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arch: riscv: implement ARCH_HAS_CUSTOM_CURRENT_IMPL with GP

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Implement `arch_curr_thread()` & `arch_set_curr_thread()`
with the global pointer (GP) register.

Signed-off-by: Yong Cong Sin <ycsin@meta.com>
Signed-off-by: Yong Cong Sin <yongcong.sin@gmail.com>
This commit is contained in:
Yong Cong Sin 2024-11-01 12:12:41 +08:00 • committed by Anas Nashif
commit 1a752e8a35
3 changed files with 25 additions and 0 deletions
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10
arch/riscv/Kconfig
View file

@ -28,6 +28,16 @@ config RISCV_GP
global pointer at program start or earlier than any instruction
using GP relative addressing.
config RISCV_CURRENT_VIA_GP
bool "Store current thread into the global pointer (GP) register"
depends on !RISCV_GP && !USERSPACE
depends on MP_MAX_NUM_CPUS > 1
select ARCH_HAS_CUSTOM_CURRENT_IMPL
help
Store the current thread's pointer into the global pointer (GP) register.
When is enabled, calls to `_current` & `k_sched_current_thread_query()` will
be reduced to a single register read.
config RISCV_ALWAYS_SWITCH_THROUGH_ECALL
bool "Do not use mret outside a trap handler context"
depends on MULTITHREADING

3
doc/releases/release-notes-4.1.rst
View file

@ -52,6 +52,9 @@ Architectures
* RISC-V
* Implements :c:func:`arch_current_thread_set` & :c:func:`arch_current_thread`, which can be enabled
by :kconfig:option:`CONFIG_RISCV_CURRENT_VIA_GP` (:github:`80716`).
* Xtensa
* native/POSIX

12
include/zephyr/arch/riscv/arch_inlines.h
View file

@ -11,6 +11,7 @@
#include <zephyr/kernel_structs.h>
#include "csr.h"
#include "reg.h"
static ALWAYS_INLINE uint32_t arch_proc_id(void)
{
@ -26,6 +27,17 @@ static ALWAYS_INLINE _cpu_t *arch_curr_cpu(void)
#endif
}
#ifdef CONFIG_RISCV_CURRENT_VIA_GP
register struct k_thread *__arch_current_thread __asm__("gp");
#define arch_current_thread() __arch_current_thread
#define arch_current_thread_set(thread) \
{ \
_current_cpu->current = thread; \
__arch_current_thread = (thread); \
}
#endif /* CONFIG_RISCV_CURRENT_VIA_GP */
static ALWAYS_INLINE unsigned int arch_num_cpus(void)
{
return CONFIG_MP_MAX_NUM_CPUS;