Re: [RFA] i386/amd64 h/w watchpoints in gdbserver

Doug Evans
2009-06-30T10:32:47Z

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On Mon, Jun 29, 2009 at 1:46 PM, Pedro Alves<pedro@codesourcery.com> wrote:
>> >> +/* Support for h/w breakpoints.
>> >> +   This support is not currently used, kept for reference.  */
>> >
>> > Any reason for not using this currently?  If there's a good reason,
>> > than let's drop it.  But I'd prefer to have it working.  :-)
>>
>> deleted.
>
> Now you left me curious as to what was missing.

For reference sake, it was deleted because using it would mean adding
new features to the patch. I wanted to keep the focus on the task at
hand. The additions are for a different feature, and it can come in
a later patch.

>> >> Index: utils.c
>> >> ===================================================================
>> >
>> > +char *
>> > +paddr (CORE_ADDR addr)
>> >
>> > This isn't documented in neither server.h or here?
>>
>> Just "going with the flow".
>
> The flow says: "look closer and you'll see that all functions
> in utils.c have description comments."

It wasn't utils.c that I was referring to. Comments added.

> I don't think a Win64 port of gdbserver will take too long
> to appear, so I'm sure this will an issue (albeit small, as this is
> debug output).  Note that casting a pointer to long as never been
> garanteed to be portable.  With the other point, all I meant
> was to look here:
>
>  http://sourceware.org/ml/gdb-patches/2009-06/msg00223.html
>
> and notice that paddr is gone, in favor of paddress.  So, it seemed
> to be that if copying an interface from GDB, might as well copy
> the one that is going to stay.

Righto.
The new paddress in gdb has a gdbarch argument which gdbserver
currently doesn't have.
I elided it. I hope that's ok.

>> I went with something
>> simple that works for now.
>> IWBN if this kind of thing were in, say, libiberty and tools could just use it.
>
> Fine, but this is not really an argument.  You'd already brought a bit of
> code over from GDB, it's just a matter of bringing in more bits.   OTOH, for
> gdbserver, it wouldn't probably be a problem to just use %p instead.  But
> I'm fine with going with cast to long for now.  It was a "Note:"
> afterall.  Someone else will have to worry about it.

The nice thing about wrapping a particular portability issue in one
place is that, well, it's in one place. :-) There are several places
in gdbserver that currently use (long) for printing CORE_ADDRs.

As far as being a "Note", I wonder if we need a convention for review
comments that are mandatory versus review comments that are just
notes, lest future reviews and responses interpret them wrongly (in
either direction).

>> >> +  /* Target-specific additions.  */
>> >
>> > Warning: "Target" overload.  We need to get into the habit
>> > of not doing this --- it makes refering to these things quite
>> > ambiguous.  Call it "arch" or something else.  There are other
>> > similar cases.
>>
>> I dunno.   there's "the_low_target" in linux-low.h
>> Perhaps we can migrate away but I don't see the above "infraction" as
>> being critical.
>
> Please!  Could spare us these extra iterations and go with
> "Low-target specific additions" then, or some other 4 or 5
> letters adjustment, right?  ;-)  I wasn't asking for a rewrite.

'k. I went with arch-specific.

>> >> +  /* ??? Will need tweaking for multi-process.  */
>> >
>> > Indeed.  Why not just set the debug_registers_changed in lwps
>> > of the current process?
>>
>> Are there any existing examples of this?
>> I would have done that had process_info contained the list of its
>> threads (it would have been trivially straightforward).
>
> Just match the pid of the current process with the pid of
> each thread?  linux-low.c does that in several places.

'k.

>> +  return 0; /* ??? fatal?  */
>
> This just means not-stopped-by-watchpoint?  Certainly not fatal.

The context here is that the function isn't called unless
stopped_by_watchpoint has returned true. Thus if stopped_data_address
then can't find the address something is wrong.
I've been thinking that stopped_by_watchpoint and stopped_data_address
should be combined, but it's not clear one would always want that.

> Right.  An extra point:
>
> On Tuesday 23 June 2009 08:37:14, Doug Evans wrote:
>> +    default:
>> +      error ("Z_packet_to_hw_type: bad watchpoint type %c", type);
>
> This should not call error, but return unsupported.

This is in a subroutine of functions defined to only handle
watchpoints. "Not supported" is handled at a higher level. I changed
"error" to "fatal" to make this more clear.

>> how about this?
>
> It looks goodish, but I'd really like to see the points I
> raise be addressed, instead of just ignored.  It just makes
> us waste the (narrow already) review bandwidth...

I disagree with the categorization of having ignored those comments.
[Plus I did apply roughly 15 of 19 comments without question. 1/2 :-)]
But no worries.
Humble apologies, and noted for future reference.

Pierre, nothing much has changed win32-wise except some functions got renamed.
I don't know if you want to first give this a spin again or not.

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2009-06-30 Doug Evans <dje@google.com>
Pierre Muller <muller@ics.u-strasbg.fr>

Add h/w watchpoint support to x86-linux, win32-i386.
* Makefile.in (SFILES): Add i386-low.c
(i386_low_h): Define.
(i386-low.o): Add dependencies.
(linux-x86-low.o): Add i386-low.h dependency.
(win32-i386-low.o): Ditto.
* i386-low.c: New file.
* i386-low.h: New file.
* configure.srv (i[34567]86-*-cygwin*): Add i386-low.o to srv_tgtobj.
(i[34567]86-*-linux*, i[34567]86-*-mingw*, x86_64-*-linux*): Ditto.
* linux-low.c (linux_add_process): Initialize arch_private.
(linux_remove_process): Free arch_private.
(add_lwp): Initialize arch_private.
(delete_lwp): Free arch_private.
(linux_resume_one_lwp): Call the_low_target.prepare_to_resume if
provided.
* linux-low.h (process_info_private): New member arch_private.
(lwp_info): New member arch_private.
(linux_target_ops): New members new_process, new_thread,
prepare_to_resume.
(ptid_of): New macro.
* linux-x86-low.c: Include stddef.h, i386-low.h.
(arch_process_info): New struct.
(arch_lwp_info): New struct.
(x86_linux_dr_get, x86_linux_dr_set): New functions.
(i386_dr_low_set_addr, i386_dr_low_set_control): New functions.
(i386_dr_low_get_status): New function.
(x86_insert_point, x86_remove_point): New functions.
(x86_stopped_by_watchpoint): New function.
(x86_stopped_data_address): New function.
(x86_linux_new_process, x86_linux_new_thread): New functions.
(x86_linux_prepare_to_resume): New function.
(the_low_target): Add entries for insert_point, remove_point,
stopped_by_watchpoint, stopped_data_address, new_process, new_thread,
prepare_to_resume.
* server.c (debug_hw_points): New global.
(monitor_show_help): Document set debug-hw-points.
(handle_query): Process "set debug-hw-points".
* server.h (debug_hw_points): Declare.
(paddress): Declare.
* utils.c (NUMCELLS, CELLSIZE): New macros.
(get_sell, xsnprintf, paddress): New functions.
* win32-arm-low.c (the_low_target): Add entries for insert_point,
remove_point, stopped_by_watchpoint, stopped_data_address.
* win32-i386-low.c: Include i386-low.h.
(debug_reg_state): Replaces dr.
(i386_dr_low_set_addr, i386_dr_low_set_control): New functions.
(i386_dr_low_get_status): New function.
(i386_insert_point, i386_remove_point): New functions.
(i386_stopped_by_watchpoint): New function.
(i386_stopped_data_address): New function.
(i386_initial_stuff): Update.
(get_thread_context,set_thread_context,i386_thread_added): Update.
(the_low_target): Add entries for insert_point,
remove_point, stopped_by_watchpoint, stopped_data_address.
* win32-low.c (win32_insert_watchpoint): New function.
(win32_remove_watchpoint): New function.
(win32_stopped_by_watchpoint): New function.
(win32_stopped_data_address): New function.
(win32_target_ops): Add entries for insert_watchpoint,
remove_watchpoint, stopped_by_watchpoint, stopped_data_address.
* win32-low.h (win32_target_ops): New members insert_point,
remove_point, stopped_by_watchpoint, stopped_data_address.

Index: Makefile.in
===================================================================
RCS file: /cvs/src/src/gdb/gdbserver/Makefile.in,v
retrieving revision 1.74
diff -u -p -r1.74 Makefile.in
--- Makefile.in 12 May 2009 22:25:00 -0000 1.74
+++ Makefile.in 30 Jun 2009 09:15:58 -0000
@@ -104,7 +104,7 @@ SFILES= $(srcdir)/gdbreplay.c $(srcdir)/
$(srcdir)/thread-db.c $(srcdir)/utils.c \
$(srcdir)/linux-arm-low.c $(srcdir)/linux-cris-low.c \
$(srcdir)/linux-crisv32-low.c \
- $(srcdir)/i387-fp.c \
+ ${srcdir}/i386-low.c $(srcdir)/i387-fp.c \
$(srcdir)/linux-ia64-low.c $(srcdir)/linux-low.c \
$(srcdir)/linux-m32r-low.c \
$(srcdir)/linux-m68k-low.c $(srcdir)/linux-mips-low.c \
@@ -287,6 +287,10 @@ signals.o: ../common/signals.c $(server_
memmem.o: ../gnulib/memmem.c
$(CC) -o memmem.o -c $(CPPFLAGS) $(INTERNAL_CFLAGS) $<

+i386_low_h = $(srcdir)/i386-low.h
+
+i386-low.o: i386-low.c $(i386_low_h) $(server_h) $(target_h)
+
i387-fp.o: i387-fp.c $(server_h)

linux-low.o: linux-low.c $(linux_low_h) $(server_h)
@@ -304,7 +308,7 @@ linux-ppc-low.o: linux-ppc-low.c $(linux
linux-s390-low.o: linux-s390-low.c $(linux_low_h) $(server_h)
linux-sh-low.o: linux-sh-low.c $(linux_low_h) $(server_h)
linux-x86-low.o: linux-x86-low.c $(linux_low_h) $(server_h) \
- $(gdb_proc_service_h)
+ $(gdb_proc_service_h) $(i386_low_h)
linux-xtensa-low.o: linux-xtensa-low.c xtensa-xtregs.c $(linux_low_h) $(server_h)

win32_low_h = $(srcdir)/win32-low.h
@@ -312,7 +316,7 @@ win32_low_h = $(srcdir)/win32-low.h
win32-low.o: win32-low.c $(win32_low_h) $(server_h) $(regdef_h) $(regcache_h)

win32-arm-low.o: win32-arm-low.c $(win32_low_h) $(server_h)
-win32-i386-low.o: win32-i386-low.c $(win32_low_h) $(server_h)
+win32-i386-low.o: win32-i386-low.c $(win32_low_h) $(server_h) $(i386_low_h)

spu-low.o: spu-low.c $(server_h)

Index: configure.srv
===================================================================
RCS file: /cvs/src/src/gdb/gdbserver/configure.srv,v
retrieving revision 1.41
diff -u -p -r1.41 configure.srv
--- configure.srv 12 May 2009 22:25:00 -0000 1.41
+++ configure.srv 30 Jun 2009 09:15:58 -0000
@@ -53,10 +53,10 @@ case "${target}" in
srv_linux_thread_db=yes
;;
i[34567]86-*-cygwin*) srv_regobj=reg-i386.o
- srv_tgtobj="win32-low.o win32-i386-low.o"
+ srv_tgtobj="i386-low.o win32-low.o win32-i386-low.o"
;;
i[34567]86-*-linux*) srv_regobj=reg-i386-linux.o
- srv_tgtobj="linux-low.o linux-x86-low.o i387-fp.o"
+ srv_tgtobj="linux-low.o linux-x86-low.o i386-low.o i387-fp.o"
srv_linux_usrregs=yes
srv_linux_regsets=yes
srv_linux_thread_db=yes
@@ -71,7 +71,7 @@ case "${target}" in
srv_mingwce=yes
;;
i[34567]86-*-mingw*) srv_regobj=reg-i386.o
- srv_tgtobj="win32-low.o win32-i386-low.o"
+ srv_tgtobj="i386-low.o win32-low.o win32-i386-low.o"
srv_mingw=yes
;;
ia64-*-linux*) srv_regobj=reg-ia64.o
@@ -170,7 +170,7 @@ case "${target}" in
srv_tgtobj="spu-low.o"
;;
x86_64-*-linux*) srv_regobj="reg-x86-64-linux.o reg-i386-linux.o"
- srv_tgtobj="linux-low.o linux-x86-low.o i387-fp.o"
+ srv_tgtobj="linux-low.o linux-x86-low.o i386-low.o i387-fp.o"
srv_linux_usrregs=yes # This is for i386 progs.
srv_linux_regsets=yes
srv_linux_thread_db=yes
Index: i386-low.c
===================================================================
RCS file: i386-low.c
diff -N i386-low.c
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ i386-low.c 30 Jun 2009 09:15:58 -0000
@@ -0,0 +1,577 @@
+/* Debug register code for the i386.
+
+ Copyright (C) 2009
+ Free Software Foundation, Inc.
+
+ This file is part of GDB.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
+
+#include "server.h"
+#include "target.h"
+#include "i386-low.h"
+
+/* Support for 8-byte wide hw watchpoints. */
+#ifndef TARGET_HAS_DR_LEN_8
+/* NOTE: sizeof (long) == 4 on win64. */
+#define TARGET_HAS_DR_LEN_8 (sizeof (void *) == 8)
+#endif
+
+enum target_hw_bp_type
+ {
+ hw_write = 0, /* Common HW watchpoint */
+ hw_read = 1, /* Read HW watchpoint */
+ hw_access = 2, /* Access HW watchpoint */
+ hw_execute = 3 /* Execute HW breakpoint */
+ };
+
+/* DR7 Debug Control register fields. */
+
+/* How many bits to skip in DR7 to get to R/W and LEN fields. */
+#define DR_CONTROL_SHIFT 16
+/* How many bits in DR7 per R/W and LEN field for each watchpoint. */
+#define DR_CONTROL_SIZE 4
+
+/* Watchpoint/breakpoint read/write fields in DR7. */
+#define DR_RW_EXECUTE (0x0) /* Break on instruction execution. */
+#define DR_RW_WRITE (0x1) /* Break on data writes. */
+#define DR_RW_READ (0x3) /* Break on data reads or writes. */
+
+/* This is here for completeness. No platform supports this
+ functionality yet (as of March 2001). Note that the DE flag in the
+ CR4 register needs to be set to support this. */
+#ifndef DR_RW_IORW
+#define DR_RW_IORW (0x2) /* Break on I/O reads or writes. */
+#endif
+
+/* Watchpoint/breakpoint length fields in DR7. The 2-bit left shift
+ is so we could OR this with the read/write field defined above. */
+#define DR_LEN_1 (0x0 << 2) /* 1-byte region watch or breakpoint. */
+#define DR_LEN_2 (0x1 << 2) /* 2-byte region watch. */
+#define DR_LEN_4 (0x3 << 2) /* 4-byte region watch. */
+#define DR_LEN_8 (0x2 << 2) /* 8-byte region watch (AMD64). */
+
+/* Local and Global Enable flags in DR7.
+
+ When the Local Enable flag is set, the breakpoint/watchpoint is
+ enabled only for the current task; the processor automatically
+ clears this flag on every task switch. When the Global Enable flag
+ is set, the breakpoint/watchpoint is enabled for all tasks; the
+ processor never clears this flag.
+
+ Currently, all watchpoint are locally enabled. If you need to
+ enable them globally, read the comment which pertains to this in
+ i386_insert_aligned_watchpoint below. */
+#define DR_LOCAL_ENABLE_SHIFT 0 /* Extra shift to the local enable bit. */
+#define DR_GLOBAL_ENABLE_SHIFT 1 /* Extra shift to the global enable bit. */
+#define DR_ENABLE_SIZE 2 /* Two enable bits per debug register. */
+
+/* Local and global exact breakpoint enable flags (a.k.a. slowdown
+ flags). These are only required on i386, to allow detection of the
+ exact instruction which caused a watchpoint to break; i486 and
+ later processors do that automatically. We set these flags for
+ backwards compatibility. */
+#define DR_LOCAL_SLOWDOWN (0x100)
+#define DR_GLOBAL_SLOWDOWN (0x200)
+
+/* Fields reserved by Intel. This includes the GD (General Detect
+ Enable) flag, which causes a debug exception to be generated when a
+ MOV instruction accesses one of the debug registers.
+
+ FIXME: My Intel manual says we should use 0xF800, not 0xFC00. */
+#define DR_CONTROL_RESERVED (0xFC00)
+
+/* Auxiliary helper macros. */
+
+/* A value that masks all fields in DR7 that are reserved by Intel. */
+#define I386_DR_CONTROL_MASK (~DR_CONTROL_RESERVED)
+
+/* The I'th debug register is vacant if its Local and Global Enable
+ bits are reset in the Debug Control register. */
+#define I386_DR_VACANT(state, i) \
+ (((state)->dr_control_mirror & (3 << (DR_ENABLE_SIZE * (i)))) == 0)
+
+/* Locally enable the break/watchpoint in the I'th debug register. */
+#define I386_DR_LOCAL_ENABLE(state, i) \
+ do { \
+ (state)->dr_control_mirror |= \
+ (1 << (DR_LOCAL_ENABLE_SHIFT + DR_ENABLE_SIZE * (i))); \
+ } while (0)
+
+/* Globally enable the break/watchpoint in the I'th debug register. */
+#define I386_DR_GLOBAL_ENABLE(state, i) \
+ do { \
+ (state)->dr_control_mirror |= \
+ (1 << (DR_GLOBAL_ENABLE_SHIFT + DR_ENABLE_SIZE * (i))); \
+ } while (0)
+
+/* Disable the break/watchpoint in the I'th debug register. */
+#define I386_DR_DISABLE(state, i) \
+ do { \
+ (state)->dr_control_mirror &= \
+ ~(3 << (DR_ENABLE_SIZE * (i))); \
+ } while (0)
+
+/* Set in DR7 the RW and LEN fields for the I'th debug register. */
+#define I386_DR_SET_RW_LEN(state, i,rwlen) \
+ do { \
+ (state)->dr_control_mirror &= \
+ ~(0x0f << (DR_CONTROL_SHIFT + DR_CONTROL_SIZE * (i))); \
+ (state)->dr_control_mirror |= \
+ ((rwlen) << (DR_CONTROL_SHIFT + DR_CONTROL_SIZE * (i))); \
+ } while (0)
+
+/* Get from DR7 the RW and LEN fields for the I'th debug register. */
+#define I386_DR_GET_RW_LEN(state, i) \
+ (((state)->dr_control_mirror \
+ >> (DR_CONTROL_SHIFT + DR_CONTROL_SIZE * (i))) & 0x0f)
+
+/* Did the watchpoint whose address is in the I'th register break? */
+#define I386_DR_WATCH_HIT(state,i) ((state)->dr_status_mirror & (1 << (i)))
+
+/* A macro to loop over all debug registers. */
+#define ALL_DEBUG_REGISTERS(i) for (i = 0; i < DR_NADDR; i++)
+
+/* Types of operations supported by i386_handle_nonaligned_watchpoint. */
+typedef enum { WP_INSERT, WP_REMOVE, WP_COUNT } i386_wp_op_t;
+\f
+/* Implementation. */
+
+/* Clear the reference counts and forget everything we knew about the
+ debug registers. */
+
+void
+i386_low_init_dregs (struct i386_debug_reg_state *state)
+{
+ int i;
+
+ ALL_DEBUG_REGISTERS (i)
+ {
+ state->dr_mirror[i] = 0;
+ state->dr_ref_count[i] = 0;
+ }
+ state->dr_control_mirror = 0;
+ state->dr_status_mirror = 0;
+}
+
+/* Print the values of the mirrored debug registers. This is enabled via
+ the "set debug-hw-points 1" monitor command. */
+
+static void
+i386_show_dr (struct i386_debug_reg_state *state,
+ const char *func, CORE_ADDR addr,
+ int len, enum target_hw_bp_type type)
+{
+ int i;
+
+ fprintf (stderr, "%s", func);
+ if (addr || len)
+ fprintf (stderr, " (addr=%lx, len=%d, type=%s)",
+ (unsigned long) addr, len,
+ type == hw_write ? "data-write"
+ : (type == hw_read ? "data-read"
+ : (type == hw_access ? "data-read/write"
+ : (type == hw_execute ? "instruction-execute"
+ /* FIXME: if/when I/O read/write
+ watchpoints are supported, add them
+ here. */
+ : "??unknown??"))));
+ fprintf (stderr, ":\n");
+ fprintf (stderr, "\tCONTROL (DR7): %08x STATUS (DR6): %08x\n",
+ state->dr_control_mirror, state->dr_status_mirror);
+ ALL_DEBUG_REGISTERS (i)
+ {
+ fprintf (stderr, "\
+\tDR%d: addr=0x%s, ref.count=%d DR%d: addr=0x%s, ref.count=%d\n",
+ i, paddress (state->dr_mirror[i]),
+ state->dr_ref_count[i],
+ i + 1, paddress (state->dr_mirror[i + 1]),
+ state->dr_ref_count[i + 1]);
+ i++;
+ }
+}
+
+/* Return the value of a 4-bit field for DR7 suitable for watching a
+ region of LEN bytes for accesses of type TYPE. LEN is assumed to
+ have the value of 1, 2, or 4. */
+
+static unsigned
+i386_length_and_rw_bits (int len, enum target_hw_bp_type type)
+{
+ unsigned rw;
+
+ switch (type)
+ {
+ case hw_execute:
+ rw = DR_RW_EXECUTE;
+ break;
+ case hw_write:
+ rw = DR_RW_WRITE;
+ break;
+ case hw_read:
+ /* The i386 doesn't support data-read watchpoints. */
+ case hw_access:
+ rw = DR_RW_READ;
+ break;
+#if 0
+ /* Not yet supported. */
+ case hw_io_access:
+ rw = DR_RW_IORW;
+ break;
+#endif
+ default:
+ error ("\
+Invalid hardware breakpoint type %d in i386_length_and_rw_bits.\n",
+ (int) type);
+ }
+
+ switch (len)
+ {
+ case 1:
+ return (DR_LEN_1 | rw);
+ case 2:
+ return (DR_LEN_2 | rw);
+ case 4:
+ return (DR_LEN_4 | rw);
+ case 8:
+ if (TARGET_HAS_DR_LEN_8)
+ return (DR_LEN_8 | rw);
+ default:
+ error ("\
+Invalid hardware breakpoint length %d in i386_length_and_rw_bits.\n", len);
+ }
+}
+
+/* Insert a watchpoint at address ADDR, which is assumed to be aligned
+ according to the length of the region to watch. LEN_RW_BITS is the
+ value of the bits from DR7 which describes the length and access
+ type of the region to be watched by this watchpoint. Return 0 on
+ success, -1 on failure. */
+
+static int
+i386_insert_aligned_watchpoint (struct i386_debug_reg_state *state,
+ CORE_ADDR addr, unsigned len_rw_bits)
+{
+ int i;
+
+ /* First, look for an occupied debug register with the same address
+ and the same RW and LEN definitions. If we find one, we can
+ reuse it for this watchpoint as well (and save a register). */
+ ALL_DEBUG_REGISTERS (i)
+ {
+ if (!I386_DR_VACANT (state, i)
+ && state->dr_mirror[i] == addr
+ && I386_DR_GET_RW_LEN (state, i) == len_rw_bits)
+ {
+ state->dr_ref_count[i]++;
+ return 0;
+ }
+ }
+
+ /* Next, look for a vacant debug register. */
+ ALL_DEBUG_REGISTERS (i)
+ {
+ if (I386_DR_VACANT (state, i))
+ break;
+ }
+
+ /* No more debug registers! */
+ if (i >= DR_NADDR)
+ return -1;
+
+ /* Now set up the register I to watch our region. */
+
+ /* Record the info in our local mirrored array. */
+ state->dr_mirror[i] = addr;
+ state->dr_ref_count[i] = 1;
+ I386_DR_SET_RW_LEN (state, i, len_rw_bits);
+ /* Note: we only enable the watchpoint locally, i.e. in the current
+ task. Currently, no i386 target allows or supports global
+ watchpoints; however, if any target would want that in the
+ future, GDB should probably provide a command to control whether
+ to enable watchpoints globally or locally, and the code below
+ should use global or local enable and slow-down flags as
+ appropriate. */
+ I386_DR_LOCAL_ENABLE (state, i);
+ state->dr_control_mirror |= DR_LOCAL_SLOWDOWN;
+ state->dr_control_mirror &= I386_DR_CONTROL_MASK;
+
+ /* Finally, actually pass the info to the inferior. */
+ i386_dr_low_set_addr (state, i);
+ i386_dr_low_set_control (state);
+
+ return 0;
+}
+
+/* Remove a watchpoint at address ADDR, which is assumed to be aligned
+ according to the length of the region to watch. LEN_RW_BITS is the
+ value of the bits from DR7 which describes the length and access
+ type of the region watched by this watchpoint. Return 0 on
+ success, -1 on failure. */
+
+static int
+i386_remove_aligned_watchpoint (struct i386_debug_reg_state *state,
+ CORE_ADDR addr, unsigned len_rw_bits)
+{
+ int i, retval = -1;
+
+ ALL_DEBUG_REGISTERS (i)
+ {
+ if (!I386_DR_VACANT (state, i)
+ && state->dr_mirror[i] == addr
+ && I386_DR_GET_RW_LEN (state, i) == len_rw_bits)
+ {
+ if (--state->dr_ref_count[i] == 0) /* No longer in use? */
+ {
+ /* Reset our mirror. */
+ state->dr_mirror[i] = 0;
+ I386_DR_DISABLE (state, i);
+ /* Reset it in the inferior. */
+ i386_dr_low_set_control (state);
+ i386_dr_low_set_addr (state, i);
+ }
+ retval = 0;
+ }
+ }
+
+ return retval;
+}
+
+/* Insert or remove a (possibly non-aligned) watchpoint, or count the
+ number of debug registers required to watch a region at address
+ ADDR whose length is LEN for accesses of type TYPE. Return 0 on
+ successful insertion or removal, a positive number when queried
+ about the number of registers, or -1 on failure. If WHAT is not a
+ valid value, bombs through internal_error. */
+
+static int
+i386_handle_nonaligned_watchpoint (struct i386_debug_reg_state *state,
+ i386_wp_op_t what, CORE_ADDR addr, int len,
+ enum target_hw_bp_type type)
+{
+ int retval = 0, status = 0;
+ int max_wp_len = TARGET_HAS_DR_LEN_8 ? 8 : 4;
+
+ static const int size_try_array[8][8] =
+ {
+ {1, 1, 1, 1, 1, 1, 1, 1}, /* Trying size one. */
+ {2, 1, 2, 1, 2, 1, 2, 1}, /* Trying size two. */
+ {2, 1, 2, 1, 2, 1, 2, 1}, /* Trying size three. */
+ {4, 1, 2, 1, 4, 1, 2, 1}, /* Trying size four. */
+ {4, 1, 2, 1, 4, 1, 2, 1}, /* Trying size five. */
+ {4, 1, 2, 1, 4, 1, 2, 1}, /* Trying size six. */
+ {4, 1, 2, 1, 4, 1, 2, 1}, /* Trying size seven. */
+ {8, 1, 2, 1, 4, 1, 2, 1}, /* Trying size eight. */
+ };
+
+ while (len > 0)
+ {
+ int align = addr % max_wp_len;
+ /* Four (eight on AMD64) is the maximum length a debug register
+ can watch. */
+ int try = (len > max_wp_len ? (max_wp_len - 1) : len - 1);
+ int size = size_try_array[try][align];
+
+ if (what == WP_COUNT)
+ {
+ /* size_try_array[] is defined such that each iteration
+ through the loop is guaranteed to produce an address and a
+ size that can be watched with a single debug register.
+ Thus, for counting the registers required to watch a
+ region, we simply need to increment the count on each
+ iteration. */
+ retval++;
+ }
+ else
+ {
+ unsigned len_rw = i386_length_and_rw_bits (size, type);
+
+ if (what == WP_INSERT)
+ status = i386_insert_aligned_watchpoint (state, addr, len_rw);
+ else if (what == WP_REMOVE)
+ status = i386_remove_aligned_watchpoint (state, addr, len_rw);
+ else
+ fatal ("\
+Invalid value %d of operation in i386_handle_nonaligned_watchpoint.\n",
+ (int) what);
+
+ /* We keep the loop going even after a failure, because some
+ of the other aligned watchpoints might still succeed
+ (e.g. if they watch addresses that are already watched,
+ in which case we just increment the reference counts of
+ occupied debug registers). If we break out of the loop
+ too early, we could cause those addresses watched by
+ other watchpoints to be disabled when breakpoint.c reacts
+ to our failure to insert this watchpoint and tries to
+ remove it. */
+ if (status)
+ retval = status;
+ }
+
+ addr += size;
+ len -= size;
+ }
+
+ return retval;
+}
+
+#define Z_PACKET_WRITE_WP '2'
+#define Z_PACKET_READ_WP '3'
+#define Z_PACKET_ACCESS_WP '4'
+
+/* Map the protocol watchpoint type TYPE to enum target_hw_bp_type. */
+
+static enum target_hw_bp_type
+Z_packet_to_hw_type (char type)
+{
+ switch (type)
+ {
+ case Z_PACKET_WRITE_WP:
+ return hw_write;
+ case Z_PACKET_READ_WP:
+ return hw_read;
+ case Z_PACKET_ACCESS_WP:
+ return hw_access;
+ default:
+ fatal ("Z_packet_to_hw_type: bad watchpoint type %c", type);
+ }
+}
+
+/* Insert a watchpoint to watch a memory region which starts at
+ address ADDR and whose length is LEN bytes. Watch memory accesses
+ of the type TYPE_FROM_PACKET. Return 0 on success, -1 on failure. */
+
+int
+i386_low_insert_watchpoint (struct i386_debug_reg_state *state,
+ char type_from_packet, CORE_ADDR addr, int len)
+{
+ int retval;
+ enum target_hw_bp_type type = Z_packet_to_hw_type (type_from_packet);
+
+ if (((len != 1 && len != 2 && len != 4)
+ && !(TARGET_HAS_DR_LEN_8 && len == 8))
+ || addr % len != 0)
+ {
+ retval = i386_handle_nonaligned_watchpoint (state, WP_INSERT,
+ addr, len, type);
+ }
+ else
+ {
+ unsigned len_rw = i386_length_and_rw_bits (len, type);
+
+ retval = i386_insert_aligned_watchpoint (state, addr, len_rw);
+ }
+
+ if (debug_hw_points)
+ i386_show_dr (state, "insert_watchpoint", addr, len, type);
+
+ return retval;
+}
+
+/* Remove a watchpoint that watched the memory region which starts at
+ address ADDR, whose length is LEN bytes, and for accesses of the
+ type TYPE_FROM_PACKET. Return 0 on success, -1 on failure. */
+
+int
+i386_low_remove_watchpoint (struct i386_debug_reg_state *state,
+ char type_from_packet, CORE_ADDR addr, int len)
+{
+ int retval;
+ enum target_hw_bp_type type = Z_packet_to_hw_type (type_from_packet);
+
+ if (((len != 1 && len != 2 && len != 4)
+ && !(TARGET_HAS_DR_LEN_8 && len == 8))
+ || addr % len != 0)
+ {
+ retval = i386_handle_nonaligned_watchpoint (state, WP_REMOVE,
+ addr, len, type);
+ }
+ else
+ {
+ unsigned len_rw = i386_length_and_rw_bits (len, type);
+
+ retval = i386_remove_aligned_watchpoint (state, addr, len_rw);
+ }
+
+ if (debug_hw_points)
+ i386_show_dr (state, "remove_watchpoint", addr, len, type);
+
+ return retval;
+}
+
+/* Return non-zero if we can watch a memory region that starts at
+ address ADDR and whose length is LEN bytes. */
+
+int
+i386_low_region_ok_for_watchpoint (struct i386_debug_reg_state *state,
+ CORE_ADDR addr, int len)
+{
+ int nregs;
+
+ /* Compute how many aligned watchpoints we would need to cover this
+ region. */
+ nregs = i386_handle_nonaligned_watchpoint (state, WP_COUNT,
+ addr, len, hw_write);
+ return nregs <= DR_NADDR ? 1 : 0;
+}
+
+/* If the inferior has some break/watchpoint that triggered, set the
+ address associated with that break/watchpoint and return true.
+ Otherwise, return false. */
+
+int
+i386_low_stopped_data_address (struct i386_debug_reg_state *state,
+ CORE_ADDR *addr_p)
+{
+ CORE_ADDR addr = 0;
+ int i;
+ int rc = 0;
+
+ /* Get dr_status_mirror for use by I386_DR_WATCH_HIT. */
+ i386_dr_low_get_status (state);
+
+ ALL_DEBUG_REGISTERS (i)
+ {
+ if (I386_DR_WATCH_HIT (state, i)
+ /* This second condition makes sure DRi is set up for a data
+ watchpoint, not a hardware breakpoint. The reason is
+ that GDB doesn't call the target_stopped_data_address
+ method except for data watchpoints. In other words, I'm
+ being paranoiac. */
+ && I386_DR_GET_RW_LEN (state, i) != 0)
+ {
+ addr = state->dr_mirror[i];
+ rc = 1;
+ if (debug_hw_points)
+ i386_show_dr (state, "watchpoint_hit", addr, -1, hw_write);
+ }
+ }
+
+ if (debug_hw_points && addr == 0)
+ i386_show_dr (state, "stopped_data_addr", 0, 0, hw_write);
+
+ if (rc)
+ *addr_p = addr;
+ return rc;
+}
+
+/* Return true if the inferior has some watchpoint that triggered.
+ Otherwise return false. */
+
+int
+i386_low_stopped_by_watchpoint (struct i386_debug_reg_state *state)
+{
+ CORE_ADDR addr = 0;
+ return i386_low_stopped_data_address (state, &addr);
+}
Index: i386-low.h
===================================================================
RCS file: i386-low.h
diff -N i386-low.h
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ i386-low.h 30 Jun 2009 09:15:58 -0000
@@ -0,0 +1,109 @@
+/* Misc. low level support for i386.
+
+ Copyright (C) 2009
+ Free Software Foundation, Inc.
+
+ This file is part of GDB.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
+
+/* Support for hardware watchpoints and breakpoints using the i386
+ debug registers.
+
+ This provides several functions for inserting and removing
+ hardware-assisted breakpoints and watchpoints, testing if one or
+ more of the watchpoints triggered and at what address, checking
+ whether a given region can be watched, etc.
+
+ The functions below implement debug registers sharing by reference
+ counts, and allow to watch regions up to 16 bytes long
+ (32 bytes on 64 bit hosts). */
+
+
+/* Debug registers' indices. */
+#define DR_FIRSTADDR 0
+#define DR_LASTADDR 3
+#define DR_NADDR 4 /* The number of debug address registers. */
+#define DR_STATUS 6
+#define DR_CONTROL 7
+
+/* Global state needed to track h/w watchpoints. */
+
+struct i386_debug_reg_state
+{
+ /* Mirror the inferior's DRi registers. We keep the status and
+ control registers separated because they don't hold addresses. */
+ CORE_ADDR dr_mirror[DR_NADDR];
+ unsigned dr_status_mirror, dr_control_mirror;
+
+ /* Reference counts for each debug register. */
+ int dr_ref_count[DR_NADDR];
+};
+
+/* Initialize STATE. */
+extern void i386_low_init_dregs (struct i386_debug_reg_state *state);
+
+/* Insert a watchpoint to watch a memory region which starts at
+ address ADDR and whose length is LEN bytes. Watch memory accesses
+ of the type TYPE_FROM_PACKET. Return 0 on success, -1 on failure. */
+extern int i386_low_insert_watchpoint (struct i386_debug_reg_state *state,
+ char type_from_packet, CORE_ADDR addr,
+ int len);
+
+/* Remove a watchpoint that watched the memory region which starts at
+ address ADDR, whose length is LEN bytes, and for accesses of the
+ type TYPE_FROM_PACKET. Return 0 on success, -1 on failure. */
+extern int i386_low_remove_watchpoint (struct i386_debug_reg_state *state,
+ char type_from_packet, CORE_ADDR addr,
+ int len);
+
+/* Return non-zero if we can watch a memory region that starts at
+ address ADDR and whose length is LEN bytes. */
+extern int i386_low_region_ok_for_watchpoint (struct i386_debug_reg_state *state,
+ CORE_ADDR addr, int len);
+
+/* If the inferior has some break/watchpoint that triggered, set the
+ address associated with that break/watchpoint and return true.
+ Otherwise, return false. */
+extern int i386_low_stopped_data_address (struct i386_debug_reg_state *state,
+ CORE_ADDR *addr_p);
+
+/* Return true if the inferior has some watchpoint that triggered.
+ Otherwise return false. */
+extern int i386_low_stopped_by_watchpoint (struct i386_debug_reg_state *state);
+\f
+/* Each target needs to provide several low-level functions
+ that will be called to insert watchpoints and hardware breakpoints
+ into the inferior, remove them, and check their status. These
+ functions are:
+
+ i386_dr_low_set_control -- set the debug control (DR7)
+ register to a given value
+
+ i386_dr_low_set_addr -- put an address into one debug register
+
+ i386_dr_low_get_status -- return the value of the debug
+ status (DR6) register.
+*/
+
+/* Update the inferior's debug register REGNUM from STATE. */
+extern void i386_dr_low_set_addr (const struct i386_debug_reg_state *state,
+ int regnum);
+
+/* Update the inferior's DR7 debug control register from STATE. */
+extern void i386_dr_low_set_control (const struct i386_debug_reg_state *state);
+
+/* Get the value of the inferior's DR6 debug status register
+ and record it in STATE. */
+extern void i386_dr_low_get_status (struct i386_debug_reg_state *state);
Index: linux-low.c
===================================================================
RCS file: /cvs/src/src/gdb/gdbserver/linux-low.c,v
retrieving revision 1.108
diff -u -p -r1.108 linux-low.c
--- linux-low.c 25 Jun 2009 22:13:53 -0000 1.108
+++ linux-low.c 30 Jun 2009 09:15:58 -0000
@@ -224,6 +224,7 @@ delete_lwp (struct lwp_info *lwp)
{
remove_thread (get_lwp_thread (lwp));
remove_inferior (&all_lwps, &lwp->head);
+ free (lwp->arch_private);
free (lwp);
}

@@ -242,6 +243,9 @@ linux_add_process (int pid, int attached
proc = add_process (pid, attached);
proc->private = xcalloc (1, sizeof (*proc->private));

+ if (the_low_target.new_process != NULL)
+ proc->private->arch_private = the_low_target.new_process ();
+
return proc;
}

@@ -251,6 +255,7 @@ linux_add_process (int pid, int attached
static void
linux_remove_process (struct process_info *process)
{
+ free (process->private->arch_private);
free (process->private);
remove_process (process);
}
@@ -376,6 +381,9 @@ add_lwp (ptid_t ptid)

lwp->head.id = ptid;

+ if (the_low_target.new_thread != NULL)
+ lwp->arch_private = the_low_target.new_thread ();
+
add_inferior_to_list (&all_lwps, &lwp->head);

return lwp;
@@ -466,7 +474,6 @@ linux_attach_lwp_1 (unsigned long lwpid,
new_lwp = (struct lwp_info *) add_lwp (ptid);
add_thread (ptid, new_lwp);

-
/* We need to wait for SIGSTOP before being able to make the next
ptrace call on this LWP. */
new_lwp->must_set_ptrace_flags = 1;
@@ -1740,6 +1747,9 @@ linux_resume_one_lwp (struct lwp_info *l
*p_sig = NULL;
}

+ if (the_low_target.prepare_to_resume != NULL)
+ the_low_target.prepare_to_resume (lwp);
+
regcache_invalidate_one ((struct inferior_list_entry *)
get_lwp_thread (lwp));
errno = 0;
Index: linux-low.h
===================================================================
RCS file: /cvs/src/src/gdb/gdbserver/linux-low.h,v
retrieving revision 1.31
diff -u -p -r1.31 linux-low.h
--- linux-low.h 25 Jun 2009 22:13:53 -0000 1.31
+++ linux-low.h 30 Jun 2009 09:15:58 -0000
@@ -56,8 +56,13 @@ struct process_info_private

/* Connection to the libthread_db library. */
td_thragent_t *thread_agent;
+
+ /* Arch-specific additions. */
+ struct arch_process_info *arch_private;
};

+struct lwp_info;
+
struct linux_target_ops
{
/* Architecture-specific setup. */
@@ -97,10 +102,24 @@ struct linux_target_ops
If DIRECTION is 1, then copy from INF to NATIVE.
If DIRECTION is 0, copy from NATIVE to INF. */
int (*siginfo_fixup) (struct siginfo *native, void *inf, int direction);
+
+ /* Hook to call when a new process is created or attached to.
+ If extra per-process architecture-specific data is needed,
+ allocate it here. */
+ struct arch_process_info * (*new_process) (void);
+
+ /* Hook to call when a new thread is detected.
+ If extra per-thread architecture-specific data is needed,
+ allocate it here. */
+ struct arch_lwp_info * (*new_thread) (void);
+
+ /* Hook to call prior to resuming a thread. */
+ void (*prepare_to_resume) (struct lwp_info *);
};

extern struct linux_target_ops the_low_target;

+#define ptid_of(proc) ((proc)->head.id)
#define pid_of(proc) ptid_get_pid ((proc)->head.id)
#define lwpid_of(proc) ptid_get_lwp ((proc)->head.id)

@@ -173,6 +192,9 @@ struct lwp_info
THREAD_KNOWN is set. */
td_thrhandle_t th;
#endif
+
+ /* Arch-specific additions. */
+ struct arch_lwp_info *arch_private;
};

extern struct inferior_list all_lwps;
Index: linux-x86-low.c
===================================================================
RCS file: /cvs/src/src/gdb/gdbserver/linux-x86-low.c,v
retrieving revision 1.2
diff -u -p -r1.2 linux-x86-low.c
--- linux-x86-low.c 13 May 2009 19:11:04 -0000 1.2
+++ linux-x86-low.c 30 Jun 2009 09:15:58 -0000
@@ -18,10 +18,12 @@
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */

+#include <stddef.h>
#include <signal.h>
#include "server.h"
#include "linux-low.h"
#include "i387-fp.h"
+#include "i386-low.h"

#include "gdb_proc_service.h"

@@ -56,6 +58,21 @@ void init_registers_x86_64_linux (void);
#define ARCH_GET_GS 0x1004
#endif

+/* Per-process arch-specific data we want to keep. */
+
+struct arch_process_info
+{
+ struct i386_debug_reg_state debug_reg_state;
+};
+
+/* Per-thread arch-specific data we want to keep. */
+
+struct arch_lwp_info
+{
+ /* Non-zero if our copy differs from what's recorded in the thread. */
+ int debug_registers_changed;
+};
+
#ifdef __x86_64__

/* Mapping between the general-purpose registers in `struct user'
@@ -317,6 +334,198 @@ x86_breakpoint_at (CORE_ADDR pc)
return 0;
}
\f
+/* Support for debug registers. */
+
+static unsigned long
+x86_linux_dr_get (ptid_t ptid, int regnum)
+{
+ int tid;
+ unsigned long value;
+
+ tid = ptid_get_lwp (ptid);
+
+ errno = 0;
+ value = ptrace (PTRACE_PEEKUSER, tid,
+ offsetof (struct user, u_debugreg[regnum]), 0);
+ if (errno != 0)
+ error ("Couldn't read debug register");
+
+ return value;
+}
+
+static void
+x86_linux_dr_set (ptid_t ptid, int regnum, unsigned long value)
+{
+ int tid;
+
+ tid = ptid_get_lwp (ptid);
+
+ errno = 0;
+ ptrace (PTRACE_POKEUSER, tid,
+ offsetof (struct user, u_debugreg[regnum]), value);
+ if (errno != 0)
+ error ("Couldn't write debug register");
+}
+
+/* Update the inferior's debug register REGNUM from STATE. */
+
+void
+i386_dr_low_set_addr (const struct i386_debug_reg_state *state, int regnum)
+{
+ struct inferior_list_entry *lp;
+ CORE_ADDR addr;
+ /* Only need to update the threads of this process. */
+ int pid = pid_of (get_thread_lwp (current_inferior));
+
+ if (! (regnum >= 0 && regnum <= DR_LASTADDR - DR_FIRSTADDR))
+ fatal ("Invalid debug register %d", regnum);
+
+ addr = state->dr_mirror[regnum];
+
+ for (lp = all_lwps.head; lp; lp = lp->next)
+ {
+ struct lwp_info *lwp = (struct lwp_info *) lp;
+
+ /* The actual update is done later, we just mark that the register
+ needs updating. */
+ if (pid_of (lwp) == pid)
+ lwp->arch_private->debug_registers_changed = 1;
+ }
+}
+
+/* Update the inferior's DR7 debug control register from STATE. */
+
+void
+i386_dr_low_set_control (const struct i386_debug_reg_state *state)
+{
+ struct inferior_list_entry *lp;
+ /* Only need to update the threads of this process. */
+ int pid = pid_of (get_thread_lwp (current_inferior));
+
+ for (lp = all_lwps.head; lp; lp = lp->next)
+ {
+ struct lwp_info *lwp = (struct lwp_info *) lp;
+
+ /* The actual update is done later, we just mark that the register
+ needs updating. */
+ if (pid_of (lwp) == pid)
+ lwp->arch_private->debug_registers_changed = 1;
+ }
+}
+
+/* Get the value of the DR6 debug status register from the inferior
+ and record it in STATE. */
+
+void
+i386_dr_low_get_status (struct i386_debug_reg_state *state)
+{
+ struct lwp_info *lwp = get_thread_lwp (current_inferior);
+ ptid_t ptid = ptid_of (lwp);
+
+ state->dr_status_mirror = x86_linux_dr_get (ptid, DR_STATUS);
+}
+\f
+/* Watchpoint support. */
+
+static int
+x86_insert_point (char type, CORE_ADDR addr, int len)
+{
+ struct process_info *proc = current_process ();
+ switch (type)
+ {
+ case '2':
+ case '3':
+ case '4':
+ return i386_low_insert_watchpoint (&proc->private->arch_private->debug_reg_state,
+ type, addr, len);
+ default:
+ /* Unsupported. */
+ return 1;
+ }
+}
+
+static int
+x86_remove_point (char type, CORE_ADDR addr, int len)
+{
+ struct process_info *proc = current_process ();
+ switch (type)
+ {
+ case '2':
+ case '3':
+ case '4':
+ return i386_low_remove_watchpoint (&proc->private->arch_private->debug_reg_state,
+ type, addr, len);
+ default:
+ /* Unsupported. */
+ return 1;
+ }
+}
+
+static int
+x86_stopped_by_watchpoint (void)
+{
+ struct process_info *proc = current_process ();
+ return i386_low_stopped_by_watchpoint (&proc->private->arch_private->debug_reg_state);
+}
+
+static CORE_ADDR
+x86_stopped_data_address (void)
+{
+ struct process_info *proc = current_process ();
+ CORE_ADDR addr;
+ if (i386_low_stopped_data_address (&proc->private->arch_private->debug_reg_state,
+ &addr))
+ return addr;
+ return 0;
+}
+\f
+/* Called when a new process is created. */
+
+static struct arch_process_info *
+x86_linux_new_process (void)
+{
+ struct arch_process_info *info = xcalloc (1, sizeof (*info));
+
+ i386_low_init_dregs (&info->debug_reg_state);
+
+ return info;
+}
+
+/* Called when a new thread is detected. */
+
+static struct arch_lwp_info *
+x86_linux_new_thread (void)
+{
+ struct arch_lwp_info *info = xcalloc (1, sizeof (*info));
+
+ info->debug_registers_changed = 1;
+
+ return info;
+}
+
+/* Called when resuming a thread.
+ If the debug regs have changed, update the thread's copies. */
+
+static void
+x86_linux_prepare_to_resume (struct lwp_info *lwp)
+{
+ if (lwp->arch_private->debug_registers_changed)
+ {
+ int i;
+ ptid_t ptid = ptid_of (lwp);
+ int pid = ptid_get_pid (ptid);
+ struct process_info *proc = find_process_pid (pid);
+ struct i386_debug_reg_state *state = &proc->private->arch_private->debug_reg_state;
+
+ for (i = DR_FIRSTADDR; i <= DR_LASTADDR; i++)
+ x86_linux_dr_set (ptid, i, state->dr_mirror[i]);
+
+ x86_linux_dr_set (ptid, DR_CONTROL, state->dr_control_mirror);
+
+ lwp->arch_private->debug_registers_changed = 0;
+ }
+}
+\f
/* When GDBSERVER is built as a 64-bit application on linux, the
PTRACE_GETSIGINFO data is always presented in 64-bit layout. Since
debugging a 32-bit inferior with a 64-bit GDBSERVER should look the same
@@ -630,10 +839,10 @@ struct linux_target_ops the_low_target =
NULL,
1,
x86_breakpoint_at,
- NULL,
- NULL,
- NULL,
- NULL,
+ x86_insert_point,
+ x86_remove_point,
+ x86_stopped_by_watchpoint,
+ x86_stopped_data_address,
/* collect_ptrace_register/supply_ptrace_register are not needed in the
native i386 case (no registers smaller than an xfer unit), and are not
used in the biarch case (HAVE_LINUX_USRREGS is not defined). */
@@ -641,4 +850,7 @@ struct linux_target_ops the_low_target =
NULL,
/* need to fix up i386 siginfo if host is amd64 */
x86_siginfo_fixup,
+ x86_linux_new_process,
+ x86_linux_new_thread,
+ x86_linux_prepare_to_resume
};
Index: server.c
===================================================================
RCS file: /cvs/src/src/gdb/gdbserver/server.c,v
retrieving revision 1.101
diff -u -p -r1.101 server.c
--- server.c 25 Jun 2009 22:13:52 -0000 1.101
+++ server.c 30 Jun 2009 09:15:58 -0000
@@ -51,6 +51,9 @@ static char **program_argv, **wrapper_ar
was originally used to debug LinuxThreads support. */
int debug_threads;

+/* Enable debugging of h/w breakpoint/watchpoint support. */
+int debug_hw_points;
+
int pass_signals[TARGET_SIGNAL_LAST];

jmp_buf toplevel;
@@ -495,6 +498,8 @@ monitor_show_help (void)
monitor_output ("The following monitor commands are supported:\n");
monitor_output (" set debug <0|1>\n");
monitor_output (" Enable general debugging messages\n");
+ monitor_output (" set debug-hw-points <0|1>\n");
+ monitor_output (" Enable h/w breakpoint/watchpoint debugging messages\n");
monitor_output (" set remote-debug <0|1>\n");
monitor_output (" Enable remote protocol debugging messages\n");
monitor_output (" exit\n");
@@ -1216,6 +1221,16 @@ handle_query (char *own_buf, int packet_
debug_threads = 0;
monitor_output ("Debug output disabled.\n");
}
+ else if (strcmp (mon, "set debug-hw-points 1") == 0)
+ {
+ debug_hw_points = 1;
+ monitor_output ("H/W point debugging output enabled.\n");
+ }
+ else if (strcmp (mon, "set debug-hw-points 0") == 0)
+ {
+ debug_hw_points = 0;
+ monitor_output ("H/W point debugging output disabled.\n");
+ }
else if (strcmp (mon, "set remote-debug 1") == 0)
{
remote_debug = 1;
Index: server.h
===================================================================
RCS file: /cvs/src/src/gdb/gdbserver/server.h,v
retrieving revision 1.58
diff -u -p -r1.58 server.h
--- server.h 24 May 2009 21:06:53 -0000 1.58
+++ server.h 30 Jun 2009 09:15:58 -0000
@@ -271,6 +271,7 @@ extern ptid_t step_thread;

extern int server_waiting;
extern int debug_threads;
+extern int debug_hw_points;
extern int pass_signals[];

extern jmp_buf toplevel;
@@ -407,6 +408,7 @@ void perror_with_name (const char *strin
void error (const char *string,...) ATTR_NORETURN ATTR_FORMAT (printf, 1, 2);
void fatal (const char *string,...) ATTR_NORETURN ATTR_FORMAT (printf, 1, 2);
void warning (const char *string,...) ATTR_FORMAT (printf, 1, 2);
+char *paddress (CORE_ADDR addr);

/* Maximum number of bytes to read/write at once. The value here
is chosen to fill up a packet (the headers account for the 32). */
Index: win32-arm-low.c
===================================================================
RCS file: /cvs/src/src/gdb/gdbserver/win32-arm-low.c,v
retrieving revision 1.8
diff -u -p -r1.8 win32-arm-low.c
--- win32-arm-low.c 3 Jan 2009 05:57:57 -0000 1.8
+++ win32-arm-low.c 30 Jun 2009 09:15:58 -0000
@@ -122,4 +122,9 @@ struct win32_target_ops the_low_target =
NULL, /* single_step */
(const unsigned char *) &arm_wince_breakpoint,
arm_wince_breakpoint_len,
+ /* Watchpoint related functions. See target.h for comments. */
+ NULL, /* insert_point */
+ NULL, /* remove_point */
+ NULL, /* stopped_by_watchpoint */
+ NULL /* stopped_data_address */
};
Index: win32-i386-low.c
===================================================================
RCS file: /cvs/src/src/gdb/gdbserver/win32-i386-low.c,v
retrieving revision 1.14
diff -u -p -r1.14 win32-i386-low.c
--- win32-i386-low.c 3 Jan 2009 05:57:57 -0000 1.14
+++ win32-i386-low.c 30 Jun 2009 09:15:58 -0000
@@ -17,6 +17,7 @@

#include "server.h"
#include "win32-low.h"
+#include "i386-low.h"

#define FCS_REGNUM 27
#define FOP_REGNUM 31
@@ -26,15 +27,101 @@
/* Defined in auto-generated file reg-i386.c. */
void init_registers_i386 (void);

-static unsigned dr[8];
+static struct i386_debug_reg_state debug_reg_state;

static int debug_registers_changed = 0;
static int debug_registers_used = 0;

+/* Update the inferior's debug register REGNUM from STATE. */
+
+void
+i386_dr_low_set_addr (const struct i386_debug_reg_state *state, int regnum)
+{
+ if (! (regnum >= 0 && regnum <= DR_LASTADDR - DR_FIRSTADDR))
+ fatal ("Invalid debug register %d", regnum);
+
+ /* debug_reg_state.dr_mirror is already set.
+ Just notify i386_set_thread_context, i386_thread_added
+ that the registers need to be updated. */
+ debug_registers_changed = 1;
+ debug_registers_used = 1;
+}
+
+/* Update the inferior's DR7 debug control register from STATE. */
+
+void
+i386_dr_low_set_control (const struct i386_debug_reg_state *state)
+{
+ /* debug_reg_state.dr_control_mirror is already set.
+ Just notify i386_set_thread_context, i386_thread_added
+ that the registers need to be updated. */
+ debug_registers_changed = 1;
+ debug_registers_used = 1;
+}
+
+/* Get the value of the DR6 debug status register from the inferior
+ and record it in STATE. */
+
+void
+i386_dr_low_get_status (struct i386_debug_reg_state *state)
+{
+ /* We don't need to do anything here, the last call to thread_rec for
+ current_event.dwThreadId id has already set it. */
+}
+
+/* Watchpoint support. */
+
+static int
+i386_insert_point (char type, CORE_ADDR addr, int len)
+{
+ switch (type)
+ {
+ case '2':
+ case '3':
+ case '4':
+ return i386_low_insert_watchpoint (&debug_reg_state,
+ type, addr, len);
+ default:
+ /* Unsupported. */
+ return 1;
+ }
+}
+
+static int
+i386_remove_point (char type, CORE_ADDR addr, int len)
+{
+ switch (type)
+ {
+ case '2':
+ case '3':
+ case '4':
+ return i386_low_remove_watchpoint (&debug_reg_state,
+ type, addr, len);
+ default:
+ /* Unsupported. */
+ return 1;
+ }
+}
+
+static int
+i386_stopped_by_watchpoint (void)
+{
+ return i386_low_stopped_by_watchpoint (&debug_reg_state);
+}
+
+static CORE_ADDR
+i386_stopped_data_address (void)
+{
+ CORE_ADDR addr;
+ if (i386_low_stopped_data_address (&debug_reg_state, &addr))
+ return addr;
+ return 0;
+}
+
static void
i386_initial_stuff (void)
{
- memset (&dr, 0, sizeof (dr));
+ i386_low_init_dregs (&debug_reg_state);
debug_registers_changed = 0;
debug_registers_used = 0;
}
@@ -55,12 +142,13 @@ i386_get_thread_context (win32_thread_in
if (th->tid == current_event->dwThreadId)
{
/* Copy dr values from the current thread. */
- dr[0] = th->context.Dr0;
- dr[1] = th->context.Dr1;
- dr[2] = th->context.Dr2;
- dr[3] = th->context.Dr3;
- dr[6] = th->context.Dr6;
- dr[7] = th->context.Dr7;
+ struct i386_debug_reg_state *dr = &debug_reg_state;
+ dr->dr_mirror[0] = th->context.Dr0;
+ dr->dr_mirror[1] = th->context.Dr1;
+ dr->dr_mirror[2] = th->context.Dr2;
+ dr->dr_mirror[3] = th->context.Dr3;
+ dr->dr_status_mirror = th->context.Dr6;
+ dr->dr_control_mirror = th->context.Dr7;
}
}

@@ -69,13 +157,14 @@ i386_set_thread_context (win32_thread_in
{
if (debug_registers_changed)
{
- th->context.Dr0 = dr[0];
- th->context.Dr1 = dr[1];
- th->context.Dr2 = dr[2];
- th->context.Dr3 = dr[3];
- /* th->context.Dr6 = dr[6];
+ struct i386_debug_reg_state *dr = &debug_reg_state;
+ th->context.Dr0 = dr->dr_mirror[0];
+ th->context.Dr1 = dr->dr_mirror[1];
+ th->context.Dr2 = dr->dr_mirror[2];
+ th->context.Dr3 = dr->dr_mirror[3];
+ /* th->context.Dr6 = dr->dr_status_mirror;
FIXME: should we set dr6 also ?? */
- th->context.Dr7 = dr[7];
+ th->context.Dr7 = dr->dr_control_mirror;
}

SetThreadContext (th->h, &th->context);
@@ -87,16 +176,17 @@ i386_thread_added (win32_thread_info *th
/* Set the debug registers for the new thread if they are used. */
if (debug_registers_used)
{
+ struct i386_debug_reg_state *dr = &debug_reg_state;
th->context.ContextFlags = CONTEXT_DEBUG_REGISTERS;
GetThreadContext (th->h, &th->context);

- th->context.Dr0 = dr[0];
- th->context.Dr1 = dr[1];
- th->context.Dr2 = dr[2];
- th->context.Dr3 = dr[3];
- /* th->context.Dr6 = dr[6];
+ th->context.Dr0 = dr->dr_mirror[0];
+ th->context.Dr1 = dr->dr_mirror[1];
+ th->context.Dr2 = dr->dr_mirror[2];
+ th->context.Dr3 = dr->dr_mirror[3];
+ /* th->context.Dr6 = dr->dr_status_mirror;
FIXME: should we set dr6 also ?? */
- th->context.Dr7 = dr[7];
+ th->context.Dr7 = dr->dr_control_mirror;

SetThreadContext (th->h, &th->context);
th->context.ContextFlags = 0;
@@ -205,4 +295,8 @@ struct win32_target_ops the_low_target =
i386_single_step,
NULL, /* breakpoint */
0, /* breakpoint_len */
+ i386_insert_point,
+ i386_remove_point,
+ i386_stopped_by_watchpoint,
+ i386_stopped_data_address
};
Index: win32-low.c
===================================================================
RCS file: /cvs/src/src/gdb/gdbserver/win32-low.c,v
retrieving revision 1.36
diff -u -p -r1.36 win32-low.c
--- win32-low.c 22 Jun 2009 19:33:41 -0000 1.36
+++ win32-low.c 30 Jun 2009 09:15:58 -0000
@@ -228,6 +228,48 @@ child_delete_thread (DWORD pid, DWORD ti
delete_thread_info (thread);
}

+/* These watchpoint related wrapper functions simply pass on the function call
+ if the low target has registered a corresponding function. */
+
+static int
+win32_insert_point (char type, CORE_ADDR addr, int len)
+{
+ if (the_low_target.insert_point != NULL)
+ return the_low_target.insert_point (type, addr, len);
+ else
+ /* Unsupported (see target.h). */
+ return 1;
+}
+
+static int
+win32_remove_point (char type, CORE_ADDR addr, int len)
+{
+ if (the_low_target.remove_point != NULL)
+ return the_low_target.remove_point (type, addr, len);
+ else
+ /* Unsupported (see target.h). */
+ return 1;
+}
+
+static int
+win32_stopped_by_watchpoint (void)
+{
+ if (the_low_target.stopped_by_watchpoint != NULL)
+ return the_low_target.stopped_by_watchpoint ();
+ else
+ return 0;
+}
+
+static CORE_ADDR
+win32_stopped_data_address (void)
+{
+ if (the_low_target.stopped_data_address != NULL)
+ return the_low_target.stopped_data_address ();
+ else
+ return 0;
+}
+
+
/* Transfer memory from/to the debugged process. */
static int
child_xfer_memory (CORE_ADDR memaddr, char *our, int len,
@@ -1697,10 +1739,10 @@ static struct target_ops win32_target_op
NULL,
win32_request_interrupt,
NULL,
- NULL,
- NULL,
- NULL,
- NULL,
+ win32_insert_point,
+ win32_remove_point,
+ win32_stopped_by_watchpoint,
+ win32_stopped_data_address,
NULL,
NULL,
NULL,
Index: win32-low.h
===================================================================
RCS file: /cvs/src/src/gdb/gdbserver/win32-low.h,v
retrieving revision 1.9
diff -u -p -r1.9 win32-low.h
--- win32-low.h 3 Jan 2009 05:57:57 -0000 1.9
+++ win32-low.h 30 Jun 2009 09:15:58 -0000
@@ -70,6 +70,12 @@ struct win32_target_ops

const unsigned char *breakpoint;
int breakpoint_len;
+
+ /* Breakpoint/Watchpoint related functions. See target.h for comments. */
+ int (*insert_point) (char type, CORE_ADDR addr, int len);
+ int (*remove_point) (char type, CORE_ADDR addr, int len);
+ int (*stopped_by_watchpoint) (void);
+ CORE_ADDR (*stopped_data_address) (void);
};

extern struct win32_target_ops the_low_target;
Index: utils.c
===================================================================
RCS file: /cvs/src/src/gdb/gdbserver/utils.c,v
retrieving revision 1.18
diff -u -p -r1.18 utils.c
--- utils.c 19 Jan 2009 00:16:46 -0000 1.18
+++ utils.c 30 Jun 2009 09:49:34 -0000
@@ -170,3 +170,46 @@ warning (const char *string,...)
fprintf (stderr, "\n");
va_end (args);
}
+
+/* Temporary storage using circular buffer. */
+#define NUMCELLS 4
+#define CELLSIZE 50
+
+/* Return the next entry in the circular buffer. */
+
+static char *
+get_cell (void)
+{
+ static char buf[NUMCELLS][CELLSIZE];
+ static int cell = 0;
+ if (++cell >= NUMCELLS)
+ cell = 0;
+ return buf[cell];
+}
+
+/* Stdarg wrapper around vsnprintf.
+ SIZE is the size of the buffer pointed to by STR. */
+
+static int
+xsnprintf (char *str, size_t size, const char *format, ...)
+{
+ va_list args;
+ int ret;
+
+ va_start (args, format);
+ ret = vsnprintf (str, size, format, args);
+ va_end (args);
+
+ return ret;
+}
+
+/* Convert a CORE_ADDR into a HEX string, like %lx.
+ The result is stored in a circular static buffer, NUMCELLS deep. */
+
+char *
+paddress (CORE_ADDR addr)
+{
+ char *str = get_cell ();
+ xsnprintf (str, CELLSIZE, "%lx", (long) addr);
+ return str;
+}