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# Copyright (c) 2008 The Regents of The University of Michigan
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met: redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer;
# redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution;
# neither the name of the copyright holders nor the names of its
# contributors may be used to endorse or promote products derived from
# this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#
# Authors: Gabe Black
intCodeTemplate = '''
def rom
{
# This vectors the CPU into an interrupt handler in long mode.
# On entry, t1 is set to the vector of the interrupt and t7 is the current
# ip. We need that because rdip returns the next ip.
extern %(startLabel)s:
#
# Get the 64 bit interrupt or trap gate descriptor from the IDT
#
# Load the gate descriptor from the IDT
slli t4, t1, 4, dataSize=8
ld t2, idtr, [1, t0, t4], 8, dataSize=8, addressSize=8
ld t4, idtr, [1, t0, t4], dataSize=8, addressSize=8
# Make sure the descriptor is a legal gate.
chks t1, t4, %(gateCheckType)s
#
# Get the target CS descriptor using the selector in the gate
# descriptor.
#
srli t10, t4, 16, dataSize=8
andi t5, t10, 0xF8, dataSize=8
andi t0, t10, 0x4, flags=(EZF,), dataSize=2
br rom_local_label("%(startLabel)s_globalDescriptor"), flags=(CEZF,)
ld t3, tsl, [1, t0, t5], dataSize=8, addressSize=8
br rom_local_label("%(startLabel)s_processDescriptor")
%(startLabel)s_globalDescriptor:
ld t3, tsg, [1, t0, t5], dataSize=8, addressSize=8
%(startLabel)s_processDescriptor:
chks t10, t3, IntCSCheck, dataSize=8
wrdl hs, t3, t10, dataSize=8
# Stick the target offset in t9.
wrdh t9, t4, t2, dataSize=8
#
# Figure out where the stack should be
#
# Record what we might set the stack selector to.
rdsel t11, ss
# Check if we're changing privelege level. At this point we can assume
# we're going to a DPL that's less than or equal to the CPL.
rdattr t10, hs, dataSize=8
srli t10, t10, 3, dataSize=8
andi t10, t10, 3, dataSize=8
rdattr t5, cs, dataSize=8
srli t5, t5, 3, dataSize=8
sub t5, t5, t10, dataSize=8
andi t0, t5, 0x3, flags=(EZF,), dataSize=8
# We're going to change priviledge, so zero out the stack selector. We
# need to let the IST have priority so we don't branch yet.
wrsel t11, t0, flags=(nCEZF,)
# Check the IST field of the gate descriptor
srli t10, t4, 32, dataSize=8
andi t10, t10, 0x7, dataSize=8
subi t0, t10, 1, flags=(ECF,), dataSize=8
br rom_local_label("%(startLabel)s_istStackSwitch"), flags=(nCECF,)
br rom_local_label("%(startLabel)s_cplStackSwitch"), flags=(nCEZF,)
# If we're here, it's because the stack isn't being switched.
# Set t6 to the new aligned rsp.
mov t6, rsp, dataSize=8
andi t6, t6, 0xF0, dataSize=1
subi t6, t6, 40 + %(errorCodeSize)d, dataSize=8
# Check that we can access everything we need to on the stack
ldst t0, hs, [1, t0, t6], dataSize=8, addressSize=8
ldst t0, hs, [1, t0, t6], \
32 + %(errorCodeSize)d, dataSize=8, addressSize=8
br rom_local_label("%(startLabel)s_stackSwitched")
%(startLabel)s_istStackSwitch:
panic "IST based stack switching isn't implemented"
br rom_local_label("%(startLabel)s_stackSwitched")
%(startLabel)s_cplStackSwitch:
panic "CPL change initiated stack switching isn't implemented"
%(startLabel)s_stackSwitched:
##
## Point of no return.
## We're now going to irrevocably modify visible state.
## Anything bad that's going to happen should have happened by now or will
## happen right now.
##
wrip t0, t9, dataSize=8
#
# Build up the interrupt stack frame
#
# Write out the contents of memory
%(errorCodeCode)s
st t7, hs, [1, t0, t6], %(errorCodeSize)d, dataSize=8, addressSize=8
limm t5, 0, dataSize=8
rdsel t5, cs, dataSize=2
st t5, hs, [1, t0, t6], 8 + %(errorCodeSize)d, dataSize=8, addressSize=8
rflags t10, dataSize=8
st t10, hs, [1, t0, t6], 16 + %(errorCodeSize)d, dataSize=8, addressSize=8
st rsp, hs, [1, t0, t6], 24 + %(errorCodeSize)d, dataSize=8, addressSize=8
rdsel t5, ss, dataSize=2
st t5, hs, [1, t0, t6], 32 + %(errorCodeSize)d, dataSize=8, addressSize=8
# Set the stack segment
mov rsp, rsp, t6, dataSize=8
wrsel ss, t11, dataSize=2
#
# Set up the target code segment
#
srli t5, t4, 16, dataSize=8
andi t5, t5, 0xFF, dataSize=8
wrdl cs, t3, t5, dataSize=8
wrsel cs, t5, dataSize=2
#
# Adjust rflags which is still in t10 from above
#
# Set IF to the lowest bit of the original gate type.
# The type field of the original gate starts at bit 40.
# Set the TF, NT, and RF bits. We'll flip them at the end.
limm t6, (1 << 8) | (1 << 14) | (1 << 16)
or t10, t10, t6
srli t5, t4, 40, dataSize=8
srli t7, t10, 9, dataSize=8
xor t5, t7, t5, dataSize=8
andi t5, t5, 1, dataSize=8
slli t5, t5, 9, dataSize=8
or t6, t5, t6, dataSize=8
# Put the results into rflags
wrflags t6, t10
eret
};
'''
microcode = \
intCodeTemplate % {\
"startLabel" : "longModeInterrupt",
"gateCheckType" : "IntGateCheck",
"errorCodeSize" : 0,
"errorCodeCode" : ""
} + \
intCodeTemplate % {\
"startLabel" : "longModeSoftInterrupt",
"gateCheckType" : "SoftIntGateCheck",
"errorCodeSize" : 0,
"errorCodeCode" : ""
} + \
intCodeTemplate % {\
"startLabel" : "longModeInterruptWithError",
"gateCheckType" : "IntGateCheck",
"errorCodeSize" : 8,
"errorCodeCode" : '''
st t15, hs, [1, t0, t6], dataSize=8, addressSize=8
'''
} + \
'''
def rom
{
# This vectors the CPU into an interrupt handler in legacy mode.
extern legacyModeInterrupt:
panic "Legacy mode interrupts not implemented (in microcode)"
eret
};
'''
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