From nobody Fri May 3 17:32:38 2024 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5A9DCC433FE for ; Fri, 30 Sep 2022 21:15:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229971AbiI3VPR (ORCPT ); Fri, 30 Sep 2022 17:15:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35166 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229952AbiI3VPO (ORCPT ); Fri, 30 Sep 2022 17:15:14 -0400 Received: from mail-yw1-x1149.google.com (mail-yw1-x1149.google.com [IPv6:2607:f8b0:4864:20::1149]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3E60078217 for ; Fri, 30 Sep 2022 14:15:12 -0700 (PDT) Received: by mail-yw1-x1149.google.com with SMTP id 00721157ae682-34d188806a8so52925977b3.19 for ; Fri, 30 Sep 2022 14:15:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date; bh=w1VewG6/ucM/kWlIiY+OEg0V0mx9+6eAtRi0Lhie0XM=; b=Tp4dwoaPnTRGNUQ5SxT2h9xiIpSnWjwEzaPEwoI8MlCxexAhEiLEqRHO8PW5T23IId 5Z4MNnMGJ6bEh3IykJGWZD1Cjl3WbZ+MzSwKdza895nUPVaPuuCpfzKe+5nXAOXo/ERI dMb/3ioM6tA4SSQlflXue7wEZ/zwv+/Hzm1gd6Y1OpWpwPDgWPqnR3FjnBJm4a0cY5Q0 ZxUnaWwDPaCeMAtGm2Cr+0jD7CykU38ZGdxw78ZwyVsMlQ8axvbF7DsfajwOUflc8Y+e N9sOLvNkGI8mgABbWzD3GKbLDl9qBOFocS14lDUJsY28r5QO41jsJwHTGvOBJWpXx1ZV 0Y8g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date; bh=w1VewG6/ucM/kWlIiY+OEg0V0mx9+6eAtRi0Lhie0XM=; b=g9ZPXNfoLuhBXFzC/RlHrehJhcRJL+DpZE1xSGqGyeJG7fWffZuXK30SkehkzjD9G1 p81uvPLCf3kF6GddX2IBdl0Vtcxey6CZja2+awT0fpZ3XoAkGdwfUQqKVyD8mvkRK9LO RYvYwagk1yy7rcn2RgyqthWZkGJlTgV5fAvG1iSk6rLKJk3ky4ZBh3AHCO0g4PloSVtQ aCgZCXkWyL1MKTZaeyP9EqNs2JyCHCuxlqI9HmA4RwdyCP5nxXFkdA/N/amNOOtqBgxM DkmaDFkw7Ff2GOdZfp9way4YRUiQiBl8KDec76+Z0oZJxUBrMzjzP1uDKGebzg9u/pNn hPWg== X-Gm-Message-State: ACrzQf1Wskx7/odqa1XA4f10cu+flneE7GZ2UhVMxxbRgyfKGdBxF6v2 ELY+gb45OgsYRyec8D++11c2ko8ziQHhxue+zQw= X-Google-Smtp-Source: AMsMyM6YfkwaQZI8VA1GX09CQYJhLs6XtLjF9X9QwGccCpJhS1/Y/ezpwRrI67d9a0y9ulfsLbxEglc5x0GPl3wehn4= X-Received: from ndesaulniers-desktop.svl.corp.google.com ([2620:0:100e:712:8142:a086:b6c7:da71]) (user=ndesaulniers job=sendgmr) by 2002:a25:70d7:0:b0:6bc:20d5:b4b7 with SMTP id l206-20020a2570d7000000b006bc20d5b4b7mr10140202ybc.175.1664572511464; Fri, 30 Sep 2022 14:15:11 -0700 (PDT) Date: Fri, 30 Sep 2022 14:15:05 -0700 In-Reply-To: <202209291607.0MlscIht-lkp@intel.com> Mime-Version: 1.0 References: <202209291607.0MlscIht-lkp@intel.com> X-Developer-Key: i=ndesaulniers@google.com; a=ed25519; pk=UIrHvErwpgNbhCkRZAYSX0CFd/XFEwqX3D0xqtqjNug= X-Developer-Signature: v=1; a=ed25519-sha256; t=1664572505; l=8791; i=ndesaulniers@google.com; s=20220923; h=from:subject; bh=lUHlzSuudiJPVlmyWzn9mgQxtMlrWznVl5z96sKGkm0=; b=klReRD9UTEurRxPEn7v7Gd0sQIl5ojDRVmi98qbP9jMxVf+iTDPbNWAIVcyl78Z2aukRN7HsHkT6 TsjkJLbTDyk437hkn9Vgicxxb0pverqsO5Ltyk3o43d6Mg62tdzh X-Mailer: git-send-email 2.38.0.rc1.362.ged0d419d3c-goog Message-ID: <20220930211505.209939-1-ndesaulniers@google.com> Subject: [PATCH v3] ARM: kprobes: move __kretprobe_trampoline to out of line assembler From: Nick Desaulniers To: Russell King , Masami Hiramatsu Cc: "Naveen N . Rao" , Anil S Keshavamurthy , "David S . Miller" , Arnd Bergmann , Nathan Chancellor , Tom Rix , sparkhuang , Ard Biesheuvel , Steven Rostedt , Linus Walleij , Chen Zhongjin , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, llvm@lists.linux.dev, Naresh Kamboju , regressions@lists.linux.dev, lkft-triage@lists.linaro.org, Nick Desaulniers , Linux Kernel Functional Testing , Logan Chien Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" commit 1069c1dd20a3 ("ARM: 9231/1: Recover kretprobes return address for EABI stack unwinder") tickled a bug in clang's integrated assembler where the .save and .pad directives must have corresponding .fnstart directives. The integrated assembler is unaware that the compiler will be generating the .fnstart directive. arch/arm/probes/kprobes/core.c:409:30: error: .fnstart must precede .save or .vsave directives :3:2: note: instantiated into assembly here .save {sp, lr, pc} ^ arch/arm/probes/kprobes/core.c:412:29: error: .fnstart must precede .pad directive :6:2: note: instantiated into assembly here .pad #52 ^ __kretprobe_trampoline's definition is already entirely inline asm. Move it to out-of-line asm to avoid breaking the build. Forward declare trampoline_handler() to avoid -Wmissing-prototypes since it's only called from assembler. Fixes another instance of -Wmissing-prototypes on kprobe_handler() so that arch/arm/probes/kprobes/core.c builds cleanly with W=3D1. Link: https://github.com/llvm/llvm-project/issues/57993 Link: https://github.com/ClangBuiltLinux/linux/issues/1718 Reported-by: Nathan Chancellor Reported-by: Linux Kernel Functional Testing Suggested-by: Logan Chien Signed-off-by: Nick Desaulniers --- Changes v2 -> v3: * Fix -Wmissing-prototypes on trampoline_handler() as reported by kernel test robot. * Update comment above trampoline_handler(). * Fix another pre-existing case of -Wmissing-prototypes on kprobe_handler() so that arch/arm/probes/kprobes/core.c builds cleanly with W=3D1. * Make note of the above in the commit message. Changes v1 -> v2: * rebase on linux-next again. * drop commented out declaration of __kretprobe_trampoline from v1. arch/arm/probes/kprobes/Makefile | 1 + arch/arm/probes/kprobes/core.c | 54 +++--------------- .../arm/probes/kprobes/kretprobe-trampoline.S | 55 +++++++++++++++++++ include/asm-generic/kprobes.h | 13 +++-- 4 files changed, 72 insertions(+), 51 deletions(-) create mode 100644 arch/arm/probes/kprobes/kretprobe-trampoline.S diff --git a/arch/arm/probes/kprobes/Makefile b/arch/arm/probes/kprobes/Mak= efile index 6159010dac4a..cdbe9dd99e28 100644 --- a/arch/arm/probes/kprobes/Makefile +++ b/arch/arm/probes/kprobes/Makefile @@ -3,6 +3,7 @@ KASAN_SANITIZE_actions-common.o :=3D n KASAN_SANITIZE_actions-arm.o :=3D n KASAN_SANITIZE_actions-thumb.o :=3D n obj-$(CONFIG_KPROBES) +=3D core.o actions-common.o checkers-common.o +obj-$(CONFIG_KPROBES) +=3D kretprobe-trampoline.o obj-$(CONFIG_ARM_KPROBES_TEST) +=3D test-kprobes.o test-kprobes-objs :=3D test-core.o =20 diff --git a/arch/arm/probes/kprobes/core.c b/arch/arm/probes/kprobes/core.c index 9090c3a74dcc..11159fcf6ba6 100644 --- a/arch/arm/probes/kprobes/core.c +++ b/arch/arm/probes/kprobes/core.c @@ -233,7 +233,7 @@ singlestep(struct kprobe *p, struct pt_regs *regs, stru= ct kprobe_ctlblk *kcb) * kprobe, and that level is reserved for user kprobe handlers, so we can't * risk encountering a new kprobe in an interrupt handler. */ -void __kprobes kprobe_handler(struct pt_regs *regs) +static void __kprobes kprobe_handler(struct pt_regs *regs) { struct kprobe *p, *cur; struct kprobe_ctlblk *kcb; @@ -366,53 +366,11 @@ int __kprobes kprobe_exceptions_notify(struct notifie= r_block *self, } =20 /* - * When a retprobed function returns, trampoline_handler() is called, - * calling the kretprobe's handler. We construct a struct pt_regs to - * give a view of registers r0-r11, sp, lr, and pc to the user - * return-handler. This is not a complete pt_regs structure, but that - * should be enough for stacktrace from the return handler with or - * without pt_regs. + * Called from __kretprobe_trampoline in assembler. Forward declare to avo= id + * -Wmissing-prototypes. */ -void __naked __kprobes __kretprobe_trampoline(void) -{ - __asm__ __volatile__ ( -#ifdef CONFIG_FRAME_POINTER - "ldr lr, =3D__kretprobe_trampoline \n\t" - /* __kretprobe_trampoline makes a framepointer on pt_regs. */ -#ifdef CONFIG_CC_IS_CLANG - "stmdb sp, {sp, lr, pc} \n\t" - "sub sp, sp, #12 \n\t" - /* In clang case, pt_regs->ip =3D lr. */ - "stmdb sp!, {r0 - r11, lr} \n\t" - /* fp points regs->r11 (fp) */ - "add fp, sp, #44 \n\t" -#else /* !CONFIG_CC_IS_CLANG */ - /* In gcc case, pt_regs->ip =3D fp. */ - "stmdb sp, {fp, sp, lr, pc} \n\t" - "sub sp, sp, #16 \n\t" - "stmdb sp!, {r0 - r11} \n\t" - /* fp points regs->r15 (pc) */ - "add fp, sp, #60 \n\t" -#endif /* CONFIG_CC_IS_CLANG */ -#else /* !CONFIG_FRAME_POINTER */ - "sub sp, sp, #16 \n\t" - "stmdb sp!, {r0 - r11} \n\t" -#endif /* CONFIG_FRAME_POINTER */ - "mov r0, sp \n\t" - "bl trampoline_handler \n\t" - "mov lr, r0 \n\t" - "ldmia sp!, {r0 - r11} \n\t" - "add sp, sp, #16 \n\t" -#ifdef CONFIG_THUMB2_KERNEL - "bx lr \n\t" -#else - "mov pc, lr \n\t" -#endif - : : : "memory"); -} - -/* Called from __kretprobe_trampoline */ -static __used __kprobes void *trampoline_handler(struct pt_regs *regs) +void *trampoline_handler(struct pt_regs *regs); +__kprobes void *trampoline_handler(struct pt_regs *regs) { return (void *)kretprobe_trampoline_handler(regs, (void *)regs->ARM_fp); } @@ -420,6 +378,8 @@ static __used __kprobes void *trampoline_handler(struct= pt_regs *regs) void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs) { + extern void __kretprobe_trampoline(void); + ri->ret_addr =3D (kprobe_opcode_t *)regs->ARM_lr; ri->fp =3D (void *)regs->ARM_fp; =20 diff --git a/arch/arm/probes/kprobes/kretprobe-trampoline.S b/arch/arm/prob= es/kprobes/kretprobe-trampoline.S new file mode 100644 index 000000000000..261c99b8c17f --- /dev/null +++ b/arch/arm/probes/kprobes/kretprobe-trampoline.S @@ -0,0 +1,55 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#include +#include +#include + +/* + * When a retprobed function returns, trampoline_handler() is called, + * calling the kretprobe's handler. We construct a struct pt_regs to + * give a view of registers r0-r11, sp, lr, and pc to the user + * return-handler. This is not a complete pt_regs structure, but that + * should be enough for stacktrace from the return handler with or + * without pt_regs. + */ +__KPROBE +SYM_FUNC_START(__kretprobe_trampoline) +UNWIND(.fnstart) + ldr lr, =3D__kretprobe_trampoline +#ifdef CONFIG_FRAME_POINTER + /* __kretprobe_trampoline makes a framepointer on pt_regs. */ +#ifdef CONFIG_CC_IS_CLANG + stmdb sp, {sp, lr, pc} + sub sp, sp, #12 + /* In clang case, pt_regs->ip =3D lr. */ + stmdb sp!, {r0 - r11, lr} + /* fp points regs->r11 (fp) */ + add fp, sp, #44 +#else /* !CONFIG_CC_IS_CLANG */ + /* In gcc case, pt_regs->ip =3D fp. */ + stmdb sp, {fp, sp, lr, pc} + sub sp, sp, #16 + stmdb sp!, {r0 - r11} + /* fp points regs->r15 (pc) */ + add fp, sp, #60 +#endif /* CONFIG_CC_IS_CLANG */ +#else /* !CONFIG_FRAME_POINTER */ + /* store SP, LR on stack and add EABI unwind hint */ + stmdb sp, {sp, lr, pc} +UNWIND(.save {sp, lr, pc}) + sub sp, sp, #16 + stmdb sp!, {r0 - r11} +UNWIND(.pad #52) +#endif /* CONFIG_FRAME_POINTER */ + mov r0, sp + bl trampoline_handler + mov lr, r0 + ldmia sp!, {r0 - r11} + add sp, sp, #16 +#ifdef CONFIG_THUMB2_KERNEL + bx lr +#else + mov pc, lr +#endif +UNWIND(.fnend) +SYM_FUNC_END(__kretprobe_trampoline) diff --git a/include/asm-generic/kprobes.h b/include/asm-generic/kprobes.h index 060eab094e5a..1509daa281b8 100644 --- a/include/asm-generic/kprobes.h +++ b/include/asm-generic/kprobes.h @@ -2,7 +2,11 @@ #ifndef _ASM_GENERIC_KPROBES_H #define _ASM_GENERIC_KPROBES_H =20 -#if defined(__KERNEL__) && !defined(__ASSEMBLY__) +#ifdef __KERNEL__ + +#ifdef __ASSEMBLY__ +# define __KPROBE .section ".kprobes.text", "ax" +#else #ifdef CONFIG_KPROBES /* * Blacklist ganerating macro. Specify functions which is not probed @@ -16,11 +20,12 @@ static unsigned long __used \ /* Use this to forbid a kprobes attach on very low level functions */ # define __kprobes __section(".kprobes.text") # define nokprobe_inline __always_inline -#else +#else /* !defined(CONFIG_KPROBES) */ # define NOKPROBE_SYMBOL(fname) # define __kprobes # define nokprobe_inline inline -#endif -#endif /* defined(__KERNEL__) && !defined(__ASSEMBLY__) */ +#endif /* defined(CONFIG_KPROBES) */ +#endif /* defined(__ASSEMBLY__) */ +#endif /* defined(__KERNEL__) */ =20 #endif /* _ASM_GENERIC_KPROBES_H */ --=20 2.38.0.rc1.362.ged0d419d3c-goog