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Re: [Qemu-devel] Re: [PATCH 02/13] Refactor and enhance break/watchpoint
From: |
Glauber Costa |
Subject: |
Re: [Qemu-devel] Re: [PATCH 02/13] Refactor and enhance break/watchpoint API |
Date: |
Tue, 14 Oct 2008 15:51:59 -0200 |
On Tue, Oct 14, 2008 at 3:45 PM, Jan Kiszka <address@hidden> wrote:
> Glauber Costa wrote:
>>> Index: b/exec.c
>>> ===================================================================
>>> --- a/exec.c
>>> +++ b/exec.c
>>> @@ -537,7 +537,6 @@ void cpu_exec_init(CPUState *env)
>>> cpu_index++;
>>> }
>>> env->cpu_index = cpu_index;
>>> - env->nb_watchpoints = 0;
>>> *penv = env;
>>> #if defined(CPU_SAVE_VERSION) && !defined(CONFIG_USER_ONLY)
>>> register_savevm("cpu_common", cpu_index, CPU_COMMON_SAVE_VERSION,
>>> @@ -1311,107 +1310,150 @@ static void breakpoint_invalidate(CPUSta
>>> #endif
>>>
>>> /* Add a watchpoint. */
>>> -int cpu_watchpoint_insert(CPUState *env, target_ulong addr, int type)
>>> +int cpu_watchpoint_insert(CPUState *env, target_ulong addr, target_ulong
>>> len,
>>> + int flags, CPUWatchpoint **watchpoint)
>>> {
>>> - int i;
>>> + CPUWatchpoint *wp;
>>>
>>> - for (i = 0; i < env->nb_watchpoints; i++) {
>>> - if (addr == env->watchpoint[i].vaddr)
>>> - return 0;
>>> - }
>>> - if (env->nb_watchpoints >= MAX_WATCHPOINTS)
>>> - return -1;
>>> + wp = qemu_malloc(sizeof(*wp));
>>> + if (!wp)
>>> + return -ENOBUFS;
>>> +
>>> + wp->vaddr = addr;
>>> + wp->len = len;
>>> + wp->flags = flags;
>>> +
>>> + wp->next = env->watchpoints;
>>> + wp->prev = NULL;
>>> + if (wp->next)
>>> + wp->next->prev = wp;
>>> + env->watchpoints = wp;
>>>
>>> - i = env->nb_watchpoints++;
>>> - env->watchpoint[i].vaddr = addr;
>>> - env->watchpoint[i].type = type;
>>> tlb_flush_page(env, addr);
>>> /* FIXME: This flush is needed because of the hack to make memory ops
>>> terminate the TB. It can be removed once the proper IO trap and
>>> re-execute bits are in. */
>>> tb_flush(env);
>>
>>> Index: b/cpu-defs.h
>>> +typedef struct CPUBreakpoint {
>>> + target_ulong pc;
>>> + int flags; /* BP_* */
>>> + struct CPUBreakpoint *prev, *next;
>>> +} CPUBreakpoint;
>>> +
>>> +typedef struct CPUWatchpoint {
>>> + target_ulong vaddr;
>>> + target_ulong len;
>>> + int flags; /* BP_* */
>>> + struct CPUWatchpoint *prev, *next;
>>> +} CPUWatchpoint;
>>> +
>>
>> Most of the time, you are transversing the list in a single direction.
>> So any particular reason to use a double linked list?
>
> When looking as this patch only, one may get along with a singly-linked
> list. But patch 13 adds a use case where the back-reference pays off.
fair.
>
>> By the way, /me thinks it is about time for us to have a generic
>> linked list implementation
>
> Probably - but $SOMEONE will have to do the time-consuming conversion
> work to make QEMU really benefit from this...
Actually we don't need a conversion. We just need an implementation,
and the conversion
happens through time, as old code gets replaced. But we still need the
$SOMEONE, and it's not
exactly my priority right now.
>
> Jan
>
>
--
Glauber Costa.
"Free as in Freedom"
http://glommer.net
"The less confident you are, the more serious you have to act."
- [Qemu-devel] [PATCH 05/13] Introduce next_cflags, (continued)
- [Qemu-devel] [PATCH 05/13] Introduce next_cflags, Jan Kiszka, 2008/10/14
- [Qemu-devel] [PATCH 06/13] Switch self-modified code recompilation to next_cflags, Jan Kiszka, 2008/10/14
- [Qemu-devel] [PATCH 03/13] Set mem_io_vaddr on io_read, Jan Kiszka, 2008/10/14
- [Qemu-devel] [PATCH 10/13] Introduce BP_WATCHPOINT_HIT flag, Jan Kiszka, 2008/10/14
- [Qemu-devel] [PATCH 12/13] Introduce BP_CPU as a breakpoint type, Jan Kiszka, 2008/10/14
- [Qemu-devel] [PATCH 02/13] Refactor and enhance break/watchpoint API, Jan Kiszka, 2008/10/14
- Re: [Qemu-devel] [PATCH 02/13] Refactor and enhance break/watchpoint API, Glauber Costa, 2008/10/14
- [Qemu-devel] [PATCH 13/13] x86: Debug register emulation, Jan Kiszka, 2008/10/14
- [Qemu-devel] [PATCH 08/13] Remove premature memop TB terminations, Jan Kiszka, 2008/10/14
- [Qemu-devel] [PATCH 07/13] Restore pc on watchpoint hits, Jan Kiszka, 2008/10/14
- [Qemu-devel] [PATCH 11/13] Add debug exception hook, Jan Kiszka, 2008/10/14
- [Qemu-devel] [PATCH 09/13] qemu: gdbstub: manage CPUs as threads, Jan Kiszka, 2008/10/14
- [Qemu-devel] [PATCH 04/13] Respect length of watchpoints, Jan Kiszka, 2008/10/14