From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 742EEC433F5 for ; Mon, 31 Jan 2022 17:24:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=SvdoTVZeCho15Yv02uPSmpWea6awF43gPFeLdMZWh5Q=; b=xj74t7DqR0LC7j LZZ8m2uqnYM9CJhPD4h8ESw+2SfzemVUNU2DgI16pkSjakrd7kEnUnLfCZFIKILRBQbYtwmDwGOJ0 kNki7SgVTG6/yBqXKQAx8NQ5To2Pql+rvtUTpuhb6/3olgnaiWePgVVmHY2W/Puezr/PuN9NE/PAs TwCsRSWPZ+ZcPKgv++lW+4fop/KxqdOJo/nT0YpkqEvq6e0E8TwwS0XvntDHLCp6jLmUiFI1z3yq6 KPIlCiUqZdcCT+fWvPcJd11exOBcnYZkpjoFZIyJOpRNOv7Ty1MDNTQb0/L+sqinaJz/2w4Fhl9lQ +kHVxyinGQp/mJoddnXg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nEaO1-00A51k-74; Mon, 31 Jan 2022 17:22:41 +0000 Received: from ams.source.kernel.org ([145.40.68.75]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nEa6F-009zK3-4h for linux-arm-kernel@lists.infradead.org; Mon, 31 Jan 2022 17:04:23 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id A28E6B82BD0; Mon, 31 Jan 2022 17:04:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1264AC340F0; Mon, 31 Jan 2022 17:04:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1643648656; bh=ldt5RXpvhMNcTmr74G6GfsymT3trO74CF4N+1KJgyak=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=b+oZ+WmHyiDw8o55+2lDyGLAp+BMmJwgJ5iJQ5OQ5mAFsOm0VIJ+/yRtoqTGvYJjX dYeJuJimHWkPu58ZYfu+cM/9D7xFbib7qS6uqtpKI0wML11YU6Ugtlim33hDnWtmjC z0dIIttBAwfynu2mUSBj5+svd7UGjr1wWLpspzHchkrZpaY7RgjVOdJkJ54YDjDRDp Nq2qcjzCL/iXIEo7eiEUhSiTWov53QKpmK0OsGafkH90T8AqJPiv5lTJfjtSRSxysR MjiAPZsTzLRUgSqYNvoj54G2VjUuBZ3s6xq3dmXiJKEsss8XdEzLMVVx5LGrNz089F CQpXatCFAoqHg== From: Ard Biesheuvel To: linux@armlinux.org.uk Cc: linux-arm-kernel@lists.infradead.org, Ard Biesheuvel , Steven Rostedt , Sudeep Holla , Cristian Marussi , Nathan Chancellor , Nick Desaulniers , Arnd Bergmann , Linus Walleij , Masami Hiramatsu Subject: [PATCH v2 08/12] ARM: ftrace: enable the graph tracer with the EABI unwinder Date: Mon, 31 Jan 2022 18:03:43 +0100 Message-Id: <20220131170347.381551-9-ardb@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220131170347.381551-1-ardb@kernel.org> References: <20220131170347.381551-1-ardb@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=7688; h=from:subject; bh=ldt5RXpvhMNcTmr74G6GfsymT3trO74CF4N+1KJgyak=; b=owEB7QES/pANAwAKAcNPIjmS2Y8kAcsmYgBh+BZqoV17n4C3rgIInis0DmHnCNYAptQkWcePYKxZ rqvcPICJAbMEAAEKAB0WIQT72WJ8QGnJQhU3VynDTyI5ktmPJAUCYfgWagAKCRDDTyI5ktmPJOR+C/ 98uep0SiTFrYJ6DeNpfanaMCyaObpxrP8xus1k/z8xvKMdX2x4maImS3YZTS5B0Ay8Y0CzRUC60jf/ bCez7sUFrqNw5jle5vWdwLvKAA7HqSgvywydRitZ6+/YZ71/wkJDA8eSsmFzTIezx3YV9SjW7DzcKV htOOMHpH6KO+9dlmvB+wnayXeOvDrD02fRBlHKFP5MMj/1vz7G00oY3U1cgaajPBbh/HhgDIKoJy4S nzXTDv5HKwyIFbAQmczO9WvbgH3IpSEpbe4XlArR7Is9ZSWCedFyi6LehniEWoprb+RKaP2iVcubMI iMs1uxteriz6uTwl3FZRXjFZUeQeqqxlMPnICxXTAMUC95CGavYU0ajuZwYODwvTueex9Dkk/uxmq3 JUz398gTLkRsKc9O3I+VwAmqbErEBKJaD+thg1s/TARA2U25IKDPsPpxvDHl907NXc33c+SknT0dfg ohldYnqhAm/dGO+UuTVC0cjw4wp8tbG0ShI5/kN8bYtlI= X-Developer-Key: i=ardb@kernel.org; a=openpgp; fpr=F43D03328115A198C90016883D200E9CA6329909 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220131_090419_543234_9548B6F7 X-CRM114-Status: GOOD ( 23.91 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Enable the function graph tracer in combination with the EABI unwinder, so that Thumb2 builds or Clang ARM builds can make use of it. This involves using the unwinder to locate the return address of an instrumented function on the stack, so that it can be overridden and made to refer to the ftrace handling routines that need to be called at function return. Given that for these builds, it is not guaranteed that the value of the link register is stored on the stack, fall back to the stack slot that will be used by the ftrace exit code to restore LR in the instrumented function's execution context. Signed-off-by: Ard Biesheuvel --- arch/arm/Kconfig | 2 +- arch/arm/Kconfig.debug | 2 +- arch/arm/include/asm/ftrace.h | 18 ------------- arch/arm/kernel/Makefile | 5 +--- arch/arm/kernel/entry-ftrace.S | 28 ++++++++++++++------ arch/arm/kernel/ftrace.c | 19 +++++++++++-- 6 files changed, 40 insertions(+), 34 deletions(-) diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 8eff55222874..3c6216f194f2 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -92,7 +92,7 @@ config ARM select HAVE_EXIT_THREAD select HAVE_FAST_GUP if ARM_LPAE select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL - select HAVE_FUNCTION_GRAPH_TRACER if !THUMB2_KERNEL && !CC_IS_CLANG + select HAVE_FUNCTION_GRAPH_TRACER select HAVE_FUNCTION_TRACER if !XIP_KERNEL && !(THUMB2_KERNEL && CC_IS_CLANG) select HAVE_FUTEX_CMPXCHG if FUTEX select HAVE_GCC_PLUGINS diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug index 07055a503022..cc7523f44be4 100644 --- a/arch/arm/Kconfig.debug +++ b/arch/arm/Kconfig.debug @@ -65,7 +65,7 @@ config UNWINDER_FRAME_POINTER config UNWINDER_ARM bool "ARM EABI stack unwinder" - depends on AEABI && !FUNCTION_GRAPH_TRACER + depends on AEABI # https://github.com/ClangBuiltLinux/linux/issues/732 depends on !LD_IS_LLD || LLD_VERSION >= 110000 select ARM_UNWIND diff --git a/arch/arm/include/asm/ftrace.h b/arch/arm/include/asm/ftrace.h index b4f5fab6b04e..5358aad67831 100644 --- a/arch/arm/include/asm/ftrace.h +++ b/arch/arm/include/asm/ftrace.h @@ -35,26 +35,8 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr) #ifndef __ASSEMBLY__ -#if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND) -/* - * return_address uses walk_stackframe to do it's work. If both - * CONFIG_FRAME_POINTER=y and CONFIG_ARM_UNWIND=y walk_stackframe uses unwind - * information. For this to work in the function tracer many functions would - * have to be marked with __notrace. So for now just depend on - * !CONFIG_ARM_UNWIND. - */ - void *return_address(unsigned int); -#else - -static inline void *return_address(unsigned int level) -{ - return NULL; -} - -#endif - #define ftrace_return_address(n) return_address(n) #define ARCH_HAS_SYSCALL_MATCH_SYM_NAME diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile index 56511856ff9d..5cebb8d5a1d6 100644 --- a/arch/arm/kernel/Makefile +++ b/arch/arm/kernel/Makefile @@ -25,10 +25,7 @@ obj-y := elf.o entry-common.o irq.o opcodes.o \ KASAN_SANITIZE_stacktrace.o := n KASAN_SANITIZE_traps.o := n -ifneq ($(CONFIG_ARM_UNWIND),y) -obj-$(CONFIG_FRAME_POINTER) += return_address.o -endif - +obj-y += return_address.o obj-$(CONFIG_ATAGS) += atags_parse.o obj-$(CONFIG_ATAGS_PROC) += atags_proc.o obj-$(CONFIG_DEPRECATED_PARAM_STRUCT) += atags_compat.o diff --git a/arch/arm/kernel/entry-ftrace.S b/arch/arm/kernel/entry-ftrace.S index bbfa0954c385..3e7bcaca5e07 100644 --- a/arch/arm/kernel/entry-ftrace.S +++ b/arch/arm/kernel/entry-ftrace.S @@ -100,7 +100,8 @@ ftrace_regs_call: #ifdef CONFIG_FUNCTION_GRAPH_TRACER .globl ftrace_graph_regs_call ftrace_graph_regs_call: - mov r0, r0 +ARM( mov r0, r0 ) +THUMB( nop.w ) #endif @ pop saved regs @@ -112,13 +113,18 @@ ftrace_graph_regs_call: #ifdef CONFIG_FUNCTION_GRAPH_TRACER .macro __ftrace_graph_regs_caller - sub r0, fp, #4 @ lr of instrumented routine (parent) +#ifdef CONFIG_UNWINDER_FRAME_POINTER + sub r0, fp, #4 @ lr of instrumented routine (parent) +#else + add r0, sp, #S_LR +#endif @ called from __ftrace_regs_caller - ldr r1, [sp, #S_PC] @ instrumented routine (func) + ldr r1, [sp, #S_PC] @ instrumented routine (func) mcount_adjust_addr r1, r1 - mov r2, fp @ frame pointer + mov r2, fpreg @ frame pointer + add r3, sp, #PT_REGS_SIZE bl prepare_ftrace_return @ pop registers saved in ftrace_regs_caller @@ -149,14 +155,19 @@ ftrace_call\suffix: #ifdef CONFIG_FUNCTION_GRAPH_TRACER .globl ftrace_graph_call\suffix ftrace_graph_call\suffix: - mov r0, r0 +ARM( mov r0, r0 ) +THUMB( nop.w ) #endif mcount_exit .endm .macro __ftrace_graph_caller +#ifdef CONFIG_UNWINDER_FRAME_POINTER sub r0, fp, #4 @ &lr of instrumented routine (&parent) +#else + add r0, sp, #20 +#endif #ifdef CONFIG_DYNAMIC_FTRACE @ called from __ftrace_caller, saved in mcount_enter ldr r1, [sp, #16] @ instrumented routine (func) @@ -165,7 +176,8 @@ ftrace_graph_call\suffix: @ called from __mcount, untouched in lr mcount_adjust_addr r1, lr @ instrumented routine (func) #endif - mov r2, fp @ frame pointer + mov r2, fpreg @ frame pointer + add r3, sp, #24 bl prepare_ftrace_return mcount_exit .endm @@ -244,14 +256,14 @@ ENDPROC(ftrace_graph_regs_caller) .purgem mcount_exit #ifdef CONFIG_FUNCTION_GRAPH_TRACER - .globl return_to_handler -return_to_handler: +ENTRY(return_to_handler) stmdb sp!, {r0-r3} add r0, sp, #16 @ sp at exit of instrumented routine bl ftrace_return_to_handler mov lr, r0 @ r0 has real ret addr ldmia sp!, {r0-r3} ret lr +ENDPROC(return_to_handler) #endif ENTRY(ftrace_stub) diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c index 1885c3fec15a..cd0b33eef6b8 100644 --- a/arch/arm/kernel/ftrace.c +++ b/arch/arm/kernel/ftrace.c @@ -22,6 +22,7 @@ #include #include #include +#include #include #ifdef CONFIG_THUMB2_KERNEL @@ -213,8 +214,10 @@ int ftrace_make_nop(struct module *mod, #endif /* CONFIG_DYNAMIC_FTRACE */ #ifdef CONFIG_FUNCTION_GRAPH_TRACER +asmlinkage void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, - unsigned long frame_pointer) + unsigned long frame_pointer, + unsigned long stack_pointer) { unsigned long return_hooker = (unsigned long) &return_to_handler; unsigned long old; @@ -225,6 +228,18 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, if (IS_ENABLED(CONFIG_UNWINDER_FRAME_POINTER)) { /* FP points one word below parent's top of stack */ frame_pointer += 4; + } else { + struct stackframe frame = { + .fp = frame_pointer, + .sp = stack_pointer, + .lr = self_addr, + .pc = self_addr, + }; + if (unwind_frame(&frame) < 0) + return; + if (frame.lr != self_addr) + parent = frame.lr_addr; + frame_pointer = frame.sp; } old = *parent; @@ -247,7 +262,7 @@ static int __ftrace_modify_caller(unsigned long *callsite, unsigned long caller_fn = (unsigned long) func; unsigned long pc = (unsigned long) callsite; unsigned long branch = arm_gen_branch(pc, caller_fn); - unsigned long nop = 0xe1a00000; /* mov r0, r0 */ + unsigned long nop = arm_gen_nop(); unsigned long old = enable ? nop : branch; unsigned long new = enable ? branch : nop; -- 2.30.2 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel