branch trick for PowerPC32

committer: jreiser <jreiser> 1108863063 +0000
2025-09-28 19:06:07 +08:00 · 2005-02-20 01:31:03 +00:00 · 2005-02-20 01:31:03 +00:00 · c933974174
commit c933974174
parent 19715903fb
1 changed files with 153 additions and 0 deletions
--- a/src/filter/ppcbxx.h
+++ b/src/filter/ppcbxx.h
@ -0,0 +1,153 @@
+/* ppcbxx.h -- PowerPC Branch trick
+
+   This file is part of the UPX executable compressor.
+
+   Copyright (C) 1996-2004 Markus Franz Xaver Johannes Oberhumer
+   Copyright (C) 1996-2004 Laszlo Molnar
+   Copyright (C) 2004-2005 John F. Reiser
+   All Rights Reserved.
+
+   UPX and the UCL library are free software; you can redistribute them
+   and/or modify them under the terms of the GNU General Public License as
+   published by the Free Software Foundation; either version 2 of
+   the License, or (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; see the file COPYING.
+   If not, write to the Free Software Foundation, Inc.,
+   59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+
+   Markus F.X.J. Oberhumer              Laszlo Molnar
+   <mfx@users.sourceforge.net>          <ml1050@users.sourceforge.net>
+
+   John F. Reiser
+   <jreiser@users.sourceforge.net>
+ */
+
+
+
+/*************************************************************************
+// filter / scan
+**************************************************************************/
+
+#define W_CTO 4  /* width of cto; must match stub/ppc_bxx.S */
+
+static int F(Filter *f)
+{
+#ifdef U
+    // filter
+    upx_byte *b = f->buf;
+    const unsigned addvalue = f->addvalue;
+#else
+    // scan
+    const upx_byte *b = f->buf;
+#endif
+    const unsigned size = f->buf_len;
+
+    unsigned ic;
+    unsigned calls = 0, noncalls = 0;
+    unsigned lastnoncall = size, lastcall = 0;
+
+    // find 26-2-W_CTO bits of displacements that contain no targets
+    {
+        unsigned char buf[256];
+        unsigned short wbuf[256];
+        memset(wbuf, 0, sizeof(wbuf));
+        memset(buf              , 0,      -(~0<<W_CTO));
+        memset(buf - (~0<<W_CTO), 1, 256 + (~0<<W_CTO));
+
+        for (ic = 0; ic < size - 4; ic+=4) if (COND(b,ic)) {
+            unsigned const off = (int)(get_be32(b+ic)<<6) >>6;
+            if (size <= (off & (~0<<2))+ic) {
+                buf[(~(~0<<W_CTO)) & (off>>(26 - W_CTO))] |= 1;
+                ++wbuf[0xff&(off>>18)];
+            }
+        }
+
+        if (getcto(f, buf) < 0) {
+            if (0!=W_CTO)
+                return -1;
+            f->cto = 0;
+        }
+    }
+    const unsigned char cto8 = f->cto;
+#ifdef U
+    const unsigned cto = (unsigned)f->cto << (24+2 - W_CTO);
+#endif
+
+    for (ic = 0; ic < size - 4; ic+=4) if (COND(b,ic)) {
+        unsigned const word = get_be32(b+ic);
+        unsigned const off = (int)(word<<6) >>6;
+        unsigned const jc = (off & (~0<<2))+ic;
+        // try to detect 'real' calls only
+        if (jc < size) {
+#ifdef U
+            set_be32(b+ic,(0xfc000003&word) | (jc+addvalue+cto));
+#endif
+            calls++;
+            lastcall = ic;
+        }
+        else {
+            assert(0==W_CTO
+            || (~(~0<<W_CTO) & (word>>(24+2 - W_CTO))) != cto8);  // this should not happen
+            lastnoncall = ic;
+            noncalls++;
+        }
+    }
+
+    f->calls = calls;
+    f->noncalls = noncalls;
+    f->lastcall = lastcall;
+
+#if 1
+    printf("\ncalls=%d noncalls=%d text_size=%x calltrickoffset=%x\n",
+        calls,noncalls,size,cto8);
+#endif
+    return 0;
+}
+
+
+/*************************************************************************
+// unfilter
+**************************************************************************/
+
+#ifdef U
+static int U(Filter *f)
+{
+    upx_byte *b = f->buf;
+    const unsigned size4 = f->buf_len - 4;
+    const unsigned addvalue = f->addvalue;
+
+    unsigned ic;
+
+   for (ic = 0; ic < size4; ic+=4) if (COND(b,ic)) {
+        unsigned const word = get_be32(b+ic);
+        if ((~(~0<<W_CTO) & (word>>(24+2 - W_CTO))) == f->cto) {
+            unsigned const jc = word & (~(~0<<(26 - W_CTO)) & (~0<<2));
+            set_be32(b+ic, (0xfc000003&word)|(0x03fffffc&(jc-ic-addvalue)));
+            f->calls++;
+            f->lastcall = ic;
+        }
+        else {
+            f->noncalls++;
+        }
+    }
+    return 0;
+}
+#endif
+
+
+#undef F
+#undef U
+
+#undef W_CTO
+
+/*
+vi:ts=4:et:nowrap
+*/
+