--- /dev/null
+/* Subroutine for function pointer canonicalization on PA-RISC with ELF32.
+ Copyright 2002, 2003, 2004, 2007, 2009 Free Software Foundation, Inc.
+ Contributed by John David Anglin (dave.anglin@nrc.ca).
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 3, or (at your option) any later
+version.
+
+GCC 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.
+
+Under Section 7 of GPL version 3, you are granted additional
+permissions described in the GCC Runtime Library Exception, version
+3.1, as published by the Free Software Foundation.
+
+You should have received a copy of the GNU General Public License and
+a copy of the GCC Runtime Library Exception along with this program;
+see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
+<http://www.gnu.org/licenses/>. */
+
+
+/* WARNING: The code is this function depends on internal and undocumented
+ details of the GNU linker and dynamic loader as implemented for parisc
+ linux. */
+
+/* This MUST match the defines sysdeps/hppa/dl-machine.h and
+ bfd/elf32-hppa.c. */
+#define GOT_FROM_PLT_STUB (4*4)
+
+/* List of byte offsets in _dl_runtime_resolve to search for "bl" branches.
+ The first "bl" branch instruction found MUST be a call to fixup. See
+ the define for TRAMPOLINE_TEMPLATE in sysdeps/hppa/dl-machine.h. If
+ the trampoline template is changed, the list must be appropriately
+ updated. The offset of -4 allows for a magic branch at the start of
+ the template should it be necessary to change the current branch
+ position. */
+#define NOFFSETS 2
+static int fixup_branch_offset[NOFFSETS] = { 32, -4 };
+
+#define GET_FIELD(X, FROM, TO) \
+ ((X) >> (31 - (TO)) & ((1 << ((TO) - (FROM) + 1)) - 1))
+#define SIGN_EXTEND(VAL,BITS) \
+ ((int) ((VAL) >> ((BITS) - 1) ? (-1 << (BITS)) | (VAL) : (VAL)))
+
+struct link_map;
+typedef int (*fptr_t) (void);
+typedef int (*fixup_t) (struct link_map *, unsigned int);
+extern unsigned int _GLOBAL_OFFSET_TABLE_;
+
+/* __canonicalize_funcptr_for_compare must be hidden so that it is not
+ placed in the dynamic symbol table. Like millicode functions, it
+ must be linked into all binaries in order access the got table of
+ that binary. However, we don't use the millicode calling convention
+ and the routine must be a normal function so that it can be compiled
+ as pic code. */
+unsigned int __canonicalize_funcptr_for_compare (fptr_t)
+ __attribute__ ((visibility ("hidden")));
+
+unsigned int
+__canonicalize_funcptr_for_compare (fptr_t fptr)
+{
+ static unsigned int fixup_plabel[2];
+ static fixup_t fixup;
+ unsigned int *plabel, *got;
+
+ /* -1 and page 0 are special. -1 is used in crtend to mark the end of
+ a list of function pointers. Also return immediately if the plabel
+ bit is not set in the function pointer. In this case, the function
+ pointer points directly to the function. */
+ if ((int) fptr == -1 || (unsigned int) fptr < 4096 || !((int) fptr & 2))
+ return (unsigned int) fptr;
+
+ /* The function pointer points to a function descriptor (plabel). If
+ the plabel hasn't been resolved, the first word of the plabel points
+ to the entry of the PLT stub just before the global offset table.
+ The second word in the plabel contains the relocation offset for the
+ function. */
+ plabel = (unsigned int *) ((unsigned int) fptr & ~3);
+ got = (unsigned int *) (plabel[0] + GOT_FROM_PLT_STUB);
+
+ /* Return the address of the function if the plabel has been resolved. */
+ if (got != &_GLOBAL_OFFSET_TABLE_)
+ return plabel[0];
+
+ /* Initialize our plabel for calling fixup if we haven't done so already.
+ This code needs to be thread safe but we don't have to be too careful
+ as the result is invariant. */
+ if (!fixup)
+ {
+ int i;
+ unsigned int *iptr;
+
+ /* Find the first "bl" branch in the offset search list. This is a
+ call to fixup or a magic branch to fixup at the beginning of the
+ trampoline template. The fixup function does the actual runtime
+ resolution of function descriptors. We only look for "bl" branches
+ with a 17-bit pc-relative displacement. */
+ for (i = 0; i < NOFFSETS; i++)
+ {
+ iptr = (unsigned int *) (got[-2] + fixup_branch_offset[i]);
+ if ((*iptr & 0xfc00e000) == 0xe8000000)
+ break;
+ }
+
+ /* This should not happen... */
+ if (i == NOFFSETS)
+ return ~0;
+
+ /* Extract the 17-bit displacement from the instruction. */
+ iptr += SIGN_EXTEND (GET_FIELD (*iptr, 19, 28) |
+ GET_FIELD (*iptr, 29, 29) << 10 |
+ GET_FIELD (*iptr, 11, 15) << 11 |
+ GET_FIELD (*iptr, 31, 31) << 16, 17);
+
+ /* Build a plabel for an indirect call to fixup. */
+ fixup_plabel[0] = (unsigned int) iptr + 8; /* address of fixup */
+ fixup_plabel[1] = got[-1]; /* ltp for fixup */
+ fixup = (fixup_t) ((int) fixup_plabel | 3);
+ }
+
+ /* Call fixup to resolve the function address. got[1] contains the
+ link_map pointer and plabel[1] the relocation offset. */
+ fixup ((struct link_map *) got[1], plabel[1]);
+
+ return plabel[0];
+}
projects / msp430-gcc.git / blobdiff