[binutils-gdb] [Cell/B.E.] Make parse_spufs_run more robust

[Ulrich Weigand <uweigand at sourceware dot org>]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=791bb1f4a6310cd7f894e370607dfc05c9cb0727

commit 791bb1f4a6310cd7f894e370607dfc05c9cb0727
Author: Ulrich Weigand <ulrich.weigand@de.ibm.com>
Date:   Thu Aug 27 19:27:40 2015 +0200

    [Cell/B.E.] Make parse_spufs_run more robust
    
    With recent changes to inferior handling, parse_spufs_run needs to be
    more careful in assumptions it makes.  In particular, this patch:
    
    - Bails out early if the current inferior has not yet been registered
      (e.g. during fork procession) to avoid assertion failures in register
      cache code.
    
    - Sets inferior_ptid to the current ptid while calling target_read_memory
      to make sure the correct process is accessed if parse_spufs_run is
      called early when inferior_ptid has not yet been switched by the caller.
    
    ChangeLog:
    
    	* spu-multiarch.c (parse_spufs_run): Bail out if inferior is not
    	registered yet.  Set inferior_ptid while calling target_read_memory.

Diff:
---
 gdb/ChangeLog       |  5 +++++
 gdb/spu-multiarch.c | 12 +++++++++++-
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 61e9851..46fb2d1 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,10 @@
 2015-08-08  Ulrich Weigand  <uweigand@de.ibm.com>
 
+	* spu-multiarch.c (parse_spufs_run): Bail out if inferior is not
+	registered yet.  Set inferior_ptid while calling target_read_memory.
+
+2015-08-08  Ulrich Weigand  <uweigand@de.ibm.com>
+
 	* nat/linux-ptrace.h (GDB_ARCH_TRAP_BRKPT): Replace by ...
 	(GDB_ARCH_IS_TRAP_BRKPT): ... this.  Add __powerpc__ case.
 	* linux-nat.c (check_stopped_by_breakpoint): Use
diff --git a/gdb/spu-multiarch.c b/gdb/spu-multiarch.c
index 459cb2f..b07c4ff 100644
--- a/gdb/spu-multiarch.c
+++ b/gdb/spu-multiarch.c
@@ -56,6 +56,7 @@ static int
 parse_spufs_run (ptid_t ptid, int *fd, CORE_ADDR *addr)
 {
   enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch ());
+  struct cleanup *old_chain;
   struct gdbarch_tdep *tdep;
   struct regcache *regcache;
   gdb_byte buf[4];
@@ -65,12 +66,21 @@ parse_spufs_run (ptid_t ptid, int *fd, CORE_ADDR *addr)
   if (gdbarch_bfd_arch_info (target_gdbarch ())->arch != bfd_arch_powerpc)
     return 0;
 
+  /* If we're called too early (e.g. after fork), we cannot
+     access the inferior yet.  */
+  if (find_inferior_ptid (ptid) == NULL)
+    return 0;
+
   /* Get PPU-side registers.  */
   regcache = get_thread_arch_regcache (ptid, target_gdbarch ());
   tdep = gdbarch_tdep (target_gdbarch ());
 
   /* Fetch instruction preceding current NIP.  */
-  if (target_read_memory (regcache_read_pc (regcache) - 4, buf, 4) != 0)
+  old_chain = save_inferior_ptid ();
+  inferior_ptid = ptid;
+  regval = target_read_memory (regcache_read_pc (regcache) - 4, buf, 4);
+  do_cleanups (old_chain);
+  if (regval != 0)
     return 0;
   /* It should be a "sc" instruction.  */
   if (extract_unsigned_integer (buf, 4, byte_order) != INSTR_SC)