From patchwork Fri May 2 23:30:44 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Deepak Gupta X-Patchwork-Id: 886756 Received: from mail-pl1-f173.google.com (mail-pl1-f173.google.com [209.85.214.173]) (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 9D5D8265CD8 for ; Fri, 2 May 2025 23:31:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.173 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746228682; cv=none; b=mgVVHK06PUefFw/LhW4C3tcgGOdHPYkDf2IJwHpjkRo4GZcEKpXsHjJo/mlOwA67T4kmgz1I4V5T9+sEXbnf/UugQO+0lMxOEpJPieQsK/bKViDdRGyzatfCiQYSbGPHSmHWdebvYBQc8P/leLtrPea1wZRHB2WESUAA+U2NnZg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746228682; c=relaxed/simple; bh=4V/vc+IGuEXLJLSMGAlz1mzVikhLjzrFyJ0kt0SiHdA=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=JaGlqrH5A274/foBVVSxY2DzcgG+gRU/+HAc1f4jb/P5y/00fhEK8QbYWES4lMXSM6bUJCcEkuhhmIVqyEMUBDJb3TfUybLJ6Xr4uE11QhYd+GSegHpXJIe8tlwITIQnwPCCeuvArdBl3I7qzRf2R1p5/C1dg80aN6wwxYtgIP4= 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=P5Fx++I5; arc=none smtp.client-ip=209.85.214.173 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="P5Fx++I5" Received: by mail-pl1-f173.google.com with SMTP id d9443c01a7336-2279915e06eso29956385ad.1 for ; Fri, 02 May 2025 16:31:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rivosinc-com.20230601.gappssmtp.com; s=20230601; t=1746228680; x=1746833480; 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=Wqa+EnEmqD/WcxsFXdACBzGsJGhuUJWdKCVGNJwyc08=; b=P5Fx++I5O+rt2LLIE2EX/1N5BUD5SGdRaT2kYYh+GsrsrHGpDhrCvOrDzy5Mnl2Rgu dlR8YEzCqJ2VdVVjfO1l40mqBh32Tuv0uNC0HqAvuNNf9kZuTsCtuzrwaSNpgjHS0a8U mFrLOK/+HezTYMjr122FvTAQqzTTxKDyVgcrB3M2v7NGVHevAlnS8wyaotooBg1cSnaO s+yiypyXXfs/m3pUbdKbEvwEyDVjDPjkhGGacyK2MBgPnRCE5FKazi3o+WNFQzFlgryk crAZBSSnyW5CFfjE+KXz8Z+xsC8SZ6+lX7m/ME3D3HifiKUbNQiozI39Au01/IB0z020 g6pg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1746228680; x=1746833480; 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=Wqa+EnEmqD/WcxsFXdACBzGsJGhuUJWdKCVGNJwyc08=; b=oaSLDcZwbK2oT/ypCU7zQR6DGJiVutK7HVRMx9c3vMKf3AEYGYm3vBjSsmUydmXfV9 FBKtSd8F5P3MYfcwg5PHBwDYMjoR9Q0KMiCadQLt3Ib3NoX9QtBv1C5vE2JW/wBHfTRj 3o3vfLiCC9xw7OjHajFgXoD4Obe1CGLhyOlLlQ6lbI0r5J7tUx3mT8yUCp6X76rxp1vO /4+a0vFfo7BlOBFzbCh8qkIE2XG/b39j9Yy7dQmHVkiXsYmOlflgPtEGTWQAdIvF9up+ bpxSFVqT50MaDOm8VOOEZRgf+0SKURTSJdkVyUNv1kMp5VLFJ//vD9F2pJoxcRYLVMG+ vEWA== X-Forwarded-Encrypted: i=1; AJvYcCXB/6qlcHXTmRD3GB5VMG7mZ7R4ShIeispd7cCu9Eokw+QNcvMeuOK9+oCMtzK79Og6qkmnZWHLJ4lHSjHoeDM=@vger.kernel.org X-Gm-Message-State: AOJu0Yx3a0yryH2aiCQVQC0DAHwD/OR81ZpdKGp4Z7sJ56ofodHs6/tW NltlodFJEsF63ix3LjAxBLvu+TJwPET9poMvYZNgMDwVJkhWRFumMDxNy+cYZVY= X-Gm-Gg: ASbGncv+zWgH5bG0QQB2lK6QIc7y7iuBm8w4PGfxuKPIwQpqNwZDLULjLX9BOKMexBX jm7DP6fapg6vgteKQzPHBuwC5TkT8zLRt+aZKPpG7xGE9qxiXEMsvJsK3EC5o74ztanR67B1CYK NhC1jH01WApNJtbIz4e9zp1emOpg83IshXNEG/rT0YoWJpiHQt207uwkU4fFrljQe3vH/F9t+DE T7svY6jIVmvhHVj6AqUOi9PHfyN/6XX6sqV+DBHZxrBminbvarxXzbuqWE/gAYdAQmuT/2NV3tl HGMQtEJCdhS75K4tjroqmfn8dDR2YhDMEJbFiGPJPbaihoZbZk4= X-Google-Smtp-Source: AGHT+IHvXL5pWhrUbiSVOochGhIxFNup+4MO6YwBLUVqWrs7X/12jWeixSydoIhUkoMUZk+BhO60Fg== X-Received: by 2002:a17:903:1a6b:b0:21f:61a9:be7d with SMTP id d9443c01a7336-22e103ecbd7mr73331515ad.49.1746228679984; Fri, 02 May 2025 16:31:19 -0700 (PDT) Received: from debug.ba.rivosinc.com ([64.71.180.162]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-22e15228ff2sm13367055ad.180.2025.05.02.16.31.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 02 May 2025 16:31:19 -0700 (PDT) From: Deepak Gupta Date: Fri, 02 May 2025 16:30:44 -0700 Subject: [PATCH v15 13/27] prctl: arch-agnostic prctl for indirect branch tracking Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20250502-v5_user_cfi_series-v15-13-914966471885@rivosinc.com> References: <20250502-v5_user_cfi_series-v15-0-914966471885@rivosinc.com> In-Reply-To: <20250502-v5_user_cfi_series-v15-0-914966471885@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 Three architectures (x86, aarch64, riscv) have support for indirect branch tracking feature in a very similar fashion. On a very high level, indirect branch tracking is a CPU feature where CPU tracks branches which uses memory operand to perform control transfer in program. As part of this tracking on indirect branches, CPU goes in a state where it expects a landing pad instr on target and if not found then CPU raises some fault (architecture dependent) x86 landing pad instr - `ENDBRANCH` arch64 landing pad instr - `BTI` riscv landing instr - `lpad` Given that three major arches have support for indirect branch tracking, This patch makes `prctl` for indirect branch tracking arch agnostic. To allow userspace to enable this feature for itself, following prtcls are defined: - PR_GET_INDIR_BR_LP_STATUS: Gets current configured status for indirect branch tracking. - PR_SET_INDIR_BR_LP_STATUS: Sets a configuration for indirect branch tracking. Following status options are allowed - PR_INDIR_BR_LP_ENABLE: Enables indirect branch tracking on user thread. - PR_INDIR_BR_LP_DISABLE; Disables indirect branch tracking on user thread. - PR_LOCK_INDIR_BR_LP_STATUS: Locks configured status for indirect branch tracking for user thread. Reviewed-by: Mark Brown Reviewed-by: Zong Li Signed-off-by: Deepak Gupta --- include/linux/cpu.h | 4 ++++ include/uapi/linux/prctl.h | 27 +++++++++++++++++++++++++++ kernel/sys.c | 30 ++++++++++++++++++++++++++++++ 3 files changed, 61 insertions(+) diff --git a/include/linux/cpu.h b/include/linux/cpu.h index e3049543008b..ea8b351b5bc5 100644 --- a/include/linux/cpu.h +++ b/include/linux/cpu.h @@ -204,4 +204,8 @@ static inline bool cpu_mitigations_auto_nosmt(void) } #endif +int arch_get_indir_br_lp_status(struct task_struct *t, unsigned long __user *status); +int arch_set_indir_br_lp_status(struct task_struct *t, unsigned long status); +int arch_lock_indir_br_lp_status(struct task_struct *t, unsigned long status); + #endif /* _LINUX_CPU_H_ */ diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h index 15c18ef4eb11..2e09b19317a3 100644 --- a/include/uapi/linux/prctl.h +++ b/include/uapi/linux/prctl.h @@ -364,4 +364,31 @@ struct prctl_mm_map { # define PR_TIMER_CREATE_RESTORE_IDS_ON 1 # define PR_TIMER_CREATE_RESTORE_IDS_GET 2 +/* + * Get the current indirect branch tracking configuration for the current + * thread, this will be the value configured via PR_SET_INDIR_BR_LP_STATUS. + */ +#define PR_GET_INDIR_BR_LP_STATUS 78 + +/* + * Set the indirect branch tracking configuration. PR_INDIR_BR_LP_ENABLE will + * enable cpu feature for user thread, to track all indirect branches and ensure + * they land on arch defined landing pad instruction. + * x86 - If enabled, an indirect branch must land on `ENDBRANCH` instruction. + * arch64 - If enabled, an indirect branch must land on `BTI` instruction. + * riscv - If enabled, an indirect branch must land on `lpad` instruction. + * PR_INDIR_BR_LP_DISABLE will disable feature for user thread and indirect + * branches will no more be tracked by cpu to land on arch defined landing pad + * instruction. + */ +#define PR_SET_INDIR_BR_LP_STATUS 79 +# define PR_INDIR_BR_LP_ENABLE (1UL << 0) + +/* + * Prevent further changes to the specified indirect branch tracking + * configuration. All bits may be locked via this call, including + * undefined bits. + */ +#define PR_LOCK_INDIR_BR_LP_STATUS 80 + #endif /* _LINUX_PRCTL_H */ diff --git a/kernel/sys.c b/kernel/sys.c index c434968e9f5d..91a1dc093c2a 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -2340,6 +2340,21 @@ int __weak arch_lock_shadow_stack_status(struct task_struct *t, unsigned long st return -EINVAL; } +int __weak arch_get_indir_br_lp_status(struct task_struct *t, unsigned long __user *status) +{ + return -EINVAL; +} + +int __weak arch_set_indir_br_lp_status(struct task_struct *t, unsigned long status) +{ + return -EINVAL; +} + +int __weak arch_lock_indir_br_lp_status(struct task_struct *t, unsigned long status) +{ + return -EINVAL; +} + #define PR_IO_FLUSHER (PF_MEMALLOC_NOIO | PF_LOCAL_THROTTLE) #ifdef CONFIG_ANON_VMA_NAME @@ -2820,6 +2835,21 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3, return -EINVAL; error = posixtimer_create_prctl(arg2); break; + case PR_GET_INDIR_BR_LP_STATUS: + if (arg3 || arg4 || arg5) + return -EINVAL; + error = arch_get_indir_br_lp_status(me, (unsigned long __user *)arg2); + break; + case PR_SET_INDIR_BR_LP_STATUS: + if (arg3 || arg4 || arg5) + return -EINVAL; + error = arch_set_indir_br_lp_status(me, arg2); + break; + case PR_LOCK_INDIR_BR_LP_STATUS: + if (arg3 || arg4 || arg5) + return -EINVAL; + error = arch_lock_indir_br_lp_status(me, arg2); + break; default: trace_task_prctl_unknown(option, arg2, arg3, arg4, arg5); error = -EINVAL;