From nobody Sun Feb 8 09:27:10 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 7908AC87FDC for ; Fri, 9 Jun 2023 07:50:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239720AbjFIHtz (ORCPT ); Fri, 9 Jun 2023 03:49:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54984 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239118AbjFIHrq (ORCPT ); Fri, 9 Jun 2023 03:47:46 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 63A2C30C8; Fri, 9 Jun 2023 00:47:43 -0700 (PDT) Date: Fri, 09 Jun 2023 07:47:39 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1686296860; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=BVqi+HwSBu5+RBoe6c7hBNQEOzIi/+hzXFyc/TgfZsk=; b=T0KqIHNI96iAZ7E5n0vBVOTmf7XC/G7Nr9FyKYnGXYKS5h2emWqnu+ekfMkHiDyZeScsQd uoJW0Rj2zinpR4R+LKO3VxuCEKIOxgC6h5x8RbAQW85NAPrk53jGXJbZb05TjqdQm0hQJ4 mVtm/or9DZtUayqp4XsxzrOoI3pLGj8kSiEqg4cK5IYXIGTT3NCRTijkzN8VA40392grSP JhxCVkdl3QvdAlllXb8YxgNzSuSM5qBR8yPLqUTsDhkgTm9TJxOhFPp3Kl6eS4nUe6lEGW +4ahAIKjBMVHuchCoOY3KRjHGmJYw3qHh16YM56HAWf8vPqyhiqgY+154CbGRA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1686296860; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=BVqi+HwSBu5+RBoe6c7hBNQEOzIi/+hzXFyc/TgfZsk=; b=TDssK2RHim3KS6VrACiWIfzr5P5MkOZmdPcJjc25UzDbzPoZmR1QlSacPto87J6Qy1kfl9 kp9Tzy1wF2JbR+DQ== From: "tip-bot2 for Josh Poimboeuf" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: objtool/core] drm/vmwgfx: Add unwind hints around RBP clobber Cc: kernel test robot , Josh Poimboeuf , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <4c795f2d87bc0391cf6543bcb224fa540b55ce4b.1685981486.git.jpoimboe@kernel.org> References: <4c795f2d87bc0391cf6543bcb224fa540b55ce4b.1685981486.git.jpoimboe@kernel.org> MIME-Version: 1.0 Message-ID: <168629685987.404.14910646503772478220.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the objtool/core branch of tip: Commit-ID: a9da8247627eefc73f909bf945031a5431a53993 Gitweb: https://git.kernel.org/tip/a9da8247627eefc73f909bf945031a543= 1a53993 Author: Josh Poimboeuf AuthorDate: Mon, 05 Jun 2023 09:12:22 -07:00 Committer: Josh Poimboeuf CommitterDate: Wed, 07 Jun 2023 10:03:12 -07:00 drm/vmwgfx: Add unwind hints around RBP clobber VMware high-bandwidth hypercalls take the RBP register as input. This breaks basic frame pointer convention, as RBP should never be clobbered. So frame pointer unwinding is broken for the instructions surrounding the hypercalls. Fortunately this doesn't break live patching with CONFIG_FRAME_POINTER, as it only unwinds from blocking tasks, and stack traces from preempted tasks are already marked unreliable anyway. However, for live patching with ORC, this could actually be a theoretical problem if vmw_port_hb_{in,out}() were still compiled with a frame pointer due to having an aligned stack. In practice that hasn't seemed to be an issue since the objtool warnings have only been seen with CONFIG_FRAME_POINTER. Add unwind hint annotations to tell the ORC unwinder to mark stack traces as unreliable. Fixes the following warnings: vmlinux.o: warning: objtool: vmw_port_hb_in+0x1df: return with modified s= tack frame vmlinux.o: warning: objtool: vmw_port_hb_out+0x1dd: return with modified = stack frame Fixes: 89da76fde68d ("drm/vmwgfx: Add VMWare host messaging capability") Reported-by: kernel test robot Link: https://lore.kernel.org/oe-kbuild-all/202305160135.97q0Elax-lkp@intel= .com/ Link: https://lore.kernel.org/r/4c795f2d87bc0391cf6543bcb224fa540b55ce4b.16= 85981486.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf --- arch/x86/include/asm/unwind_hints.h | 9 +++++++++ drivers/gpu/drm/vmwgfx/vmwgfx_msg_x86.h | 16 ++++++++++++---- 2 files changed, 21 insertions(+), 4 deletions(-) diff --git a/arch/x86/include/asm/unwind_hints.h b/arch/x86/include/asm/unw= ind_hints.h index 01cb969..85cc57c 100644 --- a/arch/x86/include/asm/unwind_hints.h +++ b/arch/x86/include/asm/unwind_hints.h @@ -76,9 +76,18 @@ =20 #else =20 +#define UNWIND_HINT_UNDEFINED \ + UNWIND_HINT(UNWIND_HINT_TYPE_UNDEFINED, 0, 0, 0) + #define UNWIND_HINT_FUNC \ UNWIND_HINT(UNWIND_HINT_TYPE_FUNC, ORC_REG_SP, 8, 0) =20 +#define UNWIND_HINT_SAVE \ + UNWIND_HINT(UNWIND_HINT_TYPE_SAVE, 0, 0, 0) + +#define UNWIND_HINT_RESTORE \ + UNWIND_HINT(UNWIND_HINT_TYPE_RESTORE, 0, 0, 0) + #endif /* __ASSEMBLY__ */ =20 #endif /* _ASM_X86_UNWIND_HINTS_H */ diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_msg_x86.h b/drivers/gpu/drm/vmwg= fx/vmwgfx_msg_x86.h index 0b74ca2..23899d7 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_msg_x86.h +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_msg_x86.h @@ -105,10 +105,14 @@ flags, magic, bp, \ eax, ebx, ecx, edx, si, di) \ ({ \ - asm volatile ("push %%rbp;" \ + asm volatile ( \ + UNWIND_HINT_SAVE \ + "push %%rbp;" \ + UNWIND_HINT_UNDEFINED \ "mov %12, %%rbp;" \ VMWARE_HYPERCALL_HB_OUT \ - "pop %%rbp;" : \ + "pop %%rbp;" \ + UNWIND_HINT_RESTORE : \ "=3Da"(eax), \ "=3Db"(ebx), \ "=3Dc"(ecx), \ @@ -130,10 +134,14 @@ flags, magic, bp, \ eax, ebx, ecx, edx, si, di) \ ({ \ - asm volatile ("push %%rbp;" \ + asm volatile ( \ + UNWIND_HINT_SAVE \ + "push %%rbp;" \ + UNWIND_HINT_UNDEFINED \ "mov %12, %%rbp;" \ VMWARE_HYPERCALL_HB_IN \ - "pop %%rbp" : \ + "pop %%rbp;" \ + UNWIND_HINT_RESTORE : \ "=3Da"(eax), \ "=3Db"(ebx), \ "=3Dc"(ecx), \