Split IRAM into 2 linker sections to move std::fcn (#5922)

* Split IRAM into 2 linker sections to move std::fcn

Callbacks need to be placed in IRAM when being called from an IRQ (like
the SPISlave callbacks).

This can be done by hacking the std::functional header and making every
single specialization of the template into an IRAM section, which would
take a lot of space for no benefit in the majority of cases.

The alternate is to specify the single instantiation types/operators
required, but the problem is the flash segment matcher would match them
before the IRAM section was begun, and rules for them would just not be
applied.

Get around this by splitting the IRAM section definition into .text and
.text1.  This is linker syntactic sugar and does not actually change the
on-chip layout.  But it does allow us to put the exception vectors at
the required absolute addresses and add single functions to IRAM.

* Add .text1 segment to space used calculation in IDE

* All functional callers are now placed in IRAM

* Write out the .text1 segment to the BIN

The extra segment name needs to be placed into the output binary as
well, or else only the init code gets stored and none of the real app is
present.  This leads to an infinite boot loop.

This change adds in the segment to the generated image.

Author: earlephilhower

platform.txt

@@ -117,7 +117,7 @@ recipe.output.save_file={build.project_name}.{build.variant}.bin
 
 ## Compute size
 recipe.size.pattern="{compiler.path}{compiler.size.cmd}" -A "{build.path}/{build.project_name}.elf"
-recipe.size.regex=^(?:\.irom0\.text|\.text|\.data|\.rodata|)\s+([0-9]+).*
+recipe.size.regex=^(?:\.irom0\.text|\.text|\.text1|\.data|\.rodata|)\s+([0-9]+).*
 recipe.size.regex.data=^(?:\.data|\.rodata|\.bss)\s+([0-9]+).*
 #recipe.size.regex.eeprom=^(?:\.eeprom)\s+([0-9]+).*
 

tools/elf2bin.py

@@ -109,7 +109,7 @@ def main():
 
     out = open(args.out, "wb")
     write_bin(out, args.eboot, ['.text'], 4096, args.flash_mode, args.flash_size, args.flash_freq, args.path)
-    write_bin(out, args.app, ['.irom0.text', '.text', '.data', '.rodata'], 0, args.flash_mode, args.flash_size, args.flash_freq, args.path)
+    write_bin(out, args.app, ['.irom0.text', '.text', '.text1', '.data', '.rodata'], 0, args.flash_mode, args.flash_size, args.flash_freq, args.path)
     out.close()
 
     return 0

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

@@ -93,6 +93,44 @@ SECTIONS
 #include "eagle.app.v6.common.ld.vtables.h"
 #endif
 
+  /* IRAM is split into .text and .text1 to allow for moving specific */
+  /* functions into IRAM that would be matched by the irom0.text matcher */
+  .text : ALIGN(4)
+  {
+    _stext = .;
+    _text_start = ABSOLUTE(.);
+     *(.UserEnter.text)
+    . = ALIGN(16);
+    *(.DebugExceptionVector.text)
+    . = ALIGN(16);
+    *(.NMIExceptionVector.text)
+    . = ALIGN(16);
+    *(.KernelExceptionVector.text)
+    LONG(0)
+    LONG(0)
+    LONG(0)
+    LONG(0)
+    . = ALIGN(16);
+    *(.UserExceptionVector.text)
+    LONG(0)
+    LONG(0)
+    LONG(0)
+    LONG(0)
+    . = ALIGN(16);
+    *(.DoubleExceptionVector.text)
+    LONG(0)
+    LONG(0)
+    LONG(0)
+    LONG(0)
+    . = ALIGN (16);
+    *(.entry.text)
+    *(.init.literal)
+    *(.init)
+
+    /* all functional callers are placed in IRAM (including SPI/IRQ callbacks/etc) here */
+    *(.text._ZNKSt8functionIF*EE*)  /* std::function<any(...)>::operator()() const */
+  } >iram1_0_seg :iram1_0_phdr
+
   .irom0.text : ALIGN(4)
   {
     _irom0_text_start = ABSOLUTE(.);
@@ -163,37 +201,10 @@ SECTIONS
     _flash_code_end = ABSOLUTE(.);
   } >irom0_0_seg :irom0_0_phdr
 
-  .text : ALIGN(4)
+
+
+  .text1 : ALIGN(4)
   {
-    _stext = .;
-    _text_start = ABSOLUTE(.);
-     *(.UserEnter.text)
-    . = ALIGN(16);
-    *(.DebugExceptionVector.text)
-    . = ALIGN(16);
-    *(.NMIExceptionVector.text)
-    . = ALIGN(16);
-    *(.KernelExceptionVector.text)
-    LONG(0)
-    LONG(0)
-    LONG(0)
-    LONG(0)
-    . = ALIGN(16);
-    *(.UserExceptionVector.text)
-    LONG(0)
-    LONG(0)
-    LONG(0)
-    LONG(0)
-    . = ALIGN(16);
-    *(.DoubleExceptionVector.text)
-    LONG(0)
-    LONG(0)
-    LONG(0)
-    LONG(0)
-    . = ALIGN (16);
-    *(.entry.text)
-    *(.init.literal)
-    *(.init)
     *(.literal .text .iram.literal .iram.text .iram.text.* .literal.* .text.* .stub .gnu.warning .gnu.linkonce.literal.* .gnu.linkonce.t.*.literal .gnu.linkonce.t.*)
 #ifdef VTABLES_IN_IRAM
     *(.rodata._ZTV*) /* C++ vtables */