From nobody Mon Oct 20 09:32:05 2025 Received: from mail-pg1-f169.google.com (mail-pg1-f169.google.com [209.85.215.169]) (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 DC538253F2B for ; Wed, 4 Jun 2025 17:16:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.169 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749057420; cv=none; b=Y/GeXI1xE+CDC76qjyrVkMJs3XEo6jUrSGx6A+c7Ta+14GSJeTT+N0jKowVSuwq4Dhnj8bJ/m6c6pqMikIYlGcJU2AUIyzq6eXH51TL4ThKiEZqM22IoC29KBg9d5Q397pSeJA027EeXLJF2cboa6s0k2sEFmhG+EYK1e+YSXb4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749057420; c=relaxed/simple; bh=MZX1nuc6r7AdZDyTz8TwYjYHi8teeiTBoLNNZOIRIYo=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=eGyYwK/zxAZ4zcMcTxOhliV/0RfuDBbeTFGKRDI06Zr/wAm60nwBRvWk+pybZ1SNhFm7Sdi6LuRgoBTw+d5IWDyWqPFNUtMQP/BnWBkdifTeoaRyoN+uTJeXfftLORUyjSNHYaIgbGRWFxZYy9S9C/DKm1g4EoFdvZPDvMFeVro= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=rivosinc.com; spf=pass smtp.mailfrom=rivosinc.com; dkim=pass (2048-bit key) header.d=rivosinc-com.20230601.gappssmtp.com header.i=@rivosinc-com.20230601.gappssmtp.com header.b=qJ+oLvgV; arc=none smtp.client-ip=209.85.215.169 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=rivosinc.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=rivosinc.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=rivosinc-com.20230601.gappssmtp.com header.i=@rivosinc-com.20230601.gappssmtp.com header.b="qJ+oLvgV" Received: by mail-pg1-f169.google.com with SMTP id 41be03b00d2f7-b26d7ddbfd7so51170a12.0 for ; Wed, 04 Jun 2025 10:16:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rivosinc-com.20230601.gappssmtp.com; s=20230601; t=1749057417; x=1749662217; darn=vger.kernel.org; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:from:to:cc:subject:date:message-id :reply-to; bh=4/f0L0aM2im1hNI4FqeJBncnA+adhlVAx9+n6QIigJg=; b=qJ+oLvgVCSv5wVvFBdmoL33F2iBizPRw0DYq1ENMTRnMf6lVxX97KODCPSps0pLD61 +qpntjuQJOB/IYGTNnahXvKYFSbDxVzlHYCv8ASEx6dfasTkDe8ZTauruUwJcx7jSun4 WsguMBoIsL/1fUMfm63NJCOpkTan+uaTiNaqsmFpL0c+hm2su2fvKFe0+O60tkKsZF5j baQxmnq4IXAYR46VgQ/1QCw/tvHzWyQPO6iFuIv8CqdYiDQylWju0GxzWT4pmIb4XJai dwd+aSdxoRMjuIeM1D/J8A+sFvpTQS9utAyplI342knEGtJbLgWimlsz2VddzpS8fkYf kc0g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1749057417; x=1749662217; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=4/f0L0aM2im1hNI4FqeJBncnA+adhlVAx9+n6QIigJg=; b=BqIBfxlpfEPrOg+ctUf3amN3+/PfwFn2FuX2b7zha+1FgeXt/91JwDjX0UuyxtWkQb ULO/2xW9WS4iPpZmO/aYnP4Iu/zZ1BPgjvAVVJl5IBHH2tmGCp87mL/IHxK4ydCwk0dJ owVgCPUUrHsKZxV17nV0p0SJ7Zkmw8OmhVLoTHvCWd4cUO47MDv4hdOyB5htgnqjRa8n 3D1VvIiakb7bnvKD7aV3GtGV2PNtePV/W11IJnxxhZ5Dwjp3XGoMSNdHHYIgC6GrhGaJ vjqCsdHqmKVf5k+ehlNTMJn9XPCjr/f384z+vBOImJkKNjLOCcVK6EK6UTJOkzW/EPT/ 8jZA== X-Gm-Message-State: AOJu0YxUxuGAwvnBE0JfTbfHuWetMh9RTAiBiX7i/NSqXEwaNuZM6Zuu rd807RlW9j9mZzO1Yfi9hc1VR7jXo3IGwqe+5+on9Pw0lTqRaPkwVYGqWHK+fWnWP4g= X-Gm-Gg: ASbGncue2B6DSkub+EWtlepiA0tR9L5Ffa2nKHBp/WnJmVUsVlYFM9LLWA7Afr8WIVu p05Tk0t5dg9BKsQ2ScsGrlM3RuK2nQgTGusfn8San192TTNEEIur5PHI1E7udZ/eg1LLHpRk92i EwGXSedlLWvK91wcGWSAqpF5nDZ4nPuBiqpixhs4nSTzmqicz3Mr2CQFo9o/INrhYQVHG2vDZLC BddXhFwKrYvAcPcIlkeo1jAN/Y4kZ8uxS9XYMAYbdbwMgVNNUGxFFJbF4B9N4gBZDeTYzYcS37I iEZKVdN+gypjHka0Feu5BNvi8S9hSIvlz1MUfPXIjc516m3J8qWRACPZftIc9YrSuZF4xHA3hE/ hfkVnRkI= X-Google-Smtp-Source: AGHT+IGUQ+606zAFEeN3EdNg/32lSEpOR8pjT3Wpzkm+BItxN7Z6b3x4NPSTnjln/92NqMxTfmUeAQ== X-Received: by 2002:a17:90b:4fca:b0:311:abba:53d2 with SMTP id 98e67ed59e1d1-3130cd96febmr6564673a91.17.1749057416742; Wed, 04 Jun 2025 10:16:56 -0700 (PDT) Received: from debug.ba.rivosinc.com ([64.71.180.162]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3124e2e9c9fsm9178972a91.30.2025.06.04.10.16.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Jun 2025 10:16:56 -0700 (PDT) From: Deepak Gupta Date: Wed, 04 Jun 2025 10:15:38 -0700 Subject: [PATCH v17 14/27] riscv: Implements arch agnostic indirect branch tracking prctls 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="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20250604-v5_user_cfi_series-v17-14-4565c2cf869f@rivosinc.com> References: <20250604-v5_user_cfi_series-v17-0-4565c2cf869f@rivosinc.com> In-Reply-To: <20250604-v5_user_cfi_series-v17-0-4565c2cf869f@rivosinc.com> To: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Andrew Morton , "Liam R. Howlett" , Vlastimil Babka , Lorenzo Stoakes , Paul Walmsley , Palmer Dabbelt , Albert Ou , Conor Dooley , Rob Herring , Krzysztof Kozlowski , Arnd Bergmann , Christian Brauner , Peter Zijlstra , Oleg Nesterov , Eric Biederman , Kees Cook , Jonathan Corbet , Shuah Khan , Jann Horn , Conor Dooley , Miguel Ojeda , Alex Gaynor , Boqun Feng , Gary Guo , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-riscv@lists.infradead.org, devicetree@vger.kernel.org, linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, alistair.francis@wdc.com, richard.henderson@linaro.org, jim.shu@sifive.com, andybnac@gmail.com, kito.cheng@sifive.com, charlie@rivosinc.com, atishp@rivosinc.com, evan@rivosinc.com, cleger@rivosinc.com, alexghiti@rivosinc.com, samitolvanen@google.com, broonie@kernel.org, rick.p.edgecombe@intel.com, rust-for-linux@vger.kernel.org, Zong Li , Deepak Gupta X-Mailer: b4 0.13.0 prctls implemented are: PR_SET_INDIR_BR_LP_STATUS, PR_GET_INDIR_BR_LP_STATUS and PR_LOCK_INDIR_BR_LP_STATUS Reviewed-by: Zong Li Signed-off-by: Deepak Gupta --- arch/riscv/include/asm/usercfi.h | 14 +++++++ arch/riscv/kernel/entry.S | 2 +- arch/riscv/kernel/process.c | 5 +++ arch/riscv/kernel/usercfi.c | 79 ++++++++++++++++++++++++++++++++++++= ++++ 4 files changed, 99 insertions(+), 1 deletion(-) diff --git a/arch/riscv/include/asm/usercfi.h b/arch/riscv/include/asm/user= cfi.h index f747ad469c7c..98820d93c6e1 100644 --- a/arch/riscv/include/asm/usercfi.h +++ b/arch/riscv/include/asm/usercfi.h @@ -16,6 +16,8 @@ struct kernel_clone_args; struct cfi_state { unsigned long ubcfi_en : 1; /* Enable for backward cfi. */ unsigned long ubcfi_locked : 1; + unsigned long ufcfi_en : 1; /* Enable for forward cfi. Note that ELP goes= in sstatus */ + unsigned long ufcfi_locked : 1; unsigned long user_shdw_stk; /* Current user shadow stack pointer */ unsigned long shdw_stk_base; /* Base address of shadow stack */ unsigned long shdw_stk_size; /* size of shadow stack */ @@ -32,6 +34,10 @@ bool is_shstk_locked(struct task_struct *task); bool is_shstk_allocated(struct task_struct *task); void set_shstk_lock(struct task_struct *task); void set_shstk_status(struct task_struct *task, bool enable); +bool is_indir_lp_enabled(struct task_struct *task); +bool is_indir_lp_locked(struct task_struct *task); +void set_indir_lp_status(struct task_struct *task, bool enable); +void set_indir_lp_lock(struct task_struct *task); =20 #define PR_SHADOW_STACK_SUPPORTED_STATUS_MASK (PR_SHADOW_STACK_ENABLE) =20 @@ -57,6 +63,14 @@ void set_shstk_status(struct task_struct *task, bool ena= ble); =20 #define set_shstk_status(task, enable) do {} while (0) =20 +#define is_indir_lp_enabled(task) false + +#define is_indir_lp_locked(task) false + +#define set_indir_lp_status(task, enable) do {} while (0) + +#define set_indir_lp_lock(task) do {} while (0) + #endif /* CONFIG_RISCV_USER_CFI */ =20 #endif /* __ASSEMBLY__ */ diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S index c4bfe2085c41..978115567bca 100644 --- a/arch/riscv/kernel/entry.S +++ b/arch/riscv/kernel/entry.S @@ -169,7 +169,7 @@ SYM_CODE_START(handle_exception) * Disable the FPU/Vector to detect illegal usage of floating point * or vector in kernel space. */ - li t0, SR_SUM | SR_FS_VS + li t0, SR_SUM | SR_FS_VS | SR_ELP =20 REG_L s0, TASK_TI_USER_SP(tp) csrrc s1, CSR_STATUS, t0 diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c index 3099fadb0397..2caddcd62848 100644 --- a/arch/riscv/kernel/process.c +++ b/arch/riscv/kernel/process.c @@ -160,6 +160,11 @@ void start_thread(struct pt_regs *regs, unsigned long = pc, set_shstk_status(current, false); set_shstk_base(current, 0, 0); set_active_shstk(current, 0); + /* + * disable indirect branch tracking on exec. + * libc will enable it later via prctl. + */ + set_indir_lp_status(current, false); =20 #ifdef CONFIG_64BIT regs->status &=3D ~SR_UXL; diff --git a/arch/riscv/kernel/usercfi.c b/arch/riscv/kernel/usercfi.c index 08620bdae696..2ebe789caa6b 100644 --- a/arch/riscv/kernel/usercfi.c +++ b/arch/riscv/kernel/usercfi.c @@ -72,6 +72,35 @@ void set_shstk_lock(struct task_struct *task) task->thread_info.user_cfi_state.ubcfi_locked =3D 1; } =20 +bool is_indir_lp_enabled(struct task_struct *task) +{ + return task->thread_info.user_cfi_state.ufcfi_en; +} + +bool is_indir_lp_locked(struct task_struct *task) +{ + return task->thread_info.user_cfi_state.ufcfi_locked; +} + +void set_indir_lp_status(struct task_struct *task, bool enable) +{ + if (!cpu_supports_indirect_br_lp_instr()) + return; + + task->thread_info.user_cfi_state.ufcfi_en =3D enable ? 1 : 0; + + if (enable) + task->thread.envcfg |=3D ENVCFG_LPE; + else + task->thread.envcfg &=3D ~ENVCFG_LPE; + + csr_write(CSR_ENVCFG, task->thread.envcfg); +} + +void set_indir_lp_lock(struct task_struct *task) +{ + task->thread_info.user_cfi_state.ufcfi_locked =3D 1; +} /* * If size is 0, then to be compatible with regular stack we want it to be= as big as * regular stack. Else PAGE_ALIGN it and return back @@ -371,3 +400,53 @@ int arch_lock_shadow_stack_status(struct task_struct *= task, =20 return 0; } + +int arch_get_indir_br_lp_status(struct task_struct *t, unsigned long __use= r *status) +{ + unsigned long fcfi_status =3D 0; + + if (!cpu_supports_indirect_br_lp_instr()) + return -EINVAL; + + /* indirect branch tracking is enabled on the task or not */ + fcfi_status |=3D (is_indir_lp_enabled(t) ? PR_INDIR_BR_LP_ENABLE : 0); + + return copy_to_user(status, &fcfi_status, sizeof(fcfi_status)) ? -EFAULT = : 0; +} + +int arch_set_indir_br_lp_status(struct task_struct *t, unsigned long statu= s) +{ + bool enable_indir_lp =3D false; + + if (!cpu_supports_indirect_br_lp_instr()) + return -EINVAL; + + /* indirect branch tracking is locked and further can't be modified by us= er */ + if (is_indir_lp_locked(t)) + return -EINVAL; + + /* Reject unknown flags */ + if (status & ~PR_INDIR_BR_LP_ENABLE) + return -EINVAL; + + enable_indir_lp =3D (status & PR_INDIR_BR_LP_ENABLE); + set_indir_lp_status(t, enable_indir_lp); + + return 0; +} + +int arch_lock_indir_br_lp_status(struct task_struct *task, + unsigned long arg) +{ + /* + * If indirect branch tracking is not supported or not enabled on task, + * nothing to lock here + */ + if (!cpu_supports_indirect_br_lp_instr() || + !is_indir_lp_enabled(task) || arg !=3D 0) + return -EINVAL; + + set_indir_lp_lock(task); + + return 0; +} --=20 2.43.0