minix/kernel/arch/i386/sconst.h
Tomas Hruby cbc9586c13 Lazy FPU
- FPU context is stored only if conflict between 2 FPU users or while
  exporting context of a process to userspace while it is the active
  user of FPU

- FPU has its owner (fpu_owner) which points to the process whose
  state is currently loaded in FPU

- the FPU exception is only turned on when scheduling a process which
  is not the owner of FPU

- FPU state is restored for the process that generated the FPU
  exception. This process runs immediately without letting scheduler
  to pick a new process to resolve the FPU conflict asap, to minimize
  the FPU thrashing and FPU exception hadler execution

- faster all non-FPU-exception kernel entries as FPU state is not
  checked nor saved

- removed MF_USED_FPU flag, only MF_FPU_INITIALIZED remains to signal
  that a process has used FPU in the past
2010-06-07 07:43:17 +00:00

151 lines
4 KiB
C

#ifndef __SCONST_H__
#define __SCONST_H__
#include "kernel/const.h"
/* Miscellaneous constants used in assembler code. */
W = _WORD_SIZE /* Machine word size. */
/* Offsets in struct proc. They MUST match proc.h. */
P_STACKBASE = 0
GSREG = P_STACKBASE
FSREG = GSREG+2 /* 386 introduces FS and GS segments*/
ESREG = FSREG+2
DSREG = ESREG+2
DIREG = DSREG+2
SIREG = DIREG+W
BPREG = SIREG+W
STREG = BPREG+W /* hole for another SP*/
BXREG = STREG+W
DXREG = BXREG+W
CXREG = DXREG+W
AXREG = CXREG+W
RETADR = AXREG+W /* return address for save() call*/
PCREG = RETADR+W
CSREG = PCREG+W
PSWREG = CSREG+W
SPREG = PSWREG+W
SSREG = SPREG+W
P_STACKTOP = SSREG+W
FP_SAVE_AREA_P = P_STACKTOP
P_LDT_SEL = FP_SAVE_AREA_P + 532
P_CR3 = P_LDT_SEL+W
P_CR3_V = P_CR3+4
P_LDT = P_CR3_V+W
P_MISC_FLAGS = P_LDT + 50
Msize = 9 /* size of a message in 32-bit words*/
/*
* offset to current process pointer right after trap, we assume we always have
* error code on the stack
*/
#define CURR_PROC_PTR 20
/*
* tests whether the interrupt was triggered in kernel. If so, jump to the
* label. Displacement tell the macro ha far is the CS value saved by the trap
* from the current %esp. The kernel code segment selector has the lower 3 bits
* zeroed
*/
#define TEST_INT_IN_KERNEL(displ, label) \
cmpl $CS_SELECTOR, displ(%esp) ;\
je label ;
/*
* saves the basic interrupt context (no error code) to the process structure
*
* displ is the displacement of %esp from the original stack after trap
* pptr is the process structure pointer
* tmp is an available temporary register
*/
#define SAVE_TRAP_CTX(displ, pptr, tmp) \
movl (0 + displ)(%esp), tmp ;\
movl tmp, PCREG(pptr) ;\
movl (4 + displ)(%esp), tmp ;\
movl tmp, CSREG(pptr) ;\
movl (8 + displ)(%esp), tmp ;\
movl tmp, PSWREG(pptr) ;\
movl (12 + displ)(%esp), tmp ;\
movl tmp, SPREG(pptr) ;\
movl tmp, STREG(pptr) ;\
movl (16 + displ)(%esp), tmp ;\
movl tmp, SSREG(pptr) ;
#define SAVE_SEGS(pptr) \
mov %ds, %ss:DSREG(pptr) ;\
mov %es, %ss:ESREG(pptr) ;\
mov %fs, %ss:FSREG(pptr) ;\
mov %gs, %ss:GSREG(pptr) ;
#define RESTORE_SEGS(pptr) \
movw %ss:DSREG(pptr), %ds ;\
movw %ss:ESREG(pptr), %es ;\
movw %ss:FSREG(pptr), %fs ;\
movw %ss:GSREG(pptr), %gs ;
/*
* restore kernel segments, %ss is kernnel data segment, %cs is aready set and
* %fs, %gs are not used
*/
#define RESTORE_KERNEL_SEGS \
mov %ss, %si ;\
mov %si, %ds ;\
mov %si, %es ;\
movw $0, %si ;\
mov %si, %gs ;\
mov %si, %fs ;
#define SAVE_GP_REGS(pptr) \
mov %eax, %ss:AXREG(pptr) ;\
mov %ecx, %ss:CXREG(pptr) ;\
mov %edx, %ss:DXREG(pptr) ;\
mov %ebx, %ss:BXREG(pptr) ;\
mov %esi, %ss:SIREG(pptr) ;\
mov %edi, %ss:DIREG(pptr) ;
#define RESTORE_GP_REGS(pptr) \
movl %ss:AXREG(pptr), %eax ;\
movl %ss:CXREG(pptr), %ecx ;\
movl %ss:DXREG(pptr), %edx ;\
movl %ss:BXREG(pptr), %ebx ;\
movl %ss:SIREG(pptr), %esi ;\
movl %ss:DIREG(pptr), %edi ;
/*
* save the context of the interrupted process to the structure in the process
* table. It pushses the %ebp to stack to get a scratch register. After %esi is
* saved, we can use it to get the saved %ebp from stack and save it to the
* final location
*
* displ is the stack displacement. In case of an exception, there are two extra
* value on the stack - error code and the exception number
*/
#define SAVE_PROCESS_CTX(displ) \
\
cld /* set the direction flag to a known state */ ;\
\
push %ebp ;\
;\
movl (CURR_PROC_PTR + 4 + displ)(%esp), %ebp ;\
;\
/* save the segment registers */ \
SAVE_SEGS(%ebp) ;\
\
SAVE_GP_REGS(%ebp) ;\
pop %esi /* get the orig %ebp and save it */ ;\
mov %esi, %ss:BPREG(%ebp) ;\
\
RESTORE_KERNEL_SEGS ;\
SAVE_TRAP_CTX(displ, %ebp, %esi) ;
/*
* clear the IF flag in eflags which are stored somewhere in memory, e.g. on
* stack. iret or popf will load the new value later
*/
#define CLEAR_IF(where) \
mov where, %eax ;\
andl $0xfffffdff, %eax ;\
mov %eax, where ;
#endif /* __SCONST_H__ */