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use popal/pushal for context switch

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Should take fewer clock nd save esp
This commit is contained in:
Mathieu Maret 2020-04-22 17:31:37 +02:00
parent 79c1fda419
commit 5141044c06
2 changed files with 15 additions and 32 deletions
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5
core/cpu_context.c
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@ -36,12 +36,13 @@ struct cpu_state {
thread, even for a user thread */
uint16_t alignment_padding; /* unused */
uint32_t eax;
uint32_t ebx;
uint32_t ecx;
uint32_t edx;
uint32_t ebx;
uint32_t ebp;
uint32_t esp;
uint32_t esi;
uint32_t edi;
uint32_t ebp;
/* MUST NEVER CHANGE (dependent on the IA32 iret instruction) */
uint32_t error_code;

42
core/cpu_context_switch.S
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@ -6,20 +6,14 @@
.globl cpu_context_switch
.type cpu_context_switch, @function
cpu_context_switch:
// arg2= to_context -- esp+64
// arg1= from_context -- esp+60
// caller ip -- esp+56
pushf // (eflags) esp+52
pushl %cs // (cs) esp+48
pushl $resume_pc // (ip) esp+44
pushl $0 // (error code) esp+40
pushl %ebp // esp+36
pushl %edi // esp+32
pushl %esi // esp+28
pushl %edx // esp+24
pushl %ecx // esp+20
pushl %ebx // esp+16
pushl %eax // esp+12
// arg2= to_context -- esp+68
// arg1= from_context -- esp+64
// caller ip -- esp+60
pushf // (eflags) esp+56
pushl %cs // (cs) esp+52
pushl $resume_pc // (ip) esp+48
pushl $0 // (error code) esp+44
pushal // (general reg) esp+12+8*4
subl $2, %esp // (alignment) esp+10
pushw %ss // esp+8
pushw %ds // esp+6
@ -32,11 +26,11 @@ cpu_context_switch:
*/
/* Store the address of the saved context */
movl 60(%esp), %ebx
movl 64(%esp), %ebx
movl %esp, (%ebx)
/* This is the proper context switch ! We change the stack here */
movl 64(%esp), %esp
movl 68(%esp), %esp
/* Restore the CPU context */
popw %gs
@ -45,13 +39,7 @@ cpu_context_switch:
popw %ds
popw %ss
addl $2,%esp
popl %eax
popl %ebx
popl %ecx
popl %edx
popl %esi
popl %edi
popl %ebp
popal
addl $4, %esp /* Ignore "error code" */
/* This restores the eflags, the cs and the eip registers */
@ -94,13 +82,7 @@ cpu_context_exit_to:
popw %ds
popw %ss
addl $2,%esp
popl %eax
popl %ebx
popl %ecx
popl %edx
popl %esi
popl %edi
popl %ebp
popal
addl $4, %esp /* Ignore "error code" */
/* This restores the eflags, the cs and the eip registers */