Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757995AbZAVOGE (ORCPT ); Thu, 22 Jan 2009 09:06:04 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752331AbZAVOFx (ORCPT ); Thu, 22 Jan 2009 09:05:53 -0500 Received: from e28smtp06.in.ibm.com ([59.145.155.6]:52068 "EHLO e28smtp06.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753363AbZAVOFw (ORCPT ); Thu, 22 Jan 2009 09:05:52 -0500 Date: Thu, 22 Jan 2009 19:35:46 +0530 From: "K.Prasad" To: Linux Kernel Mailing List Cc: Alan Stern , Roland McGrath , akpm@linux-foundation.org, mingo@elte.hu, richardj_moore@uk.ibm.com Subject: [RFC Patch 4/10] Modify kprobe exception handler to recognise single-stepping by HW Breakpoint handler Message-ID: <20090122140546.GC19592@in.ibm.com> Reply-To: prasad@linux.vnet.ibm.com References: <20090122135640.GA11161@in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090122135640.GA11161@in.ibm.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4270 Lines: 114 This patch modifies the kprobe handler to help it recognise single-stepping by the HW Breakpoint exception code. A per-cpu variable called 'sstep_reason' to distinguish the source of single-step exceptions. Signed-off-by: K.Prasad Signed-off-by: Alan Stern --- arch/x86/include/asm/debugreg.h | 29 +++++++++++++++++++++++++++++ arch/x86/include/asm/processor.h | 10 +++------- arch/x86/kernel/kprobes.c | 6 ++++++ 3 files changed, 38 insertions(+), 7 deletions(-) Index: linux-hbkpt-lkml-29-rc2/arch/x86/kernel/kprobes.c =================================================================== --- linux-hbkpt-lkml-29-rc2.orig/arch/x86/kernel/kprobes.c +++ linux-hbkpt-lkml-29-rc2/arch/x86/kernel/kprobes.c @@ -54,6 +54,7 @@ #include #include #include +#include void jprobe_return_end(void); @@ -518,6 +519,7 @@ static int __kprobes kprobe_handler(stru kprobe_opcode_t *addr; struct kprobe *p; struct kprobe_ctlblk *kcb; + unsigned int *ssr; addr = (kprobe_opcode_t *)(regs->ip - sizeof(kprobe_opcode_t)); if (*addr != BREAKPOINT_INSTRUCTION) { @@ -963,6 +965,10 @@ int __kprobes kprobe_exceptions_notify(s ret = NOTIFY_STOP; break; case DIE_DEBUG: + /* We could be here due to single-stepping after a pre-handler + * execution of HW Breakpoint or kprobes. We determine the cause + * using the bitmask flag 'sstep_reason'. + */ if (post_kprobe_handler(args->regs)) ret = NOTIFY_STOP; break; Index: linux-hbkpt-lkml-29-rc2/arch/x86/include/asm/debugreg.h =================================================================== --- linux-hbkpt-lkml-29-rc2.orig/arch/x86/include/asm/debugreg.h +++ linux-hbkpt-lkml-29-rc2/arch/x86/include/asm/debugreg.h @@ -49,6 +49,8 @@ #define DR_LOCAL_ENABLE_SHIFT 0 /* Extra shift to the local enable bit */ #define DR_GLOBAL_ENABLE_SHIFT 1 /* Extra shift to the global enable bit */ +#define DR_LOCAL_ENABLE (0x1) /* Local enable for reg 0 */ +#define DR_GLOBAL_ENABLE (0x2) /* Global enable for reg 0 */ #define DR_ENABLE_SIZE 2 /* 2 enable bits per register */ #define DR_LOCAL_ENABLE_MASK (0x55) /* Set local bits for all 4 regs */ @@ -67,4 +69,31 @@ #define DR_LOCAL_SLOWDOWN (0x100) /* Local slow the pipeline */ #define DR_GLOBAL_SLOWDOWN (0x200) /* Global slow the pipeline */ +/* + * HW breakpoint additions + */ +#ifdef __KERNEL__ + +#define HB_NUM 4 /* Number of hardware breakpoints */ + +/* For process management */ +void flush_thread_hw_breakpoint(struct task_struct *tsk); +int copy_thread_hw_breakpoint(struct task_struct *tsk, + struct task_struct *child, unsigned long clone_flags); +void dump_thread_hw_breakpoint(struct task_struct *tsk, int u_debugreg[8]); +void switch_to_thread_hw_breakpoint(struct task_struct *tsk); + +/* For CPU management */ +void load_debug_registers(void); +static inline void disable_debug_registers(void) +{ + set_debugreg(0UL, 7); +} + +/* For use by ptrace */ +unsigned long thread_get_debugreg(struct task_struct *tsk, int n); +int thread_set_debugreg(struct task_struct *tsk, int n, unsigned long val); + +#endif /* __KERNEL__ */ + #endif /* _ASM_X86_DEBUGREG_H */ Index: linux-hbkpt-lkml-29-rc2/arch/x86/include/asm/processor.h =================================================================== --- linux-hbkpt-lkml-29-rc2.orig/arch/x86/include/asm/processor.h +++ linux-hbkpt-lkml-29-rc2/arch/x86/include/asm/processor.h @@ -405,13 +405,9 @@ struct thread_struct { unsigned long ip; unsigned long fs; unsigned long gs; - /* Hardware debugging registers: */ - unsigned long debugreg0; - unsigned long debugreg1; - unsigned long debugreg2; - unsigned long debugreg3; - unsigned long debugreg6; - unsigned long debugreg7; +/* Hardware breakpoint info */ + unsigned long vdr6; + struct thread_hw_breakpoint *hw_breakpoint_info; /* Fault info: */ unsigned long cr2; unsigned long trap_no; -- 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/