fix(esp_system): xtensa: refactor linker scripts and reduce binary size for C++ apps

components/esp_system/ld/esp32/memory.ld.in

@@ -141,9 +141,6 @@ _heap_end = ALIGN(0x40000000 - _sram1_iram_len - 3, 4);
 _heap_end = 0x40000000 - CONFIG_ESP32_TRACEMEM_RESERVE_DRAM;
 #endif
 
-
-_data_seg_org = ORIGIN(rtc_data_seg);
-
 /* The lines below define location alias for .rtc.data section based on Kconfig option.
    When the option is not defined then use slow memory segment
    else the data will be placed in fast memory segment */

components/esp_system/ld/esp32/sections.ld.in

@@ -19,7 +19,7 @@ SECTIONS
   {
     ALIGNED_SYMBOL(4, _rtc_text_start)
 
-    mapping[rtc_text]
+    SECTION_MAPPINGS(rtc_text)
 
     *rtc_wake_stub*.*(.literal .text .literal.* .text.*)
 
@@ -49,7 +49,7 @@ SECTIONS
   {
     ALIGNED_SYMBOL(4, _rtc_force_fast_start)
 
-    mapping[rtc_force_fast]
+    SECTION_MAPPINGS(rtc_force_fast)
 
     *(.rtc.force_fast .rtc.force_fast.*)
 
@@ -68,7 +68,7 @@ SECTIONS
   {
     _rtc_data_start = ABSOLUTE(.);
 
-    mapping[rtc_data]
+    SECTION_MAPPINGS(rtc_data)
 
     *rtc_wake_stub*.*(.data .rodata .data.* .rodata.*)
 
@@ -83,7 +83,7 @@ SECTIONS
     *rtc_wake_stub*.*(.bss .bss.*)
     *rtc_wake_stub*.*(COMMON)
 
-    mapping[rtc_bss]
+    SECTION_MAPPINGS(rtc_bss)
 
     _rtc_bss_end = ABSOLUTE(.);
   } > rtc_data_location
@@ -100,6 +100,8 @@ SECTIONS
   {
     ALIGNED_SYMBOL(4, _rtc_noinit_start)
 
+    SECTION_MAPPINGS(rtc_noinit)
+
     *(.rtc_noinit .rtc_noinit.*)
 
     ALIGNED_SYMBOL(4, _rtc_noinit_end)
@@ -222,8 +224,7 @@ SECTIONS
     /* Code marked as running out of IRAM */
     _iram_text_start = ABSOLUTE(.);
 
-    mapping[iram0_text]
-
+    SECTION_MAPPINGS(iram0_text)
   } > iram0_0_seg
 
   .dram0.data :
@@ -237,7 +238,7 @@ SECTIONS
     *(.gnu.linkonce.s2.*)
     *(.jcr)
 
-    mapping[dram0_data]
+    SECTION_MAPPINGS(dram0_data)
 
     _data_end = ABSOLUTE(.);
   } > dram0_0_seg
@@ -250,6 +251,7 @@ SECTIONS
   {
     _ext_ram_noinit_start = ABSOLUTE(.);
 
+    SECTION_MAPPINGS(extram_noinit)
     *(.ext_ram_noinit*)
 
     ALIGNED_SYMBOL(4, _ext_ram_noinit_end)
@@ -275,7 +277,7 @@ SECTIONS
   {
     ALIGNED_SYMBOL(4, _ext_ram_bss_start)
 
-    mapping[extern_ram]
+    SECTION_MAPPINGS(extern_ram)
 
     ALIGNED_SYMBOL(4, _ext_ram_bss_end)
   } > extern_ram_seg
@@ -285,11 +287,7 @@ SECTIONS
   {
     ALIGNED_SYMBOL(8, _bss_start)
 
-    /**
-     * ldgen places all bss-related data to mapping[dram0_bss]
-     * (See components/esp_system/app.lf).
-     */
-    mapping[dram0_bss]
+    SECTION_MAPPINGS(dram0_bss)
 
     ALIGNED_SYMBOL(8, _bss_end)
   } > dram0_0_seg
@@ -326,7 +324,7 @@ SECTIONS
   {
     _flash_rodata_start = ABSOLUTE(.);
 
-    mapping[flash_rodata]
+    SECTION_MAPPINGS(flash_rodata)
 
     *(.irom1.text) /* catch stray ICACHE_RODATA_ATTR */
     *(.gnu.linkonce.r.*)
@@ -344,16 +342,6 @@ SECTIONS
     __XT_EXCEPTION_DESCS_END__ = ABSOLUTE(.);
     *(.xt_except_desc_end)
 
-#if EH_FRAME_LINKING_ENABLED
-    ALIGNED_SYMBOL(4, __eh_frame)
-    KEEP(*(.eh_frame))
-    /**
-     * As we are not linking with crtend.o, which includes the CIE terminator
-     * (see __FRAME_END__ in libgcc sources), it is manually provided here.
-     */
-    LONG(0);
-#endif // EH_FRAME_LINKING_ENABLED
-
     /**
      * C++ constructor tables.
      *
@@ -381,9 +369,37 @@ SECTIONS
     *(.lit4.*)
     *(.gnu.linkonce.lit4.*)
     _lit4_end = ABSOLUTE(.);
+    . = ALIGN(ALIGNOF(SECTION_AFTER_FLASH_RODATA));
+  } > default_rodata_seg
+  ASSERT_SECTIONS_GAP(.flash.rodata, SECTION_AFTER_FLASH_RODATA)
 
-    /* TLS data. */
-    ALIGNED_SYMBOL(4, _thread_local_start)
+#if EH_FRAME_LINKING_ENABLED
+  .eh_frame :
+  {
+    ALIGNED_SYMBOL(4, __eh_frame)
+
+    KEEP (*(.eh_frame))
+    /**
+     * As we are not linking with crtend.o, which includes the CIE terminator
+     * (see __FRAME_END__ in libgcc sources), it is manually provided here.
+     */
+    LONG(0);
+
+    __eh_frame_end = ABSOLUTE(.);
+
+    . = ALIGN(ALIGNOF(.flash.tdata));
+  } > default_rodata_seg
+#endif // EH_FRAME_LINKING_ENABLED
+
+  .flash.tdata :
+  {
+    /* Keep tdata and tbss sections contiguous (no gaps between them).
+     * The TLS runtime code calculates offsets assuming these sections are
+     * adjacent. Gaps would cause incorrect address calculations, leading
+     * to accessing wrong memory.
+     */
+    /* tdata sections */
+    _thread_local_data_start = ABSOLUTE(.);
 #if CONFIG_LIBC_PICOLIBC
     _picolibc_reent_stub_start = ABSOLUTE(.);
     KEEP(*(.tdata.errno))
@@ -395,15 +411,18 @@ SECTIONS
 #endif // CONFIG_LIBC_PICOLIBC_NEWLIB_COMPATIBILITY
     _picolibc_reent_stub_end = ABSOLUTE(.);
 #endif // CONFIG_LIBC_PICOLIBC
-    *(.tdata)
-    *(.tdata.*)
-    *(.tbss)
-    *(.tbss.*)
-    _thread_local_end = ABSOLUTE(.);
+    *(.tdata .tdata.* .gnu.linkonce.td.*)
+    _thread_local_data_end = ABSOLUTE(.);
+    /* tbss sections */
+    _thread_local_bss_start = ABSOLUTE(.);
+    *(.tbss .tbss.* .gnu.linkonce.tb.*)
+    *(.tcommon .tcommon.*)
+    _thread_local_bss_end = ABSOLUTE(.);
   } > default_rodata_seg
+  _tls_section_alignment = ALIGNOF(.flash.tdata);
   ASSERT_PICOLIBC_REENT_STUB()
-
-  _flash_rodata_align = ALIGNOF(.flash.rodata);
+  ASSERT(_thread_local_data_end == _thread_local_bss_start,
+         "tdata and tbss must be contiguous.")
 
   /**
    * This section contains all the rodata that is not used
@@ -418,7 +437,7 @@ SECTIONS
      */
     _rodata_reserved_end = ABSOLUTE(.);
 
-    mapping[rodata_noload]
+    SECTION_MAPPINGS(rodata_noload)
   } > default_rodata_seg
 
   .flash.text :
@@ -431,7 +450,7 @@ SECTIONS
     _instruction_reserved_start = ABSOLUTE(.);
     _text_start = ABSOLUTE(.);
 
-    mapping[flash_text]
+    SECTION_MAPPINGS(flash_text)
 
     *(.stub)
     *(.gnu.warning)
@@ -472,7 +491,7 @@ SECTIONS
   {
     ALIGNED_SYMBOL(4, _iram_data_start)
 
-    mapping[iram0_data]
+    SECTION_MAPPINGS(iram0_data)
 
     _iram_data_end = ABSOLUTE(.);
   } > iram0_0_seg
@@ -481,7 +500,7 @@ SECTIONS
   {
     ALIGNED_SYMBOL(4, _iram_bss_start)
 
-    mapping[iram0_bss]
+    SECTION_MAPPINGS(iram0_bss)
 
     _iram_bss_end = ABSOLUTE(.);
     ALIGNED_SYMBOL(4, _iram_end)
@@ -494,7 +513,8 @@ SECTIONS
     ALIGNED_SYMBOL(8, _heap_low_start)
   } > dram0_0_seg
 
-#include "elf_misc.ld.in"
+#include "ld.debug.sections"
+#include "ld.discard.sections"
 }
 
 ASSERT(((_iram_end - ORIGIN(iram0_0_seg)) <= LENGTH(iram0_0_seg)),