From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751841AbcEaK6T (ORCPT ); Tue, 31 May 2016 06:58:19 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:10303 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752505AbcEaK6O (ORCPT ); Tue, 31 May 2016 06:58:14 -0400 Message-Id: <201605311058.u4VAsdbn044819@mx0a-001b2d01.pphosted.com> X-IBM-Helo: d23dlp03.au.ibm.com X-IBM-MailFrom: anju@linux.vnet.ibm.com X-IBM-RcptTo: linux-kernel@vger.kernel.org From: Anju T To: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Cc: anju@linux.vnet.ibm.com, ananth@in.ibm.com, naveen.n.rao@linux.vnet.ibm.com, paulus@samba.org, srikar@linux.vnet.ibm.com, benh@kernel.crashing.org, mpe@ellerman.id.au, hemant@linux.vnet.ibm.com, mahesh@linux.vnet.ibm.com, mhiramat@kernel.org, anjutsudhakar@gmail.com Subject: [RFC PATCH v3 1/3] arch/powerpc : Add detour buffer support for optprobes Date: Tue, 31 May 2016 16:26:29 +0530 X-Mailer: git-send-email 2.1.0 In-Reply-To: <1464692191-1167-1-git-send-email-anju@linux.vnet.ibm.com> References: <1464692191-1167-1-git-send-email-anju@linux.vnet.ibm.com> X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16053110-0016-0000-0000-000001A02D26 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16053110-0017-0000-0000-000004BC8E0C X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-05-31_06:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=8 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1604210000 definitions=main-1605310127 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Detour buffer contains instructions to create an in memory pt_regs. After the execution of prehandler a call is made for instruction emulation. The NIP is decided after the probed instruction is executed. Hence a branch instruction is created to the NIP returned by emulate_step(). Instruction slot for detour buffer is allocated from the reserved area. For the time being 64KB is reserved in memory for this purpose. Signed-off-by: Anju T --- arch/powerpc/include/asm/kprobes.h | 27 +++++++ arch/powerpc/kernel/optprobes_head.S | 136 +++++++++++++++++++++++++++++++++++ 2 files changed, 163 insertions(+) create mode 100644 arch/powerpc/kernel/optprobes_head.S diff --git a/arch/powerpc/include/asm/kprobes.h b/arch/powerpc/include/asm/kprobes.h index 039b583..1cb2527 100644 --- a/arch/powerpc/include/asm/kprobes.h +++ b/arch/powerpc/include/asm/kprobes.h @@ -38,7 +38,27 @@ struct pt_regs; struct kprobe; typedef ppc_opcode_t kprobe_opcode_t; + +extern kprobe_opcode_t optinsn_slot; +/* Optinsn template address */ +extern kprobe_opcode_t optprobe_template_entry[]; +extern kprobe_opcode_t optprobe_template_call_handler[]; +extern kprobe_opcode_t optprobe_template_call_emulate[]; +extern kprobe_opcode_t optprobe_template_ret_branch[]; +extern kprobe_opcode_t optprobe_template_ret[]; +extern kprobe_opcode_t optprobe_template_insn[]; +extern kprobe_opcode_t optprobe_template_kp_addr[]; +extern kprobe_opcode_t optprobe_template_op_address1[]; +extern kprobe_opcode_t optprobe_template_op_address2[]; +extern kprobe_opcode_t optprobe_template_end[]; + #define MAX_INSN_SIZE 1 +#define MAX_OPTIMIZED_LENGTH 4 +#define MAX_OPTINSN_SIZE \ + (((unsigned long)&optprobe_template_end - \ + (unsigned long)&optprobe_template_entry) / \ + sizeof(kprobe_opcode_t)) +#define RELATIVEJUMP_SIZE 4 #ifdef CONFIG_PPC64 #if defined(_CALL_ELF) && _CALL_ELF == 2 @@ -129,5 +149,12 @@ struct kprobe_ctlblk { extern int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val, void *data); extern int kprobe_fault_handler(struct pt_regs *regs, int trapnr); + +struct arch_optimized_insn { + kprobe_opcode_t copied_insn[1]; + /* detour buffer */ + kprobe_opcode_t *insn; +}; + #endif /* __KERNEL__ */ #endif /* _ASM_POWERPC_KPROBES_H */ diff --git a/arch/powerpc/kernel/optprobes_head.S b/arch/powerpc/kernel/optprobes_head.S new file mode 100644 index 0000000..b2536bc --- /dev/null +++ b/arch/powerpc/kernel/optprobes_head.S @@ -0,0 +1,136 @@ +/* + * Code to prepare detour buffer for optprobes in Kernel. + * + * Copyright 2016, Anju T, IBM Corp. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ + +#include +#include +#include + +#define OPT_SLOT_SIZE 65536 + +.align 2 +.global optinsn_slot +optinsn_slot: + /* Reserve an area to allocate slots for detour buffer */ + .space OPT_SLOT_SIZE + +/* Create an in-memory pt_regs */ +.global optprobe_template_entry +optprobe_template_entry: + stdu r1,-INT_FRAME_SIZE(r1) + SAVE_GPR(0,r1) + /* Save the previous SP into stack */ + addi r0,r1,INT_FRAME_SIZE + std 0,GPR1(r1) + SAVE_2GPRS(2,r1) + SAVE_8GPRS(4,r1) + SAVE_10GPRS(12,r1) + SAVE_10GPRS(22,r1) + /* Save SPRS */ + mfmsr r5 + std r5,_MSR(r1) + li r5,0 + std r5,ORIG_GPR3(r1) + mfctr r5 + std r5,_CTR(r1) + mflr r5 + std r5,_LINK(r1) + mfspr r5,SPRN_XER + std r5,_XER(r1) + mfcr r5 + std r5,_CCR(r1) + lbz r5,PACASOFTIRQEN(r13) + std r5,SOFTE(r1) + li r5,0 + std r5,_TRAP(r1) + mfdar r5 + std r5,_DAR(r1) + mfdsisr r5 + std r5,_DSISR(r1) + li r5,0 + std r5,RESULT(r1) + +/* Save p->addr into stack */ +.global optprobe_template_kp_addr +optprobe_template_kp_addr: + nop + nop + nop + nop + nop + std r3,_NIP(r1) + +/* Pass parameters for optimized_callback */ +.global optprobe_template_op_address1 +optprobe_template_op_address1: + nop + nop + nop + nop + nop + addi r4,r1,STACK_FRAME_OVERHEAD + +/* Branch to the prehandler */ +.global optprobe_template_call_handler +optprobe_template_call_handler: + nop + /* Pass parameters for instruction emulation */ + addi r3,r1,STACK_FRAME_OVERHEAD +.global optprobe_template_insn +optprobe_template_insn: + nop + nop + +/* Branch to instruction emulation */ +.global optprobe_template_call_emulate +optprobe_template_call_emulate: + nop +.global optprobe_template_op_address2 +optprobe_template_op_address2: + nop + nop + nop + nop + nop + addi r4,r1,STACK_FRAME_OVERHEAD + +/* Branch to create_return_branch() function */ +.global optprobe_template_ret_branch +optprobe_template_ret_branch: + nop + /* Restore the registers */ + ld r5,_MSR(r1) + mtmsr r5 + ld r5,_CTR(r1) + mtctr r5 + ld r5,_LINK(r1) + mtlr r5 + ld r5,_XER(r1) + mtxer r5 + ld r5,_CCR(r1) + mtcr r5 + ld r5,_DAR(r1) + mtdar r5 + ld r5,_DSISR(r1) + mtdsisr r5 + REST_GPR(0,r1) + REST_2GPRS(2,r1) + REST_8GPRS(4,r1) + REST_10GPRS(12,r1) + REST_10GPRS(22,r1) + /* Restore the previous SP */ + addi r1,r1,INT_FRAME_SIZE + +/* Jump back to the normal workflow from trampoline */ +.global optprobe_template_ret +optprobe_template_ret: + nop +.global optprobe_template_end +optprobe_template_end: -- 2.1.0