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minix/kernel/arch/i386/mpx.S
Tomas Hruby b90c2d7026 rename of mode/context switching functions 
- this patch only renames schedcheck() to switch_to_user(),
  cycles_accounting_stop() to context_stop() and restart() to
  +restore_user_context()

- the motivation is that since the introduction of schedcheck() it has
  been abused for many things. It deserves a better name.  It should
  express the fact that from the moment we call the function we are in
  the process of switching to user.

- cycles_accounting_stop() was originally a single purpose function.
  As this function is called at were convenient places it is used in
  for other things too, e.g. (un)locking the kernel. Thus it deserves
  a better name too.

- using the old name, restart() does not call schedcheck(), however
  calls to restart are replaced by calls to schedcheck()
  [switch_to_user] and it calls restart() [restore_user_context]
2010-05-18 13:00:39 +00:00

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/*
* This file is part of the lowest layer of the MINIX kernel. (The other part
* is "proc.c".) The lowest layer does process switching and message handling.
* Furthermore it contains the assembler startup code for Minix and the 32-bit
* interrupt handlers. It cooperates with the code in "start.c" to set up a
* good environment for main().
*
* Kernel is entered either because of kernel-calls, ipc-calls, interrupts or
* exceptions. TSS is set so that the kernel stack is loaded. The user cotext is
* saved to the proc table and the handler of the event is called. Once the
* handler is done, switch_to_user() function is called to pick a new process,
* finish what needs to be done for the next process to run, sets its context
* and switch to userspace.
*
* For communication with the boot monitor at startup time some constant
* data are compiled into the beginning of the text segment. This facilitates
* reading the data at the start of the boot process, since only the first
* sector of the file needs to be read.
*
* Some data storage is also allocated at the end of this file. This data
* will be at the start of the data segment of the kernel and will be read
* and modified by the boot monitor before the kernel starts.
*/
#include "kernel/kernel.h" /* configures the kernel */
/* sections */
#include <machine/vm.h>
#ifdef __ACK__
.text
begtext:
#ifdef __ACK__
.rom
#else
.data
#endif
begrom:
.data
begdata:
.bss
begbss:
#endif
#include <minix/config.h>
#include <minix/const.h>
#include <minix/com.h>
#include <machine/interrupt.h>
#include "archconst.h"
#include "kernel/const.h"
#include "kernel/proc.h"
#include "sconst.h"
/* Selected 386 tss offsets. */
#define TSS3_S_SP0 4
/*
* Exported functions
* Note: in assembly language the .define statement applied to a function name
* is loosely equivalent to a prototype in C code -- it makes it possible to
* link to an entity declared in the assembly code but does not create
* the entity.
*/
.globl restore_user_context
.globl reload_cr3
.globl divide_error
.globl single_step_exception
.globl nmi
.globl breakpoint_exception
.globl overflow
.globl bounds_check
.globl inval_opcode
.globl copr_not_available
.globl double_fault
.globl copr_seg_overrun
.globl inval_tss
.globl segment_not_present
.globl stack_exception
.globl general_protection
.globl page_fault
.globl copr_error
.globl alignment_check
.globl machine_check
.globl simd_exception
.globl params_size
.globl params_offset
.globl mon_ds
.globl switch_to_user
.globl lazy_fpu
.globl hwint00 /* handlers for hardware interrupts */
.globl hwint01
.globl hwint02
.globl hwint03
.globl hwint04
.globl hwint05
.globl hwint06
.globl hwint07
.globl hwint08
.globl hwint09
.globl hwint10
.globl hwint11
.globl hwint12
.globl hwint13
.globl hwint14
.globl hwint15
/* Exported variables. */
.globl begbss
.globl begdata
.text
/*===========================================================================*/
/* MINIX */
/*===========================================================================*/
.global MINIX
MINIX:
/* this is the entry point for the MINIX kernel */
jmp over_flags /* skip over the next few bytes */
.short CLICK_SHIFT /* for the monitor: memory granularity */
flags:
/* boot monitor flags:
* call in 386 mode, make bss, make stack,
* load high, don't patch, will return,
* uses generic INT, memory vector,
* new boot code return
*/
.short 0x01FD
nop /* extra byte to sync up disassembler */
over_flags:
/* Set up a C stack frame on the monitor stack. (The monitor sets cs and ds */
/* right. The ss descriptor still references the monitor data segment.) */
movzwl %sp, %esp /* monitor stack is a 16 bit stack */
push %ebp
mov %esp, %ebp
push %esi
push %edi
cmp $0, 4(%ebp) /* monitor return vector is */
je noret /* nonzero if return possible */
incl mon_return
noret:
movl %esp, mon_sp /* save stack pointer for later return */
/* Copy the monitor global descriptor table to the address space of kernel and */
/* switch over to it. Prot_init() can then update it with immediate effect. */
sgdt gdt+GDT_SELECTOR /* get the monitor gdtr */
movl gdt+GDT_SELECTOR+2, %esi /* absolute address of GDT */
mov $gdt, %ebx /* address of kernel GDT */
mov $8*8, %ecx /* copying eight descriptors */
copygdt:
movb %es:(%esi), %al
movb %al, (%ebx)
inc %esi
inc %ebx
loop copygdt
movl gdt+DS_SELECTOR+2, %eax /* base of kernel data */
and $0x00FFFFFF, %eax /* only 24 bits */
add $gdt, %eax /* eax = vir2phys(gdt) */
movl %eax, gdt+GDT_SELECTOR+2 /* set base of GDT */
lgdt gdt+GDT_SELECTOR /* switch over to kernel GDT */
/* Locate boot parameters, set up kernel segment registers and stack. */
mov 8(%ebp), %ebx /* boot parameters offset */
mov 12(%ebp), %edx /* boot parameters length */
mov 16(%ebp), %eax /* address of a.out headers */
movl %eax, aout
mov %ds, %ax /* kernel data */
mov %ax, %es
mov %ax, %fs
mov %ax, %gs
mov %ax, %ss
mov $k_boot_stktop, %esp /* set sp to point to the top of kernel stack */
/* Save boot parameters into these global variables for i386 code */
movl %edx, params_size
movl %ebx, params_offset
movl $SS_SELECTOR, mon_ds
/* Call C startup code to set up a proper environment to run main(). */
push %edx
push %ebx
push $SS_SELECTOR
push $DS_SELECTOR
push $CS_SELECTOR
call cstart /* cstart(cs, ds, mds, parmoff, parmlen) */
add $5*4, %esp
/* Reload gdtr, idtr and the segment registers to global descriptor table set */
/* up by prot_init(). */
lgdt gdt+GDT_SELECTOR
lidt gdt+IDT_SELECTOR
ljmp $CS_SELECTOR, $csinit
csinit:
movw $DS_SELECTOR, %ax
mov %ax, %ds
mov %ax, %es
mov %ax, %fs
mov %ax, %gs
mov %ax, %ss
movw $TSS_SELECTOR, %ax /* no other TSS is used */
ltr %ax
push $0 /* set flags to known good state */
popf /* esp, clear nested task and int enable */
jmp main /* main() */
/*===========================================================================*/
/* interrupt handlers */
/* interrupt handlers for 386 32-bit protected mode */
/*===========================================================================*/
#define PIC_IRQ_HANDLER(irq) \
push $irq ;\
call irq_handle /* intr_handle(irq_handlers[irq]) */ ;\
add $4, %esp ;
/*===========================================================================*/
/* hwint00 - 07 */
/*===========================================================================*/
/* Note this is a macro, it just looks like a subroutine. */
#define hwint_master(irq) \
TEST_INT_IN_KERNEL(4, 0f) ;\
\
SAVE_PROCESS_CTX(0) ;\
push %ebp ;\
call context_stop ;\
add $4, %esp ;\
movl $0, %ebp /* for stack trace */ ;\
PIC_IRQ_HANDLER(irq) ;\
movb $END_OF_INT, %al ;\
outb $INT_CTL /* reenable interrupts in master pic */ ;\
jmp switch_to_user ;\
\
0: \
pusha ;\
call context_stop_idle ;\
PIC_IRQ_HANDLER(irq) ;\
movb $END_OF_INT, %al ;\
outb $INT_CTL /* reenable interrupts in master pic */ ;\
CLEAR_IF(10*4(%esp)) ;\
popa ;\
iret ;
/* Each of these entry points is an expansion of the hwint_master macro */
.balign 16
hwint00:
/* Interrupt routine for irq 0 (the clock). */
hwint_master(0)
.balign 16
hwint01:
/* Interrupt routine for irq 1 (keyboard) */
hwint_master(1)
.balign 16
hwint02:
/* Interrupt routine for irq 2 (cascade!) */
hwint_master(2)
.balign 16
hwint03:
/* Interrupt routine for irq 3 (second serial) */
hwint_master(3)
.balign 16
hwint04:
/* Interrupt routine for irq 4 (first serial) */
hwint_master(4)
.balign 16
hwint05:
/* Interrupt routine for irq 5 (XT winchester) */
hwint_master(5)
.balign 16
hwint06:
/* Interrupt routine for irq 6 (floppy) */
hwint_master(6)
.balign 16
hwint07:
/* Interrupt routine for irq 7 (printer) */
hwint_master(7)
/*===========================================================================*/
/* hwint08 - 15 */
/*===========================================================================*/
/* Note this is a macro, it just looks like a subroutine. */
#define hwint_slave(irq) \
TEST_INT_IN_KERNEL(4, 0f) ;\
\
SAVE_PROCESS_CTX(0) ;\
push %ebp ;\
call context_stop ;\
add $4, %esp ;\
movl $0, %ebp /* for stack trace */ ;\
PIC_IRQ_HANDLER(irq) ;\
movb $END_OF_INT, %al ;\
outb $INT_CTL /* reenable interrupts in master pic */ ;\
outb $INT2_CTL /* reenable slave 8259 */ ;\
jmp switch_to_user ;\
\
0: \
pusha ;\
call context_stop_idle ;\
PIC_IRQ_HANDLER(irq) ;\
movb $END_OF_INT, %al ;\
outb $INT_CTL /* reenable interrupts in master pic */ ;\
outb $INT2_CTL /* reenable slave 8259 */ ;\
CLEAR_IF(10*4(%esp)) ;\
popa ;\
iret ;
/* Each of these entry points is an expansion of the hwint_slave macro */
.balign 16
hwint08:
/* Interrupt routine for irq 8 (realtime clock) */
hwint_slave(8)
.balign 16
hwint09:
/* Interrupt routine for irq 9 (irq 2 redirected) */
hwint_slave(9)
.balign 16
hwint10:
/* Interrupt routine for irq 10 */
hwint_slave(10)
.balign 16
hwint11:
/* Interrupt routine for irq 11 */
hwint_slave(11)
.balign 16
hwint12:
/* Interrupt routine for irq 12 */
hwint_slave(12)
.balign 16
hwint13:
/* Interrupt routine for irq 13 (FPU exception) */
hwint_slave(13)
.balign 16
hwint14:
/* Interrupt routine for irq 14 (AT winchester) */
hwint_slave(14)
.balign 16
hwint15:
/* Interrupt routine for irq 15 */
hwint_slave(15)
/*
* IPC is only from a process to kernel
*/
.balign 16
.globl ipc_entry
ipc_entry:
SAVE_PROCESS_CTX(0)
/* save the pointer to the current process */
push %ebp
/*
* pass the syscall arguments from userspace to the handler.
* SAVE_PROCESS_CTX() does not clobber these registers, they are still
* set as the userspace have set them
*/
push %ebx
push %eax
push %ecx
/* stop user process cycles */
push %ebp
call context_stop
add $4, %esp
/* for stack trace */
movl $0, %ebp
call do_ipc
/* restore the current process pointer and save the return value */
add $3 * 4, %esp
pop %esi
mov %eax, AXREG(%esi)
jmp switch_to_user
/*
* kernel call is only from a process to kernel
*/
.balign 16
.globl kernel_call_entry
kernel_call_entry:
SAVE_PROCESS_CTX(0)
/* save the pointer to the current process */
push %ebp
/*
* pass the syscall arguments from userspace to the handler.
* SAVE_PROCESS_CTX() does not clobber these registers, they are still
* set as the userspace have set them
*/
push %eax
/* stop user process cycles */
push %ebp
call context_stop
add $4, %esp
/* for stack trace */
movl $0, %ebp
call kernel_call
/* restore the current process pointer and save the return value */
add $8, %esp
jmp switch_to_user
.balign 16
/*
* called by the exception interrupt vectors. If the exception does not push
* errorcode, we assume that the vector handler pushed 0 instead. Next pushed
* thing is the vector number. From this point on we can continue as if every
* exception pushes an error code
*/
exception_entry:
/*
* check if it is a nested trap by comparing the saved code segment
* descriptor with the kernel CS first
*/
TEST_INT_IN_KERNEL(12, exception_entry_nested)
exception_entry_from_user:
SAVE_PROCESS_CTX(8)
/* stop user process cycles */
push %ebp
call context_stop
add $4, %esp
/* for stack trace clear %ebp */
movl $0, %ebp
/*
* push a pointer to the interrupt state pushed by the cpu and the
* vector number pushed by the vector handler just before calling
* exception_entry and call the exception handler.
*/
push %esp
push $0 /* it's not a nested exception */
call exception_handler
jmp switch_to_user
exception_entry_nested:
pusha
mov %esp, %eax
add $(8 * 4), %eax
push %eax
pushl $1 /* it's a nested exception */
call exception_handler
add $8, %esp
popa
/* clear the error code and the exception number */
add $8, %esp
/* resume execution at the point of exception */
iret
/*===========================================================================*/
/* restart */
/*===========================================================================*/
restore_user_context:
mov 4(%esp), %ebp /* will assume P_STACKBASE == 0 */
/* reconstruct the stack for iret */
movl SSREG(%ebp), %eax
push %eax
movl SPREG(%ebp), %eax
push %eax
movl PSWREG(%ebp), %eax
push %eax
movl CSREG(%ebp), %eax
push %eax
movl PCREG(%ebp), %eax
push %eax
RESTORE_GP_REGS(%ebp)
RESTORE_SEGS(%ebp)
movl %ss:BPREG(%ebp), %ebp
iret /* continue process */
/*===========================================================================*/
/* exception handlers */
/*===========================================================================*/
#define EXCEPTION_ERR_CODE(vector) \
push $vector ;\
jmp exception_entry
#define EXCEPTION_NO_ERR_CODE(vector) \
pushl $0 ;\
EXCEPTION_ERR_CODE(vector)
divide_error:
EXCEPTION_NO_ERR_CODE(DIVIDE_VECTOR)
single_step_exception:
EXCEPTION_NO_ERR_CODE(DEBUG_VECTOR)
nmi:
#ifndef CONFIG_WATCHDOG
EXCEPTION_NO_ERR_CODE(NMI_VECTOR)
#else
/*
* We have to be very careful as this interrupt can occur anytime. On
* the other hand, if it interrupts a user process, we will resume the
* same process which makes things a little simpler. We know that we are
* already on kernel stack whenever it happened and we can be
* conservative and save everything as we don't need to be extremely
* efficient as the interrupt is infrequent and some overhead is already
* expected.
*/
/*
* save the important registers. We don't save %cs and %ss and they are
* saved and restored by CPU
*/
pushw %ds
pushw %es
pushw %fs
pushw %gs
pusha
/*
* We cannot be sure about the state of the kernel segment register,
* however, we always set %ds and %es to the same as %ss
*/
mov %ss, %si
mov %si, %ds
mov %si, %es
push %esp
call nmi_watchdog_handler
add $4, %esp
/* restore all the important registers as they were before the trap */
popa
popw %gs
popw %fs
popw %es
popw %ds
iret
#endif
breakpoint_exception:
EXCEPTION_NO_ERR_CODE(BREAKPOINT_VECTOR)
overflow:
EXCEPTION_NO_ERR_CODE(OVERFLOW_VECTOR)
bounds_check:
EXCEPTION_NO_ERR_CODE(BOUNDS_VECTOR)
inval_opcode:
EXCEPTION_NO_ERR_CODE(INVAL_OP_VECTOR)
copr_not_available:
TEST_INT_IN_KERNEL(4, copr_not_available_in_kernel)
clts
cld /* set direction flag to a known value */
SAVE_PROCESS_CTX_NON_LAZY(0)
/* stop user process cycles */
push %ebp
call context_stop
pop %ebp
lea P_MISC_FLAGS(%ebp), %ebx
movw (%ebx), %cx
and $MF_FPU_INITIALIZED, %cx
jnz 0f /* jump if FPU is already initialized */
orw $MF_FPU_INITIALIZED, (%ebx)
fninit
jmp copr_return
0: /* load FPU context for current process */
mov %ss:FP_SAVE_AREA_P(%ebp), %eax
cmp $0, osfxsr_feature
jz fp_l_no_fxsr /* FXSR is not avaible. */
/* DO NOT CHANGE THE OPERAND!!! gas2ack does not handle it yet */
fxrstor (%eax)
jmp copr_return
fp_l_no_fxsr:
/* DO NOT CHANGE THE OPERAND!!! gas2ack does not handle it yet */
frstor (%eax)
copr_return:
orw $MF_USED_FPU, (%ebx) /* fpu was used during last execution */
jmp switch_to_user
copr_not_available_in_kernel:
movl $0, (%esp)
call panic
double_fault:
EXCEPTION_ERR_CODE(DOUBLE_FAULT_VECTOR)
copr_seg_overrun:
EXCEPTION_NO_ERR_CODE(COPROC_SEG_VECTOR)
inval_tss:
EXCEPTION_ERR_CODE(INVAL_TSS_VECTOR)
segment_not_present:
EXCEPTION_ERR_CODE(SEG_NOT_VECTOR)
stack_exception:
EXCEPTION_ERR_CODE(STACK_FAULT_VECTOR)
general_protection:
EXCEPTION_ERR_CODE(PROTECTION_VECTOR)
page_fault:
EXCEPTION_ERR_CODE(PAGE_FAULT_VECTOR)
copr_error:
EXCEPTION_NO_ERR_CODE(COPROC_ERR_VECTOR)
alignment_check:
EXCEPTION_NO_ERR_CODE(ALIGNMENT_CHECK_VECTOR)
machine_check:
EXCEPTION_NO_ERR_CODE(MACHINE_CHECK_VECTOR)
simd_exception:
EXCEPTION_NO_ERR_CODE(SIMD_EXCEPTION_VECTOR)
/*===========================================================================*/
/* lazy_fpu */
/*===========================================================================*/
/* void lazy_fpu(struct proc *pptr)
* It's called, when we are on kernel stack.
* Actualy lazy code is just few lines, which check MF_USED_FPU,
* another part is save_init_fpu().
*/
lazy_fpu:
push %ebp
mov %esp, %ebp
push %eax
push %ebx
push %ecx
cmp $0, fpu_presence /* Do we have FPU? */
jz no_fpu_available
mov 8(%ebp), %eax /* Get pptr */
lea P_MISC_FLAGS(%eax), %ebx
movw (%ebx), %cx
and $MF_USED_FPU, %cx
jz 0f /* Don't save FPU */
mov %ss:FP_SAVE_AREA_P(%eax), %eax
cmp $0, osfxsr_feature
jz fp_s_no_fxsr /* FXSR is not avaible. */
/* DO NOT CHANGE THE OPERAND!!! gas2ack does not handle it yet */
fxsave (%eax)
fninit
jmp fp_saved
fp_s_no_fxsr:
/* DO NOT CHANGE THE OPERAND!!! gas2ack does not handle it yet */
fnsave (%eax)
fwait /* required for compatibility with processors prior pentium */
fp_saved:
andw $~MF_USED_FPU, (%ebx)
0: mov %cr0, %eax
or $0x00000008, %eax /* Set TS flag */
mov %eax, %cr0
no_fpu_available:
pop %ecx
pop %ebx
pop %eax
pop %ebp
ret
/*===========================================================================*/
/* reload_cr3 */
/*===========================================================================*/
/* PUBLIC void reload_cr3(void); */
reload_cr3:
push %ebp
mov %esp, %ebp
mov %cr3, %eax
mov %eax, %cr3
pop %ebp
ret
/*===========================================================================*/
/* data */
/*===========================================================================*/
#ifdef __ACK__
.rom /* Before the string table please */
#else
.data
#endif
.short 0x526F /* this must be the first data entry (magic #) */
.bss
/*
* the kernel stack
*/
.globl k_boot_stktop
k_boot_stack:
.space 4096 /* kernel stack */ /* FIXME use macro here */
k_boot_stktop: /* top of kernel stack */
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