92 lines
2.0 KiB
ArmAsm
92 lines
2.0 KiB
ArmAsm
#define ASM_SOURCE
|
|
#include "segment.h"
|
|
|
|
.file "syscall_wrappers.S"
|
|
|
|
.text
|
|
|
|
/* The address of the real "C" syscall function */
|
|
.extern syscallExecute
|
|
|
|
/** Update the kernel TSS in case we are switching to a thread in user
|
|
mode in order to come back into the correct kernel stack */
|
|
.extern cpu_context_update_kernel_tss
|
|
|
|
/* The address of the function to call to set back the user thread's
|
|
MMU configuration upon return to user context */
|
|
.extern threadPrepareSyscallSwitchBack
|
|
|
|
.p2align 2, 0x90
|
|
.globl syscallHandler
|
|
syscallHandler:
|
|
.type syscallHandler,@function
|
|
|
|
/* Fake error code */
|
|
pushl $0
|
|
/* Backup the context */
|
|
pushl %ebp
|
|
movl %esp, %ebp
|
|
|
|
pushl %eax
|
|
pushl %ecx
|
|
pushl %edx
|
|
pushl %ebx
|
|
pushl %esi
|
|
pushl %edi
|
|
subl $2,%esp
|
|
pushw %ss
|
|
pushw %ds
|
|
pushw %es
|
|
pushw %fs
|
|
pushw %gs
|
|
|
|
/* Set correct kernel segment descriptors' value */
|
|
movw $BUILD_SEGMENT_REG_VALUE(0, 0, SEG_KDATA), %di
|
|
pushw %di ; popw %ds
|
|
pushw %di ; popw %es
|
|
pushw %di ; popw %fs
|
|
pushw %di ; popw %gs
|
|
|
|
/* Prepare the call to do_syscall */
|
|
pushl %esp /* user_ctxt */
|
|
pushl %eax /* syscall ID */
|
|
|
|
call syscallExecute
|
|
/* Unallocate the stack used by the
|
|
do_syscall arguments */
|
|
addl $8, %esp
|
|
|
|
/* store the do_syscall return value into interrupted context */
|
|
movl %eax, 32(%esp)
|
|
|
|
/* Set the MMU configuration to that of the user thread's process */
|
|
pushl %esp /* user_ctxt */
|
|
call threadPrepareSyscallSwitchBack
|
|
addl $4, %esp /* Unallocate the stack */
|
|
|
|
/* Prepare kernel TSS because we are switching back to a user
|
|
thread: we make sure that we will come back into the kernel at a
|
|
correct stack location */
|
|
pushl %esp /* Pass the location of the context we are
|
|
restoring to the function */
|
|
call cpu_context_update_kernel_tss
|
|
addl $4, %esp
|
|
|
|
/* Restore the user context */
|
|
popw %gs
|
|
popw %fs
|
|
popw %es
|
|
popw %ds
|
|
popw %ss
|
|
addl $2,%esp
|
|
popl %edi
|
|
popl %esi
|
|
popl %ebx
|
|
popl %edx
|
|
popl %ecx
|
|
popl %eax
|
|
popl %ebp
|
|
/* Remove fake error code */
|
|
addl $4, %esp
|
|
iret
|