From nobody Mon Apr 6 11:53:05 2026 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 C26B4C07E9D for ; Mon, 26 Sep 2022 18:38:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230435AbiIZSin (ORCPT ); Mon, 26 Sep 2022 14:38:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46856 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230209AbiIZShx (ORCPT ); Mon, 26 Sep 2022 14:37:53 -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 919096DACB for ; Mon, 26 Sep 2022 11:37:50 -0700 (PDT) Received: by mail-yw1-x1149.google.com with SMTP id 00721157ae682-33dc888dc62so69852967b3.4 for ; Mon, 26 Sep 2022 11:37:50 -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=znhGVGmm6TLIt/hCvZyRbrWMCYyq9RR6vI5Xw2wMKC4=; b=d68/aWCLPiIhe6kggZL49/Bh7V4/p14HgIMbRCvVM2NXYFgGVn+Xq9brpRwfNhGn1c bzJwZSeSD28a7Y9C2q6pU7Ns5YVEFTZe/NUDWalKdLmiDD2Ycu38MkayfNaqystb+Yqe 2uitdjgk1pKgDrhsqNj5Zi+us9bovm9f4gWEJiOjaim9mYiKX/XM3sYD5w/R4o2mb4mZ CFQt2YiJ+JQ5f5ciYi+1HTq4fleAv03ZClh98oFN7wKat0tgF+afcbUELEguex2NqQsj ebHSIrxp17+FxDtmN9isOGdXvSr28CY+GxWqR7nRTLSnzGkZucq1jvCcRo3Cov2rfSOI 8Xfw== 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=znhGVGmm6TLIt/hCvZyRbrWMCYyq9RR6vI5Xw2wMKC4=; b=HTl6CGs2whbwDxwtroLNSTwwhpYtAUVBag+SxPYC8EnyF1c0UMkLZOQEMdQhkai5Rr 0eTcPyhdwdGY9co+PttaU6uTlr+uqlprkNpitk8wnlAh+8xcsUU4zNswxFvF7fobRNll KfnsoZp/FJW4wsIHJiyNP94cM3bKgs6jTKrGU4K8EO1XlnrHYFcUiEHw+q4k8Niffdi9 VAqUwRQto56rk1UQCmdPw3p7vj6DeZaEj4CumdZSQ8HTGZ2dsYI9Lhp0bQ/ZYSwY3xR9 E/reLmtdEVyqQs0oHAL/aX3DDLeVg+cTJf1iDis5ruIKqRF3mLWbPgr+Sq8eaZ7VoUJ3 aY3A== X-Gm-Message-State: ACrzQf1zlTdma9rIzT8Zam113QTiVLKDHEByCItTYQe0aXiyM5bAT3HV 1a1/sSjv3HVTUozJRqzQPYpcjCSSLDAHIVj5yio= X-Google-Smtp-Source: AMsMyM4bDMVt1tdnaBnUxux6UCle3vtahK9wHgCGdwWVS1dv1pQjCOyBISO8bmwfU2AlX2gfDPcGjZtYrAVWpRrRAUc= X-Received: from ndesaulniers-desktop.svl.corp.google.com ([2620:0:100e:712:8fb4:fe0d:d74c:5bcb]) (user=ndesaulniers job=sendgmr) by 2002:a25:f628:0:b0:6bc:bb6:aec5 with SMTP id t40-20020a25f628000000b006bc0bb6aec5mr929868ybd.139.1664217469129; Mon, 26 Sep 2022 11:37:49 -0700 (PDT) Date: Mon, 26 Sep 2022 11:37:25 -0700 In-Reply-To: Mime-Version: 1.0 References: X-Developer-Key: i=ndesaulniers@google.com; a=ed25519; pk=UIrHvErwpgNbhCkRZAYSX0CFd/XFEwqX3D0xqtqjNug= X-Developer-Signature: v=1; a=ed25519-sha256; t=1664217445; l=7895; i=ndesaulniers@google.com; s=20220923; h=from:subject; bh=x0RwTwO74GUfeRgTrJP+F6BnwHVqyXRlkCvRcvW1NlM=; b=aATOabxLSS9znVNtm6L5GIkLiNWqOo9CDSaqmGgfeElYHBzA7DRPuBx916vBrYh+uPU8ccbHNwUy 5wYW/6BNB3vDlr9XOrgMb7SvlKfMG6oNcMPwlge2WJWmJuq1ioxM X-Mailer: git-send-email 2.37.3.998.g577e59143f-goog Message-ID: <20220926183725.1112298-1-ndesaulniers@google.com> Subject: [PATCH] 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. 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 Acked-by: Ard Biesheuvel --- Note: I wasn't quite sure if a Fixes tag against 1069c1dd20a3 was appropriate here? Either way, if 1069c1dd20a3 gets picked up for stable without this, it will break clang builds. 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, 69 insertions(+), 54 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 1435b508aa36..17d7e0259e63 100644 --- a/arch/arm/probes/kprobes/core.c +++ b/arch/arm/probes/kprobes/core.c @@ -375,58 +375,10 @@ int __kprobes kprobe_exceptions_notify(struct notifie= r_block *self, return NOTIFY_DONE; } =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. - */ -void __naked __kprobes __kretprobe_trampoline(void) -{ - __asm__ __volatile__ ( - "ldr lr, =3D__kretprobe_trampoline \n\t" -#ifdef CONFIG_FRAME_POINTER - /* __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 */ - /* store SP, LR on stack and add EABI unwind hint */ - "stmdb sp, {sp, lr, pc} \n\t" - ".save {sp, lr, pc} \n\t" - "sub sp, sp, #16 \n\t" - "stmdb sp!, {r0 - r11} \n\t" - ".pad #52 \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"); -} +/*void __kretprobe_trampoline(void);*/ =20 /* Called from __kretprobe_trampoline */ -static __used __kprobes void *trampoline_handler(struct pt_regs *regs) +__kprobes void *trampoline_handler(struct pt_regs *regs) { return (void *)kretprobe_trampoline_handler(regs, (void *)regs->TRAMP_FP); } @@ -434,6 +386,8 @@ 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->TRAMP_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 2.37.3.998.g577e59143f-goog