X-Git-Url: http://drtracing.org/?a=blobdiff_plain;f=gdb%2Farch%2Farm-linux.c;h=943efe7aa544a0ccd690968e91901ff652c620a6;hb=61baf725eca99af2569262d10aca03dcde2698f6;hp=b43e4845d5e74fa91a35ceab5ee084e620b2053d;hpb=618f726fcb851883a0094aa7fa17003889b7189f;p=deliverable%2Fbinutils-gdb.git

diff --git a/gdb/arch/arm-linux.c b/gdb/arch/arm-linux.c
index b43e4845d5..943efe7aa5 100644
--- a/gdb/arch/arm-linux.c
+++ b/gdb/arch/arm-linux.c
@@ -1,6 +1,6 @@
 /* Common target dependent code for GNU/Linux on ARM systems.
 
-   Copyright (C) 1999-2016 Free Software Foundation, Inc.
+   Copyright (C) 1999-2017 Free Software Foundation, Inc.
 
    This file is part of GDB.
 
@@ -18,8 +18,10 @@
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
 #include "common-defs.h"
+#include "common-regcache.h"
 #include "arch/arm.h"
 #include "arm-linux.h"
+#include "arch/arm-get-next-pcs.h"
 
 /* Calculate the offset from stack pointer of the pc register on the stack
    in the case of a sigreturn or sigreturn_rt syscall.  */
@@ -55,3 +57,83 @@ arm_linux_sigreturn_next_pc_offset (unsigned long sp,
 
   return pc_offset;
 }
+
+/* Implementation of "fixup" method of struct arm_get_next_pcs_ops
+   for arm-linux.  */
+
+CORE_ADDR
+arm_linux_get_next_pcs_fixup (struct arm_get_next_pcs *self,
+			      CORE_ADDR nextpc)
+{
+  /* The Linux kernel offers some user-mode helpers in a high page.  We can
+     not read this page (as of 2.6.23), and even if we could then we
+     couldn't set breakpoints in it, and even if we could then the atomic
+     operations would fail when interrupted.  They are all (tail) called
+     as functions and return to the address in LR.  However, when GDB single
+     step this instruction, this instruction isn't executed yet, and LR
+     may not be updated yet.  In other words, GDB can get the target
+     address from LR if this instruction isn't BL or BLX.  */
+  if (nextpc > 0xffff0000)
+    {
+      int bl_blx_p = 0;
+      CORE_ADDR pc = regcache_read_pc (self->regcache);
+      int pc_incr = 0;
+
+      if (self->ops->is_thumb (self))
+	{
+	  unsigned short inst1
+	    = self->ops->read_mem_uint (pc, 2, self->byte_order_for_code);
+
+	  if (bits (inst1, 8, 15) == 0x47 && bit (inst1, 7))
+	    {
+	      /* BLX Rm */
+	      bl_blx_p = 1;
+	      pc_incr = 2;
+	    }
+	  else if (thumb_insn_size (inst1) == 4)
+	    {
+	      unsigned short inst2;
+
+	      inst2 = self->ops->read_mem_uint (pc + 2, 2,
+						self->byte_order_for_code);
+
+	      if ((inst1 & 0xf800) == 0xf000 && bits (inst2, 14, 15) == 0x3)
+		{
+		  /* BL <label> and BLX <label> */
+		  bl_blx_p = 1;
+		  pc_incr = 4;
+		}
+	    }
+
+	  pc_incr = MAKE_THUMB_ADDR (pc_incr);
+	}
+      else
+	{
+	  unsigned int insn
+	    = self->ops->read_mem_uint (pc, 4, self->byte_order_for_code);
+
+	  if (bits (insn, 28, 31) == INST_NV)
+	    {
+	      if (bits (insn, 25, 27) == 0x5) /* BLX <label> */
+		bl_blx_p = 1;
+	    }
+	  else
+	    {
+	      if (bits (insn, 24, 27) == 0xb  /* BL <label> */
+		  || bits (insn, 4, 27) == 0x12fff3 /* BLX Rm */)
+		bl_blx_p = 1;
+	    }
+
+	  pc_incr = 4;
+	}
+
+      /* If the instruction BL or BLX, the target address is the following
+	 instruction of BL or BLX, otherwise, the target address is in LR
+	 already.  */
+      if (bl_blx_p)
+	nextpc = pc + pc_incr;
+      else
+	nextpc = regcache_raw_get_unsigned (self->regcache, ARM_LR_REGNUM);
+    }
+  return nextpc;
+}