From patchwork Tue Jan 24 23:24:51 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Abel Vesa X-Patchwork-Id: 9536089 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id B2F876046A for ; Tue, 24 Jan 2017 23:25:38 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A7233271BC for ; Tue, 24 Jan 2017 23:25:38 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 9AEA127BA5; Tue, 24 Jan 2017 23:25:38 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.4 required=2.0 tests=BAYES_00, RCVD_IN_SORBS_SPAM autolearn=no version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [65.50.211.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 2C044271BC for ; Tue, 24 Jan 2017 23:25:38 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.87 #1 (Red Hat Linux)) id 1cWAT2-0001RZ-6h; Tue, 24 Jan 2017 23:25:36 +0000 Received: from mail-wm0-f65.google.com ([74.125.82.65]) by bombadil.infradead.org with esmtps (Exim 4.87 #1 (Red Hat Linux)) id 1cWASw-00019M-SW for linux-arm-kernel@lists.infradead.org; Tue, 24 Jan 2017 23:25:33 +0000 Received: by mail-wm0-f65.google.com with SMTP id c85so38271616wmi.1 for ; Tue, 24 Jan 2017 15:25:10 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=d2MNmAA9iP/aZ2yyMtuw4ce2VJplpMmko2DPLy/csNU=; b=btOz5uRTT8LvY7/QsJMCV/HKgq40S8LOjcsZ4gm6ooR2RhlWOkHauBItb8hywn+Tlh QiajzG+7yP36/JLy7O//62FVgW+/bqNNQcDN9iuaMiYhHo2eXJF5KcEmtv7lFFbddGsd 6UQQT69jS9RiKKXUlW8M9BfmTXeMAwp8UN7zaeQcSeYWcJQEjPk5PXMSCZxUBEQNJQI8 K5gWkX6tvHR0k29oyipwWbdvYD4QUTPQEa1VibBDw+Zy38L5+8y5+NwCEAhyS2+ZakLR 4tm8p3XGEQTvaBNBJg98I7A+q0cLkO6Jv4pFtQWTFj0gM4TN9O4nolcNLvxautWwGyL0 yFEw== X-Gm-Message-State: AIkVDXLhnK35dRWRngGGz4JEhO8Q8zMKvY/XclZVHvbc5x+4nUUL/UdDSqHJWFDjj7J1Ag== X-Received: by 10.28.174.14 with SMTP id x14mr19134473wme.75.1485300308695; Tue, 24 Jan 2017 15:25:08 -0800 (PST) Received: from localhost.localdomain (cpc91312-watf11-2-0-cust1112.15-2.cable.virginm.net. [82.14.76.89]) by smtp.gmail.com with ESMTPSA id r24sm22111467wrr.25.2017.01.24.15.25.07 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 24 Jan 2017 15:25:07 -0800 (PST) From: Abel Vesa To: linux@armlinux.org.uk, rostedt@goodmis.org, mingo@redhat.com, viro@zeniv.linux.org.uk, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, jjhiblot@traphandler.com Subject: [PATCHv2] arm: ftrace: Adds support for CONFIG_DYNAMIC_FTRACE_WITH_REGS Date: Tue, 24 Jan 2017 23:24:51 +0000 Message-Id: <1485300291-29722-1-git-send-email-abelvesa@linux.com> X-Mailer: git-send-email 2.7.4 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20170124_152531_166280_60450930 X-CRM114-Status: GOOD ( 17.95 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: abelvesa@gmail.com, pmladek@suse.com, zhouchengming1@huawei.com, robin.murphy@arm.com, Abel Vesa MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP The DYNAMIC_FTRACE_WITH_REGS configuration makes it possible for a ftrace operation to specify if registers need to saved/restored by the ftrace handler. This is needed by kgraft and possibly other ftrace-based tools, and the ARM architecture is currently lacking this feature. It would also be the first step to support the "Kprobes-on-ftrace" optimization on ARM. This patch introduces a new ftrace handler that stores the registers on the stack before calling the next stage. The registers are restored from the stack before going back to the instrumented function. A side-effect of this patch is to activate the support for ftrace_modify_call() as it defines ARCH_SUPPORTS_FTRACE_OPS for the ARM architecture. Signed-off-by: Abel Vesa --- arch/arm/Kconfig | 1 + arch/arm/include/asm/ftrace.h | 4 +++ arch/arm/kernel/entry-ftrace.S | 79 ++++++++++++++++++++++++++++++++++++++++++ arch/arm/kernel/ftrace.c | 33 ++++++++++++++++++ 4 files changed, 117 insertions(+) diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 186c4c2..db40973 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -50,6 +50,7 @@ config ARM select HAVE_DMA_API_DEBUG select HAVE_DMA_CONTIGUOUS if MMU select HAVE_DYNAMIC_FTRACE if (!XIP_KERNEL) && !CPU_ENDIAN_BE32 && MMU + select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE select HAVE_EFFICIENT_UNALIGNED_ACCESS if (CPU_V6 || CPU_V6K || CPU_V7) && MMU select HAVE_EXIT_THREAD select HAVE_FTRACE_MCOUNT_RECORD if (!XIP_KERNEL) diff --git a/arch/arm/include/asm/ftrace.h b/arch/arm/include/asm/ftrace.h index 22b7311..f379881 100644 --- a/arch/arm/include/asm/ftrace.h +++ b/arch/arm/include/asm/ftrace.h @@ -1,6 +1,10 @@ #ifndef _ASM_ARM_FTRACE #define _ASM_ARM_FTRACE +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS +#define ARCH_SUPPORTS_FTRACE_OPS 1 +#endif + #ifdef CONFIG_FUNCTION_TRACER #define MCOUNT_ADDR ((unsigned long)(__gnu_mcount_nc)) #define MCOUNT_INSN_SIZE 4 /* sizeof mcount call */ diff --git a/arch/arm/kernel/entry-ftrace.S b/arch/arm/kernel/entry-ftrace.S index c73c403..fcdcc3a 100644 --- a/arch/arm/kernel/entry-ftrace.S +++ b/arch/arm/kernel/entry-ftrace.S @@ -92,12 +92,74 @@ 2: mcount_exit .endm +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS + +.macro __ftrace_regs_caller + + add ip, sp, #4 @ move in IP the value of SP as it was + @ before the push {lr} of the mcount mechanism + stmdb sp!, {ip,lr,pc} + stmdb sp!, {r0-r11,lr} + + @ stack content at this point: + @ 0 4 44 48 52 56 60 64 + @ RO | R1 | ... | R11 | LR | SP + 4 | LR | PC | previous LR | + + mov r3, sp @ struct pt_regs* + ldr r2, =function_trace_op + ldr r2, [r2] @ pointer to the current + @ function tracing op + ldr r1, [sp, #64] @ lr of instrumented func + mcount_adjust_addr r0, lr @ instrumented function + + .globl ftrace_regs_call +ftrace_regs_call: + bl ftrace_stub + +#ifdef CONFIG_FUNCTION_GRAPH_TRACER + .globl ftrace_graph_regs_call +ftrace_graph_regs_call: + mov r0, r0 +#endif + ldr lr, [sp, #64] @ get the previous LR value from stack + ldmia sp, {r0-r11, ip, sp} @ pop the saved registers INCLUDING + @ the stack pointer + ret ip +.endm + +#ifdef CONFIG_FUNCTION_GRAPH_TRACER +.macro __ftrace_graph_regs_caller + + sub r0, fp, #4 @ lr of instrumented routine (parent) + + @ called from __ftrace_regs_caller + ldr r1, [sp, #56] @ instrumented routine (func) + mcount_adjust_addr r1, r1 + + sub r2, r0, #4 @ frame pointer + bl prepare_ftrace_return + + ldr lr, [sp, #64] @ restore lr from the stack + ldmia sp, {r0-r11, ip, sp} @ restore r0 through sp + ret ip + +.endm +#endif +#endif + .macro __ftrace_caller suffix mcount_enter mcount_get_lr r1 @ lr of instrumented func mcount_adjust_addr r0, lr @ instrumented function +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS + ldr r2, =function_trace_op + ldr r2, [r2] @ pointer to the current + @ function tracing op + mov r3, #0 @ regs is NULL +#endif + .globl ftrace_call\suffix ftrace_call\suffix: bl ftrace_stub @@ -212,6 +274,15 @@ UNWIND(.fnstart) __ftrace_caller UNWIND(.fnend) ENDPROC(ftrace_caller) + +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS +ENTRY(ftrace_regs_caller) +UNWIND(.fnstart) + __ftrace_regs_caller +UNWIND(.fnend) +ENDPROC(ftrace_regs_caller) +#endif + #endif #ifdef CONFIG_FUNCTION_GRAPH_TRACER @@ -220,6 +291,14 @@ UNWIND(.fnstart) __ftrace_graph_caller UNWIND(.fnend) ENDPROC(ftrace_graph_caller) + +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS +ENTRY(ftrace_graph_regs_caller) +UNWIND(.fnstart) + __ftrace_graph_regs_caller +UNWIND(.fnend) +ENDPROC(ftrace_graph_regs_caller) +#endif #endif .purgem mcount_enter diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c index 3f17594..d8d4753 100644 --- a/arch/arm/kernel/ftrace.c +++ b/arch/arm/kernel/ftrace.c @@ -139,6 +139,15 @@ int ftrace_update_ftrace_func(ftrace_func_t func) ret = ftrace_modify_code(pc, 0, new, false); +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS + if (!ret) { + pc = (unsigned long)&ftrace_regs_call; + new = ftrace_call_replace(pc, (unsigned long)func); + + ret = ftrace_modify_code(pc, 0, new, false); + } +#endif + #ifdef CONFIG_OLD_MCOUNT if (!ret) { pc = (unsigned long)&ftrace_call_old; @@ -157,6 +166,20 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) unsigned long ip = rec->ip; old = ftrace_nop_replace(rec); + + new = ftrace_call_replace(ip, adjust_address(rec, addr)); + + return ftrace_modify_code(rec->ip, old, new, true); +} + +int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, + unsigned long addr) +{ + unsigned long new, old; + unsigned long ip = rec->ip; + + old = ftrace_call_replace(ip, adjust_address(rec, old_addr)); + new = ftrace_call_replace(ip, adjust_address(rec, addr)); return ftrace_modify_code(rec->ip, old, new, true); @@ -229,6 +252,8 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, extern unsigned long ftrace_graph_call; extern unsigned long ftrace_graph_call_old; extern void ftrace_graph_caller_old(void); +extern unsigned long ftrace_graph_regs_call; +extern void ftrace_graph_regs_caller(void); static int __ftrace_modify_caller(unsigned long *callsite, void (*func) (void), bool enable) @@ -251,6 +276,14 @@ static int ftrace_modify_graph_caller(bool enable) ftrace_graph_caller, enable); +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS + if (!ret) + ret = __ftrace_modify_caller(&ftrace_graph_regs_call, + ftrace_graph_regs_caller, + enable); +#endif + + #ifdef CONFIG_OLD_MCOUNT if (!ret) ret = __ftrace_modify_caller(&ftrace_graph_call_old,