From patchwork Mon May 15 13:03:22 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ben Dooks X-Patchwork-Id: 1781365 X-Patchwork-Delegate: uboot@andestech.com Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=lists.denx.de (client-ip=85.214.62.61; helo=phobos.denx.de; envelope-from=u-boot-bounces@lists.denx.de; receiver=) Received: from phobos.denx.de (phobos.denx.de [85.214.62.61]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-384)) (No client certificate requested) by legolas.ozlabs.org (Postfix) with ESMTPS id 4QKfgn3qTxz20db for ; Mon, 15 May 2023 23:03:33 +1000 (AEST) Received: from h2850616.stratoserver.net (localhost [IPv6:::1]) by phobos.denx.de (Postfix) with ESMTP id 927BE8476F; Mon, 15 May 2023 15:03:30 +0200 (CEST) Authentication-Results: phobos.denx.de; dmarc=fail (p=reject dis=none) header.from=sifive.com Authentication-Results: phobos.denx.de; spf=pass smtp.mailfrom=u-boot-bounces@lists.denx.de Received: by phobos.denx.de (Postfix, from userid 109) id E563084794; Mon, 15 May 2023 15:03:28 +0200 (CEST) X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on phobos.denx.de X-Spam-Level: X-Spam-Status: No, score=-1.7 required=5.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,SPF_HELO_PASS,SPF_PASS, T_SCC_BODY_TEXT_LINE autolearn=no autolearn_force=no version=3.4.2 Received: from imap5.colo.codethink.co.uk (imap5.colo.codethink.co.uk [78.40.148.171]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (No client certificate requested) by phobos.denx.de (Postfix) with ESMTPS id A756084672 for ; Mon, 15 May 2023 15:03:26 +0200 (CEST) Authentication-Results: phobos.denx.de; dmarc=fail (p=reject dis=none) header.from=sifive.com Authentication-Results: phobos.denx.de; spf=pass smtp.mailfrom=ben@codethink.co.uk Received: from [167.98.27.226] (helo=rainbowdash) by imap5.colo.codethink.co.uk with esmtpsa (Exim 4.94.2 #2 (Debian)) id 1pyXrH-006yEy-GQ; Mon, 15 May 2023 14:03:23 +0100 Received: from ben by rainbowdash with local (Exim 4.96) (envelope-from ) id 1pyXrH-002ASq-10; Mon, 15 May 2023 14:03:23 +0100 From: Ben Dooks To: u-boot@lists.denx.de Cc: ben.dooks@codethink.co.uk, rick@andestech.com, Ben Dooks Subject: [PATCH] riscv: add backtrace support Date: Mon, 15 May 2023 14:03:22 +0100 Message-Id: <20230515130322.516871-1-ben.dooks@sifive.com> X-Mailer: git-send-email 2.39.2 MIME-Version: 1.0 X-BeenThere: u-boot@lists.denx.de X-Mailman-Version: 2.1.39 Precedence: list List-Id: U-Boot discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: u-boot-bounces@lists.denx.de Sender: "U-Boot" X-Virus-Scanned: clamav-milter 0.103.8 at phobos.denx.de X-Virus-Status: Clean When debugging, it is useful to have a backtrace to find out what is in the call stack as the previous function (RA) may not have been the culprit. Since this adds size to the build, do not add it by default and avoid putting it in the SPL build if not needed. Signed-off-by: Ben Dooks --- arch/riscv/Kconfig | 10 ++++++++++ arch/riscv/Makefile | 4 ++++ arch/riscv/cpu/start.S | 1 + arch/riscv/lib/interrupts.c | 35 +++++++++++++++++++++++++++++++++++ 4 files changed, 50 insertions(+) diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index f6ed05906a..3f2316cfb5 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -98,6 +98,16 @@ config ARCH_RV64I endchoice +config FRAMEPOINTER + bool "Build with frame pointer for stack unwinding" + help + Choose this option to use the frame pointer so the stack can be + unwound if needed. This is useful for tracing where faults came + from as the source may be several functions back + + If you say Y here, then the code size will be increased due to + having to store the fp. + choice prompt "Code Model" default CMODEL_MEDLOW diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile index 4963b5109b..0cb60c7c7e 100644 --- a/arch/riscv/Makefile +++ b/arch/riscv/Makefile @@ -45,6 +45,10 @@ endif ARCH_FLAGS = -march=$(RISCV_MARCH) -mabi=$(ABI) \ -mcmodel=$(CMODEL) +ifeq ($(CONFIG_$(SPL_)FRAMEPOINTER),y) + ARCH_FLAGS += -fno-omit-frame-pointer +endif + PLATFORM_CPPFLAGS += $(ARCH_FLAGS) CFLAGS_EFI += $(ARCH_FLAGS) diff --git a/arch/riscv/cpu/start.S b/arch/riscv/cpu/start.S index dad22bfea8..3d13722615 100644 --- a/arch/riscv/cpu/start.S +++ b/arch/riscv/cpu/start.S @@ -396,6 +396,7 @@ call_board_init_r: */ mv a0, s3 /* gd_t */ mv a1, s4 /* dest_addr */ + mv s0, zero /* fp == NULL */ /* * jump to it ... diff --git a/arch/riscv/lib/interrupts.c b/arch/riscv/lib/interrupts.c index e966afa7e3..db3d7e294b 100644 --- a/arch/riscv/lib/interrupts.c +++ b/arch/riscv/lib/interrupts.c @@ -53,6 +53,40 @@ static void show_regs(struct pt_regs *regs) #endif } +#if defined(CONFIG_FRAMEPOINTER) || defined(CONFIG_SPL_FRAMEPOINTER) +static void show_backtrace(struct pt_regs *regs) +{ + uintptr_t *fp = (uintptr_t *)regs->s0; + unsigned count = 0; + ulong ra; + + printf("backtrace:\n"); + + /* there are a few entry points where the s0 register is + * set to gd, so to avoid changing those, just abort if + * the value is the same */ + while (fp != NULL && fp != (uintptr_t *)gd) { + ra = fp[-1]; + printf("backtrace %2d: FP: " REG_FMT " RA: " REG_FMT, + count, (ulong)fp, ra); + + if (gd && gd->flags & GD_FLG_RELOC) + printf(" - RA: " REG_FMT " reloc adjusted\n", + ra - gd->reloc_off); + else + printf("\n"); + + fp = (uintptr_t *)fp[-2]; + count++; + } +} +#else +static void show_backtrace(struct pt_regs *regs) +{ + printf("No backtrace support enabled\n"); +} +#endif + /** * instr_len() - get instruction length * @@ -119,6 +153,7 @@ static void _exit_trap(ulong code, ulong epc, ulong tval, struct pt_regs *regs) epc - gd->reloc_off, regs->ra - gd->reloc_off); show_regs(regs); + show_backtrace(regs); show_code(epc); show_efi_loaded_images(epc); panic("\n");