unwinder: s390 and s390x

Signed-off-by: Jan Kratochvil <[email protected]>

6 files changed, 253 insertions, 6 deletions

diff --git a/backends/ChangeLog b/backends/ChangeLog
index dc960485..cb56d217 100644
--- a/backends/ChangeLog
+++ b/backends/ChangeLog
@@ -1,3 +1,14 @@
+2013-12-18  Jan Kratochvil  <[email protected]>
+
+	unwinder: s390 and s390x
+	* Makefile.am (s390_SRCS): Add s390_initreg.c and s390_unwind.c.
+	* s390_corenote.c (prstatus_regs): Set PC_REGISTER.  Reindent all the
+	entries.
+	* s390_init.c (s390_init): Initialize frame_nregs,
+	set_initial_registers_tid, normalize_pc and unwind.
+	* s390_initreg.c: New file.
+	* s390_unwind.c: New file.
+
 2013-12-15  Jan Kratochvil  <[email protected]>
 
 	unwinder: ppc and ppc64
diff --git a/backends/Makefile.am b/backends/Makefile.am
index 4752a643..ec9e0a3c 100644
--- a/backends/Makefile.am
+++ b/backends/Makefile.am
@@ -106,7 +106,8 @@ libebl_ppc64_pic_a_SOURCES = $(ppc64_SRCS)
 am_libebl_ppc64_pic_a_OBJECTS = $(ppc64_SRCS:.c=.os)
 
 s390_SRCS = s390_init.c s390_symbol.c s390_regs.c s390_retval.c \
-	    s390_corenote.c s390x_corenote.c s390_cfi.c
+	    s390_corenote.c s390x_corenote.c s390_cfi.c s390_initreg.c \
+	    s390_unwind.c
 libebl_s390_pic_a_SOURCES = $(s390_SRCS)
 am_libebl_s390_pic_a_OBJECTS = $(s390_SRCS:.c=.os)
 
diff --git a/backends/s390_corenote.c b/backends/s390_corenote.c
index b88c05cf..7ca35168 100644
--- a/backends/s390_corenote.c
+++ b/backends/s390_corenote.c
@@ -47,13 +47,13 @@
 
 static const Ebl_Register_Location prstatus_regs[] =
   {
-#define GR(at, n, dwreg, b)						\
+#define GR(at, n, dwreg, b...)						\
     { .offset = at * BITS/8, .regno = dwreg, .count = n, .bits = b }
 
-    GR ( 0,  1, 64, BITS),		/* pswm */
-    GR ( 1,  1, 65, BITS),		/* pswa */
-    GR ( 2, 16,  0, BITS),		/* r0-r15 */
-    GR (18, 16, 48,   32),		/* ar0-ar15 */
+    GR ( 0,  1, 64, BITS),				/* pswm */
+    GR ( 1,  1, 65, BITS, .pc_register = true ),	/* pswa */
+    GR ( 2, 16,  0, BITS),				/* r0-r15 */
+    GR (18, 16, 48,   32),				/* ar0-ar15 */
 
 #undef	GR
   };
diff --git a/backends/s390_init.c b/backends/s390_init.c
index 630a2ee3..26b20b49 100644
--- a/backends/s390_init.c
+++ b/backends/s390_init.c
@@ -62,6 +62,15 @@ s390_init (elf, machine, eh, ehlen)
   else
     HOOK (eh, core_note);
   HOOK (eh, abi_cfi);
+  /* gcc/config/ #define DWARF_FRAME_REGISTERS 34.
+     But from the gcc/config/s390/s390.h "Register usage." comment it looks as
+     if #32 (Argument pointer) and #33 (Condition code) are not used for
+     unwinding.  */
+  eh->frame_nregs = 32;
+  HOOK (eh, set_initial_registers_tid);
+  if (eh->class == ELFCLASS32)
+    HOOK (eh, normalize_pc);
+  HOOK (eh, unwind);
 
   /* Only the 64-bit format uses the incorrect hash table entry size.  */
   if (eh->class == ELFCLASS64)
diff --git a/backends/s390_initreg.c b/backends/s390_initreg.c
new file mode 100644
index 00000000..62a1531e
--- /dev/null
+++ b/backends/s390_initreg.c
@@ -0,0 +1,87 @@
+/* Fetch live process registers from TID.
+   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 "system.h"
+#include <assert.h>
+#ifdef __s390__
+# include <sys/user.h>
+# include <asm/ptrace.h>
+# include <sys/ptrace.h>
+#endif
+
+#define BACKEND s390_
+#include "libebl_CPU.h"
+
+bool
+s390_set_initial_registers_tid (pid_t tid __attribute__ ((unused)),
+			  ebl_tid_registers_t *setfunc __attribute__ ((unused)),
+				void *arg __attribute__ ((unused)))
+{
+#ifndef __s390__
+  return false;
+#else /* __s390__ */
+  struct user user_regs;
+  ptrace_area parea;
+  parea.process_addr = (uintptr_t) &user_regs;
+  parea.kernel_addr = 0;
+  parea.len = sizeof (user_regs);
+  if (ptrace (PTRACE_PEEKUSR_AREA, tid, &parea, NULL) != 0)
+    return false;
+  /* If we run as s390x we get the 64-bit registers of tid.
+     But -m31 executable seems to use only the 32-bit parts of its
+     registers so we ignore the upper half.  */
+  Dwarf_Word dwarf_regs[16];
+  for (unsigned u = 0; u < 16; u++)
+    dwarf_regs[u] = user_regs.regs.gprs[u];
+  if (! setfunc (0, 16, dwarf_regs, arg))
+    return false;
+  /* Avoid conversion double -> integer.  */
+  eu_static_assert (sizeof user_regs.regs.fp_regs.fprs[0]
+		    == sizeof dwarf_regs[0]);
+  for (unsigned u = 0; u < 16; u++)
+    dwarf_regs[u] = *((const __typeof (dwarf_regs[0]) *)
+		      &user_regs.regs.fp_regs.fprs[u]);
+  if (! setfunc (16, 16, dwarf_regs, arg))
+    return false;
+  dwarf_regs[0] = user_regs.regs.psw.addr;
+  return setfunc (-1, 1, dwarf_regs, arg);
+#endif /* __s390__ */
+}
+
+void
+s390_normalize_pc (Ebl *ebl __attribute__ ((unused)), Dwarf_Addr *pc)
+{
+  assert (ebl->class == ELFCLASS32);
+
+  /* Clear S390 bit 31.  */
+  *pc &= (1U << 31) - 1;
+}
diff --git a/backends/s390_unwind.c b/backends/s390_unwind.c
new file mode 100644
index 00000000..752bc287
--- /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;
+}