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Re: [PATCH 3/5] Add support for ARM breakpoint types in GDBServer.

On 09/29/2015 04:32 AM, Yao Qi wrote:
Antoine Tremblay <> writes:

This will contain more stuff as I post the next patch sets for single
stepping etc.. I would like to keep a more general name.

It's basically all coming from arm-tdep.c but I don't want to name it
common/arm-tdep.c to avoid confusion and Makefile problems.

arm-ctdep.c ?

How about arm.c?

There's already arm.h in there I think I can actually merge what is in there with what I have, and create arm.c.

Please move this file to arch/ directory rather than common/

It seems weird to me to have common objects somewhere else then in
common/ , if common becomes more a lib we don't want it all over the
place no ?

Would creating a common/arch be acceptable ? I guess we would have to
move things like x86-xstate.h etc.. there too ?

common/ was created in order to share code between GDB and GDBserver, see After that, we find that we'll
end up with moving most of gdb files into common/ and we'd better move
different common things into different common directory.  Nowadays, we
have nat/ common/ and arch/ directories for common things.  arm.c should
be put in arch/ directory.

Ok I understand thanks for explaining.

diff --git a/gdb/configure.tgt b/gdb/configure.tgt
index c42b4df..e831f59 100644
--- a/gdb/configure.tgt
+++ b/gdb/configure.tgt
@@ -89,7 +89,7 @@ arm*-wince-pe | arm*-*-mingw32ce*)
   	# Target: ARM based machine running GNU/Linux
-	gdb_target_obs="arm-tdep.o arm-linux-tdep.o glibc-tdep.o \
+	gdb_target_obs="arm-common.o arm-tdep.o arm-linux-tdep.o glibc-tdep.o \
   			solib-svr4.o symfile-mem.o linux-tdep.o linux-record.o"

since arm-common.o is moved out of arm-tdep.o, so it should be added to
every target which uses arm-tdep.o, such as aarch64*-*-linux*,
arm*-wince-pe, etc.

Even if they don't use it ? But ok.

No, they use it.  This patch moves thumb_insn_size to arm-common.o, but
thumb_insn_size is used by arm-tdep.c.  If we don't add arm-common.o to
every target which uses arm-tdep.o, the build will fail on these targets

build/gdb/aarch64/gdb/../../../../binutils-gdb/gdb/arm-tdep.c:846: undefined reference to `thumb_insn_size'
build/gdb/aarch64/gdb/../../../../binutils-gdb/gdb/arm-tdep.c:846: undefined reference to `thumb_insn_size'
arm-tdep.o: In function `arm_adjust_breakpoint_address':
build/gdb/aarch64/gdb/../../../../binutils-gdb/gdb/arm-tdep.c:5417: undefined reference to `thumb_insn_size'
build/gdb/aarch64/gdb/../../../../binutils-gdb/gdb/arm-tdep.c:5467: undefined reference to `thumb_insn_size'
arm-tdep.o: In function `arm_breakpoint_from_pc':
build/gdb/aarch64/gdb/../../../../binutils-gdb/gdb/arm-tdep.c:8858: undefined reference to `thumb_insn_size'

Indeed, thanks

diff --git a/gdb/gdbserver/linux-arm-low.c b/gdb/gdbserver/linux-arm-low.c
index 367c704..15ecb70 100644
--- a/gdb/gdbserver/linux-arm-low.c
+++ b/gdb/gdbserver/linux-arm-low.c
@@ -30,6 +30,8 @@
   #include "nat/gdb_ptrace.h"
   #include <signal.h>

+#include "common/arm-common.h"
   /* Defined in auto-generated files.  */
   void init_registers_arm (void);
   extern const struct target_desc *tdesc_arm;
@@ -234,19 +236,28 @@ arm_set_pc (struct regcache *regcache, CORE_ADDR pc)

   /* Correct in either endianness.  */
-static const unsigned long arm_breakpoint = 0xef9f0001;
-#define arm_breakpoint_len 4
-static const unsigned short thumb_breakpoint = 0xde01;
-static const unsigned short thumb2_breakpoint[] = { 0xf7f0, 0xa000 };
+#define arm_abi_breakpoint 0xef9f0001UL

   /* For new EABI binaries.  We recognize it regardless of which ABI
      is used for gdbserver, so single threaded debugging should work
      OK, but for multi-threaded debugging we only insert the current
      ABI's breakpoint instruction.  For now at least.  */
-static const unsigned long arm_eabi_breakpoint = 0xe7f001f0;
+#define arm_eabi_breakpoint 0xe7f001f0UL
+#ifndef __ARM_EABI__
+static const unsigned long arm_breakpoint = arm_abi_breakpoint;
+static const unsigned long arm_breakpoint = arm_eabi_breakpoint;
+#define arm_breakpoint_len 4
+static const unsigned short thumb_breakpoint = 0xde01;
+#define thumb_breakpoint_len 2
+static const unsigned short thumb2_breakpoint[] = { 0xf7f0, 0xa000 };
+#define thumb2_breakpoint_len 4

I am confused by your changes here.  Why do you change them?

Before arm_breakpoint_from_pc would be :

#ifndef __ARM_EABI__
   return (const unsigned char *) &arm_breakpoint;
-  return (const unsigned char *) &arm_eabi_breakpoint;

And arm_breakpoint_at would check for the arm_breakpoint ||

Thus the selected arm_breakpoint would be what that function returned
and arm_breakpoint was arm_abi_breakpoint.

It felt more clear to me to name those for what they are : 2 separate
entities arm_abi_breakpoint and arm_eabi_breakpoint and set the
current used one as arm_breakpoint.

This allows a cleaner breakpoint_from_pc as it just returns
arm_breakpoint rather than having the #ifdef in that function.

Any other reference to the arm_breakpoint would also be clear of #ifdefs...

Please don't combine movement and refactoring.  This patch is about
movement, so let us do movement only.  Refactor can be done separately.

Ok , would you find it acceptable still to include the refactoring in the series as the next patch or should I create it out of series ?

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