diff options
| -rw-r--r-- | scripts/vgafixup.py | 61 | ||||
| -rw-r--r-- | vgasrc/vgaentry.S | 24 |
2 files changed, 59 insertions, 26 deletions
diff --git a/scripts/vgafixup.py b/scripts/vgafixup.py index a981bbf..2053cd5 100644 --- a/scripts/vgafixup.py +++ b/scripts/vgafixup.py @@ -7,8 +7,8 @@ # The x86emu code widely used in Linux distributions when running Xorg # in vesamode is known to have issues with "retl", "leavel", "entryl", -# and some variants of "calll". This code modifies those instructions -# (ret and leave) that are known to be generated by gcc to avoid +# "leal", and some variants of "calll". This code modifies those +# instructions that are known to be generated by gcc to avoid # triggering the x86emu bugs. # It is also known that the Windows vgabios emulator has issues with @@ -16,7 +16,59 @@ # worked around by not using the gcc parameter "-fomit-frame-pointer" # when compiling. -import sys +import sys, re + +# leal parameter regex - example string: -3(%edx,%eax,8), %eax +re_leal = re.compile( + r'^\s*(?P<offset>[^(]*?)\s*' + r'\(\s*(?P<base>[^,)]*?)\s*(?:,\s*(?P<index>[^,)]*?)\s*)?' + r'(?:,\s*(?P<scale>[^,)]*?)\s*)?\)\s*' + r',\s*(?P<dest>.*?)\s*$') + +# Find an alternate set of instructions for a given "leal" instruction +def handle_leal(sline): + m = re_leal.match(sline[5:]) + if m is None or m.group('index') == '%esp': + print("Unable to fixup leal instruction: %s" % (sline,)) + sys.exit(-1) + offset, base, index, scale, dest = m.group( + 'offset', 'base', 'index', 'scale', 'dest') + if dest == '%esp': + # If destination is %esp then just use 16bit leaw instead + return 'leaw %s\n' % (sline[5:].replace('%e', '%'),) + if not scale: + scale = '1' + scale = {1: 0, 2: 1, 4: 2, 8: 3}[int(scale, 0)] + # Try to rearrange arguments to simplify 'base' (to improve code gen) + if not scale and base == index: + base, index, scale = '', index, 1 + elif not index or (not scale and base in (dest, '%esp') and index != dest): + base, index, scale = index, base, 0 + # Produce instructions to calculate "leal" + insns = ['pushfw'] + if base != dest: + # Calculate "leal" directly in dest register + if index != dest: + insns.insert(0, 'movl %s, %s' % (index, dest)) + if scale: + insns.append('shll $%d, %s' % (scale, dest)) + if base: + if base == '%esp': + offset += '+2' + insns.append('addl %s, %s' % (base, dest)) + elif base == index: + # Use "imull" method + insns.append('imull $%d, %s' % ((1<<scale)+1, dest)) + else: + # Backup/restore index register and do scaling in index register + insns.append('pushl %s' % (index,)) + insns.append('shll $%d, %s' % (scale, index)) + insns.append('addl %s, %s' % (index, dest)) + insns.append('popl %s' % (index,)) + if offset and offset != '0': + insns.append('addl $%s, %s' % (offset, dest)) + insns.append('popfw\n') + return ' ; '.join(insns) def main(): infilename, outfilename = sys.argv[1:] @@ -30,6 +82,9 @@ def main(): out.append('movl %ebp, %esp ; popl %ebp\n') elif sline.startswith('call'): out.append('pushw %ax ; callw' + sline[4:] + '\n') + elif sline.startswith('leal'): + out.append(handle_leal(sline)) + #print("-> %s\n %s" % (sline, out[-1].strip())) else: out.append(line) infile.close() diff --git a/vgasrc/vgaentry.S b/vgasrc/vgaentry.S index 7ca550d..53be2b3 100644 --- a/vgasrc/vgaentry.S +++ b/vgasrc/vgaentry.S @@ -45,33 +45,11 @@ _rom_header_signature: * Entry points ****************************************************************/ - // Force a fault if found to be running on broken x86emu versions. - DECLFUNC x86emu_fault -msg: .ascii "SeaVGABIOS: x86emu leal trap!\n" -x86emu_fault: -#if CONFIG_DEBUG_IO - movw %cs:DebugOutputPort, %dx - movw $msg, %si -1: movb %cs:(%si), %al - outb %al, (%dx) - incw %si - cmpw $x86emu_fault, %si - jl 1b -#endif -1: hlt - jmp 1b - // This macro implements a call while avoiding instructions // that old versions of x86emu have problems with. .macro VGA_CALLL cfunc #if CONFIG_VGA_FIXUP_ASM - // Make sure leal instruction works. - movl $0x8000, %ecx - leal (%ecx, %ecx, 1), %ecx - cmpl $0x10000, %ecx - jne x86emu_fault - // Use callw instead of calll - push %ax + pushw %ax callw \cfunc #else calll \cfunc |