🐛 [newlib] fix broken sbrk function

CHANGELOG.md

@@ -29,6 +29,7 @@ mimpid = 0x01040312 -> Version 01.04.03.12 -> v1.4.3.12
 
 | Date | Version | Comment | Ticket |
 |:----:|:-------:|:--------|:------:|
+| 20.07.2024 | 1.10.1.7 | :bug: fix bug in `sbrk` newlib system call (causing `malloc` to provide infinite memory until heap and stack collide) | [#957](https://github.com/stnolting/neorv32/pull/957) |
 | 20.07.2024 | 1.10.1.6 | SDI: remove explicit "RX clear flag"; add new flag to check the current state of the chip-select input | [#955](https://github.com/stnolting/neorv32/pull/955) |
 | 19.07.2024 | 1.10.1.5 | :sparkles: add "programmable" chip-select enable/disable functionality to SPI module | [#954](https://github.com/stnolting/neorv32/pull/954) |
 | 19.07.2024 | 1.10.1.4 | :bug: fix SDI "TX FIFO full" flag | [#953](https://github.com/stnolting/neorv32/pull/953) |

rtl/core/neorv32_package.vhd

@@ -29,7 +29,7 @@ package neorv32_package is
 
   -- Architecture Constants -----------------------------------------------------------------
   -- -------------------------------------------------------------------------------------------
-  constant hw_version_c : std_ulogic_vector(31 downto 0) := x"01100106"; -- hardware version
+  constant hw_version_c : std_ulogic_vector(31 downto 0) := x"01100107"; -- hardware version
   constant archid_c     : natural := 19; -- official RISC-V architecture ID
   constant XLEN         : natural := 32; -- native data path width
 

sw/common/neorv32.ld

@@ -199,6 +199,8 @@ SECTIONS
   .heap : ALIGN(4)
   {
     PROVIDE(__heap_start = .);
+    /* start section on WORD boundary */
+    . = ALIGN(4);
     . = __neorv32_heap_size;
     /* finish section on WORD boundary */
     . = ALIGN(4);

sw/example/demo_newlib/main.c

@@ -14,6 +14,7 @@
  **************************************************************************/
 #include <neorv32.h>
 #include <unistd.h>
+#include <time.h>
 #include <stdlib.h>
 
 
@@ -33,6 +34,9 @@ void __attribute__((destructor)) main_destructor_test(void) {
 
   int32_t main_ret = (int32_t)neorv32_cpu_csr_read(CSR_MSCRATCH);
   neorv32_uart0_printf("\nDestructor: main terminated with return/exit code %i.\n", main_ret);
+  if (main_ret == 7) {
+    neorv32_uart0_printf("exit() succeeded.\n");
+  }
 }
 
 
@@ -68,34 +72,51 @@ int main() {
   // say hello
   neorv32_uart0_printf("<<< Newlib demo/test program >>>\n\n");
 
+
+  // check if newlib is really available
+#ifndef __NEWLIB__
+  neorv32_uart0_printf("ERROR! Seems like the compiler toolchain does not support newlib...\n");
+  return -1;
+#endif
+  neorv32_uart0_printf("NEWLIB version %u.%u\n\n", (uint32_t)__NEWLIB__, (uint32_t)__NEWLIB_MINOR__);
+
+
   // heap size definition
-  volatile uint32_t max_heap = (uint32_t)__crt0_max_heap;
+  uint32_t max_heap = (uint32_t)&__crt0_max_heap[0];
   if (max_heap > 0){
     neorv32_uart0_printf("MAX heap size: %u bytes\n", max_heap);
   }
   else {
-    neorv32_uart0_printf("ERROR! No heap size defined (USER_FLAGS+='-Wl,--defsym,__neorv32_heap_size=1024')!\n");
+    neorv32_uart0_printf("ERROR! No heap size defined!\n");
+    neorv32_uart0_printf("Use <USER_FLAGS+='-Wl,--defsym,__neorv32_heap_size=1024'> to set the heap size.\n");
     return -1;
   }
 
-  // check if newlib is really available
-#ifndef __NEWLIB__
-  neorv32_uart0_printf("ERROR! Seems like the compiler toolchain does not support newlib...\n");
-  return -1;
-#endif
-
-  neorv32_uart0_printf("newlib version %i.%i\n\n", (int32_t)__NEWLIB__, (int32_t)__NEWLIB_MINOR__);
 
+  // rand test
   neorv32_uart0_printf("<rand> test... ");
   srand(neorv32_cpu_csr_read(CSR_CYCLE)); // set random seed
   neorv32_uart0_printf("%i, %i, %i, %i\n", rand() % 100, rand() % 100, rand() % 100, rand() % 100);
 
 
-  char *char_buffer; // pointer for dynamic memory allocation
+  // time test
+  neorv32_uart0_printf("<time> test... ");
+  time_t seconds = time(NULL);
+  neorv32_uart0_printf("Seconds since January 1, 1970 (32-bit!) = %u\n", (uint32_t)seconds);
+  neorv32_uart0_printf("%i, %i, %i, %i\n", rand() % 100, rand() % 100, rand() % 100, rand() % 100);
+
 
+  // malloc test
   neorv32_uart0_printf("<malloc> test...\n");
-  char_buffer = (char *) malloc(4 * sizeof(char)); // 4 bytes
+  char *char_buffer = (char *) malloc(4 * sizeof(char)); // 4 bytes
 
+  if (char_buffer == NULL) {
+    neorv32_uart0_printf("malloc FAILED!\n");
+    return -1;
+  }
+
+
+  // STDx tests using read and write
   // do not test read & write in simulation as there would be no UART RX input
   if (neorv32_cpu_csr_read(CSR_MXISA) & (1 << CSR_MXISA_IS_SIM)) {
     neorv32_uart0_printf("Skipping <read> & <write> tests as this seems to be a simulation.\n");
@@ -118,13 +139,15 @@ int main() {
   free(char_buffer);
 
 
+  // exit test
   // NOTE: exit is highly over-sized as it also includes clean-up functions (destructors), which
   // are not required for bare-metal or RTOS applications... better use the simple 'return' or even better
   // make sure main never returns. Anyway, let's check if 'exit' works.
   int exit_code = 7;
   neorv32_uart0_printf("<exit> terminating by exit(%i)...\n", exit_code);
   exit(exit_code);
 
+
   // should never be reached
   neorv32_uart0_printf("exit failed!\n");
   return 0;

sw/example/demo_newlib/makefile

@@ -1,5 +1,5 @@
 # Configure max HEAP size
-override USER_FLAGS += "-Wl,--defsym,__neorv32_heap_size=1024"
+override USER_FLAGS += "-Wl,--defsym,__neorv32_heap_size=3072"
 
 NEORV32_HOME ?= ../../..
 include $(NEORV32_HOME)/sw/common/common.mk