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| author |  Michael Smith <mikesmiffy128@gmail.com>
| 2025-12-18 21:35:50 +0000 |
|---|---|---|
| committer | Michael Smith <mikesmiffy128@gmail.com>
| 2026-02-16 19:11:24 +0000 |
| commit | 7a07c08abe46f97f2412f06c77204e9015f97a47 (patch) | |
| tree | 581b80f55d7d66592fda98fb492d7465cc33f191 /src/con_.S | |
| parent | 186aea515dd773bb11464714886ca5203d2be2ab (diff) | |
| download | sst-7a07c08abe46f97f2412f06c77204e9015f97a47.tar.gz sst-7a07c08abe46f97f2412f06c77204e9015f97a47.zip | |
Move to a shared static RWX section
Does away with the need to mark a region as executable on load.
Also allows the self-modified stuff and hook trampolines to fit in the
same page, so we take up ever-so-slightly less memory.
Unfortunately I had issues getting the test binary to build correctly
and eventually decided to give up as it wasn't testing much of value
anyway.
Also note that the build now allows for .c and .S files with the same
basename, which required renaming the .o files, so you might want to
clean out your .build/ directory before building this one.
Diffstat (limited to 'src/con_.S')
| -rw-r--r-- | src/con_.S | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/src/con_.S b/src/con_.S new file mode 100644 index 0000000..0c6ec2d --- /dev/null +++ b/src/con_.S @@ -0,0 +1,45 @@ +/* + * Copyright © Michael Smith <mikesmiffy128@gmail.com> + * + * Permission to use, copy, modify, and/or distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED “AS IS” AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH + * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY + * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, + * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM + * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR + * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR + * PERFORMANCE OF THIS SOFTWARE. + */ + +#include "asm.h" + +// On Windows, _con_colourmsg is subject to selfmod() in con_.c which overwrites +// it with another implementation on OE; put it in rwx. On Linux, .text is fine. +#ifdef _WIN32 +.section ASM_RWX_SECTION, ASM_RWX_SECTION_FLAGS +#else +.section .text, "xr" +#endif +.globl ASM_MANGLE(_con_colourmsg) +.p2align 4 +ASM_MANGLE(_con_colourmsg): + // For some reason the assembler arbitrarily refuses to put instructions in + // a section marked as containing uninitialised data. So, we have to list + // out the instruction bytes manually here: + // mov eax, [_con_iface] + .byte 0xA1 + .long ASM_MANGLE(_con_iface) + // mov [esp + 4], eax // put coniface in the empty stack slot + .byte 0x89 + .byte 0x44 + .byte 0x24 + .byte 0x04 + // jmp dword ptr _con_colourmsgf // jump to the real function + .byte 0xFF + .byte 0x25 + .long ASM_MANGLE(_con_colourmsgf) + +// vi: sw=4 ts=4 noet tw=80 cc=80 |