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arch: kernel: lib: toolchain: Standardize TLS keyword

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Up until now, the `__thread` keyword has been used for declaring
variables as Thread local storage. However, `__thread` is a GNU
specific keyword which thus limits compatibility with other
toolchains (for instance IAR).

This PR intoduces a new macro `Z_THREAD_LOCAL` which expands to the
corresponding C11, C23 or C++11 standard keyword based on the standard
that is specified during compilation, else it uses the old `__thread`
keyword.

Signed-off-by: Daniel Flodin <daniel.flodin@iar.com>
This commit is contained in:
Daniel Flodin 2024-09-18 14:07:42 +02:00 • committed by Carles Cufí
commit 746c59c82a
11 changed files with 37 additions and 19 deletions
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2
arch/riscv/core/thread.c
View file

@ -15,7 +15,7 @@
/*
* Per-thread (TLS) variable indicating whether execution is in user mode.
*/
__thread uint8_t is_user_mode;
Z_THREAD_LOCAL uint8_t is_user_mode;
#endif
void arch_new_thread(struct k_thread *thread, k_thread_stack_t *stack,

2
arch/xtensa/core/thread.c
View file

@ -22,7 +22,7 @@ LOG_MODULE_DECLARE(os, CONFIG_KERNEL_LOG_LEVEL);
/*
* Per-thread (TLS) variable indicating whether execution is in user mode.
*/
__thread uint32_t is_user_mode;
Z_THREAD_LOCAL uint32_t is_user_mode;
#endif
#endif /* CONFIG_USERSPACE */

8
doc/kernel/services/other/thread_local_storage.rst
View file

@ -29,25 +29,25 @@ making a system call.
Declaring and Using Thread Local Variables
******************************************
The keyword ``__thread`` can be used to declare thread local variables.
The macro ``Z_THREAD_LOCAL`` can be used to declare thread local variables.
For example, to declare a thread local variable in header files:
.. code-block:: c
extern __thread int i;
extern Z_THREAD_LOCAL int i;
And to declare the actual variable in source files:
.. code-block:: c
__thread int i;
Z_THREAD_LOCAL int i;
Keyword ``static`` can also be used to limit the variable within a source file:
.. code-block:: c
static __thread int j;
static Z_THREAD_LOCAL int j;
Using the thread local variable is the same as using other variable, for example:

18
include/zephyr/toolchain/common.h
View file

@ -39,6 +39,24 @@
#endif
#endif
/*
* Thread local variables are declared with different keywords depending on
* which C/C++ standard that is used. C++11 and C23 uses "thread_local" whilst
* C11 uses "_Thread_local". Previously the GNU "__thread" keyword was used
* which is the same in both gcc and g++.
*/
#ifndef Z_THREAD_LOCAL
#if defined(__cplusplus) && (__cplusplus) >= 201103L /* C++11 */
#define Z_THREAD_LOCAL thread_local
#elif defined(__STDC_VERSION__) && (__STDC_VERSION__) >= 202311L /* C23 */
#define Z_THREAD_LOCAL thread_local
#elif defined(__STDC_VERSION__) && (__STDC_VERSION__) >= 201112L /* C11 */
#define Z_THREAD_LOCAL _Thread_local
#else /* Default back to old behavior which used the GNU keyword. */
#define Z_THREAD_LOCAL __thread
#endif
#endif /* Z_THREAD_LOCAL */
/*
* Generate a reference to an external symbol.
* The reference indicates to the linker that the symbol is required

2
kernel/compiler_stack_protect.c
View file

@ -47,7 +47,7 @@ void _StackCheckHandler(void)
* The canary value gets initialized in z_cstart().
*/
#ifdef CONFIG_STACK_CANARIES_TLS
__thread volatile uintptr_t __stack_chk_guard;
Z_THREAD_LOCAL volatile uintptr_t __stack_chk_guard;
#elif CONFIG_USERSPACE
K_APP_DMEM(z_libc_partition) volatile uintptr_t __stack_chk_guard;
#else

2
kernel/errno.c
View file

@ -27,7 +27,7 @@ const int _k_neg_eagain = -EAGAIN;
#if defined(CONFIG_LIBC_ERRNO)
/* nothing needed here */
#elif defined(CONFIG_ERRNO_IN_TLS)
__thread int z_errno_var;
Z_THREAD_LOCAL int z_errno_var;
#else
#ifdef CONFIG_USERSPACE

2
kernel/init.c
View file

@ -291,7 +291,7 @@ void z_bss_zero_pinned(void)
#ifdef CONFIG_STACK_CANARIES
#ifdef CONFIG_STACK_CANARIES_TLS
extern __thread volatile uintptr_t __stack_chk_guard;
extern Z_THREAD_LOCAL volatile uintptr_t __stack_chk_guard;
#else
extern volatile uintptr_t __stack_chk_guard;
#endif /* CONFIG_STACK_CANARIES_TLS */

2
kernel/xip.c
View file

@ -12,7 +12,7 @@
#ifdef CONFIG_STACK_CANARIES
#ifdef CONFIG_STACK_CANARIES_TLS
extern __thread volatile uintptr_t __stack_chk_guard;
extern Z_THREAD_LOCAL volatile uintptr_t __stack_chk_guard;
#else
extern volatile uintptr_t __stack_chk_guard;
#endif /* CONFIG_STACK_CANARIES_TLS */

4
lib/os/thread_entry.c
View file

@ -15,11 +15,11 @@
#ifdef CONFIG_CURRENT_THREAD_USE_TLS
#include <zephyr/random/random.h>
__thread k_tid_t z_tls_current;
Z_THREAD_LOCAL k_tid_t z_tls_current;
#endif
#ifdef CONFIG_STACK_CANARIES_TLS
extern __thread volatile uintptr_t __stack_chk_guard;
extern Z_THREAD_LOCAL volatile uintptr_t __stack_chk_guard;
#endif /* CONFIG_STACK_CANARIES_TLS */
/*

2
tests/kernel/mem_protect/stackprot/src/main.c
View file

@ -143,7 +143,7 @@ ZTEST(stackprot, test_create_alt_thread)
}
#ifdef CONFIG_STACK_CANARIES_TLS
extern __thread volatile uintptr_t __stack_chk_guard;
extern Z_THREAD_LOCAL volatile uintptr_t __stack_chk_guard;
#else
extern volatile uintptr_t __stack_chk_guard;
#endif

12
tests/kernel/threads/tls/src/main.c
View file

@ -51,14 +51,14 @@ K_APP_BMEM(part_common) static k_tid_t tls_tid[NUM_THREADS];
K_APP_BMEM(part_common) static enum test_result tls_result[NUM_THREADS];
/* Thread data with initialized values */
static uint8_t __thread thread_data8 = STATIC_DATA8;
static uint32_t __thread thread_data32 = STATIC_DATA32;
static uint64_t __thread thread_data64 = STATIC_DATA64;
static uint8_t Z_THREAD_LOCAL thread_data8 = STATIC_DATA8;
static uint32_t Z_THREAD_LOCAL thread_data32 = STATIC_DATA32;
static uint64_t Z_THREAD_LOCAL thread_data64 = STATIC_DATA64;
/* Zeroed thread data */
static uint8_t __thread thread_bss8;
static uint32_t __thread thread_bss32;
static uint64_t __thread thread_bss64;
static uint8_t Z_THREAD_LOCAL thread_bss8;
static uint32_t Z_THREAD_LOCAL thread_bss32;
static uint64_t Z_THREAD_LOCAL thread_bss64;
static void tls_thread_entry(void *p1, void *p2, void *p3)
{