[libc][picolibc] add tls support

Author: iDings

bsp/qemu-vexpress-a9/link.lds

@@ -85,6 +85,35 @@ SECTIONS
     }
     __data_end = .;
 
+    . = ALIGN(8);
+    .tdata :
+    {
+         __tdata_start = .;
+        *(.tdata .tdata.* .gnu.linkonce.td.*)
+        __tdata_end = .;
+    }
+    __tdata_source = LOADADDR(.tdata);
+    __tdata_size = SIZEOF(.tdata);
+
+    /*
+     * TLS zeroed data is relocated as if it immediately followed
+     * the tdata values. However, the linker 'magically' erases the
+     * memory allocation so that no ROM is consumed by this
+     * section
+     */
+    .tbss :
+    {
+        *(.tbss .tbss.* .gnu.linkonce.tb.*)
+        *(.tcommon)
+        __tbss_end = .;
+    }
+    __tls_size = __tbss_end - __tdata_start;
+    __tbss_size = __tls_size - __tdata_size;
+    PROVIDE( __tbss_offset = ADDR(.tbss) - ADDR(.tdata) );
+    PROVIDE( __tls_align = MAX(ALIGNOF(.tdata), ALIGNOF(.tbss)) );
+    PROVIDE( __arm32_tls_tcb_offset = MAX(8, __tls_align) );
+    PROVIDE( __arm64_tls_tcb_offset = MAX(16, __tls_align) );
+
     . = ALIGN(4);
     __bss_start = .;
     .bss       :

bsp/qemu-vexpress-a9/rtconfig.py

@@ -49,7 +49,9 @@ def get_mac_address():
     STRIP   = PREFIX + 'strip'
     CFPFLAGS = ' -msoft-float'
     AFPFLAGS = ' -mfloat-abi=softfp -mfpu=neon'
-    DEVICE   = ' -march=armv7-a -mtune=cortex-a7 -ftree-vectorize -ffast-math -funwind-tables -fno-strict-aliasing'
+    DEVICE = ''
+    #DEVICE += ' --specs=picolibc.specs --picolibc-prefix=' + EXEC_PATH + '/../'
+    DEVICE += ' -march=armv7-a -mtune=cortex-a7 -ftree-vectorize -ffast-math -funwind-tables -fno-strict-aliasing'
 
     CXXFLAGS= DEVICE + CFPFLAGS + ' -Wall -fdiagnostics-color=always'
     CFLAGS  = DEVICE + CFPFLAGS + ' -Wall -Wno-cpp -std=gnu99 -D_POSIX_SOURCE -fdiagnostics-color=always'

examples/libc/SConscript

@@ -1,6 +1,9 @@
 from building import *
 
 src   = Glob('*.c')
-group = DefineGroup('UTest', src, depend = ['RT_USING_NEWLIBC', 'RT_USING_PTHREADS'])
+if GetDepend(['RT_USING_PICOLIBC']):
+    group = DefineGroup('UTest', src, depend = ['RT_USING_PTHREADS'])
+else:
+    group = DefineGroup('UTest', src, depend = ['RT_USING_NEWLIBC', 'RT_USING_PTHREADS'])
 
 Return('group')

examples/libc/tls.c

@@ -0,0 +1,45 @@
+/*
+ * Copyright (c) 2006-2021, RT-Thread Development Team
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ * 2023-12-19     iDings      first version
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <finsh.h>
+#include <rtthread.h>
+
+static __thread int i;
+
+static void child_routine(void *param)
+{
+    printf("child_thread: i:%d\n", i);
+    i = 300;
+    printf("child_thread: i:%d\n", i);
+}
+
+static int tls_test(void)
+{
+    rt_thread_t child;
+
+    char name[RT_NAME_MAX];
+    rt_thread_get_name(rt_thread_self(), name, sizeof(name));
+
+    printf("i:%d\n", i);
+    i = 200;
+    printf("main_thread: i:%d\n", i);
+
+    child = rt_thread_create("tls_thread", child_routine, NULL, 4096, 10, 20);
+    rt_thread_startup(child);
+
+    sleep(1);
+    printf("main_thread: i:%d\n", i);
+
+    return 0;
+}
+MSH_CMD_EXPORT(tls_test, thread local storage example);

include/rtdef.h

@@ -71,6 +71,13 @@
 #endif /* defined(RT_USING_SIGNALS) || defined(RT_USING_SMART) */
 #endif /* RT_USING_NANO */
 
+#ifdef RT_USING_PICOLIBC
+#include <picolibc.h>
+#ifdef PICOLIBC_TLS
+#include <picotls.h>
+#endif
+#endif
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -998,6 +1005,10 @@ struct rt_thread
 #endif
 #endif
 
+#ifdef PICOLIBC_TLS
+    void *tls;
+#endif
+
     rt_atomic_t                 ref_count;
     struct rt_spinlock          spinlock;
     rt_ubase_t                  user_data;              /**< private user data beyond this thread */

src/scheduler_mp.c

@@ -546,6 +546,9 @@ void rt_schedule(void)
                 _rt_schedule_remove_thread(to_thread, RT_FALSE);
                 to_thread->stat = RT_THREAD_RUNNING | (to_thread->stat & ~RT_THREAD_STAT_MASK);
 
+#ifdef PICOLIBC_TLS
+                _set_tls(to_thread->tls);
+#endif
                 /* switch to new thread */
                 LOG_D("[%d]switch to priority#%d "
                          "thread:%.*s(sp:0x%08x), "
@@ -700,6 +703,9 @@ void rt_scheduler_do_irq_switch(void *context)
                 _rt_schedule_remove_thread(to_thread, RT_FALSE);
                 to_thread->stat = RT_THREAD_RUNNING | (to_thread->stat & ~RT_THREAD_STAT_MASK);
 
+#ifdef PICOLIBC_TLS
+                _set_tls(to_thread->tls);
+#endif
 #ifdef RT_USING_OVERFLOW_CHECK
                 _scheduler_stack_check(to_thread);
 #endif /* RT_USING_OVERFLOW_CHECK */

src/scheduler_up.c

@@ -295,6 +295,9 @@ void rt_schedule(void)
                 rt_schedule_remove_thread(to_thread);
                 to_thread->stat = RT_THREAD_RUNNING | (to_thread->stat & ~RT_THREAD_STAT_MASK);
 
+#ifdef PICOLIBC_TLS
+                _set_tls(to_thread->tls);
+#endif
                 /* switch to new thread */
                 LOG_D("[%d]switch to priority#%d "
                          "thread:%.*s(sp:0x%08x), "

src/thread.c

@@ -184,6 +184,15 @@ static rt_err_t _thread_init(struct rt_thread *thread,
     thread->entry = (void *)entry;
     thread->parameter = parameter;
 
+#ifdef PICOLIBC_TLS
+#define TLS_ALIGN       (_tls_align() > 8 ? _tls_align() : 8)
+    char *tls = (char *)stack_start + stack_size - _tls_size();
+    thread->tls = (void *)RT_ALIGN_DOWN((rt_ubase_t)tls, TLS_ALIGN);
+    stack_size = (char *)thread->tls - (char *)stack_start;
+
+    _init_tls(thread->tls);
+#endif
+
     /* stack init */
     thread->stack_addr = stack_start;
     thread->stack_size = stack_size;