From 7a07c08abe46f97f2412f06c77204e9015f97a47 Mon Sep 17 00:00:00 2001 From: Michael Smith Date: Thu, 18 Dec 2025 21:35:50 +0000 Subject: 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. --- src/hook.c | 14 +++++--------- 1 file changed, 5 insertions(+), 9 deletions(-) (limited to 'src/hook.c') diff --git a/src/hook.c b/src/hook.c index 0355c18..baaa710 100644 --- a/src/hook.c +++ b/src/hook.c @@ -28,14 +28,9 @@ // Almost certainly breaks in some weird cases. Oh well! Most of the time, // vtable hooking is more reliable, this is only for, uh, emergencies. -static _Alignas(4096) uchar trampolines[4096]; -static uchar *curtrampoline = trampolines; - -bool hook_init() { - // PE doesn't support rwx sections, not sure about ELF. Meh, just set it - // here instead. - return os_mprot(trampolines, 4096, PAGE_EXECUTE_READWRITE); -} +#define SPACE 2048 // NOTE: MUST match SPACE in hook.S! +extern uchar _hook_trampolinespc[]; // defined in hook.S +static uchar *curtrampoline = _hook_trampolinespc; struct hook_inline_prep_ret hook_inline_prep(void *func, void **trampoline) { uchar *p = func; @@ -61,7 +56,8 @@ struct hook_inline_prep_ret hook_inline_prep(void *func, void **trampoline) { len += ilen; if (len >= 5) { // we should have statically made trampoline buffer size big enough - assume(curtrampoline - trampolines < sizeof(trampolines) - len - 6); + assume(curtrampoline - (uchar *)_hook_trampolinespc < + SPACE - len - 6); *curtrampoline = len; // stuff length in there for quick unhooking uchar *newtrampoline = curtrampoline + 1; curtrampoline += len + 6; -- cgit v1.2.3-54-g00ecf