base/SOURCES/gdb-rhbz1086894-incomplete-bt-coredump-signal-handler.patch

commit f2205de0080d999c9b67872c9db471c31b53e378
Author: Hui Zhu <teawater@gmail.com>
Date:   Tue May 20 13:19:06 2014 +0800

    Fix issue #15778: GDB Aarch64 signal frame unwinder issue
    
    The root cause of this issue is unwinder of "#3  <signal handler called>"
    doesn't supply right values of registers.
    When GDB want to get the previous frame of "#3  <signal handler called>",
    it will call cache init function of unwinder "aarch64_linux_sigframe_init".
    The address or the value of the registers is get from this function.
    So the bug is inside thie function.
    
    I check the asm code of "#3  <signal handler called>":
    (gdb) frame 3
    (gdb) p $pc
    $1 = (void (*)()) 0x7f931fa4d0
    (gdb) disassemble $pc, +10
    Dump of assembler code from 0x7f931fa4d0 to 0x7f931fa4da:
    => 0x0000007f931fa4d0:	mov	x8, #0x8b                  	// #139
       0x0000007f931fa4d4:	svc	#0x0
       0x0000007f931fa4d8:	nop
    
    This is the syscall sys_rt_sigreturn, Linux kernel function "restore_sigframe"
    will set the frame:
    	for (i = 0; i < 31; i++)
    		__get_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
    				 err);
    	__get_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
    	__get_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
    The struct of uc_mcontext is:
    struct sigcontext {
    	__u64 fault_address;
    	/* AArch64 registers */
    	__u64 regs[31];
    	__u64 sp;
    	__u64 pc;
    	__u64 pstate;
    	/* 4K reserved for FP/SIMD state and future expansion */
    	__u8 __reserved[4096] __attribute__((__aligned__(16)));
    };
    
    But in GDB function "aarch64_linux_sigframe_init", the code the get address
    of registers is:
      for (i = 0; i < 31; i++)
        {
          trad_frame_set_reg_addr (this_cache,
    			       AARCH64_X0_REGNUM + i,
    			       sigcontext_addr + AARCH64_SIGCONTEXT_XO_OFFSET
    			       + i * AARCH64_SIGCONTEXT_REG_SIZE);
        }
    
      trad_frame_set_reg_addr (this_cache, AARCH64_FP_REGNUM, fp);
      trad_frame_set_reg_addr (this_cache, AARCH64_LR_REGNUM, fp + 8);
      trad_frame_set_reg_addr (this_cache, AARCH64_PC_REGNUM, fp + 8);
    
    The code that get pc and sp is not right, so I change the code according
    to Linux kernel code:
      trad_frame_set_reg_addr (this_cache, AARCH64_SP_REGNUM,
    			   sigcontext_addr + AARCH64_SIGCONTEXT_XO_OFFSET
    			     + 31 * AARCH64_SIGCONTEXT_REG_SIZE);
      trad_frame_set_reg_addr (this_cache, AARCH64_PC_REGNUM,
    			   sigcontext_addr + AARCH64_SIGCONTEXT_XO_OFFSET
    			     + 32 * AARCH64_SIGCONTEXT_REG_SIZE);
    
    The issue was fixed by this change, and I did the regression test.  It
    also fixed a lot of other XFAIL and FAIL.
    
    2014-05-20  Hui Zhu  <hui@codesourcery.com>
    	    Yao Qi  <yao@codesourcery.com>
    
    	PR backtrace/16558
    	* aarch64-linux-tdep.c (aarch64_linux_sigframe_init): Update comments
    	and change address of sp and pc.

Index: gdb-7.6.1/gdb/aarch64-linux-tdep.c
===================================================================
--- gdb-7.6.1.orig/gdb/aarch64-linux-tdep.c
+++ gdb-7.6.1/gdb/aarch64-linux-tdep.c
@@ -47,28 +47,30 @@
 
 /* Signal frame handling.
 
-      +----------+  ^
-      | saved lr |  |
-   +->| saved fp |--+
-   |  |          |
-   |  |          |
-   |  +----------+
-   |  | saved lr |
-   +--| saved fp |
-   ^  |          |
-   |  |          |
-   |  +----------+
-   ^  |          |
-   |  | signal   |
-   |  |          |
-   |  | saved lr |-->interrupted_function_pc
-   +--| saved fp |
-   |  +----------+
-   |  | saved lr |--> default_restorer (movz x8, NR_sys_rt_sigreturn; svc 0)
-   +--| saved fp |<- FP
-      |          |
-      |          |<- SP
-      +----------+
+      +------------+  ^
+      | saved lr   |  |
+   +->| saved fp   |--+
+   |  |            |
+   |  |            |
+   |  +------------+
+   |  | saved lr   |
+   +--| saved fp   |
+   ^  |            |
+   |  |            |
+   |  +------------+
+   ^  |            |
+   |  | signal     |
+   |  |            |        SIGTRAMP_FRAME (struct rt_sigframe)
+   |  | saved regs |
+   +--| saved sp   |--> interrupted_sp
+   |  | saved pc   |--> interrupted_pc
+   |  |            |
+   |  +------------+
+   |  | saved lr   |--> default_restorer (movz x8, NR_sys_rt_sigreturn; svc 0)
+   +--| saved fp   |<- FP
+      |            |         NORMAL_FRAME
+      |            |<- SP
+      +------------+
 
   On signal delivery, the kernel will create a signal handler stack
   frame and setup the return address in LR to point at restorer stub.
@@ -117,6 +119,8 @@
   d28015a8        movz    x8, #0xad
   d4000001        svc     #0x0
 
+  This is a system call sys_rt_sigreturn.
+
   We detect signal frames by snooping the return code for the restorer
   instruction sequence.
 
@@ -140,7 +144,6 @@ aarch64_linux_sigframe_init (const struc
 {
   struct gdbarch *gdbarch = get_frame_arch (this_frame);
   CORE_ADDR sp = get_frame_register_unsigned (this_frame, AARCH64_SP_REGNUM);
-  CORE_ADDR fp = get_frame_register_unsigned (this_frame, AARCH64_FP_REGNUM);
   CORE_ADDR sigcontext_addr =
     sp
     + AARCH64_RT_SIGFRAME_UCONTEXT_OFFSET
@@ -154,12 +157,14 @@ aarch64_linux_sigframe_init (const struc
 			       sigcontext_addr + AARCH64_SIGCONTEXT_XO_OFFSET
 			       + i * AARCH64_SIGCONTEXT_REG_SIZE);
     }
+  trad_frame_set_reg_addr (this_cache, AARCH64_SP_REGNUM,
+			   sigcontext_addr + AARCH64_SIGCONTEXT_XO_OFFSET
+			     + 31 * AARCH64_SIGCONTEXT_REG_SIZE);
+  trad_frame_set_reg_addr (this_cache, AARCH64_PC_REGNUM,
+			   sigcontext_addr + AARCH64_SIGCONTEXT_XO_OFFSET
+			     + 32 * AARCH64_SIGCONTEXT_REG_SIZE);
 
-  trad_frame_set_reg_addr (this_cache, AARCH64_FP_REGNUM, fp);
-  trad_frame_set_reg_addr (this_cache, AARCH64_LR_REGNUM, fp + 8);
-  trad_frame_set_reg_addr (this_cache, AARCH64_PC_REGNUM, fp + 8);
-
-  trad_frame_set_id (this_cache, frame_id_build (fp, func));
+  trad_frame_set_id (this_cache, frame_id_build (sp, func));
 }
 
 static const struct tramp_frame aarch64_linux_rt_sigframe =
Index: gdb-7.6.1/gdb/testsuite/gdb.arch/aarch64-rhbz1086894-bt-signal-handler.exp
===================================================================
--- /dev/null
+++ gdb-7.6.1/gdb/testsuite/gdb.arch/aarch64-rhbz1086894-bt-signal-handler.exp
@@ -0,0 +1,35 @@
+# Copyright (C) 2014 Free Software Foundation, Inc.
+#
+# This program 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 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.  If not, see <http://www.gnu.org/licenses/>.
+
+# Internal testing for RHEL-7.1.
+
+standard_testfile
+
+if { ![istarget "aarch64*"] } {
+        verbose "Skipping $testfile"
+        return
+}
+
+if { [prepare_for_testing ${testfile}.exp ${testfile} ${srcfile}] } {
+        return -1
+}
+
+if ![runto_main] {
+        return -1
+}
+
+gdb_test "continue" "Continuing.\r\n\r\nProgram received signal SIGSEGV.*" "run until SIGSEGV"
+
+gdb_test "backtrace" "#$decimal\\s+$hex in pause .*from.*" "backtrace on signal handler"
Index: gdb-7.6.1/gdb/testsuite/gdb.arch/aarch64-rhbz1086894-bt-signal-handler.c
===================================================================
--- /dev/null
+++ gdb-7.6.1/gdb/testsuite/gdb.arch/aarch64-rhbz1086894-bt-signal-handler.c
@@ -0,0 +1,40 @@
+/* Copyright 2014 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program 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 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.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* Internal test for RHEL-7.1.  */
+
+#include <sys/types.h>
+#include <signal.h>
+#include <unistd.h>
+#include <assert.h>
+
+static void
+handle_alrm(int signo)
+{
+  kill (getpid (), SIGSEGV);
+  assert (0);
+}
+
+int
+main (int argc, char *argv[])
+{
+  signal (SIGALRM, handle_alrm);
+  alarm (1);
+  pause ();
+  assert (0);
+  return 0;
+}