From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 9431 invoked by alias); 11 Feb 2013 17:13:46 -0000 Received: (qmail 9408 invoked by uid 22791); 11 Feb 2013 17:13:45 -0000 X-SWARE-Spam-Status: No, hits=-6.2 required=5.0 tests=AWL,BAYES_00,KHOP_RCVD_UNTRUST,KHOP_SPAMHAUS_DROP,RCVD_IN_DNSWL_HI,RCVD_IN_HOSTKARMA_W,RP_MATCHES_RCVD,SPF_HELO_PASS,TW_EG X-Spam-Check-By: sourceware.org Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Mon, 11 Feb 2013 17:13:29 +0000 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r1BHDQ6O027976 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Mon, 11 Feb 2013 12:13:27 -0500 Received: from host2.jankratochvil.net (ovpn-116-18.ams2.redhat.com [10.36.116.18]) by int-mx01.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id r1BHDJwr000806 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES128-SHA bits=128 verify=NO); Mon, 11 Feb 2013 12:13:22 -0500 Date: Mon, 11 Feb 2013 17:13:00 -0000 From: Jan Kratochvil To: "Metzger, Markus T" Cc: "gdb-patches@sourceware.org" , "markus.t.metzger@gmail.com" Subject: [draft patch] unwinder for btrace [Re: [rfc 3/5] record: make it build again] Message-ID: <20130211171319.GA17524@host2.jankratochvil.net> References: <1360337423-27095-1-git-send-email-markus.t.metzger@intel.com> <1360337423-27095-4-git-send-email-markus.t.metzger@intel.com> <20130210221059.GC4819@host2.jankratochvil.net> <20130211141451.GA8962@host2.jankratochvil.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130211141451.GA8962@host2.jankratochvil.net> User-Agent: Mutt/1.5.21 (2010-09-15) X-IsSubscribed: yes Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org X-SW-Source: 2013-02/txt/msg00251.txt.bz2 On Mon, 11 Feb 2013 15:14:51 +0100, Jan Kratochvil wrote: > FYI I have some draft -limitation unwinder for btrace here today, > to post it later. ./gdb -q ./gdb -ex start -ex record -ex stepi -ex reverse-stepi -ex bt -ex q No more reverse-execution history. main (argc=, argv=) at gdb.c:29 29 memset (&args, 0, sizeof args); #0 main (argc=, argv=) at gdb.c:29 Backtrace stopped: not enough registers or memory available to unwind further That get_frame_unwind_stop_reason "optimization" to avoid calling an unwinder was present already in the initial post: [rfc, frame] Add backtrace stop reasons http://sourceware.org/ml/gdb-patches/2006-08/msg00129.html Message-ID: <20060819154646.GA25238@nevyn.them.org> I don't know its real reason but it is needed for this patch otherwise: main (argc=, argv=) at gdb.c:29 For btrace you will need ptid_t of the unwound thread as the RECORD_IS_REPLAY flag is apparently irrelevant there. I find inferior_ptid to use there acceptable despite it is discouraged now, passing there ptid_t from the unwinder framework needs some larger changes. No real regressions on {x86_64,x86_64-m32,i686}-fedora19pre-linux-gnu and in gdbserver mode, with the patch as is the various *reverse* tests apparently FAIL due to the values (both displayed and implicitly missing). There should be a testcase but that will be dependent upon the btrace integration. Regards, Jan gdb/ 2013-02-11 Jan Kratochvil New record unwinder reporting . * dwarf2-frame.c (dwarf2_frame_cfa): Move UNWIND_UNAVAILABLE check earlier. * frame-unwind.c: Include target.h. (frame_unwind_try_unwinder): New function with code from ... (frame_unwind_find_by_frame): ... here. New variable unwinder_from_target, call also target_get_unwinder and frame_unwind_try_unwinder for it. * frame.c (get_frame_unwind_stop_reason): Unconditionally call get_prev_frame_1. * record.c: Include frame-unwind.h. (record_frame_unwind_stop_reason, record_frame_this_id) (record_frame_prev_register, record_frame_sniffer, record_frame_unwind): New. (init_record_ops, init_record_core_ops): Install it. * target.c (target_get_unwinder): New. * target.h (struct target_ops): New field to_get_unwinder. (target_get_unwinder): New declaration. diff --git a/gdb/dwarf2-frame.c b/gdb/dwarf2-frame.c index ec4edfa..45be107 100644 --- a/gdb/dwarf2-frame.c +++ b/gdb/dwarf2-frame.c @@ -1497,16 +1497,16 @@ dwarf2_frame_cfa (struct frame_info *this_frame) { while (get_frame_type (this_frame) == INLINE_FRAME) this_frame = get_prev_frame (this_frame); + if (get_frame_unwind_stop_reason (this_frame) == UNWIND_UNAVAILABLE) + throw_error (NOT_AVAILABLE_ERROR, + _("can't compute CFA for this frame: " + "required registers or memory are unavailable")); /* This restriction could be lifted if other unwinders are known to compute the frame base in a way compatible with the DWARF unwinder. */ if (!frame_unwinder_is (this_frame, &dwarf2_frame_unwind) && !frame_unwinder_is (this_frame, &dwarf2_tailcall_frame_unwind)) error (_("can't compute CFA for this frame")); - if (get_frame_unwind_stop_reason (this_frame) == UNWIND_UNAVAILABLE) - throw_error (NOT_AVAILABLE_ERROR, - _("can't compute CFA for this frame: " - "required registers or memory are unavailable")); return get_frame_base (this_frame); } diff --git a/gdb/frame-unwind.c b/gdb/frame-unwind.c index b66febf..cf33147 100644 --- a/gdb/frame-unwind.c +++ b/gdb/frame-unwind.c @@ -27,6 +27,7 @@ #include "exceptions.h" #include "gdb_assert.h" #include "gdb_obstack.h" +#include "target.h" static struct gdbarch_data *frame_unwind_data; @@ -88,6 +89,48 @@ frame_unwind_append_unwinder (struct gdbarch *gdbarch, (*ip)->unwinder = unwinder; } +/* Call SNIFFER from UNWINDER. If it succeeded set UNWINDER for + THIS_FRAME and return 1. Otherwise the function keeps THIS_FRAME + unchanged and returns 0. */ + +static int +frame_unwind_try_unwinder (struct frame_info *this_frame, void **this_cache, + const struct frame_unwind *unwinder) +{ + struct cleanup *old_cleanup; + volatile struct gdb_exception ex; + int res = 0; + + old_cleanup = frame_prepare_for_sniffer (this_frame, unwinder); + + TRY_CATCH (ex, RETURN_MASK_ERROR) + { + res = unwinder->sniffer (unwinder, this_frame, this_cache); + } + if (ex.reason < 0 && ex.error == NOT_AVAILABLE_ERROR) + { + /* This usually means that not even the PC is available, + thus most unwinders aren't able to determine if they're + the best fit. Keep trying. Fallback prologue unwinders + should always accept the frame. */ + do_cleanups (old_cleanup); + return 0; + } + else if (ex.reason < 0) + throw_exception (ex); + else if (res) + { + discard_cleanups (old_cleanup); + return 1; + } + else + { + do_cleanups (old_cleanup); + return 0; + } + gdb_assert_not_reached ("frame_unwind_try_unwinder"); +} + /* Iterate through sniffers for THIS_FRAME frame until one returns with an unwinder implementation. THIS_FRAME->UNWIND must be NULL, it will get set by this function. Possibly initialize THIS_CACHE. */ @@ -98,37 +141,18 @@ frame_unwind_find_by_frame (struct frame_info *this_frame, void **this_cache) struct gdbarch *gdbarch = get_frame_arch (this_frame); struct frame_unwind_table *table = gdbarch_data (gdbarch, frame_unwind_data); struct frame_unwind_table_entry *entry; + const struct frame_unwind *unwinder_from_target; + + unwinder_from_target = target_get_unwinder (); + if (unwinder_from_target != NULL + && frame_unwind_try_unwinder (this_frame, this_cache, + unwinder_from_target)) + return; for (entry = table->list; entry != NULL; entry = entry->next) - { - struct cleanup *old_cleanup; - volatile struct gdb_exception ex; - int res = 0; - - old_cleanup = frame_prepare_for_sniffer (this_frame, entry->unwinder); - - TRY_CATCH (ex, RETURN_MASK_ERROR) - { - res = entry->unwinder->sniffer (entry->unwinder, this_frame, - this_cache); - } - if (ex.reason < 0 && ex.error == NOT_AVAILABLE_ERROR) - { - /* This usually means that not even the PC is available, - thus most unwinders aren't able to determine if they're - the best fit. Keep trying. Fallback prologue unwinders - should always accept the frame. */ - } - else if (ex.reason < 0) - throw_exception (ex); - else if (res) - { - discard_cleanups (old_cleanup); - return; - } + if (frame_unwind_try_unwinder (this_frame, this_cache, entry->unwinder)) + return; - do_cleanups (old_cleanup); - } internal_error (__FILE__, __LINE__, _("frame_unwind_find_by_frame failed")); } diff --git a/gdb/frame.c b/gdb/frame.c index 0821b6e..8fc1ca9 100644 --- a/gdb/frame.c +++ b/gdb/frame.c @@ -2357,13 +2357,10 @@ get_frame_sp (struct frame_info *this_frame) enum unwind_stop_reason get_frame_unwind_stop_reason (struct frame_info *frame) { - /* If we haven't tried to unwind past this point yet, then assume - that unwinding would succeed. */ - if (frame->prev_p == 0) - return UNWIND_NO_REASON; + /* Fill-in STOP_REASON. */ + get_prev_frame_1 (frame); + gdb_assert (frame->prev_p); - /* Otherwise, we set a reason when we succeeded (or failed) to - unwind. */ return frame->stop_reason; } diff --git a/gdb/record.c b/gdb/record.c index 1a68738..dffce98 100644 --- a/gdb/record.c +++ b/gdb/record.c @@ -34,6 +34,7 @@ #include "inf-loop.h" #include "gdb_bfd.h" #include "observer.h" +#include "frame-unwind.h" #include @@ -1953,6 +1954,59 @@ record_execution_direction (void) return record_execution_dir; } +/* Implement stop_reason method for record_frame_unwind. */ + +static enum unwind_stop_reason +record_frame_unwind_stop_reason (struct frame_info *this_frame, + void **this_cache) +{ + return UNWIND_UNAVAILABLE; +} + +/* Implement this_id method for record_frame_unwind. */ + +static void +record_frame_this_id (struct frame_info *this_frame, void **this_cache, + struct frame_id *this_id) +{ + /* Leave there the outer_frame_id value. */ +} + +/* Implement prev_register method for record_frame_unwind. */ + +static struct value * +record_frame_prev_register (struct frame_info *this_frame, void **this_cache, + int regnum) +{ + throw_error (NOT_AVAILABLE_ERROR, + _("Registers are not available in btrace record history")); +} + +/* Implement sniffer method for record_frame_unwind. */ + +static int +record_frame_sniffer (const struct frame_unwind *self, + struct frame_info *this_frame, void **this_cache) +{ + return RECORD_IS_REPLAY; +} + +/* btrace recording does not store previous memory content, neither the stack + frames content. Any unwinding would return errorneous results as the stack + contents no longer matches the changed PC value restored from history. + Therefore this unwinder reports any possibly unwound registers as + . */ + +static const struct frame_unwind record_frame_unwind = +{ + NORMAL_FRAME, + record_frame_unwind_stop_reason, + record_frame_this_id, + record_frame_prev_register, + NULL, + record_frame_sniffer +}; + static void init_record_ops (void) { @@ -1984,6 +2038,7 @@ init_record_ops (void) record_ops.to_can_async_p = record_can_async_p; record_ops.to_is_async_p = record_is_async_p; record_ops.to_execution_direction = record_execution_direction; + record_ops.to_get_unwinder = &record_frame_unwind; record_ops.to_magic = OPS_MAGIC; } @@ -2209,6 +2264,7 @@ init_record_core_ops (void) record_core_ops.to_can_async_p = record_can_async_p; record_core_ops.to_is_async_p = record_is_async_p; record_core_ops.to_execution_direction = record_execution_direction; + record_core_ops.to_get_unwinder = &record_frame_unwind; record_core_ops.to_magic = OPS_MAGIC; } diff --git a/gdb/target.c b/gdb/target.c index 9d8bf6e..28f00af 100644 --- a/gdb/target.c +++ b/gdb/target.c @@ -4147,6 +4147,20 @@ target_ranged_break_num_registers (void) return -1; } +/* See target.h. */ + +const struct frame_unwind * +target_get_unwinder (void) +{ + struct target_ops *t; + + for (t = current_target.beneath; t != NULL; t = t->beneath) + if (t->to_get_unwinder != NULL) + return t->to_get_unwinder; + + return NULL; +} + static void debug_to_prepare_to_store (struct regcache *regcache) { diff --git a/gdb/target.h b/gdb/target.h index 1971265..95bfb47 100644 --- a/gdb/target.h +++ b/gdb/target.h @@ -857,6 +857,10 @@ struct target_ops /* Is the target able to use agent in current state? */ int (*to_can_use_agent) (void); + /* This unwinder is tried before any other arch unwinders. Use NULL if it + is not used. */ + const struct frame_unwind *to_get_unwinder; + int to_magic; /* Need sub-structure for target machine related rather than comm related? */ @@ -1735,6 +1739,9 @@ extern char *target_fileio_read_stralloc (const char *filename); extern int target_core_of_thread (ptid_t ptid); +/* See to_get_unwinder in struct target_ops. */ +extern const struct frame_unwind *target_get_unwinder (void); + /* Verify that the memory in the [MEMADDR, MEMADDR+SIZE) range matches the contents of [DATA,DATA+SIZE). Returns 1 if there's a match, 0 if there's a mismatch, and -1 if an error is encountered while