#!/bin/sh
# -----------------------------------------------------------------------
# gentramp.sh - Copyright (c) 2010, Plausible Labs Cooperative, Inc.
#
# ARM Trampoline Page Generator
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# ``Software''), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be included
# in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED ``AS IS'', WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
# HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
# WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
# DEALINGS IN THE SOFTWARE.
# -----------------------------------------------------------------------
PROGNAME=$0
# Each trampoline is exactly 3 instructions, or 12 bytes. If any of these values change,
# the entire arm trampoline implementation must be updated to match, too.
# Size of an individual trampoline, in bytes
TRAMPOLINE_SIZE=12
# Page size, in bytes
PAGE_SIZE=4096
# Compute the size of the reachable config page; The first 16 bytes of the config page
# are unreachable due to our maximum pc-relative ldr offset.
PAGE_AVAIL=`expr $PAGE_SIZE - 16`
# Compute the number of of available trampolines.
TRAMPOLINE_COUNT=`expr $PAGE_AVAIL / $TRAMPOLINE_SIZE`
header () {
echo "# GENERATED CODE - DO NOT EDIT"
echo "# This file was generated by $PROGNAME"
echo ""
# Write out the license header
cat << EOF
# Copyright (c) 2010, Plausible Labs Cooperative, Inc.
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# ``Software''), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be included
# in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED ``AS IS'', WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
# HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
# WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
# DEALINGS IN THE SOFTWARE.
# -----------------------------------------------------------------------
EOF
# Write out the trampoline table, aligned to the page boundary
echo ".text"
echo ".align 12"
echo ".globl _ffi_closure_trampoline_table_page"
echo "_ffi_closure_trampoline_table_page:"
}
# WARNING - Don't modify the trampoline code size without also updating the relevant libffi code
trampoline () {
cat << END
// trampoline
// Save to stack
stmfd sp!, {r0-r3}
// Load the context argument from the config page.
// This places the first usable config value at _ffi_closure_trampoline_table-4080
// This accounts for the above 4-byte stmfd instruction, plus 8 bytes constant when loading from pc.
ldr r0, [pc, #-4092]
// Load the jump address from the config page.
ldr pc, [pc, #-4092]
END
}
main () {
# Write out the header
header
# Write out the trampolines
local i=0
while [ $i -lt ${TRAMPOLINE_COUNT} ]; do
trampoline
local i=`expr $i + 1`
done
}
main
