App loading with more features

1. Relocations are performed, obviating the need for manual `pic`
   sprinkling.

2. Globals with initial values (vs all-0 globals in BSS) are now
   initialized to those values.

.github/workflows/rust.yml

@@ -73,6 +73,7 @@ jobs:
           toolchain: nightly
           override: true
           components: rust-src
+      - run: echo "/rsdk/scripts" >> $GITHUB_PATH
       - uses: actions/checkout@v2
       - name: Cargo build
         uses: actions-rs/cargo@v1
@@ -93,11 +94,13 @@ jobs:
           release: '9-2019-q4'
       - name: Install clang
         run: sudo apt-get update && sudo apt install -y clang
-      - uses: actions-rs/toolchain@v1
+      - name: Install toolchains
+        uses: actions-rs/toolchain@v1
         with:
           toolchain: nightly
           override: true
           components: rust-src
+      - run: echo "$PWD/scripts" >> $GITHUB_PATH
       - name: Install dependencies
         run: |
           sudo apt-get update && sudo apt-get install -y qemu-user-static

link.ld

@@ -1,43 +1,118 @@
+PHDRS
+{
+    flash0 PT_LOAD ;
+    data   PT_LOAD ;
+    flash2 PT_LOAD ;
+    sram PT_LOAD ;
+
+    headers PT_PHDR PHDRS ;
+}
+
 SECTIONS
 {
+  /* Code, read only, no relocations needed. */
   .text :
   {
-    _text = .;
+    /* Here begins flash. This symbol is used by the ideompotent `pic`
+       function as the lower bound of addressed to relocate. */
     _nvram_start = .;
 
+    _text = .;
+
     *(.boot*)
     *(.text*)
-    *(.rodata*) 
-
+    /* .rodata is moved out so we can update it */
     . = ALIGN(PAGE_SIZE);
+
     _etext = .;
-  } > FLASH
+  } > FLASH :flash0
+  _text_len = _etext - _text;
 
-  .nvm_data : ALIGN(PAGE_SIZE)
+  /* Relocations, read only, no relocations aginst the relocations themselves
+     needed! */
+  .rel_flash : ALIGN(PAGE_SIZE)
   {
+    _relocs = .;
+
+    /* define _reloc_size in the build.rs */
+    . += _reloc_size;
+    /*(.rel.rodata .rel.rodata*)*/
+    /*(.rel.data .rel.data*)*/
+    /*(.rel.nvm_data .rel.nvm_data*)*/
+    . = ALIGN(PAGE_SIZE);
+
+    _erelocs = .;
+
+    . = ALIGN(PAGE_SIZE);
+
+    /* After this section we have mutable flash. Must be a multiple of PAGE_SIZE from _nvram_start. */
     _nvram_data = .;
-    *(.nvm_data*)
+  } > FLASH :flash0
+  _relocs_len = _erelocs - _relocs;
+
+  /* Immutable globals, read only during app running proper, but
+     relocations are needed. (So not read-only completely.) */
+  .rodata : ALIGN(PAGE_SIZE)
+  {
+    /* Moved here from .text so we can permantly apply relocations to it with
+       nvm_write() */
     . = ALIGN(PAGE_SIZE);
-    _envram_data = .;
-    _install_parameters = .;
-    _nvram_end = .;
-  } > FLASH 
+    _rodata = .;
+    _rodata_src = .;
+    *(.rodata*)
+    /**(.rodata*)*/
+    . = ALIGN(PAGE_SIZE);
+    _erodata = .;
+  } > FLASH :flash0
+  _rodata_len = _erodata - _rodata;
 
-  .data : ALIGN(4)
+  /* Mutable Globals, writable, relocations are needed. */
+  .data : ALIGN(PAGE_SIZE)
   {
     _data = .;
     *(vtable)
     *(.data*)
+    . = ALIGN(PAGE_SIZE);
     _edata = .;
-  } > SRAM
+    FILL(0xa4a4);
+  } > SRAM AT> FLASH :data =0xa4a4
+  _data_len = SIZEOF(.data); /* _edata - _data; */
+
+  /* Persistent data, read and written during app running proper,
+     relocations are also needed. */
+  .nvm_data : ALIGN(PAGE_SIZE)
+  {
+    _nvm_data = .;
+    _nvm_data_src = .;
+    *(.nvm_data*)
+    . = ALIGN(PAGE_SIZE);
+    _envm_data = .;
+
+    /* Debugging: Add some extra buffer space just to make sure we don't cloober install_parameters */
+    . += PAGE_SIZE*4;
+    /* and make sure we're on a page boundary for them */
+    . = ALIGN(PAGE_SIZE);
+    _install_parameters = .;
+
+    /* After this section we no longer have Flash memory at all. */
+
+    /* This symbol is used by the mutable portion of flash calculations. */
+    _envram_data = .;
+    /* This symbol is used by the ideompotent `pic` function as the upper
+       bound of addressed to relocate. */
+    _nvram_end = .;
+  } > FLASH :flash2
+  _nvm_data_len = _envm_data - _nvm_data;
 
-  ASSERT( (_edata - _data) <= 0, ".data section must be empty" )
+  _sidata = LOADADDR(.data);
+  _sidata_src = LOADADDR(.data);
 
-   .bss :
+  .bss :
   {
     _bss = .;
     *(.bss*)
     _ebss = .;
+    _bss_len = ABSOLUTE(_ebss) - ABSOLUTE(_bss);
 
     . = ALIGN(4);
     app_stack_canary = .;
@@ -46,19 +121,34 @@ SECTIONS
     . = _stack_validation + STACK_SIZE;
     _stack = ABSOLUTE(END_STACK) - STACK_SIZE;
     _estack = ABSOLUTE(END_STACK);
-  } > SRAM
+  } > SRAM :sram
 
   .stack_sizes (INFO):
   {
     KEEP(*(.stack_sizes));
-  }
+  } :NONE
+
+  /*
+  .rel (INFO):
+  {
+    KEEP(*(.rel.*));
+  } :NONE
+  */
+
+  /*.text.debug_info (INFO):
+  {
+	  *(.text.debug_info)
+  }*/
 
   /DISCARD/ :
   {
     libc.a ( * )
     libm.a ( * )
     libgcc.a ( * )
     *(.ARM.exidx* .gnu.linkonce.armexidx.*)
+    *(.ARM.extab*)
+    /* *(.rel.debug_info)
+    *(.rela.debug_info) */
     *(.debug_info)
   }
 }

nanos.json

@@ -4,11 +4,11 @@
   "atomic-cas": false,
   "c-enum-min-bits": 8,
   "data-layout": "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64",
-  "emit-debug-gdb-scripts": false,
+  "emit-debug-gdb-scripts": true,
   "executables": true,
   "features": "+strict-align",
   "frame-pointer": "always",
-  "linker": "rust-lld",
+  "linker": "link_wrap.sh",
   "linker-flavor": "ld.lld",
   "llvm-target": "thumbv6m-none-eabi",
   "panic-strategy": "abort",

nanosplus.json

@@ -6,7 +6,7 @@
   "emit-debug-gdb-scripts": false,
   "executables": true,
   "frame-pointer": "always",
-  "linker": "rust-lld",
+  "linker": "link_wrap.sh",
   "linker-flavor": "ld.lld",
   "llvm-target": "thumbv8m.main-none-eabi",
   "max-atomic-width": 32,

nanox.json

@@ -7,7 +7,7 @@
   "emit-debug-gdb-scripts": false,
   "executables": true,
   "frame-pointer": "always",
-  "linker": "rust-lld",
+  "linker": "link_wrap.sh",
   "linker-flavor": "ld.lld",
   "llvm-target": "thumbv6m-none-eabi",
   "panic-strategy": "abort",
@@ -26,5 +26,4 @@
   "target-pointer-width": "32",
   "os": "nanox",
   "target-family": [ "bolos" ]
-
 }

scripts/link_wrap.sh

@@ -0,0 +1,45 @@
+#!/usr/bin/env bash
+
+set -eu
+
+set -x
+
+LD=${LD:-rust-lld}
+# Needed because LLD gets behavior from argv[0]
+LD=${LD/-ld/-lld}
+${LD} "$@" --emit-relocs
+
+echo RUST_LLD DONE
+
+while [ $# -gt 0 -a "$1" != "-o" ];
+do
+	shift;
+done
+OUT="$2"
+
+echo OUT IS $OUT
+
+# the relocations for the constants section are required
+${OBJCOPY} --dump-section .rel.rodata=$OUT-rodata-reloc $OUT /dev/null
+# there might not _be_ nonempty .data or .nvm_data sections, so there might be no relocations for it; fail gracefully.
+${OBJCOPY} --dump-section .rel.data=$OUT-data-reloc $OUT /dev/null || true
+${OBJCOPY} --dump-section .rel.nvm_data=$OUT-nvm-reloc $OUT /dev/null || true
+# Concatenate the relocation sections; this should still write $OUT-relocs even if $OUT-data-reloc doesn't exist.
+cat $OUT-rodata-reloc $OUT-nvm-reloc $OUT-data-reloc > $OUT-relocs || true
+# pad the relocs out to size - we should probably make some way to adjust this size from the source.
+
+reloc_allocated_size="$((0x$(${NM} $OUT | grep _reloc_size | cut -d' ' -f1)))"
+reloc_real_size="$(stat --format %s $OUT-relocs)"
+# Check that our relocations _actually_ fit.
+if [ "$reloc_real_size" -gt "$reloc_allocated_size" ]
+then
+	echo "Insufficient size for relocs; increase it in build.rs."
+	echo "Available size: " $reloc_allocated_size " Used size: " $reloc_real_size
+	exit 1
+else
+	echo "Sufficient size:" $reloc_allocated_size $reloc_real_size
+fi
+
+truncate -s $reloc_allocated_size $OUT-relocs
+# and write the relocs to their section in the flash image.
+${OBJCOPY} --update-section .rel_flash=$OUT-relocs $OUT