From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f43.google.com (mail-wm1-f43.google.com [209.85.128.43]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EBF45296BB3 for ; Thu, 25 Sep 2025 06:50:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.43 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758783030; cv=none; b=IAdu15HFCeuIoE3JRrdlEud8eFs8W4GVvyTD7mWX0kmfSOPIQUIK4XQDhdXXzKR4vQdo6a++TQZDvdNDXhK3brO4PEr5wv1It24USYTjHWLNR/gIECeGx4bFXLJKoWKdO93r81cTkSpTXM4m2sZr3hpQu0i5F3QBq3aYeZ96vrA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758783030; c=relaxed/simple; bh=Dt5KswCCqFPRf4u4rnxljQ70zWX66Ck+w414xBA7gCk=; h=From:Date:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Sd121WKEBic1X20wv/LGmFtU1K5jUI0DNJorsaiOfRfK3uK2Ktil+zaADTkRsVQ7Fqqtm7xM8xNQpBtuVVvXafIfuQ5BBv7N7cmH2CAD5plWpuDXgMOESc7UZa4F6o9zLCr4X1Afw/NDj2b86uvsR80Lbxv+zZpKD7KbZoTbAoI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=Ft5uzJdn; arc=none smtp.client-ip=209.85.128.43 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Ft5uzJdn" Received: by mail-wm1-f43.google.com with SMTP id 5b1f17b1804b1-46e1cc6299cso5064285e9.1 for ; Wed, 24 Sep 2025 23:50:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1758783027; x=1759387827; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:date:from:from:to:cc:subject:date:message-id:reply-to; bh=4A7uHFyGsqg+/5gcAVyLzJeZKPdXHFpebcPVRaYpAr0=; b=Ft5uzJdnIKRgS7AoCC/3Qf+9chNRN/xp2PBYMwZfrTVExAA0GeFO8bKG+FpNxQl4aF iFcBgwCiEfHe2m3Zgn43RTS/meY1z+YXLUQQ6tz9VHfZnHQZBk1ngsv8Hr+TjUsFAADn nMX3a7d3ssN2I1sZ8/c2LPpnnwpvlptKWt18PL+6nUG5htGDh/29cLF12WNO9rf9PAAI uaHzSArBNZvU51kOiJVrIBKdBh/yTTqlPihE32LNuqGoc0x2MHv1TT7XgUE/XMqBYhnx ieWTY5g8wwOn4es1XagDFbZnmdFVBH//Err4SKrcRXFZkyLY8XkX+foUK5TjsUX/Mq/M eeDA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1758783027; x=1759387827; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:date:from:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=4A7uHFyGsqg+/5gcAVyLzJeZKPdXHFpebcPVRaYpAr0=; b=Z2hbEIzqPp5XfCEQ18XjJxoTp5gVmMlLR38jWIxYJWvsZU84/X3YYUadAQvuYgu+J+ PwuOzQEibxiUGfBsaz9Mk73/3DK2uA1OefBjwtKiy0Tm6flU/ukZ7Rs9P2F2II2SouBC i5rdWZyF0PJDNV+qVWjFY5M6wE6W/xCDglwQMRCU8cYzLt/atAlnRE4RXFgiFQUvUYx0 VDv9uvztKaEa4OjFT16ZeHF75Ap7hrK5ppWtCT/cPI6cE5Bh/bNsSzLKicEgnVH0WeDJ 9eFEVmiW6f1imph8krR9kM7p5wnLh5DrZwy1Hf3QC+mmdytjl0Lfm/+jgSZ5jwLsMHZ0 SimQ== X-Forwarded-Encrypted: i=1; AJvYcCVefotg32wKcnP6hNVBnmC996Abk+w3hHvQLKYmtaP7ktH3/E0yERZRhyH+145jCVmUE22GWis/1tVBbe8+yRRXKV0=@vger.kernel.org X-Gm-Message-State: AOJu0Yxll+DdiXcr8BKpcZ7I4GWvUm4wGOKUxJGgpQU651rj4l3pb8fN S4BlzcwrZgfpxCV68Kz+XnBPTDmvaJYkFlSu3kgi0JyZKw9FJ1oBfGTt X-Gm-Gg: ASbGncsnn7Kr1K9qsrNO+YqsJuv5y24JMK5BJA8tReEOZNMoCU8f7vmUJIPFZ7wf8GN r2i5lwqO+EgPu44/ZO43/0R0qvCUtaQ+OJXEhPZBmc83QSdPE8hehpMtPJFPOMB6uF9/BEGX+5b OuuIsf5QeX3PcORr8ygnbQABJ4YOFMwEXUkYPYvQNxJSilsCwtD8Zad5v5WoGCbhk+EqWxLGdXG bNrgc1nLtxUPRXc6Pv1I+asn50hPnGvuxRh6/RidPklE4KXVA2P2981AQpoNDlb7AEfAb8hn3gw Jdq6JZYmlpv6w7Pg8vvzu5TJ4x26T+6NH1K7riAcCMJVLkLfzeWlCL97xuMnpKd38zdfz9AV X-Google-Smtp-Source: AGHT+IFDrBvdqgW3dfAsa53PUDyLwpuKBZY/PKiwkfqmYxUGGh4GPPrCN0aoqOBwEKILDjVmZ7uA8g== X-Received: by 2002:a05:600c:35ca:b0:458:a7b5:9f6c with SMTP id 5b1f17b1804b1-46e329ab712mr24367705e9.11.1758783026884; Wed, 24 Sep 2025 23:50:26 -0700 (PDT) Received: from krava ([2a02:8308:a00c:e200::31e0]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-46e33bf6ecbsm20412955e9.22.2025.09.24.23.50.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Sep 2025 23:50:26 -0700 (PDT) From: Jiri Olsa X-Google-Original-From: Jiri Olsa Date: Thu, 25 Sep 2025 08:50:24 +0200 To: Feng Yang Cc: rostedt@goodmis.org, mhiramat@kernel.org, mark.rutland@arm.com, catalin.marinas@arm.com, will@kernel.org, revest@chromium.org, alexei.starovoitov@gmail.com, olsajiri@gmail.com, andrii@kernel.org, ast@kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, bpf@vger.kernel.org Subject: Re: [PATCH] tracing: Fix the bug where bpf_get_stackid returns -EFAULT on the ARM64 Message-ID: References: <20250925020822.119302-1-yangfeng59949@163.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250925020822.119302-1-yangfeng59949@163.com> On Thu, Sep 25, 2025 at 10:08:22AM +0800, Feng Yang wrote: > From: Feng Yang > > When using bpf_program__attach_kprobe_multi_opts on ARM64 to hook a BPF program > that contains the bpf_get_stackid function, the BPF program fails > to obtain the stack trace and returns -EFAULT. > > This is because ftrace_partial_regs omits the configuration of the pstate register, > leaving pstate at the default value of 0. When get_perf_callchain executes, > it uses user_mode(regs) to determine whether it is in kernel mode. > This leads to a misjudgment that the code is in user mode, > so perf_callchain_kernel is not executed and the function returns directly. > As a result, trace->nr becomes 0, and finally -EFAULT is returned. > > Therefore, the assignment of the pstate register is added here. > > Fixes: b9b55c8912ce ("tracing: Add ftrace_partial_regs() for converting ftrace_regs to pt_regs") > Closes: https://lore.kernel.org/bpf/20250919071902.554223-1-yangfeng59949@163.com/ > Signed-off-by: Feng Yang Tested-by: Jiri Olsa thanks, jirka > --- > arch/arm64/include/asm/ftrace.h | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h > index bfe3ce9df197..ba7cf7fec5e9 100644 > --- a/arch/arm64/include/asm/ftrace.h > +++ b/arch/arm64/include/asm/ftrace.h > @@ -153,6 +153,7 @@ ftrace_partial_regs(const struct ftrace_regs *fregs, struct pt_regs *regs) > regs->pc = afregs->pc; > regs->regs[29] = afregs->fp; > regs->regs[30] = afregs->lr; > + regs->pstate = PSR_MODE_EL1h; > return regs; > } > > -- > 2.25.1 >