xv6-65oo2/trapasm.S
kolya c7317d4dc7 always save and restore %fs, %gs to ensure old segment entries are never
accessible to user from the hidden CPU segment registers.
2008-09-24 01:48:31 +00:00

43 lines
696 B
ArmAsm

.text
.set SEG_KDATA_SEL, 0x10 # selector for SEG_KDATA
# vectors.S sends all traps here.
.globl alltraps
alltraps:
# Build trap frame.
pushl %ds
pushl %es
pushl %fs
pushl %gs
pushal
# Set up data segments.
movl $SEG_KDATA_SEL, %eax
movw %ax,%ds
movw %ax,%es
# Call trap(tf), where tf=%esp
pushl %esp
call trap
addl $4, %esp
# Return falls through to trapret...
.globl trapret
trapret:
popal
popl %gs
popl %fs
popl %es
popl %ds
addl $0x8, %esp # trapno and errcode
iret
# A forked process switches to user mode by calling
# forkret1(tf), where tf is the trap frame to use.
.globl forkret1
forkret1:
movl 4(%esp), %esp
jmp trapret