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[PATCH v22 00/28] riscv control-flow integrity for usermode

by Deepak Gupta

v22: fixing build error due to -march=zicfiss being picked in gcc-13 and above but not actually doing any codegen or recognizing instruction for zicfiss. Change in v22 makes dependence on `-fcf-protection=full` compiler flag to ensure that toolchain has support and then only CONFIG_RISCV_USER_CFI will be visible in menuconfig. v21: fixed build errors. 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=<path-to-where-to-build> --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=<your riscv toolchain> -j$(nproc) PLATFORM=generic Linux ----- Running defconfig is fine. CFI is enabled by default if the toolchain supports it. $ make ARCH=riscv CROSS_COMPILE=<path-to-cfi-riscv-gnu-toolchain>/build/bin/riscv64-unknown-linux-gnu- -j$(nproc) defconfig $ make ARCH=riscv CROSS_COMPILE=<path-to-cfi-riscv-gnu-toolchain>/build/bin/riscv64-unknown-linux-gnu- -j$(nproc) Running ------- Modify your qemu command to have: -bios <path-to-cfi-opensbi>/build/platform/generic/firmware/fw_dynamic.bin -cpu rv64,zicfilp=true,zicfiss=true,zimop=true,zcmop=true References ========== [1] - https://github.com/riscv/riscv-cfi [2] - https://lore.kernel.org/all/20240814081126.956287-1-samuel.holland@sifive.c… [3] - https://lwn.net/Articles/889475/ [4] - https://developer.arm.com/documentation/109576/0100/Branch-Target-Identific… [5] - https://www.intel.com/content/dam/develop/external/us/en/documents/catc17-i… [6] - https://lwn.net/Articles/940403/ To: Thomas Gleixner <tglx(a)linutronix.de> To: Ingo Molnar <mingo(a)redhat.com> To: Borislav Petkov <bp(a)alien8.de> To: Dave Hansen <dave.hansen(a)linux.intel.com> To: x86(a)kernel.org To: H. Peter Anvin <hpa(a)zytor.com> To: Andrew Morton <akpm(a)linux-foundation.org> To: Liam R. Howlett <Liam.Howlett(a)oracle.com> To: Vlastimil Babka <vbabka(a)suse.cz> To: Lorenzo Stoakes <lorenzo.stoakes(a)oracle.com> To: Paul Walmsley <paul.walmsley(a)sifive.com> To: Palmer Dabbelt <palmer(a)dabbelt.com> To: Albert Ou <aou(a)eecs.berkeley.edu> To: Conor Dooley <conor(a)kernel.org> To: Rob Herring <robh(a)kernel.org> To: Krzysztof Kozlowski <krzk+dt(a)kernel.org> To: Arnd Bergmann <arnd(a)arndb.de> To: Christian Brauner <brauner(a)kernel.org> To: Peter Zijlstra <peterz(a)infradead.org> To: Oleg Nesterov <oleg(a)redhat.com> To: Eric Biederman <ebiederm(a)xmission.com> To: Kees Cook <kees(a)kernel.org> To: Jonathan Corbet <corbet(a)lwn.net> To: Shuah Khan <shuah(a)kernel.org> To: Jann Horn <jannh(a)google.com> To: Conor Dooley <conor+dt(a)kernel.org> To: Miguel Ojeda <ojeda(a)kernel.org> To: Alex Gaynor <alex.gaynor(a)gmail.com> To: Boqun Feng <boqun.feng(a)gmail.com> To: Gary Guo <gary(a)garyguo.net> To: Björn Roy Baron <bjorn3_gh(a)protonmail.com> To: Benno Lossin <benno.lossin(a)proton.me> To: Andreas Hindborg <a.hindborg(a)kernel.org> To: Alice Ryhl <aliceryhl(a)google.com> To: Trevor Gross <tmgross(a)umich.edu> Cc: linux-kernel(a)vger.kernel.org Cc: linux-fsdevel(a)vger.kernel.org Cc: linux-mm(a)kvack.org Cc: linux-riscv(a)lists.infradead.org Cc: devicetree(a)vger.kernel.org Cc: linux-arch(a)vger.kernel.org Cc: linux-doc(a)vger.kernel.org Cc: linux-kselftest(a)vger.kernel.org Cc: alistair.francis(a)wdc.com Cc: richard.henderson(a)linaro.org Cc: jim.shu(a)sifive.com Cc: andybnac(a)gmail.com Cc: kito.cheng(a)sifive.com Cc: charlie(a)rivosinc.com Cc: atishp(a)rivosinc.com Cc: evan(a)rivosinc.com Cc: cleger(a)rivosinc.com Cc: alexghiti(a)rivosinc.com Cc: samitolvanen(a)google.com Cc: broonie(a)kernel.org Cc: rick.p.edgecombe(a)intel.com Cc: rust-for-linux(a)vger.kernel.org changelog --------- v22: - CONFIG_RISCV_USER_CFI was by default "n". With dual vdso support it is default "y" (if toolchain supports it). Fixing build error due to "-march=zicfiss" being picked in gcc-13 partially. gcc-13 only recognizes the flag but not actually doing any codegen or recognizing instruction for zicfiss. Change in v22 makes dependence on `-fcf-protection=full` compiler flag to ensure that toolchain has support and then only CONFIG_RISCV_USER_CFI will be visible in menuconfig. - picked up tags and some cosmetic changes in commit message for dual vdso patch. v21: - Fixing build errors due to changes in arch/riscv/include/asm/vdso.h Using #ifdef instead of IS_ENABLED in arch/riscv/include/asm/vdso.h vdso-cfi-offsets.h should be included only when CONFIG_RISCV_USER_CFI is selected. v20: - rebased on v6.18-rc1. - Added two vDSO support. If `CONFIG_RISCV_USER_CFI` is selected two vDSOs are compiled (one for hardware prior to RVA23 and one for RVA23 onwards). Kernel exposes RVA23 vDSO if hardware/cpu implements zimop else exposes existing vDSO to userspace. - default selection for `CONFIG_RISCV_USER_CFI` is "Yes". - replaced "__ASSEMBLY__" with "__ASSEMBLER__" 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.… - 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@riv… 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…) - Link to v5: https://lore.kernel.org/r/20241001-v5_user_cfi_series-v1-0-3ba65b6e550f@riv… (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 v22: - Link to v21: https://lore.kernel.org/r/20251015-v5_user_cfi_series-v21-0-6a07856e90e7@ri… Changes in v21: - Link to v20: https://lore.kernel.org/r/20251013-v5_user_cfi_series-v20-0-b9de4be9912e@ri… Changes in v20: - Link to v19: https://lore.kernel.org/r/20250731-v5_user_cfi_series-v19-0-09b468d7beab@ri… Changes in v19: - Link to v18: https://lore.kernel.org/r/20250711-v5_user_cfi_series-v18-0-a8ee62f9f38e@ri… Changes in v18: - Link to v17: https://lore.kernel.org/r/20250604-v5_user_cfi_series-v17-0-4565c2cf869f@ri… Changes in v17: - Link to v16: https://lore.kernel.org/r/20250522-v5_user_cfi_series-v16-0-64f61a35eee7@ri… Changes in v16: - Link to v15: https://lore.kernel.org/r/20250502-v5_user_cfi_series-v15-0-914966471885@ri… 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@ri… 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@ri… 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@ri… 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@ri… 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@ri… --- Andy Chiu (1): riscv: signal: abstract header saving for setup_sigcontext Deepak Gupta (26): 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 arch/riscv: dual vdso creation logic and select vdso based on hw 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 | 22 + arch/riscv/Makefile | 8 +- 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/vdso.h | 13 +- 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 | 2 + 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.c | 7 + arch/riscv/kernel/vdso/Makefile | 40 +- arch/riscv/kernel/vdso/flush_icache.S | 4 + arch/riscv/kernel/vdso/gen_vdso_offsets.sh | 4 +- arch/riscv/kernel/vdso/getcpu.S | 4 + arch/riscv/kernel/vdso/note.S | 3 + 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/kernel/vdso_cfi/Makefile | 25 + arch/riscv/kernel/vdso_cfi/vdso-cfi.S | 11 + 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 + 62 files changed, 2475 insertions(+), 41 deletions(-) --- base-commit: 3a8660878839faadb4f1a6dd72c3179c1df56787 change-id: 20240930-v5_user_cfi_series-3dc332f8f5b2 -- - 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[PATCH net v2 0/3] mptcp: Fix conflicts between MPTCP and sockmap

by Jiayuan Chen

Overall, we encountered a warning [1] that can be triggered by running the selftest I provided. MPTCP creates subflows for data transmission between two endpoints. However, BPF can use sockops to perform additional operations when TCP completes the three-way handshake. The issue arose because we used sockmap in sockops, which replaces sk->sk_prot and some handlers. Since subflows also have their own specialized handlers, this creates a conflict and leads to traffic failure. Therefore, we need to reject operations targeting subflows. This patchset simply prevents the combination of subflows and sockmap without changing any functionality. A complete integration of MPTCP and sockmap would require more effort, for example, we would need to retrieve the parent socket from subflows in sockmap and implement handlers like read_skb. If maintainers don't object, we can further improve this in subsequent work. v1: https://lore.kernel.org/mptcp/a0a2b87119a06c5ffaa51427a0964a05534fe6f1@linu… [1] truncated warning: [ 18.234652] ------------[ cut here ]------------ [ 18.234664] WARNING: CPU: 1 PID: 388 at net/mptcp/protocol.c:68 mptcp_stream_accept+0x34c/0x380 [ 18.234726] Modules linked in: [ 18.234755] RIP: 0010:mptcp_stream_accept+0x34c/0x380 [ 18.234762] RSP: 0018:ffffc90000cf3cf8 EFLAGS: 00010202 [ 18.234800] PKRU: 55555554 [ 18.234806] Call Trace: [ 18.234810] <TASK> [ 18.234837] do_accept+0xeb/0x190 [ 18.234861] ? __x64_sys_pselect6+0x61/0x80 [ 18.234898] ? _raw_spin_unlock+0x12/0x30 [ 18.234915] ? alloc_fd+0x11e/0x190 [ 18.234925] __sys_accept4+0x8c/0x100 [ 18.234930] __x64_sys_accept+0x1f/0x30 [ 18.234933] x64_sys_call+0x202f/0x20f0 [ 18.234966] do_syscall_64+0x72/0x9a0 [ 18.234979] ? switch_fpu_return+0x60/0xf0 [ 18.234993] ? irqentry_exit_to_user_mode+0xdb/0x1e0 [ 18.235002] ? irqentry_exit+0x3f/0x50 [ 18.235005] ? clear_bhb_loop+0x50/0xa0 [ 18.235022] ? clear_bhb_loop+0x50/0xa0 [ 18.235025] ? clear_bhb_loop+0x50/0xa0 [ 18.235028] entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 18.235066] </TASK> [ 18.235109] ---[ end trace 0000000000000000 ]--- [ 18.235677] sockmap: MPTCP sockets are not supported Jiayuan Chen (3): net,mptcp: fix incorrect IPv4/IPv6 fallback detection with BPF Sockmap bpf,sockmap: disallow MPTCP sockets from sockmap updates selftests/bpf: Add mptcp test with sockmap net/core/sock_map.c | 9 ++ net/mptcp/protocol.c | 7 +- .../testing/selftests/bpf/prog_tests/mptcp.c | 136 ++++++++++++++++++ .../selftests/bpf/progs/mptcp_sockmap.c | 43 ++++++ 4 files changed, 193 insertions(+), 2 deletions(-) create mode 100644 tools/testing/selftests/bpf/progs/mptcp_sockmap.c -- 2.43.0

1 month, 1 week

2
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[PATCH 0/9] mm/damon: support pin-point targets removal

by SeongJae Park

DAMON maintains the targets in a list, and allows committing only an entire list of targets having the new parameters. Targets having same index on the lists are treated as matching source and destination targets. If an existing target cannot find a matching one in the sources list, the target is removed. This means that there is no way to remove only a specific monitoring target in the middle of the current targets list. Such pin-point target removal is really needed in some use cases, though. Monitoring access patterns on virtual address spaces of processes that spawned from the same ancestor is one example. If a process of the group is terminated, the user may want to remove the matching DAMON target as soon as possible, to save in-kernel memory usage for the unnecessary target data. The user may also want to do that without turning DAMON off or removing unnecessary targets, to keep the current monitoring results for other active processes. Extend DAMON kernel API and sysfs ABI to support the pin-point removal in the following way. For API, add a new damon_target field, namely 'obsolete'. If the field on parameters commit source target is set, it means the matching destination target is obsolete. Then the parameters commit logic removes the destination target from the existing targets list. For sysfs ABI, add a new file under the target directory, namely 'obsolete_target'. It is connected with the 'obsolete' field of the commit source targets, so internally using the new API. Also add a selftest for the new feature. The related helper scripts for manipulating the sysfs interface and dumping in-kernel DAMON status are also extended for this. Note that the selftest part was initially posted as an individual RFC series [1], but now merged into this one. Bijan Tabatabai (bijan311(a)gmail.com) has originally reported this issue, and participated in this solution design on a GitHub issue [1] for DAMON user-space tool. Changes from RFC (https://lore.kernel.org/20251016214736.84286-1-sj@kernel.org) - Wordsmith commit messages - Add Reviewed-by: tags from Bijan - Add a kselftest for the functionality of the new feature (https://lore.kernel.org/20251018204448.8906-1-sj@kernel.org) [1] https://github.com/damonitor/damo/issues/36 SeongJae Park (9): mm/damon/core: add damon_target->obsolete for pin-point removal mm/damon/sysfs: test commit input against realistic destination mm/damon/sysfs: implement obsolete_target file Docs/admin-guide/mm/damon/usage: document obsolete_target file Docs/ABI/damon: document obsolete_target sysfs file selftests/damon/_damon_sysfs: support obsolete_target file drgn_dump_damon_status: dump damon_target->obsolete sysfs.py: extend assert_ctx_committed() for monitoring targets selftests/damon/sysfs: add obsolete_target test .../ABI/testing/sysfs-kernel-mm-damon | 7 +++ Documentation/admin-guide/mm/damon/usage.rst | 13 +++-- include/linux/damon.h | 6 +++ mm/damon/core.c | 10 +++- mm/damon/sysfs.c | 51 ++++++++++++++++++- tools/testing/selftests/damon/_damon_sysfs.py | 11 +++- .../selftests/damon/drgn_dump_damon_status.py | 1 + tools/testing/selftests/damon/sysfs.py | 48 +++++++++++++++++ 8 files changed, 140 insertions(+), 7 deletions(-) base-commit: a3e008fdd7964bc3e6d876491c202d476406ed59 -- 2.47.3

1 month, 1 week

1
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[PATCH net-next 0/5] psp: track stats from core and provide a driver stats api

by Daniel Zahka

This series introduces stats counters for psp. Device key rotations, and so called 'stale-events' are common to all drivers and are tracked by the core. A driver facing api is provided for reporting stats required by the "Implementation Requirements" section of the PSP Architecture Specification. Drivers must implement these stats. Lastly, implementations of the driver stats api for mlx5 and netdevsim are included. Here is the output of running the psp selftest suite and then printing out stats with the ynl cli on system with a psp-capable CX7: $ ./ksft-psp-stats/drivers/net/psp.py TAP version 13 1..28 ok 1 psp.test_case # SKIP Test requires IPv4 connectivity ok 2 psp.data_basic_send_v0_ip6 ok 3 psp.test_case # SKIP Test requires IPv4 connectivity ok 4 psp.data_basic_send_v1_ip6 ok 5 psp.test_case # SKIP Test requires IPv4 connectivity ok 6 psp.data_basic_send_v2_ip6 # SKIP ('PSP version not supported', 'hdr0-aes-gmac-128') ok 7 psp.test_case # SKIP Test requires IPv4 connectivity ok 8 psp.data_basic_send_v3_ip6 # SKIP ('PSP version not supported', 'hdr0-aes-gmac-256') ok 9 psp.test_case # SKIP Test requires IPv4 connectivity ok 10 psp.data_mss_adjust_ip6 ok 11 psp.dev_list_devices ok 12 psp.dev_get_device ok 13 psp.dev_get_device_bad ok 14 psp.dev_rotate ok 15 psp.dev_rotate_spi ok 16 psp.assoc_basic ok 17 psp.assoc_bad_dev ok 18 psp.assoc_sk_only_conn ok 19 psp.assoc_sk_only_mismatch ok 20 psp.assoc_sk_only_mismatch_tx ok 21 psp.assoc_sk_only_unconn ok 22 psp.assoc_version_mismatch ok 23 psp.assoc_twice ok 24 psp.data_send_bad_key ok 25 psp.data_send_disconnect ok 26 psp.data_stale_key ok 27 psp.removal_device_rx # XFAIL Test only works on netdevsim ok 28 psp.removal_device_bi # XFAIL Test only works on netdevsim # Totals: pass:19 fail:0 xfail:2 xpass:0 skip:7 error:0 # # Responder logs (0): # STDERR: # Set PSP enable on device 1 to 0x3 # Set PSP enable on device 1 to 0x0 $ cd ynl/ $ ./pyynl/cli.py --spec netlink/specs/psp.yaml --dump get-stats [{'dev-id': 1, 'key-rotations': 5, 'rx-auth-fail': 21, 'rx-bad': 0, 'rx-bytes': 11844, 'rx-error': 0, 'rx-packets': 94, 'stale-events': 6, 'tx-bytes': 1128456, 'tx-error': 0, 'tx-packets': 780}] Daniel Zahka (2): selftests: drv-net: psp: add assertions on core-tracked psp dev stats netdevsim: implement psp device stats Jakub Kicinski (3): psp: report basic stats from the core psp: add stats from psp spec to driver facing api net/mlx5e: Add PSP stats support for Rx/Tx flows Documentation/netlink/specs/psp.yaml | 95 +++++++ .../mellanox/mlx5/core/en_accel/psp.c | 239 ++++++++++++++++-- .../mellanox/mlx5/core/en_accel/psp.h | 18 ++ .../mellanox/mlx5/core/en_accel/psp_rxtx.c | 1 + .../net/ethernet/mellanox/mlx5/core/en_main.c | 5 + drivers/net/netdevsim/netdevsim.h | 5 + drivers/net/netdevsim/psp.c | 27 ++ include/net/psp/types.h | 35 +++ include/uapi/linux/psp.h | 18 ++ net/psp/psp-nl-gen.c | 19 ++ net/psp/psp-nl-gen.h | 2 + net/psp/psp_main.c | 3 +- net/psp/psp_nl.c | 99 ++++++++ net/psp/psp_sock.c | 4 +- tools/testing/selftests/drivers/net/psp.py | 13 + 15 files changed, 566 insertions(+), 17 deletions(-) -- 2.47.3

1 month, 1 week

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[PATCH 0/4] KVM: selftests: Add test of SET_NESTED_STATE with 48-bit L2 on 57-bit L1

by Jim Mattson

Prior to commit 9245fd6b8531 ("KVM: x86: model canonical checks more precisely"), KVM_SET_NESTED_STATE would fail if the state was captured with L2 active, L1 had CR4.LA57 set, L2 did not, and the VMCS12.HOST_GSBASE (or other host-state field checked for canonicality) had an address greater than 48 bits wide. Add a regression test that reproduces the KVM_SET_NESTED_STATE failure conditions. To do so, the first three patches add support for 5-level paging in the selftest L1 VM. Jim Mattson (4): KVM: selftests: Use a loop to create guest page tables KVM: selftests: Use a loop to walk guest page tables KVM: selftests: Add VM_MODE_PXXV57_4K VM mode KVM: selftests: Add a VMX test for LA57 nested state tools/testing/selftests/kvm/Makefile.kvm | 1 + .../testing/selftests/kvm/include/kvm_util.h | 1 + tools/testing/selftests/kvm/lib/kvm_util.c | 21 +++ .../testing/selftests/kvm/lib/x86/processor.c | 66 ++++----- tools/testing/selftests/kvm/lib/x86/vmx.c | 7 +- .../kvm/x86/vmx_la57_nested_state_test.c | 137 ++++++++++++++++++ 6 files changed, 195 insertions(+), 38 deletions(-) create mode 100644 tools/testing/selftests/kvm/x86/vmx_la57_nested_state_test.c -- 2.51.0.470.ga7dc726c21-goog

1 month, 1 week

3
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[PATCH net 0/2] netconsole: Fix userdata race condition

by Gustavo Luiz Duarte

This series fixes a race condition in netconsole's userdata handling where concurrent message transmission could read partially updated userdata fields, resulting in corrupted netconsole output. The first patch adds a selftest that reproduces the race condition by continuously sending messages while rapidly changing userdata values, detecting any torn reads in the output. The second patch fixes the issue by ensuring update_userdata() holds the target_list_lock while updating both extradata_complete and userdata_length, preventing readers from seeing inconsistent state. This targets net tree as it fixes a bug introduced in commit df03f830d099 ("net: netconsole: cache userdata formatted string in netconsole_target"). Signed-off-by: Gustavo Luiz Duarte <gustavold(a)gmail.com> --- Gustavo Luiz Duarte (2): selftests: netconsole: Add race condition test for userdata corruption netconsole: Fix race condition in between reader and writer of userdata drivers/net/netconsole.c | 5 ++ .../selftests/drivers/net/netcons_race_userdata.sh | 87 ++++++++++++++++++++++ 2 files changed, 92 insertions(+) --- base-commit: ffff5c8fc2af2218a3332b3d5b97654599d50cde change-id: 20251020-netconsole-fix-race-f465f37b57ea Best regards, -- Gustavo Luiz Duarte <gustavold(a)gmail.com>

1 month, 1 week

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[PATCH RESEND] selftests/cachestat: add tmpshmcstat file to .gitignore

by Madhur Kumar

Add the tmpshmcstat file to .gitignore to avoid accidentally staging the build artifact Signed-off-by: Madhur Kumar <madhurkumar004(a)gmail.com> --- tools/testing/selftests/cachestat/.gitignore | 1 + 1 file changed, 1 insertion(+) diff --git a/tools/testing/selftests/cachestat/.gitignore b/tools/testing/selftests/cachestat/.gitignore index d6c30b43a4bb..abbb13b6e96b 100644 --- a/tools/testing/selftests/cachestat/.gitignore +++ b/tools/testing/selftests/cachestat/.gitignore @@ -1,2 +1,3 @@ # SPDX-License-Identifier: GPL-2.0-only test_cachestat +tmpshmcstat -- 2.51.0

1 month, 1 week

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[PATCH v4 00/23] ARM64 PMU Partitioning

by Colton Lewis

This series creates a new PMU scheme on ARM, a partitioned PMU that allows reserving a subset of counters for more direct guest access, significantly reducing overhead. More details, including performance benchmarks, can be read in the v1 cover letter linked below. v4: * Apply Mark Brown's non-UNDEF FGT control commit to the PMU FGT controls and calculate those controls with the others in kvm_calculate_traps() * Introduce lazy context swaps for guests that only turns on for guests that have enabled partitioning and accessed PMU registers. * Rename pmu-part.c to pmu-direct.c because future features might achieve direct PMU access without partitioning. * Better explain certain commits, such as why the untrapped registers are safe to untrap. * Reduce the PMU include cleanup down to only what is still necessary and explain why. v3: https://lore.kernel.org/kvm/20250626200459.1153955-1-coltonlewis@google.com/ v2: https://lore.kernel.org/kvm/20250620221326.1261128-1-coltonlewis@google.com/ v1: https://lore.kernel.org/kvm/20250602192702.2125115-1-coltonlewis@google.com/ Colton Lewis (21): arm64: cpufeature: Add cpucap for HPMN0 KVM: arm64: Reorganize PMU functions perf: arm_pmuv3: Introduce method to partition the PMU perf: arm_pmuv3: Generalize counter bitmasks perf: arm_pmuv3: Keep out of guest counter partition KVM: arm64: Account for partitioning in kvm_pmu_get_max_counters() KVM: arm64: Set up FGT for Partitioned PMU KVM: arm64: Writethrough trapped PMEVTYPER register KVM: arm64: Use physical PMSELR for PMXEVTYPER if partitioned KVM: arm64: Writethrough trapped PMOVS register KVM: arm64: Write fast path PMU register handlers KVM: arm64: Setup MDCR_EL2 to handle a partitioned PMU KVM: arm64: Account for partitioning in PMCR_EL0 access KVM: arm64: Context swap Partitioned PMU guest registers KVM: arm64: Enforce PMU event filter at vcpu_load() KVM: arm64: Extract enum debug_owner to enum vcpu_register_owner KVM: arm64: Implement lazy PMU context swaps perf: arm_pmuv3: Handle IRQs for Partitioned PMU guest counters KVM: arm64: Inject recorded guest interrupts KVM: arm64: Add ioctl to partition the PMU when supported KVM: arm64: selftests: Add test case for partitioned PMU Marc Zyngier (1): KVM: arm64: Reorganize PMU includes Mark Brown (1): KVM: arm64: Introduce non-UNDEF FGT control Documentation/virt/kvm/api.rst | 21 + arch/arm/include/asm/arm_pmuv3.h | 38 + arch/arm64/include/asm/arm_pmuv3.h | 61 +- arch/arm64/include/asm/kvm_host.h | 34 +- arch/arm64/include/asm/kvm_pmu.h | 123 +++ arch/arm64/include/asm/kvm_types.h | 7 +- arch/arm64/kernel/cpufeature.c | 8 + arch/arm64/kvm/Makefile | 2 +- arch/arm64/kvm/arm.c | 22 + arch/arm64/kvm/debug.c | 33 +- arch/arm64/kvm/hyp/include/hyp/debug-sr.h | 6 +- arch/arm64/kvm/hyp/include/hyp/switch.h | 181 ++++- arch/arm64/kvm/pmu-direct.c | 395 ++++++++++ arch/arm64/kvm/pmu-emul.c | 674 +--------------- arch/arm64/kvm/pmu.c | 725 ++++++++++++++++++ arch/arm64/kvm/sys_regs.c | 137 +++- arch/arm64/tools/cpucaps | 1 + arch/arm64/tools/sysreg | 6 +- drivers/perf/arm_pmuv3.c | 128 +++- include/linux/perf/arm_pmu.h | 1 + include/linux/perf/arm_pmuv3.h | 14 +- include/uapi/linux/kvm.h | 4 + tools/include/uapi/linux/kvm.h | 2 + .../selftests/kvm/arm64/vpmu_counter_access.c | 62 +- 24 files changed, 1910 insertions(+), 775 deletions(-) create mode 100644 arch/arm64/kvm/pmu-direct.c base-commit: 79150772457f4d45e38b842d786240c36bb1f97f -- 2.50.0.727.gbf7dc18ff4-goog

1 month, 1 week

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next-20251020: selftests: helpers.h:10:10: fatal error: kselftest.h: No such file or directory

by Naresh Kamboju

The selftests x86_64 builds failed due to following build warnings / errors on the Linux next-20251020 and next-20251021 tags with gcc-14 and clang-21. First seen on next-20251020 Good: next-20251020 Bad: next-20251017 Regression Analysis: - New regression? yes - Reproducibility? yes ### Build errors x86_64-linux-gnu-gcc -m64 -o kselftest/x86/single_step_syscall_64 -O2 -g -std=gnu99 -pthread -Wall -isystem usr/include -no-pie -DCAN_BUILD_64 single_step_syscall.c -lrt -ldl In file included from single_step_syscall.c:34: helpers.h:10:10: fatal error: kselftest.h: No such file or directory 10 | #include "kselftest.h" | ^~~~~~~~~~~~~ compilation terminated. make[4]: *** [Makefile:86: kselftest/x86/single_step_syscall_64] Error 1 ### Suspected patch git log --oneline next-20251017..next-20251020 -- tools/testing/selftests/x86/ 4d89827dfb274 selftests: complete kselftest include centralization Build regressions: next-20251020: selftests: helpers.h:10:10: fatal error: kselftest.h: No such file or directory Reported-by: Linux Kernel Functional Testing <lkft(a)linaro.org> ### Steps to reproduce - tuxmake --runtime podman --target-arch x86_64 --toolchain gcc-14 \ --kconfig https://storage.tuxsuite.com/public/linaro/lkft/builds/34JgN0fZ9uXj6HVnjvjq… \ debugkernel cpupower headers kernel kselftest modules ## Source * Kernel version: 6.18.0-rc2 * Git tree: https://kernel.googlesource.com/pub/scm/linux/kernel/git/next/linux-next.git * Git describe: next-20251021 and next-20251020 * Git commit: fe45352cd106ae41b5ad3f0066c2e54dbb2dfd70 * Architectures: x86_64 * Toolchains: gcc-14 and clang-21 * Kconfigs: defconfig+selftests/*/configs ## Build * Build log: https://storage.tuxsuite.com/public/linaro/lkft/builds/34JgN0fZ9uXj6HVnjvjq… * Build details: https://regressions.linaro.org/lkft/linux-next-master/next-20251020/kselfte… * Build link: https://storage.tuxsuite.com/public/linaro/lkft/builds/34JgN0fZ9uXj6HVnjvjq… * Kernel config: https://storage.tuxsuite.com/public/linaro/lkft/builds/34JgN0fZ9uXj6HVnjvjq… -- Linaro LKFT https://lkft.linaro.org

1 month, 1 week

3
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[PATCH] selftest: net: prevent use of uninitialized variable

by Alessandro Zanni

Fix to avoid the usage of the `ret` variable uninitialized in the following macro expansions. It solves the following warning: In file included from netlink-dumps.c:21: netlink-dumps.c: In function ‘dump_extack’: ../kselftest_harness.h:788:35: warning: ‘ret’ may be used uninitialized [-Wmaybe-uninitialized] 788 | intmax_t __exp_print = (intmax_t)__exp; \ | ^~~~~~~~~~~ ../kselftest_harness.h:631:9: note: in expansion of macro ‘__EXPECT’ 631 | __EXPECT(expected, #expected, seen, #seen, ==, 0) | ^~~~~~~~ netlink-dumps.c:169:9: note: in expansion of macro ‘EXPECT_EQ’ 169 | EXPECT_EQ(ret, FOUND_EXTACK); | ^~~~~~~~~ The issue can be reproduced, building the tests, with the command: make -C tools/testing/selftests TARGETS=net Signed-off-by: Alessandro Zanni <alessandro.zanni87(a)gmail.com> --- tools/testing/selftests/net/netlink-dumps.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/testing/selftests/net/netlink-dumps.c b/tools/testing/selftests/net/netlink-dumps.c index 7618ebe528a4..8ebb8b1b9c5c 100644 --- a/tools/testing/selftests/net/netlink-dumps.c +++ b/tools/testing/selftests/net/netlink-dumps.c @@ -112,7 +112,7 @@ static const struct { TEST(dump_extack) { int netlink_sock; - int i, cnt, ret; + int i, cnt, ret = 0; char buf[8192]; int one = 1; ssize_t n; -- 2.43.0

1 month, 1 week

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