Squashed 'third_party/elfutils/' content from commit 555e15e
Change-Id: I61cde98949e47e5c8c09c33260de17f30921be79
git-subtree-dir: third_party/elfutils
git-subtree-split: 555e15ebe8bf1eb33d00747173cfc80cc65648a4
diff --git a/backends/s390_unwind.c b/backends/s390_unwind.c
new file mode 100644
index 0000000..752bc28
--- /dev/null
+++ b/backends/s390_unwind.c
@@ -0,0 +1,139 @@
+/* Get previous frame state for an existing frame state.
+ Copyright (C) 2013 Red Hat, Inc.
+ This file is part of elfutils.
+
+ This file is free software; you can redistribute it and/or modify
+ it under the terms of either
+
+ * the GNU Lesser General Public License as published by the Free
+ Software Foundation; either version 3 of the License, or (at
+ your option) any later version
+
+ or
+
+ * 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
+
+ or both in parallel, as here.
+
+ elfutils 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 copies of the GNU General Public License and
+ the GNU Lesser General Public License along with this program. If
+ not, see <http://www.gnu.org/licenses/>. */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <stdlib.h>
+#include <assert.h>
+
+#define BACKEND s390_
+#include "libebl_CPU.h"
+
+/* s390/s390x do not annotate signal handler frame by CFI. It would be also
+ difficult as PC points into a stub built on stack. Function below is called
+ only if unwinder could not find CFI. Function then verifies the register
+ state for this frame really belongs to a signal frame. In such case it
+ fetches original registers saved by the signal frame. */
+
+bool
+s390_unwind (Ebl *ebl, Dwarf_Addr pc, ebl_tid_registers_t *setfunc,
+ ebl_tid_registers_get_t *getfunc, ebl_pid_memory_read_t *readfunc,
+ void *arg, bool *signal_framep)
+{
+ /* Caller already assumed caller adjustment but S390 instructions are 4 bytes
+ long. Undo it. */
+ if ((pc & 0x3) != 0x3)
+ return false;
+ pc++;
+ /* We can assume big-endian read here. */
+ Dwarf_Word instr;
+ if (! readfunc (pc, &instr, arg))
+ return false;
+ /* Fetch only the very first two bytes. */
+ instr = (instr >> (ebl->class == ELFCLASS64 ? 48 : 16)) & 0xffff;
+ /* See GDB s390_sigtramp_frame_sniffer. */
+ /* Check for 'svc' as the first instruction. */
+ if (((instr >> 8) & 0xff) != 0x0a)
+ return false;
+ /* Check for 'sigreturn' or 'rt_sigreturn' as the second instruction. */
+ if ((instr & 0xff) != 119 && (instr & 0xff) != 173)
+ return false;
+ /* See GDB s390_sigtramp_frame_unwind_cache. */
+ Dwarf_Word this_sp;
+ if (! getfunc (0 + 15, 1, &this_sp, arg))
+ return false;
+ unsigned word_size = ebl->class == ELFCLASS64 ? 8 : 4;
+ Dwarf_Addr next_cfa = this_sp + 16 * word_size + 32;
+ /* "New-style RT frame" is not supported,
+ assuming "Old-style RT frame and all non-RT frames".
+ Pointer to the array of saved registers is at NEXT_CFA + 8. */
+ Dwarf_Word sigreg_ptr;
+ if (! readfunc (next_cfa + 8, &sigreg_ptr, arg))
+ return false;
+ /* Skip PSW mask. */
+ sigreg_ptr += word_size;
+ /* Read PSW address. */
+ Dwarf_Word val;
+ if (! readfunc (sigreg_ptr, &val, arg))
+ return false;
+ if (! setfunc (-1, 1, &val, arg))
+ return false;
+ sigreg_ptr += word_size;
+ /* Then the GPRs. */
+ Dwarf_Word gprs[16];
+ for (int i = 0; i < 16; i++)
+ {
+ if (! readfunc (sigreg_ptr, &gprs[i], arg))
+ return false;
+ sigreg_ptr += word_size;
+ }
+ /* Then the ACRs. Skip them, they are not used in CFI. */
+ for (int i = 0; i < 16; i++)
+ sigreg_ptr += 4;
+ /* The floating-point control word. */
+ sigreg_ptr += 8;
+ /* And finally the FPRs. */
+ Dwarf_Word fprs[16];
+ for (int i = 0; i < 16; i++)
+ {
+ if (! readfunc (sigreg_ptr, &val, arg))
+ return false;
+ if (ebl->class == ELFCLASS32)
+ {
+ Dwarf_Addr val_low;
+ if (! readfunc (sigreg_ptr + 4, &val_low, arg))
+ return false;
+ val = (val << 32) | val_low;
+ }
+ fprs[i] = val;
+ sigreg_ptr += 8;
+ }
+ /* If we have them, the GPR upper halves are appended at the end. */
+ if (ebl->class == ELFCLASS32)
+ {
+ /* Skip signal number. */
+ sigreg_ptr += 4;
+ for (int i = 0; i < 16; i++)
+ {
+ if (! readfunc (sigreg_ptr, &val, arg))
+ return false;
+ Dwarf_Word val_low = gprs[i];
+ val = (val << 32) | val_low;
+ gprs[i] = val;
+ sigreg_ptr += 4;
+ }
+ }
+ if (! setfunc (0, 16, gprs, arg))
+ return false;
+ if (! setfunc (16, 16, fprs, arg))
+ return false;
+ *signal_framep = true;
+ return true;
+}