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 DC78DC433EF for ; Thu, 3 Feb 2022 08:27:06 +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=egdZxQ6idnehuDTrNkbJijPcHzi1RvOIucbYCDSQ99I=; b=g9pcHTjldWzsgj OpPDN1+wey0X9rhx/hr6u5b3ajy1vkw+zpnuT9bPvs7GVqU5z/dMeIQniuWZ4+Nq8MYocoksfjzK/ /WTCOIcM8tWSQpfrVGVRODq8ih7q0LQGLSfVwusHYwLpKiACrLm12j1ZSHJ+KK4UoeR9ib2c/JYrv PPlqXFxeFvPGlxpkDJGkxqFvhgSw0BsQyjs542acuaBOSGzn5PLdd2McFnVVFPr+Unlk8gcfgv1pD 52gQH2zjRdNmD0dNzipWiNpqXg051uEM6aYfJCtNZ4GMvXw/33aQZaCVBQF9qE/MWdufz+6CYsPVi IkSQsSV9zACFS5aoKQqA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nFXQj-000KZc-FP; Thu, 03 Feb 2022 08:25:25 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nFXO0-000JLS-KA for linux-arm-kernel@lists.infradead.org; Thu, 03 Feb 2022 08:22:38 +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 dfw.source.kernel.org (Postfix) with ESMTPS id 243846183B; Thu, 3 Feb 2022 08:22:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4608BC340F1; Thu, 3 Feb 2022 08:22:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1643876555; bh=jDyLlp5R8JKd1yO6ZwBlZOCMA1O/6ilTHSfAdHXS0+Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=f4wSHFtC0w0kuM0JsYN5HPMIfCwxTHEjtk2RulkWgDzOszHVh5tEmrtPBCNjG/nBm +UYM82oU3F+ARLII1xv+bHbBQBymVCAgbNfPKEXOighI3r59Sj+IWZfuj0wASQjZzn x28sIts/m75o5qqnKn9wdYUKUh7OCICXTBhaMiADzk1cjibXct4ziGW2WntKfeF9VP U0j9FxN6KH1Y3E6hA3ynExe0VwaEChcM8E7tkxASj9eEb0v0olCv5i22YNVL97mRiw 01ocAheGnAWAh/nGEtl7LpXW5U8Dbu5voUYtrQ7LTqrPZ1VPCWnY9pKbfWCOEqKpMK +hNMdCifafL/A== 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 v3 08/13] ARM: ftrace: enable the graph tracer with the EABI unwinder Date: Thu, 3 Feb 2022 09:21:59 +0100 Message-Id: <20220203082204.1176734-9-ardb@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220203082204.1176734-1-ardb@kernel.org> References: <20220203082204.1176734-1-ardb@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=7723; h=from:subject; bh=jDyLlp5R8JKd1yO6ZwBlZOCMA1O/6ilTHSfAdHXS0+Q=; b=owEB7QES/pANAwAKAcNPIjmS2Y8kAcsmYgBh+5ChMeK55nHWvOs0I3bHN6uWZqEMVZiksw/tdegy Hhgvj7SJAbMEAAEKAB0WIQT72WJ8QGnJQhU3VynDTyI5ktmPJAUCYfuQoQAKCRDDTyI5ktmPJHfXC/ 9JxAboaAkHZ7jduvR8KrPR3zKGumf80JtG9K/Ts5HWqKzuHDzIfRf9uTSd8SlkQoza2+cBljGbkxaJ nxnbuS0vqI+NxorhL3wam+ZHuTzl5OBjBlAcqw2RuD66EyNoC7R7yiPGjs8c2ltY3oNpBF4d9LElzY TcddtAK1O7Uotj+QZ3rf/8mOMUWMXuO9t5SD+7p+vRMnuHX7Y5nh1bEGb6YM1K2nNelOOAPyxaZOUp 9uetpz2PfjfbLBPdoUE65S9i0DGxkl2c7jct3GfiJblkqM2fCqn8ZIQLMHvGhI5kLkgkBYXMb85Mnt 2OacYgvdHx7as1P9ZqyCo6oHS2lgKw39RV1gLtt92MHeajw8sfPLtD3fpY9LlC/jp1upQStieJKC2i dAY9kfmuYLiNMbLRQE5cDOYeGmsjkUcs/UlPUijwLKcJ3agL+baK9C7FgN4gay6ij5fcTKO+I3hEgT P3SsrZnVuKnIx9Pv1intAievf9uI16YK71ixj9JVvgfLo= 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-20220203_002236_774776_DCF64A31 X-CRM114-Status: GOOD ( 23.74 ) 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 Reviewed-by: Steven Rostedt (Google) --- 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 ea2396900c7d..83cc068586bc 100644 --- a/arch/arm/kernel/ftrace.c +++ b/arch/arm/kernel/ftrace.c @@ -22,6 +22,7 @@ #include #include #include +#include #include /* @@ -224,8 +225,10 @@ 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; @@ -236,6 +239,18 @@ 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; @@ -258,7 +273,7 @@ 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