From patchwork Mon Oct 17 19:39:31 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tomas Vanek X-Patchwork-Id: 58958 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 7DC4D385741D for ; Mon, 17 Oct 2022 19:39:53 +0000 (GMT) X-Original-To: gdb-patches@sourceware.org Delivered-To: gdb-patches@sourceware.org Received: from smtp00.avonet.cz (smtp00.avonet.cz [217.112.162.55]) by sourceware.org (Postfix) with ESMTP id 832143858418 for ; Mon, 17 Oct 2022 19:39:32 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 832143858418 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=fbl.cz Authentication-Results: sourceware.org; spf=fail smtp.mailfrom=fbl.cz Received: from ktus.lan (217-115-245-101.cust.avonet.cz [217.115.245.101]) by smtp00.avonet.cz (Postfix) with ESMTP id 4MrnPc0HxKz1xns; Mon, 17 Oct 2022 21:39:32 +0200 (CEST) From: Tomas Vanek To: gdb-patches@sourceware.org Subject: [PATCH] gdb: Modify until_break_command to act correctly on SIGTRAMP_FRAME Date: Mon, 17 Oct 2022 21:39:31 +0200 Message-Id: <1666035571-19996-1-git-send-email-vanekt@fbl.cz> X-Mailer: git-send-email 1.9.1 X-Spam-Status: No, score=-12.7 required=5.0 tests=BAYES_00, GIT_PATCH_0, KAM_DMARC_STATUS, SPF_FAIL, SPF_HELO_NONE, TXREP 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: , Errors-To: gdb-patches-bounces+patchwork=sourceware.org@sourceware.org Sender: "Gdb-patches" This patch partially depends on gdb/arm: Terminate frame unwinding in M-profile lockup state (without it lockup state is unwound as it were normal stack frame) The commands 'advance' and 'until' try to set a breakpoint on the bogus return address derived from Arm M-profile magic address (actually EXC_RETURN or a PC value indicating lockup). The offending breakpoint should be set at return address to the caller function. The magic value 0xffffffff in LR indicates there is no caller (return to this address would lock up the CPU). Similar behaviour of 'advance' and 'until' is observed in an exception handler routine. In this case LR contains e.g. 0xfffffff1 (EXC_RETURN) and GDB tries to set a breakpoint at 0xfffffff0. It should use a return value stacked by the exception instead. Testbench setup: STM32G474, a Cortex-M4 device. Any Cortex-M device can be used. A test application (an ordinary blink) with a standard startup is loaded to the device flash. Steps to reproduce the problem: start GDB server $ openocd -f interface/cmsis-dap.cfg -f target/stm32g4x.cfg start GDB in second terminal $ arm-none-eabi-gdb blink.elf (gdb) target extended-remote localhost:3333 Reset the device and halt it: (gdb) monitor reset halt target halted due to debug-request, current mode: Thread xPSR: 0x01000000 pc: 0x08000e14 msp: 0x20020000 Step by one instruction to re-read GDB register cache: (gdb) stepi Check registers, LR should be 0xffffffff after reset: (gdb) info registers ... sp 0x20020000 0x20020000 lr 0xffffffff -1 pc 0x8000e16 0x8000e16 xPSR 0x1000000 16777216 ... (gdb) set debug remote Issue 'advance' command: (gdb) advance main [remote] Sending packet: $mfffffffe,2#fa [remote] Packet received: 0000 [remote] Sending packet: $mfffffffe,2#fa [remote] Packet received: 0000 [remote] Sending packet: $m8000526,2#30 [remote] Packet received: 2046 [remote] Sending packet: $Z1,8000526,2#7a [remote] Packet received: OK [remote] packet_ok: Packet Z1 (hardware-breakpoint) is supported [remote] Sending packet: $Z0,fffffffe,2#43 [remote] Packet received: E0E [remote] packet_ok: Packet Z0 (software-breakpoint) is supported Warning: Cannot insert breakpoint 0. Cannot access memory at address 0xfffffffe Command aborted. (gdb) Relevant messages from OpenOCD: Error: Failed to read memory at 0xfffff000 Error: can't add breakpoint: unknown reason This patch adds skipping over frames that are not suitable for guarding with a breakpoint inspired by 'finish' command. If no suitable frame is found, a momentrary breakpoint is not set. --- gdb/breakpoint.c | 22 +++++++++++++++++----- 1 file changed, 17 insertions(+), 5 deletions(-) diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c index f6591d4..bb85342 100644 --- a/gdb/breakpoint.c +++ b/gdb/breakpoint.c @@ -10467,6 +10467,7 @@ enum async_reply_reason until_break_command (const char *arg, int from_tty, int anywhere) { frame_info_ptr frame; + frame_info_ptr caller_frame; struct gdbarch *frame_gdbarch; struct frame_id stack_frame_id; struct frame_id caller_frame_id; @@ -10505,7 +10506,17 @@ enum async_reply_reason frame = get_selected_frame (NULL); frame_gdbarch = get_frame_arch (frame); stack_frame_id = get_stack_frame_id (frame); - caller_frame_id = frame_unwind_caller_id (frame); + + caller_frame = get_prev_frame_always (frame); + + while (caller_frame) + { + if (get_frame_type (caller_frame) != TAILCALL_FRAME + && gdbarch_code_of_frame_writable (get_frame_arch (caller_frame), caller_frame)) + break; + + caller_frame = get_prev_frame_always (caller_frame); + } /* Keep within the current frame, or in frames called by the current one. */ @@ -10514,14 +10525,15 @@ enum async_reply_reason gdb::optional lj_deleter; - if (frame_id_p (caller_frame_id)) + if (caller_frame) { struct symtab_and_line sal2; struct gdbarch *caller_gdbarch; - sal2 = find_pc_line (frame_unwind_caller_pc (frame), 0); - sal2.pc = frame_unwind_caller_pc (frame); - caller_gdbarch = frame_unwind_caller_arch (frame); + sal2 = find_pc_line (get_frame_pc (caller_frame), 0); + sal2.pc = get_frame_pc (caller_frame); + caller_gdbarch = get_frame_arch (caller_frame); + caller_frame_id = get_frame_id (caller_frame); breakpoint_up caller_breakpoint = set_momentary_breakpoint (caller_gdbarch, sal2,