From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A35B52F691D for ; Thu, 25 Jun 2026 18:03:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782410631; cv=none; b=rg0w6gkOC5S5bHrtAWfU/p40nt4mXNxbcGvcWhbjjE8GP/fuo7ZOWJW93dmCwyclAj+fQaegcnS3iB0bKqS70s+k7dDlTriT2Ye4UghMGcMVOIxLdfqzfWNxa7yG6BGdjTw1NVpwU6+HMZVN2QGHQTF5DcrqEBhBlNNxQDC9vEg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782410631; c=relaxed/simple; bh=G0ln5qW2gREdhLQo2lNTNOweKGI8B30MYoFCS1mKv2Y=; h=Date:From:To:cc:Subject:In-Reply-To:Message-ID:References: MIME-Version:Content-Type; b=lq63MMZDjHIEnCXWqduyyqMS87C7Msl9y9maxxdaksIe7DPVjbzqG0mo7jXwuJ+UwzB0v0lM+ZWO57GY4kgg5s1yz1a6toRCxcNuORUtYqH33JVIUQbZMAuvfPK9VzK0UcmhQurlRNP4Wa5zN4AbCI3HA48JHkV17nRRor/9y7o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=JGbPKCCC; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="JGbPKCCC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 87B741F000E9; Thu, 25 Jun 2026 18:03:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782410630; bh=ldT3ZutHnlLTCWaVkRW0eAVXtxjtKLGOznBPZGps30o=; h=Date:From:To:cc:Subject:In-Reply-To:References; b=JGbPKCCCqs05F2yhEokShHu5Uk9KOg2AgyMzKJ50zPSXbU3iBE3O2EzUTF1PS+Oum zC4IDaaDyksVxH0CfD2xyNnjvI6sjPC6MKMcAuISQJNEqcWZdxuvsJk/s8Pk3rDPlE arkMirEAW/kQ9Gm4qHfD6Sx42m+LhaJiB9CqA6E3s6kgPVLlYqIXeEke1FwvtcRz7D 5uwnsSQ8B5lJcKxhDeiOM6WJEryN6r3DO9tj3pxOpRrHXUjmYcHj/sRjajrOV+f2SI /YxHcCi5UxCDtqhT0v7U2kuVReUcmNJUTrI4ttebz51VzB2ciYKseJ3rjZZlMBZLqI kB1HE7xwtK6bg== Date: Thu, 25 Jun 2026 12:03:48 -0600 (MDT) From: Paul Walmsley To: Joel Stanley cc: Aurelien Jarno , linux-kernel@vger.kernel.org, Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Jim Shu , Zong Li , Deepak Gupta , "open list:RISC-V ARCHITECTURE" Subject: Re: [PATCH] arch/riscv: vdso: remove CFI landing pad from rt_sigreturn In-Reply-To: <20260623204058.498120-1-aurelien@aurel32.net> Message-ID: References: <20260623204058.498120-1-aurelien@aurel32.net> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Hi Joel, On Tue, 23 Jun 2026, Aurelien Jarno wrote: > When CONFIG_RISCV_USER_CFI is enabled, the CFI version of the vDSO, has > a CFI landing pad instruction at the start of __vdso_rt_sigreturn. This > breaks libgcc's unwinding code which matches on the first two > instructions. Other unwinders that rely on similar instruction matching > may also be affected. > > Since __vdso_rt_sigreturn is reached as part of signal-return handling > rather than via an indirect call/jump from userspace, it does not need a > CFI landing pad. Remove it and restore the instruction sequence expected > by existing unwinding code. > > This matches what was done on arm64 in commit 9a964285572b ("arm64: > vdso: Don't prefix sigreturn trampoline with a BTI C instruction") for a > similar issue. > > Fixes: 37f57bd3faea ("arch/riscv: compile vdso with landing pad and shadow stack note") > Co-authored-by: Joel Stanley > Signed-off-by: Aurelien Jarno I'd like to take this one. But since you're listed as the co-author, I probably need your Signed-off-by: as well. Care to reply with it? thanks - Paul