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Teach gdb how to step into ARM Windows CE dlls.


Hi,

This patch teaches gdb how to step into ARM Windows CE dlls in a similar fashion
to how it is done for i386 in i386-tdep.c:i386_pe_skip_trampoline_code.

Tested against a arm-wince-mingw32ce gdbserver, there where no regressions, and
the tests related to stepping into dlls now pass.

Cheers,
Pedro Alves


2007-08-11  Pedro Alves  <pedro_alves@portugalmail.pt>

	* arm-tdep.h (arm_skip_stub): Declare.
	* arm-wince-tdep.c: Include gdbcore.h.
	(arm_pe_skip_trampoline_code): New function.
	(arm_wince_init_abi): Register arm_pe_skip_trampoline_code as
	gdbarch_skip_trampoline_code callback.

---
 gdb/arm-tdep.h       |    1 +
 gdb/arm-wince-tdep.c |   41 ++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 41 insertions(+), 1 deletion(-)

Index: src/gdb/arm-tdep.h
===================================================================
--- src.orig/gdb/arm-tdep.h	2007-07-03 20:57:42.000000000 +0100
+++ src/gdb/arm-tdep.h	2007-08-08 00:46:10.000000000 +0100
@@ -182,6 +182,7 @@ struct gdbarch_tdep
 #define LOWEST_PC (gdbarch_tdep (current_gdbarch)->lowest_pc)
 #endif
 
+CORE_ADDR arm_skip_stub (struct frame_info *, CORE_ADDR);
 int arm_software_single_step (struct frame_info *);
 
 /* Functions exported from armbsd-tdep.h.  */
Index: src/gdb/arm-wince-tdep.c
===================================================================
--- src.orig/gdb/arm-wince-tdep.c	2007-07-31 14:59:44.000000000 +0100
+++ src/gdb/arm-wince-tdep.c	2007-08-08 01:00:06.000000000 +0100
@@ -22,6 +22,7 @@
 
 #include "defs.h"
 #include "osabi.h"
+#include "gdbcore.h"
 #include "solib-svr4.h"
 #include "target.h"
 
@@ -36,6 +37,44 @@ static const char arm_wince_thumb_le_bre
 #define ARM_WINCE_JB_ELEMENT_SIZE	INT_REGISTER_SIZE
 #define ARM_WINCE_JB_PC			21
 
+static CORE_ADDR
+arm_pe_skip_trampoline_code (struct frame_info *frame, CORE_ADDR pc)
+{
+  unsigned long indirect;
+  struct minimal_symbol *indsym;
+  char *symname;
+  CORE_ADDR next_pc;
+
+  /* The format of an ARM DLL trampoline is:
+       ldr  ip, [pc]
+       ldr  pc, [ip]
+       .dw __imp_<func>  */
+
+  if (!pc
+      || read_memory_unsigned_integer (pc + 0, 4) != 0xe59fc000
+      || read_memory_unsigned_integer (pc + 4, 4) != 0xe59cf000)
+    return 0;
+
+  indirect = read_memory_unsigned_integer (pc + 8, 4);
+  if (!indirect)
+    return 0;
+
+  indsym = lookup_minimal_symbol_by_pc (indirect);
+  if (indsym == NULL)
+    return 0;
+
+  symname = SYMBOL_LINKAGE_NAME (indsym);
+  if (symname == NULL || strncmp (symname, "__imp_", 6) != 0)
+    return 0;
+
+  next_pc = read_memory_unsigned_integer (indirect, 4);
+  if (next_pc != 0)
+    return next_pc;
+
+  /* Check with the default arm gdbarch_skip_trampoline.  */
+  return arm_skip_stub (frame, pc);
+}
+
 static void
 arm_wince_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 {
@@ -56,7 +95,7 @@ arm_wince_init_abi (struct gdbarch_info 
   set_gdbarch_char_signed (gdbarch, 1);
 
   /* Shared library handling.  */
-  set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target);
+  set_gdbarch_skip_trampoline_code (gdbarch, arm_pe_skip_trampoline_code);
 
   /* Single stepping.  */
   set_gdbarch_software_single_step (gdbarch, arm_software_single_step);



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