sparc: add support for thread local storage

Adds the necessary bits to initialize TLS in the stack
area and sets up CPU registers during context switch. Register g7 is
used to point to the thread data. Thread data is accessed with negative
offsets from g7.

Signed-off-by: Martin Åberg <martin.aberg@gaisler.com>

arch/Kconfig

@@ -45,6 +45,7 @@ config SPARC
 	select BIG_ENDIAN
 	select ATOMIC_OPERATIONS_BUILTIN if SPARC_CASA
 	select ATOMIC_OPERATIONS_C if !SPARC_CASA
+	select ARCH_HAS_THREAD_LOCAL_STORAGE
 	help
 	  SPARC architecture
 

arch/sparc/core/CMakeLists.txt

@@ -17,3 +17,4 @@ zephyr_library_sources(
 )
 
 zephyr_library_sources_ifdef(CONFIG_IRQ_OFFLOAD irq_offload.c)
+zephyr_library_sources_ifdef(CONFIG_THREAD_LOCAL_STORAGE tls.c)

arch/sparc/core/switch.S

@@ -118,6 +118,9 @@ SECTION_FUNC(TEXT, z_sparc_context_switch)
 
 	/* restore output registers */
 	ldd	[%o0 + _thread_offset_to_o6], %o6
+#ifdef CONFIG_THREAD_LOCAL_STORAGE
+	ld	[%o0 + _thread_offset_to_tls], %g7
+#endif
 
 	ld	[%o0 + _thread_offset_to_psr], %g1  /* %g1 = new thread psr */
 

arch/sparc/core/tls.c

@@ -0,0 +1,22 @@
+/*
+ * Copyright (c) 2019-2020 Cobham Gaisler AB
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <kernel.h>
+#include <kernel_structs.h>
+#include <kernel_internal.h>
+#include <kernel_tls.h>
+#include <app_memory/app_memdomain.h>
+#include <sys/util.h>
+
+size_t arch_tls_stack_setup(struct k_thread *new_thread, char *stack_ptr)
+{
+	new_thread->tls = POINTER_TO_UINT(stack_ptr);
+
+	stack_ptr -= z_tls_data_size();
+	z_tls_copy(stack_ptr);
+
+	return z_tls_data_size();
+}

include/arch/sparc/linker.ld

@@ -42,6 +42,7 @@ SECTIONS
     _image_text_end = .;
 
 #include <linker/common-rom.ld>
+#include <linker/thread-local-storage.ld>
 
     SECTION_PROLOGUE(_RODATA_SECTION_NAME,,)
 	{