Merge pull request #12928 from benpicco/newlib-multiheap

sys/newlib: enable multiple heaps in _sbrk_r()

cpu/cortexm_common/ldscripts/cortexm_base.ld

@@ -185,4 +185,9 @@ SECTIONS
         /* Round size so that we can use 4 byte copy in init */
         . = ALIGN(4);
     } > bkup-ram
+
+    .heap3 (NOLOAD) : ALIGN(4) {
+        _sheap1 = . ;
+        _eheap1 = ORIGIN(bkup-ram) + LENGTH(bkup-ram);
+    } > bkup-ram
 }

cpu/lpc2387/include/cpu_conf.h

@@ -83,6 +83,12 @@ extern unsigned __stack_irq_size;
 #define ISR_STACKSIZE                   ((unsigned) &__stack_irq_size)
 /** @} */
 
+/**
+ * @brief   The CPU has 4 blocks of SRAM at different addresses.
+ *          (primary RAM, USB RAM, Ethernet RAM & Backup RAM)
+ */
+#define NUM_HEAPS (4)
+
 #ifdef __cplusplus
 }
 #endif

cpu/lpc2387/ldscripts/lpc2387.ld

@@ -175,10 +175,10 @@ SECTIONS
     _sram = ORIGIN(ram);
     _eram = ORIGIN(ram) + LENGTH(ram);
 
-    __heap2_size = LENGTH(ram_ethernet);
-    .heap2 (NOLOAD) :
+    .heap1 ALIGN(4) (NOLOAD) :
     {
-        PROVIDE(__heap2_start = . );
+        _sheap1 = ORIGIN(ram_ethernet);
+        _eheap1 = ORIGIN(ram_ethernet) + LENGTH(ram_ethernet);
     } > ram_ethernet
 
     . = ORIGIN(ram_usb);
@@ -187,12 +187,11 @@ SECTIONS
         *(.usbdata)
     } > ram_usb
 
-    .heap3 ALIGN(0x1000) (NOLOAD) :
+    .heap2 ALIGN(4) (NOLOAD) :
     {
-        __heap3_size = ORIGIN(ram_usb) + LENGTH(ram_usb) - ABSOLUTE(.);
-        PROVIDE(__heap3_start = . );
+        _sheap2 = . ;
+        _eheap2 = ORIGIN(ram_usb) + LENGTH(ram_usb);
     } > ram_usb
-    __heap_size = SIZEOF(.heap3);
 
     _sbackup_data_load = LOADADDR(.backup.data);
     .backup.data :  ALIGN(4) {
@@ -210,4 +209,9 @@ SECTIONS
         /* Round size so that we can use 4 byte copy in init */
         . = ALIGN(4);
     } > ram_battery
+
+    .heap3 (NOLOAD) : ALIGN(4) {
+        _sheap3 = . ;
+        _eheap3 = ORIGIN(ram_battery) + LENGTH(ram_battery);
+    } > ram_battery
 }

cpu/sam0_common/include/cpu_conf.h

@@ -126,6 +126,13 @@ as shown in the NVM Row Organization figure. */
 #endif
 /** @} */
 
+/**
+ * @brief   The CPU has Low Power RAM that can be used as Heap
+ */
+#ifdef CPU_HAS_BACKUP_RAM
+#define NUM_HEAPS (2)
+#endif
+
 #ifdef __cplusplus
 }
 #endif

sys/newlib_syscalls_default/syscalls.c

@@ -56,12 +56,79 @@
 #include "xtimer.h"
 #endif
 
+#ifndef NUM_HEAPS
+#define NUM_HEAPS 1
+#endif
+
 /**
  * @brief manage the heap
  */
 extern char _sheap;                 /* start of the heap */
 extern char _eheap;                 /* end of the heap */
-char *heap_top = &_sheap + 4;
+
+/**
+ * @brief Additional heap sections that may be defined in the linkerscript.
+ *
+ *        The compiler should not generate references to those symbols if
+ *        they are not used, so only provide them if additional memory sections
+ *        that can be used as heap are available.
+ * @{
+ */
+extern char _sheap1;
+extern char _eheap1;
+
+extern char _sheap2;
+extern char _eheap2;
+
+extern char _sheap3;
+extern char _eheap3;
+/* @} */
+
+struct heap {
+    char* start;
+    char* end;
+};
+
+static char *heap_top[NUM_HEAPS] = {
+    &_sheap,
+#if NUM_HEAPS > 1
+    &_sheap1,
+#endif
+#if NUM_HEAPS > 2
+    &_sheap2,
+#endif
+#if NUM_HEAPS > 3
+    &_sheap3,
+#endif
+#if NUM_HEAPS > 4
+#error "Unsupported NUM_HEAPS value, edit newlib_syscalls_default/syscalls.c to add more heaps."
+#endif
+};
+
+static const struct heap heaps[NUM_HEAPS] = {
+    {
+        .start = &_sheap,
+        .end   = &_eheap
+    },
+#if NUM_HEAPS > 1
+    {
+        .start = &_sheap1,
+        .end   = &_eheap1
+    },
+#endif
+#if NUM_HEAPS > 2
+    {
+        .start = &_sheap2,
+        .end   = &_eheap2
+    },
+#endif
+#if NUM_HEAPS > 3
+    {
+        .start = &_sheap3,
+        .end   = &_eheap3
+    },
+#endif
+};
 
 /* MIPS newlib crt implements _init,_fini and _exit and manages the heap */
 #ifndef __mips__
@@ -108,15 +175,22 @@ void _exit(int n)
  */
 void *_sbrk_r(struct _reent *r, ptrdiff_t incr)
 {
+    void *res = (void*)UINTPTR_MAX;
     unsigned int state = irq_disable();
-    void *res = heap_top;
 
-    if ((heap_top + incr > &_eheap) || (heap_top + incr < &_sheap)) {
-        r->_errno = ENOMEM;
-        res = (void *)-1;
+    for (unsigned i = 0; i < NUM_HEAPS; ++i) {
+        if ((heap_top[i] + incr > heaps[i].end) ||
+            (heap_top[i] + incr < heaps[i].start)) {
+            continue;
+        }
+
+        res = heap_top[i];
+        heap_top[i] += incr;
+        break;
     }
-    else {
-        heap_top += incr;
+
+    if (res == (void*)UINTPTR_MAX) {
+        r->_errno = ENOMEM;
     }
 
     irq_restore(state);