core: add errno and other TLS variables support

.gitignore

@@ -8,3 +8,4 @@ cxxflags.txt
 includes.txt
 syms-dynamic.ld
 syms-static.ld
+tls-syms.S

cores/arduino/llext_wrappers.c

@@ -62,6 +62,11 @@
 		__real_##name(a);                                                                          \
 	}
 
+#ifdef CONFIG_ARM
+/* ARM EABI thread pointer access */
+W0(size_t, __aeabi_read_tp)
+#endif
+
 /* string.h */
 W3(void *, memcpy, void *, const void *, size_t)
 W3(void *, memmove, void *, const void *, size_t)

extra/build.sh

@@ -102,6 +102,7 @@ cp ${BUILD_DIR}/zephyr/.config firmwares/zephyr-$variant.config
 
 # Generate the provides.ld file for linked builds
 echo "Generating exported symbol scripts"
+extra/gen_provides.py "${BUILD_DIR}/zephyr/zephyr.elf" -T > ${VARIANT_DIR}/tls-syms.S
 extra/gen_provides.py "${BUILD_DIR}/zephyr/zephyr.elf" -L > ${VARIANT_DIR}/syms-dynamic.ld
 extra/gen_provides.py "${BUILD_DIR}/zephyr/zephyr.elf" -LF \
 	"+kheap_llext_heap" \

extra/gen_provides.py

@@ -122,17 +122,29 @@ def main():
     argparser.add_argument('-F', '--funcs',
             action='store_true',
             help='Extract all public functions')
+    argparser.add_argument('-T', '--tls-defs',
+            action='store_true',
+            help='Extract TLS symbol offsets to a .S file')
     argparser.add_argument('file',
             help='ELF file to parse')
     argparser.add_argument('syms', nargs='*',
             help='Symbols to export')
 
     args = argparser.parse_intermixed_args()
 
+    wants_provides = bool(args.syms or args.funcs or args.llext)
+    if wants_provides and args.tls_defs:
+        sys.stderr.write("Cannot generate TLS defs when also generating PROVIDEs.\n")
+        sys.exit(1)
+    elif not wants_provides and not args.tls_defs:
+        sys.stderr.write("Nothing specified for export.\n")
+        sys.exit(1)
+
     exact_syms = set()
     regex_syms = set()
     deref_syms = set()
     sized_syms = set()
+    tls_syms = set() # tuple of (name, value, size)
     rename_map = {}
     for sym in args.syms:
         sym_class = None
@@ -184,6 +196,11 @@ def main():
         fail = False
 
         for name, sym in all_syms.items():
+            if sym['st_info']['type'] == 'STT_TLS':
+                # Collect TLS symbol information, ignore for PROVIDEs
+                tls_syms.add((name, sym['st_value'], sym['st_size']))
+                continue
+
             value = None
             comment = []
             if name in exact_syms or any(re.match(r, name) for r in regex_syms):
@@ -220,10 +237,6 @@ def main():
             if name in sized_syms:
                 out_syms[name + "_size"] = (sym['st_size'], [f"size of {name}"])
 
-        if not out_syms:
-            sys.stderr.write("No symbols found matching the criteria.\n")
-            fail = True
-
         if fail:
             sys.exit(1)
 
@@ -235,16 +248,47 @@ def main():
  * SHA256: {elf_sha}
  */
 """)
-        sym_comment = nul_comment = ""
-        for name, (value, comments) in sorted(out_syms.items(), key=lambda x: x[0]):
-            if args.verbose:
-                comment = ', '.join(sorted(comments))
-                sym_comment = f"/* {comment} */"
-                nul_comment = f" ({comment})"
-            if value:
-                print(f"PROVIDE({name} = {value:#010x});{sym_comment}")
+
+        if wants_provides:
+            if not out_syms:
+                print("/* No symbols found matching the criteria */")
+                sys.stderr.write("warning: no symbols found matching the criteria.\n")
             else:
-                print(f"/* NULL {name}{nul_comment} */")
+                sym_comment = nul_comment = ""
+                for name, (value, comments) in sorted(out_syms.items(), key=lambda x: x[0]):
+                    if args.verbose:
+                        comment = ', '.join(sorted(comments))
+                        sym_comment = f"/* {comment} */"
+                        nul_comment = f" ({comment})"
+                    if value:
+                        print(f"PROVIDE({name} = {value:#010x});{sym_comment}")
+                    else:
+                        print(f"/* NULL {name}{nul_comment} */")
+
+        if args.tls_defs:
+            # ARM and AArch64 use '@' as a line-comment character in GAS, so the
+            # assembler requires '%' as the type prefix there.  All other targets use '@'.
+            prefix = '%' if elf['e_machine'] in ('EM_ARM', 'EM_AARCH64') else '@'
+
+            # The TLS Variant 1 layout (used by ARM/AArch64) places a Thread
+            # Control Block (TCB) before the TLS data.  The thread pointer
+            # returned by __aeabi_read_tp() points to the TCB, so the actual
+            # runtime address of a TLS variable must be offset by that size.
+            #
+            # TCB is 2 pointers: 8 bytes on 32-bit, 16 bytes on 64-bit.
+            # See zephyr/arch/arm/core/tls.c: arch_tls_stack_setup().
+            tcb_size = (elf.elfclass // 8) * 2
+            print(f"/* Offsets include {tcb_size} bytes for TCB data */")
+
+            # Sort by offset first, then size
+            for name, offset, size in sorted(tls_syms, key=lambda x: (x[1], x[2])):
+                offset += tcb_size
+                print(
+                    f"\n/* TLS offset {offset:#x}: {name} ({size} bytes) */\n"
+                    f".global {name}\n"
+                    f".type {name}, {prefix}tls_object\n"
+                    f".set {name}, {offset}"
+                )
 
 #-------------------------------------------------------------------------------
 if __name__ == '__main__':

loader/llext_exports.c

@@ -289,6 +289,10 @@ EXPORT_SYMBOL(ring_buf_area_finish);
 #endif
 
 EXPORT_SYMBOL(sys_clock_cycle_get_32);
+
+#if defined(CONFIG_ARM)
+extern uint32_t __aeabi_read_tp(void);
+EXPORT_LIBC_SYM(__aeabi_read_tp);
 FORCE_EXPORT_SYM(__aeabi_dcmpun);
 FORCE_EXPORT_SYM(__aeabi_dcmple);
 FORCE_EXPORT_SYM(__aeabi_d2lz);
@@ -318,6 +322,7 @@ FORCE_EXPORT_SYM(__aeabi_idivmod);
 FORCE_EXPORT_SYM(__aeabi_ldivmod);
 FORCE_EXPORT_SYM(__aeabi_ul2f);
 FORCE_EXPORT_SYM(__aeabi_dcmpge);
+#endif
 
 #if defined (CONFIG_CPP)
 FORCE_EXPORT_SYM(__cxa_pure_virtual);