Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753865Ab3JQLTF (ORCPT ); Thu, 17 Oct 2013 07:19:05 -0400 Received: from mail-pd0-f178.google.com ([209.85.192.178]:54487 "EHLO mail-pd0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750863Ab3JQLSv (ORCPT ); Thu, 17 Oct 2013 07:18:51 -0400 From: Sandeepa Prabhu To: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org, patches@linaro.org, linaro-kernel@lists.linaro.org, catalin.marinas@arm.com, will.deacon@arm.com, steve.capper@linaro.org, nico@linaro.org, srikar@linux.vnet.ibm.com, rostedt@goodmis.org, masami.hiramatsu.pt@hitachi.com, dsaxena@linaro.org, jiang.liu@huawei.com, Vijaya.Kumar@caviumnetworks.com, Sandeepa Prabhu Subject: [PATCH RFC v4 1/6] arm64: support single-step and breakpoint handler hooks Date: Thu, 17 Oct 2013 16:47:46 +0530 Message-Id: <1382008671-4515-2-git-send-email-sandeepa.prabhu@linaro.org> X-Mailer: git-send-email 1.8.1.2 In-Reply-To: <1382008671-4515-1-git-send-email-sandeepa.prabhu@linaro.org> References: <1382008671-4515-1-git-send-email-sandeepa.prabhu@linaro.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5362 Lines: 186 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 -- 1.8.1.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/