From patchwork Fri Oct 18 11:07:46 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vijay Kilari X-Patchwork-Id: 3065681 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 2AE2BBF924 for ; Fri, 18 Oct 2013 11:10:20 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id B569C20461 for ; Fri, 18 Oct 2013 11:10:18 +0000 (UTC) Received: from casper.infradead.org (casper.infradead.org [85.118.1.10]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 8A94E20459 for ; Fri, 18 Oct 2013 11:10:16 +0000 (UTC) Received: from merlin.infradead.org ([2001:4978:20e::2]) by casper.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1VX7vp-0004dF-Ix; Fri, 18 Oct 2013 11:09:26 +0000 Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1VX7vR-0007dh-L3; Fri, 18 Oct 2013 11:09:01 +0000 Received: from mail-pd0-x230.google.com ([2607:f8b0:400e:c02::230]) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1VX7vO-0007bf-5f for linux-arm-kernel@lists.infradead.org; Fri, 18 Oct 2013 11:08:59 +0000 Received: by mail-pd0-f176.google.com with SMTP id g10so3557958pdj.35 for ; Fri, 18 Oct 2013 04:08:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=tQFNgWAOL+7mjGunewArc3Gb3m+ntva0+V7GKJMvDNo=; b=apt2cfsHPrkJaM9kP8J5Ak5ph+P1qiH567bVqeX6GsqZ5qCzPH8ls/sNKNRtKVZ+yq tYLc3tnF2DrSNWlRjAB+Ot3tHxomb/8mrqYzkxVZgaRTQONA5nirMCpq1tZ/WzY+BQYm VN6UBERHMclYzV2wSjq2ANouTgyWyMzjWpp6b0cCMol7n3h9D27O6TPQg+vf+FhCfvo2 phyrUd9izkTLrvFWs1abQTzOEMSjoq7nFujk4dho1N3M3Sd2Ur1OHAZB+/JTQ1xo5OJe hfez2wlSOfAopchLXLmLmQXs7PSSU9nZPA5hxtCTybZyM24gvd20ABFYVbhSXrAZo+t7 D2wg== X-Received: by 10.66.221.8 with SMTP id qa8mr481853pac.188.1382094516746; Fri, 18 Oct 2013 04:08:36 -0700 (PDT) Received: from ubuntu.caveonetworks.com ([115.119.134.194]) by mx.google.com with ESMTPSA id xs1sm3587419pac.7.2013.10.18.04.08.33 for (version=TLSv1.1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Fri, 18 Oct 2013 04:08:36 -0700 (PDT) From: vijay.kilari@gmail.com To: will.deacon@arm.com, sandeepa.prabhu@linaro.org, jason.wessel@windriver.com Subject: [PATCH v3 1/4] arm64: support single-step and breakpoint handler hooks Date: Fri, 18 Oct 2013 16:37:46 +0530 Message-Id: <1382094469-7971-2-git-send-email-vijay.kilari@gmail.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1382094469-7971-1-git-send-email-vijay.kilari@gmail.com> References: <1382094469-7971-1-git-send-email-vijay.kilari@gmail.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20131018_070858_471843_ABC6B21F X-CRM114-Status: GOOD ( 16.85 ) X-Spam-Score: -2.0 (--) Cc: linaro-kernel@lists.linaro.org, linux@arm.linux.org.uk, Prasun.Kapoor@caviumnetworks.com, takahiro.akashi@linaro.org, Deepak Saxena , linux-arm-kernel@lists.infradead.org X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-4.5 required=5.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED, FREEMAIL_FROM, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, T_DKIM_INVALID, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Sandeepa Prabhu AArch64 Single Steping and Breakpoint debug exceptions will be used by multiple debug framworks like kprobes & kgdb. This patch implements the hooks for those frameworks to register their own handlers for handling breakpoint and single step events. Reworked the debug exception handler in entry.S: do_dbg to route software breakpoint (BRK64) exception to do_debug_exception() Signed-off-by: Sandeepa Prabhu Signed-off-by: Deepak Saxena --- arch/arm64/include/asm/debug-monitors.h | 21 ++++++++ arch/arm64/kernel/debug-monitors.c | 86 ++++++++++++++++++++++++++++++- arch/arm64/kernel/entry.S | 2 + 3 files changed, 108 insertions(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/debug-monitors.h b/arch/arm64/include/asm/debug-monitors.h index a2232d0..6231479 100644 --- a/arch/arm64/include/asm/debug-monitors.h +++ b/arch/arm64/include/asm/debug-monitors.h @@ -62,6 +62,27 @@ struct task_struct; #define DBG_ARCH_ID_RESERVED 0 /* In case of ptrace ABI updates. */ +#define DBG_HOOK_HANDLED 0 +#define DBG_HOOK_ERROR 1 + +struct step_hook { + struct list_head node; + int (*fn)(struct pt_regs *regs, unsigned int esr); +}; + +void register_step_hook(struct step_hook *hook); +void unregister_step_hook(struct step_hook *hook); + +struct break_hook { + struct list_head node; + u32 esr_val; + u32 esr_mask; + int (*fn)(struct pt_regs *regs, unsigned int esr); +}; + +void register_break_hook(struct break_hook *hook); +void unregister_break_hook(struct break_hook *hook); + u8 debug_monitors_arch(void); void enable_debug_monitors(enum debug_el el); diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c index cbfacf7..e42ad5f 100644 --- a/arch/arm64/kernel/debug-monitors.c +++ b/arch/arm64/kernel/debug-monitors.c @@ -188,6 +188,48 @@ static void clear_regs_spsr_ss(struct pt_regs *regs) regs->pstate = spsr; } +/* EL1 Single Step Handler hooks */ +static LIST_HEAD(step_hook); +DEFINE_RWLOCK(step_hook_lock); + +void register_step_hook(struct step_hook *hook) +{ + write_lock(&step_hook_lock); + list_add(&hook->node, &step_hook); + write_unlock(&step_hook_lock); +} + +void unregister_step_hook(struct step_hook *hook) +{ + write_lock(&step_hook_lock); + list_del(&hook->node); + write_unlock(&step_hook_lock); +} + +/* + * Call registered single step handers + * There is no Syndrome info to check for determining the handler. + * So we call all the registered handlers, until the right handler is + * found which returns zero. + */ +static int call_step_hook(struct pt_regs *regs, unsigned int esr) +{ + struct step_hook *hook; + int retval = DBG_HOOK_ERROR; + + read_lock(&step_hook_lock); + + list_for_each_entry(hook, &step_hook, node) { + retval = hook->fn(regs, esr); + if (retval == DBG_HOOK_HANDLED) + break; + } + + read_unlock(&step_hook_lock); + + return retval; +} + static int single_step_handler(unsigned long addr, unsigned int esr, struct pt_regs *regs) { @@ -215,7 +257,10 @@ static int single_step_handler(unsigned long addr, unsigned int esr, */ user_rewind_single_step(current); } else { - /* TODO: route to KGDB */ + /* call registered single step handlers */ + if (call_step_hook(regs, esr) == DBG_HOOK_HANDLED) + return 0; + pr_warning("Unexpected kernel single-step exception at EL1\n"); /* * Re-enable stepping since we know that we will be @@ -227,11 +272,50 @@ static int single_step_handler(unsigned long addr, unsigned int esr, return 0; } + +static LIST_HEAD(break_hook); +DEFINE_RWLOCK(break_hook_lock); + +void register_break_hook(struct break_hook *hook) +{ + write_lock(&break_hook_lock); + list_add(&hook->node, &break_hook); + write_unlock(&break_hook_lock); +} + +void unregister_break_hook(struct break_hook *hook) +{ + write_lock(&break_hook_lock); + list_del(&hook->node); + write_unlock(&break_hook_lock); +} + +static int call_break_hook(struct pt_regs *regs, unsigned int esr) +{ + struct break_hook *hook; + int (*fn)(struct pt_regs *regs, unsigned int esr) = NULL; + + read_lock(&break_hook_lock); + list_for_each_entry(hook, &break_hook, node) + if ((esr & hook->esr_mask) == hook->esr_val) + fn = hook->fn; + read_unlock(&break_hook_lock); + + return fn ? fn(regs, esr) : DBG_HOOK_ERROR; +} + static int brk_handler(unsigned long addr, unsigned int esr, struct pt_regs *regs) { siginfo_t info; + /* call the registered breakpoint handler */ + if (call_break_hook(regs, esr) == DBG_HOOK_HANDLED) + return 0; + + pr_warn("unexpected brk exception at %lx, esr=0x%x\n", + (long)instruction_pointer(regs), esr); + if (!user_mode(regs)) return -EFAULT; diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 3881fd1..7fbc510 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -288,6 +288,8 @@ el1_dbg: /* * Debug exception handling */ + cmp x24, #ESR_EL1_EC_BRK64 // if BRK64 + cinc x24, x24, eq // set bit '0' tbz x24, #0, el1_inv // EL1 only mrs x0, far_el1 mov x2, sp // struct pt_regs