blockimp_arm.tramp

#!/bin/sh

# -----------------------------------------------------------------------
#  Copyright (c) 2010-2011, Plausible Labs Cooperative, Inc.
#  All Rights Reserved.
# 
#  Permission is hereby granted, free of charge, to any person obtaining
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#  ``Software''), to deal in the Software without restriction, including
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#  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
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#  -----------------------------------------------------------------------

# Architecture definitions. We support either armv6 or armv7
if [ "${CURRENT_ARCH}" = "armv6" ] || [ "${CURRENT_ARCH}" = "armv7" ]; then
    ARCH="${CURRENT_ARCH}"
else
    ARCH=""
fi

PAGE_SIZE="4096"

# The name of this page
PAGE_NAME=pl_blockimp_table_page

# Prefix to be placed at the start of the trampoline page
trampoline_prefix () {
asm << 'EOF'
    _block_tramp_dispatch:
        # trampoline address+8 is in r12 -- calculate our config page address
        sub r12, #0x8
        sub r12, #0x1000
        
        # Set the 'self' argument as the second argument
        mov r1, r0
        
        # Load the block pointer as the first argument
        ldr r0, [r12]

        # Jump to the block pointer
        ldr pc, [r0, #0xc]
EOF
}

# Generate a single trampoline
trampoline () {
asm << 'EOF'
    # Save pc+8, then jump to the shared prefix implementation
    mov r12, pc
    b _block_tramp_dispatch;
EOF
}