michaelh/zephyr
1
0
Fork 0
Code Releases Activity

arm64: optimize offsets in z_arm64_context_switch

Browse source 
We can use build-time offsets from a struct k_thread pointer directly
to struct _callee_saved members. No need to compute that at run time.

Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
This commit is contained in:
Nicolas Pitre 2021-05-03 13:58:57 -04:00 • committed by Anas Nashif
commit 76494f8589
2 changed files with 32 additions and 26 deletions
Download patch file Download diff file Expand all files Collapse all files

43
arch/arm64/core/switch.S
View file

@ -30,24 +30,19 @@ _ASM_FILE_PROLOGUE
GTEXT(z_arm64_context_switch) GTEXT(z_arm64_context_switch)
SECTION_FUNC(TEXT, z_arm64_context_switch) SECTION_FUNC(TEXT, z_arm64_context_switch)
ldr x3, =_thread_offset_to_callee_saved
/* addr of callee-saved regs in thread in x2 */
add x2, x1, x3
/* Save the current SP_EL0 */ /* Save the current SP_EL0 */
mrs x4, sp_el0 mrs x4, sp_el0
stp x19, x20, [x2, ___callee_saved_t_x19_x20_OFFSET] stp x19, x20, [x1, #_thread_offset_to_callee_saved_x19_x20]
stp x21, x22, [x2, ___callee_saved_t_x21_x22_OFFSET] stp x21, x22, [x1, #_thread_offset_to_callee_saved_x21_x22]
stp x23, x24, [x2, ___callee_saved_t_x23_x24_OFFSET] stp x23, x24, [x1, #_thread_offset_to_callee_saved_x23_x24]
stp x25, x26, [x2, ___callee_saved_t_x25_x26_OFFSET] stp x25, x26, [x1, #_thread_offset_to_callee_saved_x25_x26]
stp x27, x28, [x2, ___callee_saved_t_x27_x28_OFFSET] stp x27, x28, [x1, #_thread_offset_to_callee_saved_x27_x28]
stp x29, x4, [x2, ___callee_saved_t_x29_sp_el0_OFFSET] stp x29, x4, [x1, #_thread_offset_to_callee_saved_x29_sp_el0]
/* Save the current SP_ELx */ /* Save the current SP_ELx */
mov x4, sp mov x4, sp
str x4, [x2, ___callee_saved_t_sp_elx_OFFSET] str x4, [x1, #_thread_offset_to_callee_saved_sp_elx]
/* save current thread's exception depth */ /* save current thread's exception depth */
mrs x4, tpidrro_el0 mrs x4, tpidrro_el0
@ -69,8 +64,7 @@ SECTION_FUNC(TEXT, z_arm64_context_switch)
#ifdef CONFIG_THREAD_LOCAL_STORAGE #ifdef CONFIG_THREAD_LOCAL_STORAGE
/* Grab the TLS pointer */ /* Grab the TLS pointer */
ldr x2, =_thread_offset_to_tls ldr x2, [x0, #_thread_offset_to_tls]
ldr x2, [x0, x2]
/* Store in the "Thread ID" register. /* Store in the "Thread ID" register.
* This register is used as a base pointer to all * This register is used as a base pointer to all
@ -79,22 +73,19 @@ SECTION_FUNC(TEXT, z_arm64_context_switch)
msr tpidr_el0, x2 msr tpidr_el0, x2
#endif #endif
/* addr of callee-saved regs in thread in x2 */ ldp x19, x20, [x0, #_thread_offset_to_callee_saved_x19_x20]
add x2, x0, x3 ldp x21, x22, [x0, #_thread_offset_to_callee_saved_x21_x22]
ldp x23, x24, [x0, #_thread_offset_to_callee_saved_x23_x24]
ldp x19, x20, [x2, ___callee_saved_t_x19_x20_OFFSET] ldp x25, x26, [x0, #_thread_offset_to_callee_saved_x25_x26]
ldp x21, x22, [x2, ___callee_saved_t_x21_x22_OFFSET] ldp x27, x28, [x0, #_thread_offset_to_callee_saved_x27_x28]
ldp x23, x24, [x2, ___callee_saved_t_x23_x24_OFFSET] ldp x29, x4, [x0, #_thread_offset_to_callee_saved_x29_sp_el0]
ldp x25, x26, [x2, ___callee_saved_t_x25_x26_OFFSET]
ldp x27, x28, [x2, ___callee_saved_t_x27_x28_OFFSET]
ldp x29, x1, [x2, ___callee_saved_t_x29_sp_el0_OFFSET]
/* Restore SP_EL0 */ /* Restore SP_EL0 */
msr sp_el0, x1 msr sp_el0, x4
/* Restore SP_EL1 */ /* Restore SP_EL1 */
ldr x1, [x2, ___callee_saved_t_sp_elx_OFFSET] ldr x4, [x0, #_thread_offset_to_callee_saved_sp_elx]
mov sp, x1 mov sp, x4
#ifdef CONFIG_USERSPACE #ifdef CONFIG_USERSPACE
stp xzr, x30, [sp, #-16]! stp xzr, x30, [sp, #-16]!

15
arch/arm64/include/offsets_short_arch.h
View file

@ -12,4 +12,19 @@
#define _thread_offset_to_exception_depth \ #define _thread_offset_to_exception_depth \
(___thread_t_arch_OFFSET + ___thread_arch_t_exception_depth_OFFSET) (___thread_t_arch_OFFSET + ___thread_arch_t_exception_depth_OFFSET)
#define _thread_offset_to_callee_saved_x19_x20 \
(___thread_t_callee_saved_OFFSET + ___callee_saved_t_x19_x20_OFFSET)
#define _thread_offset_to_callee_saved_x21_x22 \
(___thread_t_callee_saved_OFFSET + ___callee_saved_t_x21_x22_OFFSET)
#define _thread_offset_to_callee_saved_x23_x24 \
(___thread_t_callee_saved_OFFSET + ___callee_saved_t_x23_x24_OFFSET)
#define _thread_offset_to_callee_saved_x25_x26 \
(___thread_t_callee_saved_OFFSET + ___callee_saved_t_x25_x26_OFFSET)
#define _thread_offset_to_callee_saved_x27_x28 \
(___thread_t_callee_saved_OFFSET + ___callee_saved_t_x27_x28_OFFSET)
#define _thread_offset_to_callee_saved_x29_sp_el0 \
(___thread_t_callee_saved_OFFSET + ___callee_saved_t_x29_sp_el0_OFFSET)
#define _thread_offset_to_callee_saved_sp_elx \
(___thread_t_callee_saved_OFFSET + ___callee_saved_t_sp_elx_OFFSET)
#endif /* ZEPHYR_ARCH_ARM64_INCLUDE_OFFSETS_SHORT_ARCH_H_ */ #endif /* ZEPHYR_ARCH_ARM64_INCLUDE_OFFSETS_SHORT_ARCH_H_ */