Kernel/ARM: faster context save

diff --git a/kernel/arch/earm/mpx.S b/kernel/arch/earm/mpx.S
index cbc211457c52219509f670562234960d86362355..bf8b2ed160e9c26dc4710d16eb317699b3cf7962 100644 (file)
--- a/kernel/arch/earm/mpx.S
+++ b/kernel/arch/earm/mpx.S
@@ -61,15 +61,13 @@ IMPORT(svc_stack)
 
 /* Save the register context to the proc structure */
 .macro save_process_ctx
-       push    {lr}
-       ldr     lr, [sp, #12] /* proc ptr */
-       stm     lr, {r0-r14}^
-       ldr     r12, [sp, #8]
-       str     r12, [lr, #PSREG]
-       ldr     r12, [sp, #4]
-       str     r12, [lr, #PCREG]
-       pop     {lr}
-       add     sp, sp, #8
+       add     sp, sp, #8      /* srsdb pushed cpsr and pc on the stack */
+       ldr     lr, [sp]        /* lr = proc_ptr */
+       stm     lr, {r0-r14}^   /* proc_ptr->p_reg.r0-r14 = r0-r14 */
+       ldr     r12, [sp, #-8]  /* r12 = pc stored on the stack */
+       str     r12, [lr, #PCREG] /* proc_ptr->p_reg.pc = r12 */
+       ldr     r12, [sp, #-4]  /* r12 = cpsr stored on the stack */
+       str     r12, [lr, #PSREG] /* proc_ptr->p_reg.psr = r12 */
 .endm
 
 .macro exception_handler exc_name, exc_num, lr_offset