[PATCH] gdb/arm: Stop unwinding on error, but do not assert

["Torbjörn SVENSSON" <torbjorn.svensson@foss.st.com>]

When it's impossible to read the FPCCR and XPSR, the unwinding is
unpredictable as the it's not possible to determine the correct
frame size or padding.
The only sane thing to do in this condition is to stop the unwinding.

Without this patch, gdb would assert if this errornous state was
detected.

Signed-off-by: Torbjörn SVENSSON  <torbjorn.svensson@foss.st.com>
---
 gdb/arm-tdep.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/gdb/arm-tdep.c b/gdb/arm-tdep.c
index d357066653b..ce5c8c23fd4 100644
--- a/gdb/arm-tdep.c
+++ b/gdb/arm-tdep.c
@@ -3591,9 +3591,10 @@ arm_m_exception_cache (struct frame_info *this_frame)
 	  ULONGEST fpcar;
 
 	  /* Read FPCCR register.  */
-	  gdb_assert (safe_read_memory_unsigned_integer (FPCCR,
-							 ARM_INT_REGISTER_SIZE,
-							 byte_order, &fpccr));
+	 if (!safe_read_memory_unsigned_integer (FPCCR, ARM_INT_REGISTER_SIZE,
+						 byte_order, &fpccr))
+	   error (_("Could not fetch required FPCCR content.  Further unwind "
+		    "is impossible."));
 
 	  /* Read FPCAR register.  */
 	  if (!safe_read_memory_unsigned_integer (FPCAR, ARM_INT_REGISTER_SIZE,
@@ -3669,9 +3670,11 @@ arm_m_exception_cache (struct frame_info *this_frame)
 	 aligner between the top of the 32-byte stack frame and the
 	 previous context's stack pointer.  */
       ULONGEST xpsr;
-      gdb_assert (safe_read_memory_unsigned_integer (cache->saved_regs[
-						     ARM_PS_REGNUM].addr (), 4,
-						     byte_order, &xpsr));
+      if (!safe_read_memory_unsigned_integer (cache->saved_regs[ ARM_PS_REGNUM]
+					      .addr (), 4, byte_order, &xpsr))
+	 error (_("Could not fetch required XPSR content.  Further unwind is "
+		  "impossible."));
+
       if (bit (xpsr, 9) != 0)
 	{
 	  CORE_ADDR new_sp = arm_cache_get_prev_sp_value (cache, tdep) + 4;
-- 
2.25.1