */
+static os_event_t s_loop_queue[LOOP_QUEUE_SIZE];
+
+/* Used to implement optimistic_yield */
+static uint32_t s_micros_at_task_start;
+
+
 extern "C" {
 extern const uint32_t __attribute__((section(".ver_number"))) core_version = ARDUINO_ESP8266_GIT_VER;
 const char* core_release = 
@@ -52,19 +71,10 @@ const char* core_release =
 #endif
 } // extern "C"
 
-int atexit(void (*func)()) {
-    (void) func;
-    return 0;
-}
-
-extern "C" void ets_update_cpu_frequency(int freqmhz);
 void initVariant() __attribute__((weak));
 void initVariant() {
 }
 
-extern void loop();
-extern void setup();
-
 void preloop_update_frequency() __attribute__((weak));
 void preloop_update_frequency() {
 #if defined(F_CPU) && (F_CPU == 160000000L)
@@ -73,17 +83,10 @@ void preloop_update_frequency() {
 #endif
 }
 
-extern void (*__init_array_start)(void);
-extern void (*__init_array_end)(void);
-
-cont_t g_cont __attribute__ ((aligned (16)));
-static os_event_t g_loop_queue[LOOP_QUEUE_SIZE];
-
-static uint32_t g_micros_at_task_start;
 
 extern "C" void esp_yield() {
-    if (cont_can_yield(&g_cont)) {
-        cont_yield(&g_cont);
+    if (cont_can_yield(g_pcont)) {
+        cont_yield(g_pcont);
     }
 }
 
@@ -92,7 +95,7 @@ extern "C" void esp_schedule() {
 }
 
 extern "C" void __yield() {
-    if (cont_can_yield(&g_cont)) {
+    if (cont_can_yield(g_pcont)) {
         esp_schedule();
         esp_yield();
     }
@@ -104,8 +107,8 @@ extern "C" void __yield() {
 extern "C" void yield(void) __attribute__ ((weak, alias("__yield")));
 
 extern "C" void optimistic_yield(uint32_t interval_us) {
-    if (cont_can_yield(&g_cont) &&
-        (system_get_time() - g_micros_at_task_start) > interval_us)
+    if (cont_can_yield(g_pcont) &&
+        (system_get_time() - s_micros_at_task_start) > interval_us)
     {
         yield();
     }
@@ -125,9 +128,9 @@ static void loop_wrapper() {
 
 static void loop_task(os_event_t *events) {
     (void) events;
-    g_micros_at_task_start = system_get_time();
-    cont_run(&g_cont, &loop_wrapper);
-    if (cont_check(&g_cont) != 0) {
+    s_micros_at_task_start = system_get_time();
+    cont_run(g_pcont, &loop_wrapper);
+    if (cont_check(g_pcont) != 0) {
         panic();
     }
 }
@@ -145,6 +148,22 @@ void init_done() {
     esp_schedule();
 }
 
+/* This is the entry point of the application.
+ * It gets called on the default stack, which grows down from the top
+ * of DRAM area.
+ * .bss has not been zeroed out yet, but .data and .rodata are in place.
+ * Cache is not enabled, so only ROM and IRAM functions can be called.
+ * Peripherals (except for SPI0 and UART0) are not initialized.
+ * This function does not return.
+ */
+extern "C" void ICACHE_RAM_ATTR app_entry(void)
+{
+    /* Allocate continuation context on this stack, and save pointer to it. */
+    cont_t s_cont __attribute__((aligned(16)));
+    g_pcont = &s_cont;
+    /* Call the entry point of the SDK code. */
+    call_user_start();
+}
 
 extern "C" void user_init(void) {
     struct rst_info *rtc_info_ptr = system_get_rst_info();
@@ -156,10 +175,10 @@ extern "C" void user_init(void) {
 
     initVariant();
 
-    cont_init(&g_cont);
+    cont_init(g_pcont);
 
     ets_task(loop_task,
-        LOOP_TASK_PRIORITY, g_loop_queue,
+        LOOP_TASK_PRIORITY, s_loop_queue,
         LOOP_QUEUE_SIZE);
 
     system_init_done_cb(&init_done);

cores/esp8266/core_esp8266_postmortem.c

@@ -32,7 +32,7 @@
 
 extern void __real_system_restart_local();
 
-extern cont_t g_cont;
+extern cont_t* g_pcont;
 
 // These will be pointers to PROGMEM const strings
 static const char* s_panic_file = 0;
@@ -131,8 +131,8 @@ void __wrap_system_restart_local() {
         ets_printf_P("\nSoft WDT reset\n");
     }
 
-    uint32_t cont_stack_start = (uint32_t) &(g_cont.stack);
-    uint32_t cont_stack_end = (uint32_t) g_cont.stack_end;
+    uint32_t cont_stack_start = (uint32_t) &(g_pcont->stack);
+    uint32_t cont_stack_end = (uint32_t) g_pcont->stack_end;
     uint32_t stack_end;
 
     // amount of stack taken by interrupt or exception handler

cores/esp8266/libc_replacements.c

@@ -122,39 +122,7 @@ void _exit(int status) {
     abort();
 }
 
-#if 0
-
-int ICACHE_RAM_ATTR printf(const char* format, ...) {
-    va_list arglist;
-    va_start(arglist, format);
-    int ret = ets_vprintf(ets_putc, format, arglist);
-    va_end(arglist);
-    return ret;
+int atexit(void (*func)()) {
+    (void) func;
+    return 0;
 }
-
-int ICACHE_RAM_ATTR sprintf(char* buffer, const char* format, ...) {
-    int ret;
-    va_list arglist;
-    va_start(arglist, format);
-    ret = ets_vsprintf(buffer, format, arglist);
-    va_end(arglist);
-    return ret;
-}
-
-int ICACHE_RAM_ATTR snprintf(char* buffer, size_t size, const char* format, ...) {
-    int ret;
-    va_list arglist;
-    va_start(arglist, format);
-    ret = ets_vsnprintf(buffer, size, format, arglist);
-    va_end(arglist);
-    return ret;
-}
-
-int ICACHE_RAM_ATTR vprintf(const char * format, va_list arg) {
-    return ets_vprintf(ets_putc, format, arg);
-}
-
-int ICACHE_RAM_ATTR vsnprintf(char * buffer, size_t size, const char * format, va_list arg) {
-    return ets_vsnprintf(buffer, size, format, arg);
-}
-#endif

platform.txt

@@ -37,7 +37,7 @@ compiler.c.flags=-c {compiler.warning_flags} -Os -g -Wpointer-arith -Wno-implici
 compiler.S.cmd=xtensa-lx106-elf-gcc
 compiler.S.flags=-c -g -x assembler-with-cpp -MMD -mlongcalls
 
-compiler.c.elf.flags=-g {compiler.warning_flags} -Os -nostdlib -Wl,--no-check-sections -u call_user_start {build.float} -Wl,-static "-L{compiler.sdk.path}/lib" "-L{compiler.sdk.path}/ld" "-L{compiler.libc.path}/lib" "-T{build.flash_ld}" -Wl,--gc-sections -Wl,-wrap,system_restart_local -Wl,-wrap,spi_flash_read
+compiler.c.elf.flags=-g {compiler.warning_flags} -Os -nostdlib -Wl,--no-check-sections -u app_entry {build.float} -Wl,-static "-L{compiler.sdk.path}/lib" "-L{compiler.sdk.path}/ld" "-L{compiler.libc.path}/lib" "-T{build.flash_ld}" -Wl,--gc-sections -Wl,-wrap,system_restart_local -Wl,-wrap,spi_flash_read
 
 compiler.c.elf.cmd=xtensa-lx106-elf-gcc
 compiler.c.elf.libs=-lhal -lphy -lpp -lnet80211 {build.lwip_lib} -lwpa -lcrypto -lmain -lwps -laxtls -lespnow -lsmartconfig -lairkiss -lwpa2 -lstdc++ -lm -lc -lgcc

tools/platformio-build.py

@@ -80,7 +80,8 @@ env.Append(
     ],
     LINKFLAGS=[
         "-Wl,-wrap,system_restart_local",
-        "-Wl,-wrap,spi_flash_read"
+        "-Wl,-wrap,spi_flash_read",
+        "-u,app_entry"
     ]
 )
 

tools/sdk/include/ets_sys.h

@@ -215,6 +215,7 @@ int ets_vprintf(int (*print_function)(int), const char * format, va_list arg) __
 int ets_putc(int);
 bool ets_task(ETSTask task, uint8 prio, ETSEvent *queue, uint8 qlen);
 bool ets_post(uint8 prio, ETSSignal sig, ETSParam par);
+void ets_update_cpu_frequency(uint32_t ticks_per_us);
 
 
 #ifdef __cplusplus

tools/sdk/ld/eagle.app.v6.common.ld

@@ -9,7 +9,7 @@ PHDRS
   irom0_0_phdr PT_LOAD;
 }
 /*  Default entry point:  */
-ENTRY(call_user_start)
+ENTRY(app_entry)
 EXTERN(_DebugExceptionVector)
 EXTERN(_DoubleExceptionVector)
 EXTERN(_KernelExceptionVector)
@@ -75,6 +75,10 @@ SECTIONS
     _Pri_3_HandlerAddress = ABSOLUTE(.);
     _data_end = ABSOLUTE(.);
   } >dram0_0_seg :dram0_0_phdr
+  .noinit : ALIGN(4)
+  {
+    *(.noinit)
+  } >dram0_0_seg :dram0_0_phdr
   .irom0.text : ALIGN(4)
   {
     _irom0_text_start = ABSOLUTE(.);

tools/sdk/ld/eagle.app.v6.common.ld.h

@@ -12,7 +12,7 @@ PHDRS
 
 
 /*  Default entry point:  */
-ENTRY(call_user_start)
+ENTRY(app_entry)
 EXTERN(_DebugExceptionVector)
 EXTERN(_DoubleExceptionVector)
 EXTERN(_KernelExceptionVector)
@@ -83,6 +83,11 @@ SECTIONS
     _Pri_3_HandlerAddress = ABSOLUTE(.);
     _data_end = ABSOLUTE(.);
   } >dram0_0_seg :dram0_0_phdr
+
+  .noinit : ALIGN(4)
+  {
+    *(.noinit)
+  } >dram0_0_seg :dram0_0_phdr
   
 #ifdef VTABLES_IN_DRAM
 #include "eagle.app.v6.common.ld.vtables.h"