Use picolibc instead of newlib-nano

platform/CMakeLists.txt

@@ -90,6 +90,7 @@ target_sources(platform_s
 target_sources(tfm_s
     PRIVATE
         ext/common/faults.c
+        ext/common/picolibc.c
 )
 
 target_link_libraries(platform_s

platform/ext/common/gcc/tfm_common_bl2.ld

@@ -153,6 +153,26 @@ SECTIONS
     } > RAM AT > FLASH
     Image$$ER_DATA$$Base = ADDR(.data);
 
+    .tdata : ALIGN_WITH_INPUT
+    {
+        *(.tdata .tdata.* .gnu.linkonce.td.*)
+        PROVIDE( __data_end = . );
+        PROVIDE( __tdata_end = . );
+    } >RAM AT>FLASH
+
+    .tbss (NOLOAD) :
+    {
+        *(.tbss .tbss.* .gnu.linkonce.tb.*)
+        *(.tcommon)
+        PROVIDE( __tls_end = . );
+        PROVIDE( __tbss_end = . );
+    } >RAM AT>RAM
+
+    .tbss_space (NOLOAD) : {
+        . = ADDR(.tbss);
+        . = . + SIZEOF(.tbss);
+    } >RAM AT>RAM
+
     .bss : ALIGN(4)
     {
         . = ALIGN(4);
@@ -163,6 +183,16 @@ SECTIONS
         __bss_end__ = .;
     } > RAM
 
+    PROVIDE( __bss_end = __bss_end__ );
+    PROVIDE( __data_start = ADDR(.data) );
+    PROVIDE( __data_source = LOADADDR(.data) );
+    PROVIDE( __data_size = __data_end - __data_start );
+    PROVIDE( __tls_base = SIZEOF(.tdata) ? ADDR(.tdata) : ADDR(.tbss) );
+    PROVIDE( __tls_align = MAX(ALIGNOF(.tdata), ALIGNOF(.tbss)) );
+    PROVIDE( __arm32_tls_tcb_offset = MAX(8, __tls_align) );
+    PROVIDE( __bss_start = ADDR(.tbss));
+    PROVIDE( __bss_size = __bss_end - __bss_start );
+
 #if defined (__ARM_FEATURE_CMSE) && (__ARM_FEATURE_CMSE == 3U)
     .msp_stack (NOLOAD) : ALIGN(32)
     {
@@ -200,4 +230,6 @@ SECTIONS
     Image$$ARM_LIB_HEAP$$ZI$$Limit = ADDR(.heap) + SIZEOF(.heap);
 
     PROVIDE(__stack = Image$$ARM_LIB_STACK$$ZI$$Limit);
+    PROVIDE( __heap_start = __HeapBase );
+    PROVIDE( __heap_end = __HeapLimit );
 }

platform/ext/common/gcc/tfm_common_ns.ld

@@ -128,22 +128,51 @@ SECTIONS
 
         KEEP(*(.jcr*))
         . = ALIGN(4);
-        /* All data end */
-        __data_end__ = .;
 
     } > RAM
 
-    .bss :
+    .tdata : AT (__etext + SIZEOF(.data))
+    {
+        *(.tdata .tdata.* .gnu.linkonce.td.*)
+        PROVIDE( __data_end = . );
+        PROVIDE( __data_end__ = . );
+        PROVIDE( __tdata_end = . );
+    } > RAM
+
+    .tbss (NOLOAD) :
     {
         . = ALIGN(4);
         __bss_start__ = .;
+        *(.tbss .tbss.* .gnu.linkonce.tb.*)
+        *(.tcommon)
+        PROVIDE( __tls_end = . );
+        PROVIDE( __tbss_end = . );
+    } > RAM
+
+    .tbss_space (NOLOAD) :
+    {
+        . = ADDR(.tbss);
+        . = . + SIZEOF(.tbss);
+    } > RAM
+
+    .bss :
+    {
+        . = ALIGN(4);
         *(.bss*)
         *(COMMON)
         . = ALIGN(4);
         __bss_end__ = .;
     } > RAM
 
-    bss_size = __bss_end__ - __bss_start__;
+    PROVIDE( __bss_end = __bss_end__ );
+    PROVIDE( __data_start = ADDR(.data) );
+    PROVIDE( __data_source = LOADADDR(.data) );
+    PROVIDE( __data_size = __data_end - __data_start );
+    PROVIDE( __bss_start = ADDR(.tbss) );
+    PROVIDE( __bss_size = __bss_end - __bss_start );
+    PROVIDE( __tls_base = SIZEOF(.tdata) ? ADDR(.tdata) : ADDR(.tbss) );
+    PROVIDE( __tls_align = MAX(ALIGNOF(.tdata), ALIGNOF(.tbss)) );
+    PROVIDE( __arm32_tls_tcb_offset = MAX(8, __tls_align) );
 
     .stack : ALIGN(32)
     {
@@ -164,4 +193,6 @@ SECTIONS
     } > RAM
 
     PROVIDE(__stack = __StackTop);
+    PROVIDE( __heap_start = __HeapBase );
+    PROVIDE( __heap_end = __HeapLimit );
 }

platform/ext/common/gcc/tfm_common_s.ld.template

@@ -192,6 +192,9 @@ SECTIONS
         . = ALIGN(4); /* This alignment is needed to make the section size 4 bytes aligned */
     } > CODE_RAM AT > FLASH
 
+    /* Reset current position for subsequent sections */
+    . = LOADADDR(.ER_CODE_SRAM) + SIZEOF(.ER_CODE_SRAM);
+
     ASSERT(S_RAM_CODE_START % 4 == 0, "S_RAM_CODE_START must be divisible by 4")
 
     Image$$ER_CODE_SRAM$$RO$$Base = ADDR(.ER_CODE_SRAM);
@@ -573,13 +576,35 @@ SECTIONS
         . = ALIGN(4);
 
     } > RAM AT> FLASH
+
+    .TFM_TDATA : ALIGN_WITH_INPUT
+    {
+        *(.tdata .tdata.* .gnu.linkonce.td.*)
+        PROVIDE( __data_end = . );
+        PROVIDE( __tdata_end = . );
+    } > RAM AT> FLASH
+
     Image$$ER_TFM_DATA$$RW$$Base = ADDR(.TFM_DATA);
-    Image$$ER_TFM_DATA$$RW$$Limit = ADDR(.TFM_DATA) + SIZEOF(.TFM_DATA);
+    Image$$ER_TFM_DATA$$RW$$Limit = ADDR(.TFM_TDATA) + SIZEOF(.TFM_TDATA);
 
-    .TFM_BSS ALIGN(4) (NOLOAD) :
+    .TFM_TBSS (NOLOAD) :
     {
         __bss_start__ = .;
 
+        *(.tbss .tbss.* .gnu.linkonce.tb.*)
+        *(.tcommon)
+        PROVIDE( __tls_end = . );
+        PROVIDE( __tbss_end = . );
+    } > RAM AT> RAM
+
+    .TFM_TBSS_SPACE (NOLOAD) :
+    {
+        . = ADDR(.TFM_TBSS);
+        . = . + SIZEOF(.TFM_TBSS);
+    } > RAM AT> RAM
+
+    .TFM_BSS ALIGN(4) (NOLOAD) :
+    {
         /* The runtime partition placed order is same as load partition */
         __partition_runtime_start__ = .;
         KEEP(*(.bss.part_runtime_priority_00))
@@ -600,16 +625,26 @@ SECTIONS
         *(COMMON)
         . = ALIGN(4);
         __bss_end__ = .;
+        __bss_end = .;
     } > RAM AT> RAM
-    Image$$ER_TFM_DATA$$ZI$$Base = ADDR(.TFM_BSS);
+    Image$$ER_TFM_DATA$$ZI$$Base = ADDR(.TFM_TBSS);
     Image$$ER_TFM_DATA$$ZI$$Limit = ADDR(.TFM_BSS) + SIZEOF(.TFM_BSS);
     Image$$ER_PART_RT_POOL$$ZI$$Base = __partition_runtime_start__;
     Image$$ER_PART_RT_POOL$$ZI$$Limit = __partition_runtime_end__;
     Image$$ER_SERV_RT_POOL$$ZI$$Base = __service_runtime_start__;
     Image$$ER_SERV_RT_POOL$$ZI$$Limit = __service_runtime_end__;
 
     Image$$ER_TFM_DATA$$Base = ADDR(.TFM_DATA);
-    Image$$ER_TFM_DATA$$Limit = ADDR(.TFM_DATA) + SIZEOF(.TFM_DATA) + SIZEOF(.TFM_BSS);
+    Image$$ER_TFM_DATA$$Limit = ADDR(.TFM_BSS) + SIZEOF(.TFM_BSS);
+
+    PROVIDE( __data_start = ADDR(.TFM_DATA) );
+    PROVIDE( __data_source = LOADADDR(.TFM_DATA) );
+    PROVIDE( __data_size = __data_end - __data_start );
+    PROVIDE( __bss_start = ADDR(.TFM_TBSS) );
+    PROVIDE( __bss_size = __bss_end - __bss_start );
+    PROVIDE( __tls_base = SIZEOF(.TFM_TDATA) ? ADDR(.TFM_TDATA) : ADDR(.TFM_TBSS) );
+    PROVIDE( __tls_align = MAX(ALIGNOF(.TFM_TDATA), ALIGNOF(.TFM_TBSS)) );
+    PROVIDE(__arm32_tls_tcb_offset = MAX(8, __tls_align) );
 
 #if defined(CONFIG_TFM_USE_TRUSTZONE)
     Image$$ER_VENEER$$Base = ADDR(.gnu.sgstubs);

platform/ext/common/gcc/tfm_isolation_s.ld.template

@@ -210,20 +210,22 @@ SECTIONS
         . = ALIGN(4);
         /* preinit data */
         PROVIDE_HIDDEN (__preinit_array_start = .);
+        PROVIDE_HIDDEN (__bothinit_array_start = .);
         KEEP(*(.preinit_array))
         PROVIDE_HIDDEN (__preinit_array_end = .);
 
         . = ALIGN(4);
         /* init data */
         PROVIDE_HIDDEN (__init_array_start = .);
-        KEEP(*(SORT(.init_array.*)))
+        KEEP(*(SORT_BY_INIT_PRIORITY(.init_array.*)))
         KEEP(*(.init_array))
         PROVIDE_HIDDEN (__init_array_end = .);
+        PROVIDE_HIDDEN (__bothinit_array_end = .);
 
         . = ALIGN(4);
         /* finit data */
         PROVIDE_HIDDEN (__fini_array_start = .);
-        KEEP(*(SORT(.fini_array.*)))
+        KEEP(*(SORT_BY_INIT_PRIORITY(.fini_array.*)))
         KEEP(*(.fini_array))
         PROVIDE_HIDDEN (__fini_array_end = .);
 
@@ -251,6 +253,10 @@ SECTIONS
         LONG (ADDR(.ER_CODE_SRAM))
         LONG (SIZEOF(.ER_CODE_SRAM) / 4)
 #endif
+        LONG (LOADADDR(.TFM_TDATA))
+        LONG (ADDR(.TFM_TLS_BASE))
+        LONG (SIZEOF(.TFM_TDATA) / 4)
+
         __copy_table_end__ = .;
 
         /* .zero.table */
@@ -265,6 +271,10 @@ SECTIONS
         LONG (ADDR(.TFM_SP_META_PTR))
         LONG (SIZEOF(.TFM_SP_META_PTR) / 4)
 #endif
+
+        LONG (ADDR(.TFM_TLS_BASE) + SIZEOF(.TFM_TDATA))
+        LONG ((SIZEOF(.TFM_TLS_BASE) - SIZEOF(.TFM_TDATA)) / 4)
+
         __zero_table_end__ = .;
 
         /* Capture all remaining code (except RAM code) in the privileged TF-M
@@ -327,6 +337,9 @@ SECTIONS
         . = ALIGN(4); /* This alignment is needed to make the section size 4 bytes aligned */
     } > CODE_RAM AT > FLASH
 
+    /* Reset current position for subsequent sections */
+    . = LOADADDR(.ER_CODE_SRAM) + SIZEOF(.ER_CODE_SRAM);
+
     ASSERT(S_RAM_CODE_START % 4 == 0, "S_RAM_CODE_START must be divisible by 4")
 
     Image$$ER_CODE_SRAM$$RO$$Base = ADDR(.ER_CODE_SRAM);
@@ -549,6 +562,10 @@ SECTIONS
         . = ALIGN(4);
     } > RAM AT > FLASH
 
+    PROVIDE(__data_source = LOADADDR(.TFM_DATA));
+    PROVIDE(__data_start = ADDR(.TFM_DATA));
+    PROVIDE(__data_size = SIZEOF(.TFM_DATA));
+
     .TFM_BSS ALIGN(4) (NOLOAD) :
     {
         __bss_start__ = .;
@@ -574,6 +591,31 @@ SECTIONS
         . = ALIGN(4);
         __bss_end__ = .;
     } > RAM
+
+    PROVIDE(__bss_start = ADDR(.TFM_BSS));
+    PROVIDE(__bss_size = SIZEOF(.TFM_BSS));
+
+    .TFM_TDATA :
+    {
+	PROVIDE( __tls_start_addr = . );
+        *(.tdata .tdata.* .gnu.linkonce.td.*)
+    } > RAM
+
+    .TFM_TBSS :
+    {
+        *(.tbss .tbss.* .gnu.linkonce.tb.*)
+        *(.tcommon)
+	PROVIDE( __tls_end_addr = . );
+    } > RAM
+
+    .TFM_TLS_BASE : {
+	. = . + (__tls_end_addr - __tls_start_addr);
+    } > RAM
+    PROVIDE( __tls_base = ADDR(.TFM_TLS_BASE) );
+    PROVIDE( __tls_align = MAX(ALIGNOF(.TFM_TDATA), ALIGNOF(.TFM_TBSS)) );
+    PROVIDE( __arm32_tls_tcb_offset = MAX(8, __tls_align) );
+    PROVIDE( __arm64_tls_tcb_offset = MAX(16, __tls_align) );
+
     Image$$ER_PART_RT_POOL$$ZI$$Base = __partition_runtime_start__;
     Image$$ER_PART_RT_POOL$$ZI$$Limit = __partition_runtime_end__;
     Image$$ER_SERV_RT_POOL$$ZI$$Base = __service_runtime_start__;

platform/ext/common/llvm/tfm_isolation_s.ld.template

@@ -303,6 +303,9 @@ SECTIONS
         . = ALIGN(4); /* This alignment is needed to make the section size 4 bytes aligned */
     } > CODE_RAM AT > FLASH
 
+    /* Reset current position for subsequent sections */
+    . = LOADADDR(.ER_CODE_SRAM) + SIZEOF(.ER_CODE_SRAM);
+
     ASSERT(S_RAM_CODE_START % 4 == 0, "S_RAM_CODE_START must be divisible by 4")
 
     Image$$ER_CODE_SRAM$$RO$$Base = ADDR(.ER_CODE_SRAM);

platform/ext/common/picolibc.c

@@ -0,0 +1,48 @@
+/*
+ * Copyright © 2025, Keith Packard <[email protected]>
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
+ */
+
+#include <stdint.h>
+#include <string.h>
+#include "config_impl.h"
+
+/*
+ * Picolibc's startup code only initializes a single data and bss
+ * segment.  Augment that by initializing the remaining segments using
+ * the lists provided by the linker script in a constructor which will
+ * be called from _start
+ */
+
+#if defined(__PICOLIBC__) && TFM_ISOLATION_LEVEL > 0
+
+static void __attribute__((constructor))
+picolibc_startup(void)
+{
+  typedef struct __copy_table {
+    uint32_t const* src;
+    uint32_t* dest;
+    uint32_t  wlen;
+  } __copy_table_t;
+
+  typedef struct __zero_table {
+    uint32_t* dest;
+    uint32_t  wlen;
+  } __zero_table_t;
+
+  extern const __copy_table_t __copy_table_start__;
+  extern const __copy_table_t __copy_table_end__;
+  extern const __zero_table_t __zero_table_start__;
+  extern const __zero_table_t __zero_table_end__;
+
+  for (__copy_table_t const* pTable = &__copy_table_start__; pTable < &__copy_table_end__; ++pTable) {
+    memcpy(pTable->dest, pTable->src, pTable->wlen << 2);
+  }
+
+  for (__zero_table_t const* pTable = &__zero_table_start__; pTable < &__zero_table_end__; ++pTable) {
+    memset(pTable->dest, 0, pTable->wlen << 2);
+  }
+}
+#endif

platform/ext/common/syscalls_stub.c

@@ -14,6 +14,14 @@
 #include <stddef.h>
 #include <stdint.h>
 
+#ifdef __PICOLIBC__
+__attribute__((weak))
+void _exit(int status)
+{
+    (void) status;
+    for(;;);
+}
+#else
 __attribute__((weak))
 void _close(void)
 {
@@ -53,3 +61,5 @@ __attribute__((weak))
 void _write(void)
 {
 }
+
+#endif /* !__PICOLIBC__ */

platform/ext/common/uart_stdout.c

@@ -85,7 +85,7 @@ int fputc(int ch, FILE *f)
 /* Redirect sdtio for PicoLib in LLVM toolchain
    as per https://github.com/picolibc/picolibc/blob/main/doc/os.md
    'fputch()' named intentionally different from 'fputc()' from picolib */
-#elif defined(__clang_major__)
+#elif defined(__PICOLIBC__)
 
 int fputch(char ch, struct __file *f)
 {