Reduce Heap Size to limit within give Address space of dts

[akifejaz]

I'been trying to build simple test through Zephyr and running it on Spike & My Custom proc. I'm seeing some strange behavior even through my dts file looks something like

  ram0: memory@800000000 {
    #address-cells = <2>;
    #size-cells = <2>;
    device_type = "memory";
    reg = <0x00000008 0x00 0x00 0x04000000>;
  };

The code still tries to access read/write out of boundary like 0x803fffffe I've seen the save behavior on spike, is there some setting I missed regarding this that is controlling heap region?

I tried these changes didn't worked for me.
heap.h

diff --git a/lib/heap/heap.h b/lib/heap/heap.h
index 1be3bd91392..0dddd7f562b 100644
--- a/lib/heap/heap.h
+++ b/lib/heap/heap.h
@@ -53,7 +53,7 @@

 enum chunk_fields { LEFT_SIZE, SIZE_AND_USED, FREE_PREV, FREE_NEXT };

-#define CHUNK_UNIT 8U
+#define CHUNK_UNIT 1U

 typedef struct { char bytes[CHUNK_UNIT]; } chunk_unit_t;

@@ -79,13 +79,7 @@ struct z_heap {

 static inline bool big_heap_chunks(chunksz_t chunks)
 {
-       if (IS_ENABLED(CONFIG_SYS_HEAP_SMALL_ONLY)) {
-               return false;
-       }
-       if (IS_ENABLED(CONFIG_SYS_HEAP_BIG_ONLY) || sizeof(void *) > 4U) {
-               return true;
-       }
-       return chunks > 0x7fffU;
+       return false;
 }

 static inline bool big_heap_bytes(size_t bytes)
@@ -219,12 +213,12 @@ static inline bool solo_free_header(struct z_heap *h, chunkid_t c)

 static inline size_t chunk_header_bytes(struct z_heap *h)
 {
-       return big_heap(h) ? 8 : 4;
+       return 2;
 }

 static inline size_t heap_footer_bytes(size_t size)
 {
-       return big_heap_bytes(size) ? 8 : 4;
+       return 2;
 }

Logs from my simulator.
It throws out of bound error which looks fine to me since the memory address code is accessing is out of bound as per dts set.

Icount: 5178
Cycle: 5754 PC: 00000008000004be Instr: 0019971b SLLIW     X14  (0000000007ff0bdc) X19  (0000000003ff85ee) 0000000000000001 OK

Icount: 5179
Cycle: 5755 PC: 00000008000004c2 Instr: 0204d493 Compressed:SRLI      X9   (0000000003ff8666) X9   (03ff866600000000) 0000000000000020 OK

Icount: 5180
Cycle: 5756 PC: 00000008000004c4 Instr: 00e79123 SH        X15  (0000000800007a10) X14  (0000000007ff0bdc) 0000000000000002 OK

Icount: 5181
Cycle: 5766 PC: 00000008000004c8 Instr: 01279023 SH        X15  (0000000800007a10) X18  (0000000000000078) 0000000000000000 OK

Icount: 5182
Cycle: 5767 PC: 00000008000004cc Instr: 008484b3 Compressed:ADD       X9   (0000000803fffffe) X9   (0000000003ff8666) X8   (0000000800007998)  OK

Icount: 5183
Cycle: 5768 PC: 00000008000004ce Instr: 00100793 Compressed:ADDI      X15  (0000000000000001) X0   (0000000000000000) 0000000000000001 OK

Error: (E549) uncaught exception: ./include/memory.h:36 MEMORY:write address 0x3fffffe is out of bounds
In file: ../../../src/sysc/kernel/sc_except.cpp:101
In process: soc.tile_0.run_core @ 3438002 ns

Relevant .dis file section

Can someone please help me this? will really appreciate. Thanks!

[akifejaz]

Hi can someone please comment on this, really stuck at it? Would really appreciate.
@holtmann @vcgomes @jukkar @nashif