From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 7DAF84C9F; Fri, 1 Aug 2025 01:11:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=205.233.56.17 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754010676; cv=none; b=Q3jNd7x90f4yJtntMGdohuPh4MM0ut5kEbHW9UR7dFE7niDkZrA58bjHOjMsDLhBKqt2zHSmIBPzXaKVWrQPx5GJYS+U6iRgkF+8lvpisoXVkITLMp5aumL/JbpswO3bMSkBp6K/ctrqJJ+CeqsG/IG6gNZntoHwtnTp9WBV+xg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754010676; c=relaxed/simple; bh=Z08Hnxo3JLUQeXYu0SXcXSOBsQpO/H4vXl2Qan/4akU=; h=Date:From:To:Cc:Subject:Message-ID:References:Mime-Version: Content-Type:Content-Disposition:In-Reply-To; b=gXOgzxcF94Lneaqrg18bPOFR/9e+5RbuVjYgheOrXNgpcZ7oRqVzSUv/9e9jtMJeRnpi6Z+KoDby3TCRrGx+/NYok4hDO6cHen4id2kLJZId17/Z6NpEJplAqQVHB3BKVY9LcvnLkV0hfbq62NR2kKwicohpAfuA7n4Llobzifs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=communityfibre.ca; spf=pass smtp.mailfrom=communityfibre.ca; arc=none smtp.client-ip=205.233.56.17 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=communityfibre.ca Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=communityfibre.ca Received: by kanga.kvack.org (Postfix, from userid 63042) id AFCFC8E0001; Thu, 31 Jul 2025 21:09:42 -0400 (EDT) Date: Thu, 31 Jul 2025 21:09:42 -0400 From: Benjamin LaHaise To: Deepak Gupta Cc: 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 , =?iso-8859-1?Q?Bj=F6rn?= Roy Baron , Andreas Hindborg , Alice Ryhl , Trevor Gross , Benno Lossin , 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 , David Hildenbrand Subject: Re: [PATCH v19 00/27] riscv control-flow integrity for usermode Message-ID: <20250801010942.GB4474@kvack.org> References: <20250731-v5_user_cfi_series-v19-0-09b468d7beab@rivosinc.com> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20250731-v5_user_cfi_series-v19-0-09b468d7beab@rivosinc.com> User-Agent: Mutt/1.4.2.2i Be advised that all emails from @rivosinc.com sent via the mailing list are rejected by all mailing list recipients @gmail.com and any other domains using Google's mail infrastructure. Quite simply: only implementing SPF is no longer sufficient for your messages to be delivered anymore. -ben On Thu, Jul 31, 2025 at 04:19:10PM -0700, Deepak Gupta wrote: > Basics and overview > =================== > > Software with larger attack surfaces (e.g. network facing apps like databases, > browsers or apps relying on browser runtimes) suffer from memory corruption > issues which can be utilized by attackers to bend control flow of the program > to eventually gain control (by making their payload executable). Attackers are > able to perform such attacks by leveraging call-sites which rely on indirect > calls or return sites which rely on obtaining return address from stack memory. > > To mitigate such attacks, risc-v extension zicfilp enforces that all indirect > calls must land on a landing pad instruction `lpad` else cpu will raise software > check exception (a new cpu exception cause code on riscv). > Similarly for return flow, risc-v extension zicfiss extends architecture with > > - `sspush` instruction to push return address on a shadow stack > - `sspopchk` instruction to pop return address from shadow stack > and compare with input operand (i.e. return address on stack) > - `sspopchk` to raise software check exception if comparision above > was a mismatch > - Protection mechanism using which shadow stack is not writeable via > regular store instructions > > More information an details can be found at extensions github repo [1]. > > Equivalent to landing pad (zicfilp) on x86 is `ENDBRANCH` instruction in Intel > CET [3] and branch target identification (BTI) [4] on arm. > Similarly x86's Intel CET has shadow stack [5] and arm64 has guarded control > stack (GCS) [6] which are very similar to risc-v's zicfiss shadow stack. > > x86 and arm64 support for user mode shadow stack is already in mainline. > > Kernel awareness for user control flow integrity > ================================================ > > This series picks up Samuel Holland's envcfg changes [2] as well. So if those are > being applied independently, they should be removed from this series. > > Enabling: > > In order to maintain compatibility and not break anything in user mode, kernel > doesn't enable control flow integrity cpu extensions on binary by default. > Instead exposes a prctl interface to enable, disable and lock the shadow stack > or landing pad feature for a task. This allows userspace (loader) to enumerate > if all objects in its address space are compiled with shadow stack and landing > pad support and accordingly enable the feature. Additionally if a subsequent > `dlopen` happens on a library, user mode can take a decision again to disable > the feature (if incoming library is not compiled with support) OR terminate the > task (if user mode policy is strict to have all objects in address space to be > compiled with control flow integirty cpu feature). prctl to enable shadow stack > results in allocating shadow stack from virtual memory and activating for user > address space. x86 and arm64 are also following same direction due to similar > reason(s). > > clone/fork: > > On clone and fork, cfi state for task is inherited by child. Shadow stack is > part of virtual memory and is a writeable memory from kernel perspective > (writeable via a restricted set of instructions aka shadow stack instructions) > Thus kernel changes ensure that this memory is converted into read-only when > fork/clone happens and COWed when fault is taken due to sspush, sspopchk or > ssamoswap. In case `CLONE_VM` is specified and shadow stack is to be enabled, > kernel will automatically allocate a shadow stack for that clone call. > > map_shadow_stack: > > x86 introduced `map_shadow_stack` system call to allow user space to explicitly > map shadow stack memory in its address space. It is useful to allocate shadow > for different contexts managed by a single thread (green threads or contexts) > risc-v implements this system call as well. > > signal management: > > If shadow stack is enabled for a task, kernel performs an asynchronous control > flow diversion to deliver the signal and eventually expects userspace to issue > sigreturn so that original execution can be resumed. Even though resume context > is prepared by kernel, it is in user space memory and is subject to memory > corruption and corruption bugs can be utilized by attacker in this race window > to perform arbitrary sigreturn and eventually bypass cfi mechanism. > Another issue is how to ensure that cfi related state on sigcontext area is not > trampled by legacy apps or apps compiled with old kernel headers. > > In order to mitigate control-flow hijacting, kernel prepares a token and place > it on shadow stack before signal delivery and places address of token in > sigcontext structure. During sigreturn, kernel obtains address of token from > sigcontext struture, reads token from shadow stack and validates it and only > then allow sigreturn to succeed. Compatiblity issue is solved by adopting > dynamic sigcontext management introduced for vector extension. This series > re-factor the code little bit to allow future sigcontext management easy (as > proposed by Andy Chiu from SiFive) > > config and compilation: > > Introduce a new risc-v config option `CONFIG_RISCV_USER_CFI`. Selecting this > config option picks the kernel support for user control flow integrity. This > optin is presented only if toolchain has shadow stack and landing pad support. > And is on purpose guarded by toolchain support. Reason being that eventually > vDSO also needs to be compiled in with shadow stack and landing pad support. > vDSO compile patches are not included as of now because landing pad labeling > scheme is yet to settle for usermode runtime. > > To get more information on kernel interactions with respect to > zicfilp and zicfiss, patch series adds documentation for > `zicfilp` and `zicfiss` in following: > Documentation/arch/riscv/zicfiss.rst > Documentation/arch/riscv/zicfilp.rst > > How to test this series > ======================= > > Toolchain > --------- > $ git clone git@github.com:sifive/riscv-gnu-toolchain.git -b cfi-dev > $ riscv-gnu-toolchain/configure --prefix= --with-arch=rv64gc_zicfilp_zicfiss --enable-linux --disable-gdb --with-extra-multilib-test="rv64gc_zicfilp_zicfiss-lp64d:-static" > $ make -j$(nproc) > > Qemu > ---- > Get the lastest qemu > $ cd qemu > $ mkdir build > $ cd build > $ ../configure --target-list=riscv64-softmmu > $ make -j$(nproc) > > Opensbi > ------- > $ git clone git@github.com:deepak0414/opensbi.git -b v6_cfi_spec_split_opensbi > $ make CROSS_COMPILE= -j$(nproc) PLATFORM=generic > > Linux > ----- > Running defconfig is fine. CFI is enabled by default if the toolchain > supports it. > > $ make ARCH=riscv CROSS_COMPILE=/build/bin/riscv64-unknown-linux-gnu- -j$(nproc) defconfig > $ make ARCH=riscv CROSS_COMPILE=/build/bin/riscv64-unknown-linux-gnu- -j$(nproc) > > In case you're building your own rootfs using toolchain, please make sure you > pick following patch to ensure that vDSO compiled with lpad and shadow stack. > > "arch/riscv: compile vdso with landing pad" > > Branch where above patch can be picked > https://github.com/deepak0414/linux-riscv-cfi/tree/vdso_user_cfi_v6.12-rc1 > > Running > ------- > > Modify your qemu command to have: > -bios /build/platform/generic/firmware/fw_dynamic.bin > -cpu rv64,zicfilp=true,zicfiss=true,zimop=true,zcmop=true > > vDSO related Opens (in the flux) > ================================= > > I am listing these opens for laying out plan and what to expect in future > patch sets. And of course for the sake of discussion. > > Shadow stack and landing pad enabling in vDSO > ---------------------------------------------- > vDSO must have shadow stack and landing pad support compiled in for task > to have shadow stack and landing pad support. This patch series doesn't > enable that (yet). Enabling shadow stack support in vDSO should be > straight forward (intend to do that in next versions of patch set). Enabling > landing pad support in vDSO requires some collaboration with toolchain folks > to follow a single label scheme for all object binaries. This is necessary to > ensure that all indirect call-sites are setting correct label and target landing > pads are decorated with same label scheme. > > How many vDSOs > --------------- > Shadow stack instructions are carved out of zimop (may be operations) and if CPU > doesn't implement zimop, they're illegal instructions. Kernel could be running on > a CPU which may or may not implement zimop. And thus kernel will have to carry 2 > different vDSOs and expose the appropriate one depending on whether CPU implements > zimop or not. > > References > ========== > [1] - https://github.com/riscv/riscv-cfi > [2] - https://lore.kernel.org/all/20240814081126.956287-1-samuel.holland@sifive.com/ > [3] - https://lwn.net/Articles/889475/ > [4] - https://developer.arm.com/documentation/109576/0100/Branch-Target-Identification > [5] - https://www.intel.com/content/dam/develop/external/us/en/documents/catc17-introduction-intel-cet-844137.pdf > [6] - https://lwn.net/Articles/940403/ > > To: Thomas Gleixner > To: Ingo Molnar > To: Borislav Petkov > To: Dave Hansen > To: x86@kernel.org > To: H. Peter Anvin > To: Andrew Morton > To: Liam R. Howlett > To: Vlastimil Babka > To: Lorenzo Stoakes > To: Paul Walmsley > To: Palmer Dabbelt > To: Albert Ou > To: Conor Dooley > To: Rob Herring > To: Krzysztof Kozlowski > To: Arnd Bergmann > To: Christian Brauner > To: Peter Zijlstra > To: Oleg Nesterov > To: Eric Biederman > To: Kees Cook > To: Jonathan Corbet > To: Shuah Khan > To: Jann Horn > To: Conor Dooley > To: Miguel Ojeda > To: Alex Gaynor > To: Boqun Feng > To: Gary Guo > To: Björn Roy Baron > To: Benno Lossin > To: Andreas Hindborg > To: Alice Ryhl > To: Trevor Gross > Cc: linux-kernel@vger.kernel.org > Cc: linux-fsdevel@vger.kernel.org > Cc: linux-mm@kvack.org > Cc: linux-riscv@lists.infradead.org > Cc: devicetree@vger.kernel.org > Cc: linux-arch@vger.kernel.org > Cc: linux-doc@vger.kernel.org > Cc: linux-kselftest@vger.kernel.org > Cc: alistair.francis@wdc.com > Cc: richard.henderson@linaro.org > Cc: jim.shu@sifive.com > Cc: andybnac@gmail.com > Cc: kito.cheng@sifive.com > Cc: charlie@rivosinc.com > Cc: atishp@rivosinc.com > Cc: evan@rivosinc.com > Cc: cleger@rivosinc.com > Cc: alexghiti@rivosinc.com > Cc: samitolvanen@google.com > Cc: broonie@kernel.org > Cc: rick.p.edgecombe@intel.com > Cc: rust-for-linux@vger.kernel.org > > changelog > --------- > v19: > - riscv_nousercfi was `int`. changed it to unsigned long. > Thanks to Alex Ghiti for reporting it. It was a bug. > - ELP is cleared on trap entry only when CONFIG_64BIT. > - restore ssp back on return to usermode was being done > before `riscv_v_context_nesting_end` on trap exit path. > If kernel shadow stack were enabled this would result in > kernel operating on user shadow stack and panic (as I found > in my testing of kcfi patch series). So fixed that. > > v18: > - rebased on 6.16-rc1 > - uprobe handling clears ELP in sstatus image in pt_regs > - vdso was missing shadow stack elf note for object files. > added that. Additional asm file for vdso needed the elf marker > flag. toolchain should complain if `-fcf-protection=full` and > marker is missing for object generated from asm file. Asked > toolchain folks to fix this. Although no reason to gate the merge > on that. > - Split up compile options for march and fcf-protection in vdso > Makefile > - CONFIG_RISCV_USER_CFI option is moved under "Kernel features" menu > Added `arch/riscv/configs/hardening.config` fragment which selects > CONFIG_RISCV_USER_CFI > > v17: > - fixed warnings due to empty macros in usercfi.h (reported by alexg) > - fixed prefixes in commit titles reported by alexg > - took below uprobe with fcfi v2 patch from Zong Li and squashed it with > "riscv/traps: Introduce software check exception and uprobe handling" > https://lore.kernel.org/all/20250604093403.10916-1-zong.li@sifive.com/ > > v16: > - If FWFT is not implemented or returns error for shadow stack activation, then > no_usercfi is set to disable shadow stack. Although this should be picked up > by extension validation and activation. Fixed this bug for zicfilp and zicfiss > both. Thanks to Charlie Jenkins for reporting this. > - If toolchain doesn't support cfi, cfi kselftest shouldn't build. Suggested by > Charlie Jenkins. > - Default for CONFIG_RISCV_USER_CFI is set to no. Charlie/Atish suggested to > keep it off till we have more hardware availibility with RVA23 profile and > zimop/zcmop implemented. Else this will start breaking people's workflow > - Includes the fix if "!RV64 and !SBI" then definitions for FWFT in > asm-offsets.c error. > > v15: > - Toolchain has been updated to include `-fcf-protection` flag. This > exists for x86 as well. Updated kernel patches to compile vDSO and > selftest to compile with `fcf-protection=full` flag. > - selecting CONFIG_RISCV_USERCFI selects CONFIG_RISCV_SBI. > - Patch to enable shadow stack for kernel wasn't hidden behind > CONFIG_RISCV_USERCFI and CONFIG_RISCV_SBI. fixed that. > > v14: > - rebased on top of palmer/sbi-v3. Thus dropped clement's FWFT patches > Updated RISCV_ISA_EXT_XXXX in hwcap and hwprobe constants. > - Took Radim's suggestions on bitfields. > - Placed cfi_state at the end of thread_info block so that current situation > is not disturbed with respect to member fields of thread_info in single > cacheline. > > v13: > - cpu_supports_shadow_stack/cpu_supports_indirect_br_lp_instr uses > riscv_has_extension_unlikely() > - uses nops(count) to create nop slide > - RISCV_ACQUIRE_BARRIER is not needed in `amo_user_shstk`. Removed it > - changed ternaries to simply use implicit casting to convert to bool. > - kernel command line allows to disable zicfilp and zicfiss independently. > updated kernel-parameters.txt. > - ptrace user abi for cfi uses bitmasks instead of bitfields. Added ptrace > kselftest. > - cosmetic and grammatical changes to documentation. > > v12: > - It seems like I had accidently squashed arch agnostic indirect branch > tracking prctl and riscv implementation of those prctls. Split them again. > - set_shstk_status/set_indir_lp_status perform CSR writes only when CPU > support is available. As suggested by Zong Li. > - Some minor clean up in kselftests as suggested by Zong Li. > > v11: > - patch "arch/riscv: compile vdso with landing pad" was unconditionally > selecting `_zicfilp` for vDSO compile. fixed that. Changed `lpad 1` to > to `lpad 0`. > v10: > - dropped "mm: helper `is_shadow_stack_vma` to check shadow stack vma". This patch > is not that interesting to this patch series for risc-v. There are instances in > arch directories where VM_SHADOW_STACK flag is anyways used. Dropping this patch > to expedite merging in riscv tree. > - Took suggestions from `Clement` on "riscv: zicfiss / zicfilp enumeration" to > validate presence of cfi based on config. > - Added a patch for vDSO to have `lpad 0`. I had omitted this earlier to make sure > we add single vdso object with cfi enabled. But a vdso object with scheme of > zero labeled landing pad is least common denominator and should work with all > objects of zero labeled as well as function-signature labeled objects. > > v9: > - rebased on master (39a803b754d5 fix braino in "9p: fix ->rename_sem exclusion") > - dropped "mm: Introduce ARCH_HAS_USER_SHADOW_STACK" (master has it from arm64/gcs) > - dropped "prctl: arch-agnostic prctl for shadow stack" (master has it from arm64/gcs) > > v8: > - rebased on palmer/for-next > - dropped samuel holland's `envcfg` context switch patches. > they are in parlmer/for-next > > v7: > - Removed "riscv/Kconfig: enable HAVE_EXIT_THREAD for riscv" > Instead using `deactivate_mm` flow to clean up. > see here for more context > https://lore.kernel.org/all/20230908203655.543765-1-rick.p.edgecombe@intel.com/#t > - Changed the header include in `kselftest`. Hopefully this fixes compile > issue faced by Zong Li at SiFive. > - Cleaned up an orphaned change to `mm/mmap.c` in below patch > "riscv/mm : ensure PROT_WRITE leads to VM_READ | VM_WRITE" > - Lock interfaces for shadow stack and indirect branch tracking expect arg == 0 > Any future evolution of this interface should accordingly define how arg should > be setup. > - `mm/map.c` has an instance of using `VM_SHADOW_STACK`. Fixed it to use helper > `is_shadow_stack_vma`. > - Link to v6: https://lore.kernel.org/r/20241008-v5_user_cfi_series-v6-0-60d9fe073f37@rivosinc.com > > v6: > - Picked up Samuel Holland's changes as is with `envcfg` placed in > `thread` instead of `thread_info` > - fixed unaligned newline escapes in kselftest > - cleaned up messages in kselftest and included test output in commit message > - fixed a bug in clone path reported by Zong Li > - fixed a build issue if CONFIG_RISCV_ISA_V is not selected > (this was introduced due to re-factoring signal context > management code) > > v5: > - rebased on v6.12-rc1 > - Fixed schema related issues in device tree file > - Fixed some of the documentation related issues in zicfilp/ss.rst > (style issues and added index) > - added `SHADOW_STACK_SET_MARKER` so that implementation can define base > of shadow stack. > - Fixed warnings on definitions added in usercfi.h when > CONFIG_RISCV_USER_CFI is not selected. > - Adopted context header based signal handling as proposed by Andy Chiu > - Added support for enabling kernel mode access to shadow stack using > FWFT > (https://github.com/riscv-non-isa/riscv-sbi-doc/blob/master/src/ext-firmware-features.adoc) > - Link to v5: https://lore.kernel.org/r/20241001-v5_user_cfi_series-v1-0-3ba65b6e550f@rivosinc.com > (Note: I had an issue in my workflow due to which version number wasn't > picked up correctly while sending out patches) > > v4: > - rebased on 6.11-rc6 > - envcfg: Converged with Samuel Holland's patches for envcfg management on per- > thread basis. > - vma_is_shadow_stack is renamed to is_vma_shadow_stack > - picked up Mark Brown's `ARCH_HAS_USER_SHADOW_STACK` patch > - signal context: using extended context management to maintain compatibility. > - fixed `-Wmissing-prototypes` compiler warnings for prctl functions > - Documentation fixes and amending typos. > - Link to v4: https://lore.kernel.org/all/20240912231650.3740732-1-debug@rivosinc.com/ > > v3: > - envcfg > logic to pick up base envcfg had a bug where `ENVCFG_CBZE` could have been > picked on per task basis, even though CPU didn't implement it. Fixed in > this series. > > - dt-bindings > As suggested, split into separate commit. fixed the messaging that spec is > in public review > > - arch_is_shadow_stack change > arch_is_shadow_stack changed to vma_is_shadow_stack > > - hwprobe > zicfiss / zicfilp if present will get enumerated in hwprobe > > - selftests > As suggested, added object and binary filenames to .gitignore > Selftest binary anyways need to be compiled with cfi enabled compiler which > will make sure that landing pad and shadow stack are enabled. Thus removed > separate enable/disable tests. Cleaned up tests a bit. > > - Link to v3: https://lore.kernel.org/lkml/20240403234054.2020347-1-debug@rivosinc.com/ > > v2: > - Using config `CONFIG_RISCV_USER_CFI`, kernel support for riscv control flow > integrity for user mode programs can be compiled in the kernel. > > - Enabling of control flow integrity for user programs is left to user runtime > > - This patch series introduces arch agnostic `prctls` to enable shadow stack > and indirect branch tracking. And implements them on riscv. > > --- > Changes in v19: > - Link to v18: https://lore.kernel.org/r/20250711-v5_user_cfi_series-v18-0-a8ee62f9f38e@rivosinc.com > > Changes in v18: > - Link to v17: https://lore.kernel.org/r/20250604-v5_user_cfi_series-v17-0-4565c2cf869f@rivosinc.com > > Changes in v17: > - Link to v16: https://lore.kernel.org/r/20250522-v5_user_cfi_series-v16-0-64f61a35eee7@rivosinc.com > > Changes in v16: > - Link to v15: https://lore.kernel.org/r/20250502-v5_user_cfi_series-v15-0-914966471885@rivosinc.com > > Changes in v15: > - changelog posted just below cover letter > - Link to v14: https://lore.kernel.org/r/20250429-v5_user_cfi_series-v14-0-5239410d012a@rivosinc.com > > Changes in v14: > > - changelog posted just below cover letter > - Link to v13: https://lore.kernel.org/r/20250424-v5_user_cfi_series-v13-0-971437de586a@rivosinc.com > > Changes in v13: > - changelog posted just below cover letter > - Link to v12: https://lore.kernel.org/r/20250314-v5_user_cfi_series-v12-0-e51202b53138@rivosinc.com > > Changes in v12: > - changelog posted just below cover letter > - Link to v11: https://lore.kernel.org/r/20250310-v5_user_cfi_series-v11-0-86b36cbfb910@rivosinc.com > > Changes in v11: > - changelog posted just below cover letter > - Link to v10: https://lore.kernel.org/r/20250210-v5_user_cfi_series-v10-0-163dcfa31c60@rivosinc.com > > --- > Andy Chiu (1): > riscv: signal: abstract header saving for setup_sigcontext > > Deepak Gupta (25): > mm: VM_SHADOW_STACK definition for riscv > dt-bindings: riscv: zicfilp and zicfiss in dt-bindings (extensions.yaml) > riscv: zicfiss / zicfilp enumeration > riscv: zicfiss / zicfilp extension csr and bit definitions > riscv: usercfi state for task and save/restore of CSR_SSP on trap entry/exit > riscv/mm : ensure PROT_WRITE leads to VM_READ | VM_WRITE > riscv/mm: manufacture shadow stack pte > riscv/mm: teach pte_mkwrite to manufacture shadow stack PTEs > riscv/mm: write protect and shadow stack > riscv/mm: Implement map_shadow_stack() syscall > riscv/shstk: If needed allocate a new shadow stack on clone > riscv: Implements arch agnostic shadow stack prctls > prctl: arch-agnostic prctl for indirect branch tracking > riscv: Implements arch agnostic indirect branch tracking prctls > riscv/traps: Introduce software check exception and uprobe handling > riscv/signal: save and restore of shadow stack for signal > riscv/kernel: update __show_regs to print shadow stack register > riscv/ptrace: riscv cfi status and state via ptrace and in core files > riscv/hwprobe: zicfilp / zicfiss enumeration in hwprobe > riscv: kernel command line option to opt out of user cfi > riscv: enable kernel access to shadow stack memory via FWFT sbi call > riscv: create a config for shadow stack and landing pad instr support > riscv: Documentation for landing pad / indirect branch tracking > riscv: Documentation for shadow stack on riscv > kselftest/riscv: kselftest for user mode cfi > > Jim Shu (1): > arch/riscv: compile vdso with landing pad and shadow stack note > > Documentation/admin-guide/kernel-parameters.txt | 8 + > Documentation/arch/riscv/index.rst | 2 + > Documentation/arch/riscv/zicfilp.rst | 115 +++++ > Documentation/arch/riscv/zicfiss.rst | 179 +++++++ > .../devicetree/bindings/riscv/extensions.yaml | 14 + > arch/riscv/Kconfig | 21 + > arch/riscv/Makefile | 5 +- > arch/riscv/configs/hardening.config | 4 + > arch/riscv/include/asm/asm-prototypes.h | 1 + > arch/riscv/include/asm/assembler.h | 44 ++ > arch/riscv/include/asm/cpufeature.h | 12 + > arch/riscv/include/asm/csr.h | 16 + > arch/riscv/include/asm/entry-common.h | 2 + > arch/riscv/include/asm/hwcap.h | 2 + > arch/riscv/include/asm/mman.h | 26 + > arch/riscv/include/asm/mmu_context.h | 7 + > arch/riscv/include/asm/pgtable.h | 30 +- > arch/riscv/include/asm/processor.h | 1 + > arch/riscv/include/asm/thread_info.h | 3 + > arch/riscv/include/asm/usercfi.h | 95 ++++ > arch/riscv/include/asm/vector.h | 3 + > arch/riscv/include/uapi/asm/hwprobe.h | 2 + > arch/riscv/include/uapi/asm/ptrace.h | 34 ++ > arch/riscv/include/uapi/asm/sigcontext.h | 1 + > arch/riscv/kernel/Makefile | 1 + > arch/riscv/kernel/asm-offsets.c | 10 + > arch/riscv/kernel/cpufeature.c | 27 + > arch/riscv/kernel/entry.S | 38 ++ > arch/riscv/kernel/head.S | 27 + > arch/riscv/kernel/process.c | 27 +- > arch/riscv/kernel/ptrace.c | 95 ++++ > arch/riscv/kernel/signal.c | 148 +++++- > arch/riscv/kernel/sys_hwprobe.c | 2 + > arch/riscv/kernel/sys_riscv.c | 10 + > arch/riscv/kernel/traps.c | 54 ++ > arch/riscv/kernel/usercfi.c | 545 +++++++++++++++++++++ > arch/riscv/kernel/vdso/Makefile | 11 +- > arch/riscv/kernel/vdso/flush_icache.S | 4 + > arch/riscv/kernel/vdso/getcpu.S | 4 + > arch/riscv/kernel/vdso/rt_sigreturn.S | 4 + > arch/riscv/kernel/vdso/sys_hwprobe.S | 4 + > arch/riscv/kernel/vdso/vgetrandom-chacha.S | 5 +- > arch/riscv/mm/init.c | 2 +- > arch/riscv/mm/pgtable.c | 16 + > include/linux/cpu.h | 4 + > include/linux/mm.h | 7 + > include/uapi/linux/elf.h | 2 + > include/uapi/linux/prctl.h | 27 + > kernel/sys.c | 30 ++ > tools/testing/selftests/riscv/Makefile | 2 +- > tools/testing/selftests/riscv/cfi/.gitignore | 3 + > tools/testing/selftests/riscv/cfi/Makefile | 16 + > tools/testing/selftests/riscv/cfi/cfi_rv_test.h | 82 ++++ > tools/testing/selftests/riscv/cfi/riscv_cfi_test.c | 173 +++++++ > tools/testing/selftests/riscv/cfi/shadowstack.c | 385 +++++++++++++++ > tools/testing/selftests/riscv/cfi/shadowstack.h | 27 + > 56 files changed, 2389 insertions(+), 30 deletions(-) > --- > base-commit: a2a05801de77ca5122fc34e3eb84d6359ef70389 > change-id: 20240930-v5_user_cfi_series-3dc332f8f5b2 > -- > - debug > -- "Thought is the essence of where you are now."