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[PATCH] mem-break: Fix breakpoint insertion location

Fix a commit cd6c3b4ffc4e ("New gdbarch methods breakpoint_kind_from_pc 
and sw_breakpoint_from_kind") regression and restore the use of 
->placed_size rather than ->reqstd_address as the location for a memory 
breakpoint to be inserted at.  Previously `gdbarch_breakpoint_from_pc' 
was used that made that adjustment in `default_memory_insert_breakpoint' 
from the preinitialized value, however with the said commit that call is 
gone, so the passed ->placed_size has to be used for the initialization.

The regression manifests itself as the inability to debug any MIPS/Linux 
compressed ISA dynamic executable as GDB corrupts the dynamic loader 
with one of its implicit breakpoints, causing the program to crash, as 
seen for example with the `mips-linux-gnu' target, o32 ABI, MIPS16 code, 
and the gdb.base/advance.exp test case:

(gdb) continue

Program received signal SIGBUS, Bus error.
_dl_debug_initialize (ldbase=0, ns=0) at dl-debug.c:51
51	    r = &_r_debug;
(gdb) FAIL: gdb.base/advance.exp: Can't run to main

	* mem-break.c (default_memory_insert_breakpoint): Use 
	`->placed_address' rather than `->reqstd_address' for the 
	breakpoint location.

 No regressions between plain commit cd6c3b4ffc4e^ and commit cd6c3b4ffc4e 
with this change applied in `mips-linux-gnu', o32, MIPS16 testing.  This 
brings that configuration back to sanity.

 OK for master and (as a grave regression) for 8.0?


 gdb/mem-break.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: binutils/gdb/mem-break.c
--- binutils.orig/gdb/mem-break.c	2017-07-30 22:45:34.000000000 +0100
+++ binutils/gdb/mem-break.c	2017-07-30 23:41:28.595612206 +0100
@@ -37,7 +37,7 @@ int
 default_memory_insert_breakpoint (struct gdbarch *gdbarch,
 				  struct bp_target_info *bp_tgt)
-  CORE_ADDR addr = bp_tgt->reqstd_address;
+  CORE_ADDR addr = bp_tgt->placed_address;
   const unsigned char *bp;
   gdb_byte *readbuf;
   int bplen;

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