On Mon, Mar 05, 2012 at 04:41:27PM +0000, Julian Pidancet wrote:
On Mon, Mar 5, 2012 at 4:21 PM, Kevin O'Connor <kevin@koconnor.net> wrote:
On Mon, Mar 05, 2012 at 04:05:11PM +0000, Julian Pidancet wrote:
Replacing instructions and handling displacement is probably going to be a huge pain.
I don't think that will be an issue. One can tell gcc to generate assembler and then post-process that. The gcc created assembler is still label based so no positional issues should arise.
Yes you're right. Post-processing the intermediate assembly will definitely be a huge win.
I put together the below as a quick hack. It boots to DOS okay. I'm not sure the exact test case for x86emu and I didn't test that. It's just a quick hack, but it should highlight the idea. -Kevin diff --git a/Makefile b/Makefile index 5d834b7..6cba6d5 100644 --- a/Makefile +++ b/Makefile @@ -31,7 +31,7 @@ COMMONCFLAGS = -I$(OUT) -Os -MD -g \ -Wall -Wno-strict-aliasing -Wold-style-definition \ $(call cc-option,$(CC),-Wtype-limits,) \ -m32 -march=i386 -mregparm=3 -mpreferred-stack-boundary=2 \ - -mrtd -minline-all-stringops \ + -minline-all-stringops \ -freg-struct-return -ffreestanding -fno-delete-null-pointer-checks \ -ffunction-sections -fdata-sections -fno-common COMMONCFLAGS += $(call cc-option,$(CC),-nopie,) @@ -193,7 +193,12 @@ SRCVGA=src/output.c src/util.c src/pci.c \ CFLAGS16VGA = $(CFLAGS16INC) -Isrc -$(OUT)vgaccode16.o: $(OUT)autoconf.h ; $(call whole-compile, $(CFLAGS16VGA), $(SRCVGA),$@) +$(OUT)vgaccode16.raw.s: $(OUT)autoconf.h ; $(call whole-compile, $(CFLAGS16VGA) -S, $(SRCVGA),$@) + +$(OUT)vgaccode16.o: $(OUT)vgaccode16.raw.s + @echo " Fixup VGA rom assembler" + $(Q)$(PYTHON) ./tools/vgafixup.py $< $(OUT)vgaccode16.s + $(Q)as --32 src/code16gcc.s $(OUT)vgaccode16.s -o $@ $(OUT)vgaentry.o: vgaentry.S $(OUT)autoconf.h @echo " Compiling (16bit) $@" diff --git a/tools/vgafixup.py b/tools/vgafixup.py new file mode 100644 index 0000000..db37037 --- /dev/null +++ b/tools/vgafixup.py @@ -0,0 +1,28 @@ +#!/usr/bin/env python +# Work around x86emu bugs by replacing problematic instructions. +# +# Copyright (C) 2012 Kevin O'Connor <kevin@koconnor.net> +# +# This file may be distributed under the terms of the GNU GPLv3 license. + +import sys + +def main(): + infilename, outfilename = sys.argv[1:] + infile = open(infilename, 'rb') + out = [] + for line in infile: + sline = line.strip() + if sline == 'ret': + out.append('retw $2\n') + elif sline == 'leave': + out.append('movl %ebp, %esp ; popl %ebp\n') + else: + out.append(line) + infile.close() + outfile = open(outfilename, 'wb') + outfile.write(''.join(out)) + outfile.close() + +if __name__ == '__main__': + main() diff --git a/vgasrc/clext.c b/vgasrc/clext.c index e5dce35..fc5459a 100644 --- a/vgasrc/clext.c +++ b/vgasrc/clext.c @@ -526,7 +526,7 @@ ASM16( "a0h_callback:" "cli\n" "hlt\n" - "retf"); + "lretw"); static void clext_1012a0(struct bregs *regs)
On Mon, Mar 5, 2012 at 5:18 PM, Kevin O'Connor <kevin@koconnor.net> wrote:
On Mon, Mar 05, 2012 at 04:41:27PM +0000, Julian Pidancet wrote:
On Mon, Mar 5, 2012 at 4:21 PM, Kevin O'Connor <kevin@koconnor.net> wrote:
On Mon, Mar 05, 2012 at 04:05:11PM +0000, Julian Pidancet wrote:
Replacing instructions and handling displacement is probably going to be a huge pain.
I don't think that will be an issue. One can tell gcc to generate assembler and then post-process that. The gcc created assembler is still label based so no positional issues should arise.
Yes you're right. Post-processing the intermediate assembly will definitely be a huge win.
I put together the below as a quick hack. It boots to DOS okay. I'm not sure the exact test case for x86emu and I didn't test that. It's just a quick hack, but it should highlight the idea.
-Kevin
diff --git a/Makefile b/Makefile index 5d834b7..6cba6d5 100644 --- a/Makefile +++ b/Makefile @@ -31,7 +31,7 @@ COMMONCFLAGS = -I$(OUT) -Os -MD -g \ -Wall -Wno-strict-aliasing -Wold-style-definition \ $(call cc-option,$(CC),-Wtype-limits,) \ -m32 -march=i386 -mregparm=3 -mpreferred-stack-boundary=2 \ - -mrtd -minline-all-stringops \ + -minline-all-stringops \ -freg-struct-return -ffreestanding -fno-delete-null-pointer-checks \ -ffunction-sections -fdata-sections -fno-common COMMONCFLAGS += $(call cc-option,$(CC),-nopie,) @@ -193,7 +193,12 @@ SRCVGA=src/output.c src/util.c src/pci.c \
CFLAGS16VGA = $(CFLAGS16INC) -Isrc
-$(OUT)vgaccode16.o: $(OUT)autoconf.h ; $(call whole-compile, $(CFLAGS16VGA), $(SRCVGA),$@) +$(OUT)vgaccode16.raw.s: $(OUT)autoconf.h ; $(call whole-compile, $(CFLAGS16VGA) -S, $(SRCVGA),$@) + +$(OUT)vgaccode16.o: $(OUT)vgaccode16.raw.s + @echo " Fixup VGA rom assembler" + $(Q)$(PYTHON) ./tools/vgafixup.py $< $(OUT)vgaccode16.s + $(Q)as --32 src/code16gcc.s $(OUT)vgaccode16.s -o $@
$(OUT)vgaentry.o: vgaentry.S $(OUT)autoconf.h @echo " Compiling (16bit) $@" diff --git a/tools/vgafixup.py b/tools/vgafixup.py new file mode 100644 index 0000000..db37037 --- /dev/null +++ b/tools/vgafixup.py @@ -0,0 +1,28 @@ +#!/usr/bin/env python +# Work around x86emu bugs by replacing problematic instructions. +# +# Copyright (C) 2012 Kevin O'Connor <kevin@koconnor.net> +# +# This file may be distributed under the terms of the GNU GPLv3 license. + +import sys + +def main(): + infilename, outfilename = sys.argv[1:] + infile = open(infilename, 'rb') + out = [] + for line in infile: + sline = line.strip() + if sline == 'ret': + out.append('retw $2\n') + elif sline == 'leave': + out.append('movl %ebp, %esp ; popl %ebp\n') + else: + out.append(line) + infile.close() + outfile = open(outfilename, 'wb') + outfile.write(''.join(out)) + outfile.close() + +if __name__ == '__main__': + main() diff --git a/vgasrc/clext.c b/vgasrc/clext.c index e5dce35..fc5459a 100644 --- a/vgasrc/clext.c +++ b/vgasrc/clext.c @@ -526,7 +526,7 @@ ASM16( "a0h_callback:" "cli\n" "hlt\n" - "retf"); + "lretw");
static void clext_1012a0(struct bregs *regs)
Great job ! I just tried you patch and it seems to do the job. I am not using the latest master branch though, so it would be good to have a confirmation that it works fine by someone else. Thanks for working so quickly. I think you can ship it. PS: I identified why Xorg was complaining about the ROM checksum, and recently posted a trivial patch to fix it. Could you have a look at this one ? -- Julian
On 03/05/12 18:18, Kevin O'Connor wrote:
I put together the below as a quick hack. It boots to DOS okay. I'm not sure the exact test case for x86emu and I didn't test that. It's just a quick hack, but it should highlight the idea.
Gets Xorg going as-is, looks like it catches all critical instructions are catched already. cheers, Gerd
participants (3)
-
Gerd Hoffmann -
Julian Pidancet -
Kevin O'Connor