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

components/esp_system/ld/esp32s2/memory.ld.in

@@ -165,8 +165,6 @@ _heap_start = _heap_low_start;
 
 _heap_end = 0x40000000;
 
-_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/esp32s2/sections.ld.in

@@ -28,11 +28,7 @@ SECTIONS
 
     HIDDEN(_rtc_code_start = .);
 
-    mapping[rtc_text]
-
-    /* mutable libs begin */
-    mutable[rtc_text]
-    /* mutable libs end */
+    SECTION_MAPPINGS(rtc_text)
 
     *rtc_wake_stub*.*(.literal .text .literal.* .text.*)
 
@@ -67,11 +63,7 @@ SECTIONS
   {
     ALIGNED_SYMBOL(4, _rtc_force_fast_start)
 
-    mapping[rtc_force_fast]
-
-    /* mutable libs begin */
-    mutable[rtc_force_fast]
-    /* mutable libs end */
+    SECTION_MAPPINGS(rtc_force_fast)
 
     *(.rtc.force_fast .rtc.force_fast.*)
 
@@ -90,11 +82,7 @@ SECTIONS
   {
     _rtc_data_start = ABSOLUTE(.);
 
-    mapping[rtc_data]
-
-    /* mutable libs begin */
-    mutable[rtc_data]
-    /* mutable libs end */
+    SECTION_MAPPINGS(rtc_data)
 
     *rtc_wake_stub*.*(.data .rodata .data.* .rodata.*)
 
@@ -109,11 +97,7 @@ SECTIONS
     *rtc_wake_stub*.*(.bss .bss.*)
     *rtc_wake_stub*.*(COMMON)
 
-    mapping[rtc_bss]
-
-    /* mutable libs begin */
-    mutable[rtc_bss]
-    /* mutable libs end */
+    SECTION_MAPPINGS(rtc_bss)
 
     _rtc_bss_end = ABSOLUTE(.);
   } > rtc_data_location
@@ -130,7 +114,7 @@ SECTIONS
   {
     ALIGNED_SYMBOL(4, _rtc_noinit_start)
 
-    mapping[rtc_noinit]
+    SECTION_MAPPINGS(rtc_noinit)
 
     *(.rtc_noinit .rtc_noinit.*)
 
@@ -229,12 +213,7 @@ SECTIONS
     /* Code marked as running out of IRAM */
     _iram_text_start = ABSOLUTE(.);
 
-    mapping[iram0_text]
-
-    /* mutable libs begin */
-    mutable[iram0_text]
-    FAST_REFLASHING_PADDING;
-    /* mutable libs end */
+    SECTION_MAPPINGS_WITH_PADDING(iram0_text)
 
     /* Padding for possible CPU prefetch + alignment for PMS split lines */
     . += _esp_memprot_prefetch_pad_size;
@@ -262,12 +241,7 @@ SECTIONS
     *(.gnu.linkonce.s2.*)
     *(.jcr)
 
-    mapping[dram0_data]
-
-    /* mutable libs begin */
-    mutable[dram0_data]
-    FAST_REFLASHING_PADDING;
-    /* mutable libs end */
+    SECTION_MAPPINGS_WITH_PADDING(dram0_data)
 
     _data_end = ABSOLUTE(.);
   } > dram0_0_seg
@@ -293,11 +267,7 @@ SECTIONS
   {
     ALIGNED_SYMBOL(4, _ext_ram_bss_start)
 
-    mapping[extern_ram]
-
-    /* mutable libs begin */
-    mutable[extern_ram]
-    /* mutable libs end */
+    SECTION_MAPPINGS(extern_ram)
 
     ALIGNED_SYMBOL(4, _ext_ram_bss_end)
   } > extern_ram_seg
@@ -312,6 +282,7 @@ SECTIONS
   {
     _ext_ram_noinit_start = ABSOLUTE(.);
 
+    SECTION_MAPPINGS(extram_noinit)
     *(.ext_ram_noinit*)
 
     ALIGNED_SYMBOL(4, _ext_ram_noinit_end)
@@ -323,15 +294,7 @@ 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]
-
-    /* mutable libs begin */
-    mutable[dram0_bss]
-    /* mutable libs end */
+    SECTION_MAPPINGS(dram0_bss)
 
     ALIGNED_SYMBOL(8, _bss_end)
   } > dram0_0_seg
@@ -365,7 +328,7 @@ SECTIONS
   {
     _flash_rodata_start = ABSOLUTE(.);
 
-    mapping[flash_rodata]
+    SECTION_MAPPINGS_WITH_PADDING(flash_rodata)
 
     *(.irom1.text) /* catch stray ICACHE_RODATA_ATTR */
     *(.gnu.linkonce.r.*)
@@ -383,16 +346,6 @@ 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.
      *
@@ -418,11 +371,6 @@ SECTIONS
     KEEP (*(SORT_BY_INIT_PRIORITY(.esp_system_init_fn.*)))
     _esp_system_init_fn_array_end = ABSOLUTE(.);
 
-    /* mutable libs begin */
-    mutable[flash_rodata]
-    FAST_REFLASHING_PADDING;
-    /* mutable libs end */
-
     _rodata_end = ABSOLUTE(.);
 
     /* Literals are also RO data. */
@@ -431,9 +379,37 @@ 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))
@@ -445,15 +421,18 @@ 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
@@ -468,11 +447,8 @@ SECTIONS
      */
     _rodata_reserved_end = ABSOLUTE(.);
 
-    mapping[rodata_noload]
+    SECTION_MAPPINGS(rodata_noload)
 
-    /* mutable libs begin */
-    mutable[rodata_noload]
-    /* mutable libs end */
   } > default_rodata_seg
 
   .flash.text :
@@ -485,12 +461,7 @@ SECTIONS
     _instruction_reserved_start = ABSOLUTE(.);
     _text_start = ABSOLUTE(.);
 
-    mapping[flash_text]
-
-    /* mutable libs begin */
-    mutable[flash_text]
-    FAST_REFLASHING_PADDING;
-    /* mutable libs end */
+    SECTION_MAPPINGS_WITH_PADDING(flash_text)
 
     *(.stub)
     *(.gnu.warning)
@@ -534,7 +505,8 @@ 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_text_end - ORIGIN(iram0_0_seg)) <= LENGTH(iram0_0_seg)),