From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm1-f51.google.com (mail-wm1-f51.google.com [209.85.128.51]) by sourceware.org (Postfix) with ESMTPS id 86BEE3858D32 for ; Mon, 27 Jun 2022 21:10:49 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 86BEE3858D32 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=palves.net Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=gmail.com Received: by mail-wm1-f51.google.com with SMTP id 189so5703919wmz.2 for ; Mon, 27 Jun 2022 14:10:49 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:subject:date:message-id:mime-version :content-transfer-encoding; bh=jrGwp3ElEi5rc578J5q8i89ivgw7nGNZZPuP0vmn5ps=; b=FprU5dyuOuoF+wBG0Pi5cvd97XRWEngEqkTcA8nNkpN4tH3HG+mF8Ji5nVuZFwE+f+ bMeQvQpfDmfyciwqHiu+sR7LDH/Q3kwdKAYxotpKCiCVC3ApwVVJ3ULUkiXZ7tcCZC8g ZGKKGsyNB7wYZu0Oi4wJXjoqDHs8GNlXOoMohfbSKR8/b3mqs3TtHuR44ST3POHGIaGR Jsp6wEmlXxjzagIJGijU5BetCA47scCG8K4oQHkMjQmPOed3HH+ltay6pS/nXz5B9IPF Eu/gMRb9t3dQVPx2K5f9sfkUrmEaAb/+vhuyQ314fZ8ls0ksAF+MNJv4oiFVDhoba9T0 Qnhg== X-Gm-Message-State: AJIora/E4e0HOQLVr9d+QynjfggYK6uv0cfw07znYvi0zaALMihmGyyI Yr5DdKM+SZl9GfVCYkYl72lOp7HbTuw= X-Google-Smtp-Source: AGRyM1uB5ChyLbAt+92oqzB6ghtU0djI6sdHgsbR6a+udfIAmrYSLozuZZLuIW0DZEYkIMNnISPZog== X-Received: by 2002:a1c:720f:0:b0:3a0:2ac9:5231 with SMTP id n15-20020a1c720f000000b003a02ac95231mr17615087wmc.39.1656364247525; Mon, 27 Jun 2022 14:10:47 -0700 (PDT) Received: from localhost ([2001:8a0:f924:2600:5b14:8ad0:780f:bdda]) by smtp.gmail.com with ESMTPSA id m17-20020adfe0d1000000b0021b866397a7sm11744553wri.1.2022.06.27.14.10.46 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 27 Jun 2022 14:10:46 -0700 (PDT) From: Pedro Alves To: gdb-patches@sourceware.org Subject: [PATCH] gdb+gdbserver/Linux: Remove USE_SIGTRAP_SIGINFO fallback Date: Mon, 27 Jun 2022 22:10:45 +0100 Message-Id: <20220627211045.2339994-1-pedro@palves.net> X-Mailer: git-send-email 2.36.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-9.9 required=5.0 tests=BAYES_00, FREEMAIL_FORGED_FROMDOMAIN, FREEMAIL_FROM, GIT_PATCH_0, HEADER_FROM_DIFFERENT_DOMAINS, KAM_DMARC_STATUS, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H2, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 27 Jun 2022 21:10:52 -0000 It's been over 7 years (since commit faf09f0119da) since Linux GDB and GDBserver started relying on SIGTRAP si_code to tell whether a breakpoint triggered, which is important for non-stop mode. When that then-new code was added, I had left the then-old code as fallback, in case some architectured still needed it. Given AFAIK there haven't been complaints since, this commit finally removes the fallback code, along with USE_SIGTRAP_SIGINFO. Change-Id: I140a5333a9fe70e90dbd186aca1f081549b2e63d --- gdb/linux-nat.c | 53 ++---------------------------------------- gdb/nat/linux-ptrace.h | 11 ++++----- gdbserver/linux-low.cc | 39 ++----------------------------- 3 files changed, 8 insertions(+), 95 deletions(-) diff --git a/gdb/linux-nat.c b/gdb/linux-nat.c index b9164e621db..008791c12dc 100644 --- a/gdb/linux-nat.c +++ b/gdb/linux-nat.c @@ -2439,17 +2439,6 @@ status_callback (struct lwp_info *lp) discard = 1; } -#if !USE_SIGTRAP_SIGINFO - else if (!breakpoint_inserted_here_p (regcache->aspace (), pc)) - { - linux_nat_debug_printf ("previous breakpoint of %s, at %s gone", - lp->ptid.to_string ().c_str (), - paddress (target_gdbarch (), lp->stop_pc)); - - discard = 1; - } -#endif - if (discard) { linux_nat_debug_printf ("pending event of %s cancelled.", @@ -2529,9 +2518,7 @@ save_stop_reason (struct lwp_info *lp) struct gdbarch *gdbarch; CORE_ADDR pc; CORE_ADDR sw_bp_pc; -#if USE_SIGTRAP_SIGINFO siginfo_t siginfo; -#endif gdb_assert (lp->stop_reason == TARGET_STOPPED_BY_NO_REASON); gdb_assert (lp->status != 0); @@ -2545,7 +2532,6 @@ save_stop_reason (struct lwp_info *lp) pc = regcache_read_pc (regcache); sw_bp_pc = pc - gdbarch_decr_pc_after_break (gdbarch); -#if USE_SIGTRAP_SIGINFO if (linux_nat_get_siginfo (lp->ptid, &siginfo)) { if (siginfo.si_signo == SIGTRAP) @@ -2588,22 +2574,6 @@ save_stop_reason (struct lwp_info *lp) } } } -#else - if ((!lp->step || lp->stop_pc == sw_bp_pc) - && software_breakpoint_inserted_here_p (regcache->aspace (), - sw_bp_pc)) - { - /* The LWP was either continued, or stepped a software - breakpoint instruction. */ - lp->stop_reason = TARGET_STOPPED_BY_SW_BREAKPOINT; - } - - if (hardware_breakpoint_inserted_here_p (regcache->aspace (), pc)) - lp->stop_reason = TARGET_STOPPED_BY_HW_BREAKPOINT; - - if (lp->stop_reason == TARGET_STOPPED_BY_NO_REASON) - check_stopped_by_watchpoint (lp); -#endif if (lp->stop_reason == TARGET_STOPPED_BY_SW_BREAKPOINT) { @@ -2649,7 +2619,7 @@ linux_nat_target::stopped_by_sw_breakpoint () bool linux_nat_target::supports_stopped_by_sw_breakpoint () { - return USE_SIGTRAP_SIGINFO; + return true; } /* Returns true if the LWP had stopped for a hardware @@ -2670,7 +2640,7 @@ linux_nat_target::stopped_by_hw_breakpoint () bool linux_nat_target::supports_stopped_by_hw_breakpoint () { - return USE_SIGTRAP_SIGINFO; + return true; } /* Select one LWP out of those that have events pending. */ @@ -3252,25 +3222,6 @@ linux_nat_wait_1 (ptid_t ptid, struct target_waitstatus *ourstatus, gdb_assert (lp != NULL); - /* Now that we've selected our final event LWP, un-adjust its PC if - it was a software breakpoint, and we can't reliably support the - "stopped by software breakpoint" stop reason. */ - if (lp->stop_reason == TARGET_STOPPED_BY_SW_BREAKPOINT - && !USE_SIGTRAP_SIGINFO) - { - struct regcache *regcache = get_thread_regcache (linux_target, lp->ptid); - struct gdbarch *gdbarch = regcache->arch (); - int decr_pc = gdbarch_decr_pc_after_break (gdbarch); - - if (decr_pc != 0) - { - CORE_ADDR pc; - - pc = regcache_read_pc (regcache); - regcache_write_pc (regcache, pc + decr_pc); - } - } - /* We'll need this to determine whether to report a SIGSTOP as GDB_SIGNAL_0. Need to take a copy because resume_clear_callback clears it. */ diff --git a/gdb/nat/linux-ptrace.h b/gdb/nat/linux-ptrace.h index 4694046e1e8..3edc2363aa2 100644 --- a/gdb/nat/linux-ptrace.h +++ b/gdb/nat/linux-ptrace.h @@ -97,9 +97,9 @@ struct buffer; #define __WALL 0x40000000 /* Wait for any child. */ #endif -/* True if whether a breakpoint/watchpoint triggered can be determined - from the si_code of SIGTRAP's siginfo_t (TRAP_BRKPT/TRAP_HWBKPT). - That is, if the kernel can tell us whether the thread executed a +/* Whether a breakpoint/watchpoint triggered can be determined from + the si_code of SIGTRAP's siginfo_t (TRAP_BRKPT/TRAP_HWBKPT). That + is, since the kernel can tell us whether the thread executed a software breakpoint, we trust it. The kernel will be determining that from the hardware (e.g., from which exception was raised in the CPU). Relying on whether a breakpoint is planted in memory at @@ -112,10 +112,7 @@ struct buffer; architectures. The moribund location mechanism helps with that somewhat but it is an heuristic, and can well fail. Getting that information out of the kernel and ultimately out of the CPU is the - way to go. That said, some architecture may get the si_code wrong, - and as such we're leaving fallback code in place. We'll remove - this after a while if no problem is reported. */ -#define USE_SIGTRAP_SIGINFO 1 + way to go. */ /* The x86 kernel gets some of the si_code values backwards, like this: diff --git a/gdbserver/linux-low.cc b/gdbserver/linux-low.cc index 8b8614f6ed4..9305928bbbf 100644 --- a/gdbserver/linux-low.cc +++ b/gdbserver/linux-low.cc @@ -790,9 +790,7 @@ linux_process_target::save_stop_reason (lwp_info *lwp) { CORE_ADDR pc; CORE_ADDR sw_breakpoint_pc; -#if USE_SIGTRAP_SIGINFO siginfo_t siginfo; -#endif if (!low_supports_breakpoints ()) return false; @@ -804,7 +802,6 @@ linux_process_target::save_stop_reason (lwp_info *lwp) scoped_restore_current_thread restore_thread; switch_to_thread (get_lwp_thread (lwp)); -#if USE_SIGTRAP_SIGINFO if (ptrace (PTRACE_GETSIGINFO, lwpid_of (current_thread), (PTRACE_TYPE_ARG3) 0, &siginfo) == 0) { @@ -846,21 +843,6 @@ linux_process_target::save_stop_reason (lwp_info *lwp) } } } -#else - /* We may have just stepped a breakpoint instruction. E.g., in - non-stop mode, GDB first tells the thread A to step a range, and - then the user inserts a breakpoint inside the range. In that - case we need to report the breakpoint PC. */ - if ((!lwp->stepping || lwp->stop_pc == sw_breakpoint_pc) - && low_breakpoint_at (sw_breakpoint_pc)) - lwp->stop_reason = TARGET_STOPPED_BY_SW_BREAKPOINT; - - if (hardware_breakpoint_inserted_here (pc)) - lwp->stop_reason = TARGET_STOPPED_BY_HW_BREAKPOINT; - - if (lwp->stop_reason == TARGET_STOPPED_BY_NO_REASON) - check_stopped_by_watchpoint (lwp); -#endif if (lwp->stop_reason == TARGET_STOPPED_BY_SW_BREAKPOINT) { @@ -1648,23 +1630,6 @@ linux_process_target::thread_still_has_status_pending (thread_info *thread) discard = 1; } -#if !USE_SIGTRAP_SIGINFO - else if (lp->stop_reason == TARGET_STOPPED_BY_SW_BREAKPOINT - && !low_breakpoint_at (pc)) - { - threads_debug_printf ("previous SW breakpoint of %ld gone", - lwpid_of (thread)); - discard = 1; - } - else if (lp->stop_reason == TARGET_STOPPED_BY_HW_BREAKPOINT - && !hardware_breakpoint_inserted_here (pc)) - { - threads_debug_printf ("previous HW breakpoint of %ld gone", - lwpid_of (thread)); - discard = 1; - } -#endif - if (discard) { threads_debug_printf ("discarding pending breakpoint status"); @@ -5555,7 +5520,7 @@ linux_process_target::stopped_by_sw_breakpoint () bool linux_process_target::supports_stopped_by_sw_breakpoint () { - return USE_SIGTRAP_SIGINFO; + return true; } /* Implement the stopped_by_hw_breakpoint target_ops @@ -5575,7 +5540,7 @@ linux_process_target::stopped_by_hw_breakpoint () bool linux_process_target::supports_stopped_by_hw_breakpoint () { - return USE_SIGTRAP_SIGINFO; + return true; } /* Implement the supports_hardware_single_step target_ops method. */ base-commit: f18acc9c4e5d18f4783f3a7d59e3ec95d7af0199 -- 2.36.0