diff options
Diffstat (limited to 'cpukit/score/cpu/i386/cpu_asm.S')
| -rw-r--r-- | cpukit/score/cpu/i386/cpu_asm.S | 76 |
1 files changed, 55 insertions, 21 deletions
diff --git a/cpukit/score/cpu/i386/cpu_asm.S b/cpukit/score/cpu/i386/cpu_asm.S index 6b609ab4ce..23360959f5 100644 --- a/cpukit/score/cpu/i386/cpu_asm.S +++ b/cpukit/score/cpu/i386/cpu_asm.S @@ -51,6 +51,8 @@ SYM (_CPU_Context_switch): movl RUNCONTEXT_ARG(esp),eax /* eax = running threads context */ + GET_SELF_CPU_CONTROL edx /* edx has address for per_CPU information */ + movl PER_CPU_ISR_DISPATCH_DISABLE(edx),ecx pushf /* push eflags */ popl REG_EFLAGS(eax) /* save eflags */ movl esp,REG_ESP(eax) /* save stack pointer */ @@ -58,39 +60,43 @@ SYM (_CPU_Context_switch): movl ebx,REG_EBX(eax) /* save ebx */ movl esi,REG_ESI(eax) /* save source register */ movl edi,REG_EDI(eax) /* save destination register */ + movl ecx, I386_CONTEXT_CONTROL_ISR_DISPATCH_DISABLE(eax) -#ifdef RTEMS_SMP - /* The executing context no longer executes on this processor */ - movb $0, I386_CONTEXT_CONTROL_IS_EXECUTING_OFFSET(eax) -#endif - + movl eax,ecx /* ecx = running threads context */ movl HEIRCONTEXT_ARG(esp),eax /* eax = heir threads context */ #ifdef RTEMS_SMP - /* Wait for heir context to stop execution */ -1: - movb I386_CONTEXT_CONTROL_IS_EXECUTING_OFFSET(eax), bl - testb bl, bl - jne 1b - - /* The heir context executes now on this processor */ - movb $1, I386_CONTEXT_CONTROL_IS_EXECUTING_OFFSET(eax) + /* + * The executing thread no longer executes on this processor. Switch + * the stack to the temporary interrupt stack of this processor. Mark + * the context of the executing thread as not executing. + */ + leal PER_CPU_INTERRUPT_FRAME_AREA + CPU_INTERRUPT_FRAME_SIZE(edx),esp + movb $0, I386_CONTEXT_CONTROL_IS_EXECUTING_OFFSET(ecx) + +.L_check_is_executing: + lock bts $0,I386_CONTEXT_CONTROL_IS_EXECUTING_OFFSET(eax) /* Indicator in carry flag */ + jc .L_get_potential_new_heir #endif -restore: +/* Start restoring context */ +.L_restore: + movl I386_CONTEXT_CONTROL_ISR_DISPATCH_DISABLE(eax),ecx + movl ecx,PER_CPU_ISR_DISPATCH_DISABLE(edx) + movl REG_ESP(eax),esp /* restore stack pointer */ pushl REG_EFLAGS(eax) /* push eflags */ popf /* restore eflags */ - movl REG_ESP(eax),esp /* restore stack pointer */ movl REG_EBP(eax),ebp /* restore base pointer */ movl REG_EBX(eax),ebx /* restore ebx */ movl REG_ESI(eax),esi /* restore source register */ movl REG_EDI(eax),edi /* restore destination register */ - movl REG_GS_0(eax), ecx /* restore gs segment */ + GET_CPU_ID ecx + movl REG_GS_0(eax), edx /* restore gs segment */ + movl edx, _Global_descriptor_table+24(,ecx,8) movl REG_GS_1(eax), edx - movl ecx, _Global_descriptor_table + 24 - movl edx, _Global_descriptor_table + 28 - movl $24, ecx - mov ecx, gs + movl edx, _Global_descriptor_table+28(,ecx,8) + leal 24(,ecx,8), edx + movl edx, gs ret /* @@ -109,7 +115,35 @@ restore: SYM (_CPU_Context_restore): movl NEWCONTEXT_ARG(esp),eax /* eax = running threads context */ - jmp restore + GET_SELF_CPU_CONTROL edx /* edx has address for per_CPU information */ + jmp .L_restore + +#ifdef RTEMS_SMP + +.L_get_potential_new_heir: + + /* We may have a new heir */ + + /* Read the executing and heir */ + movl PER_CPU_OFFSET_EXECUTING(edx),ebx + movl PER_CPU_OFFSET_HEIR(edx),esi + + /* + * Update the executing only if necessary to avoid cache line + * monopolization. + */ + cmp esi,ebx + je .L_check_is_executing + + /* Calculate the heir context pointer */ + addl esi,eax + subl ebx,eax + + /* Update the executing */ + movl esi,PER_CPU_OFFSET_EXECUTING(edx) + + jmp .L_check_is_executing +#endif /*void _CPU_Context_save_fp_context( &fp_context_ptr ) * void _CPU_Context_restore_fp_context( &fp_context_ptr ) |