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[RFC PATCH v2 00/20] context_tracking,x86: Defer some IPIs until a user->kernel transition

by Valentin Schneider

Context ======= We've observed within Red Hat that isolated, NOHZ_FULL CPUs running a pure-userspace application get regularly interrupted by IPIs sent from housekeeping CPUs. Those IPIs are caused by activity on the housekeeping CPUs leading to various on_each_cpu() calls, e.g.: 64359.052209596 NetworkManager 0 1405 smp_call_function_many_cond (cpu=0, func=do_kernel_range_flush) smp_call_function_many_cond+0x1 smp_call_function+0x39 on_each_cpu+0x2a flush_tlb_kernel_range+0x7b __purge_vmap_area_lazy+0x70 _vm_unmap_aliases.part.42+0xdf change_page_attr_set_clr+0x16a set_memory_ro+0x26 bpf_int_jit_compile+0x2f9 bpf_prog_select_runtime+0xc6 bpf_prepare_filter+0x523 sk_attach_filter+0x13 sock_setsockopt+0x92c __sys_setsockopt+0x16a __x64_sys_setsockopt+0x20 do_syscall_64+0x87 entry_SYSCALL_64_after_hwframe+0x65 The heart of this series is the thought that while we cannot remove NOHZ_FULL CPUs from the list of CPUs targeted by these IPIs, they may not have to execute the callbacks immediately. Anything that only affects kernelspace can wait until the next user->kernel transition, providing it can be executed "early enough" in the entry code. The original implementation is from Peter [1]. Nicolas then added kernel TLB invalidation deferral to that [2], and I picked it up from there. Deferral approach ================= Storing each and every callback, like a secondary call_single_queue turned out to be a no-go: the whole point of deferral is to keep NOHZ_FULL CPUs in userspace for as long as possible - no signal of any form would be sent when deferring an IPI. This means that any form of queuing for deferred callbacks would end up as a convoluted memory leak. Deferred IPIs must thus be coalesced, which this series achieves by assigning IPIs a "type" and having a mapping of IPI type to callback, leveraged upon kernel entry. What about IPIs whose callback take a parameter, you may ask? Peter suggested during OSPM23 [3] that since on_each_cpu() targets housekeeping CPUs *and* isolated CPUs, isolated CPUs can access either global or housekeeping-CPU-local state to "reconstruct" the data that would have been sent via the IPI. This series does not affect any IPI callback that requires an argument, but the approach would remain the same (one coalescable callback executed on kernel entry). Kernel entry vs execution of the deferred operation =================================================== There is a non-zero length of code that is executed upon kernel entry before the deferred operation can be itself executed (i.e. before we start getting into context_tracking.c proper). This means one must take extra care to what can happen in the early entry code, and that <bad things> cannot happen. For instance, we really don't want to hit instructions that have been modified by a remote text_poke() while we're on our way to execute a deferred sync_core(). Patches ======= o Patches 1-9 have been submitted separately and are included for the sake of testing o Patches 10-14 focus on having objtool detect problematic static key usage in early entry o Patch 15 adds the infrastructure for IPI deferral. o Patches 16-17 add some RCU testing infrastructure o Patch 18 adds text_poke() IPI deferral. o Patches 19-20 add vunmap() flush_tlb_kernel_range() IPI deferral These ones I'm a lot less confident about, mostly due to lacking instrumentation/verification. The actual deferred callback is also incomplete as it's not properly noinstr: vmlinux.o: warning: objtool: __flush_tlb_all_noinstr+0x19: call to native_write_cr4() leaves .noinstr.text section and it doesn't support PARAVIRT - it's going to need a pv_ops.mmu entry, but I have *no idea* what a sane implementation would be for Xen so I haven't touched that yet. Patches are also available at: https://gitlab.com/vschneid/linux.git -b redhat/isolirq/defer/v2 Testing ======= Note: this is a different machine than used for v1, because that machine decided to act difficult. Xeon E5-2699 system with SMToff, NOHZ_FULL, isolated CPUs. RHEL9 userspace. Workload is using rteval (kernel compilation + hackbench) on housekeeping CPUs and a dummy stay-in-userspace loop on the isolated CPUs. The main invocation is: $ trace-cmd record -e "csd_queue_cpu" -f "cpu & CPUS{$ISOL_CPUS}" \ -e "ipi_send_cpumask" -f "cpumask & CPUS{$ISOL_CPUS}" \ -e "ipi_send_cpu" -f "cpu & CPUS{$ISOL_CPUS}" \ rteval --onlyload --loads-cpulist=$HK_CPUS \ --hackbench-runlowmem=True --duration=$DURATION This only records IPIs sent to isolated CPUs, so any event there is interference (with a bit of fuzz at the start/end of the workload when spawning the processes). All tests were done with a duration of 30 minutes. v6.5-rc1 (+ cpumask filtering patches): # This is the actual IPI count $ trace-cmd report | grep callback | awk '{ print $(NF) }' | sort | uniq -c | sort -nr 338 callback=generic_smp_call_function_single_interrupt+0x0 # These are the different CSD's that caused IPIs $ trace-cmd report | grep csd_queue | awk '{ print $(NF-1) }' | sort | uniq -c | sort -nr 9207 func=do_flush_tlb_all 1116 func=do_sync_core 62 func=do_kernel_range_flush 3 func=nohz_full_kick_func v6.5-rc1 + patches: # This is the actual IPI count $ trace-cmd report | grep callback | awk '{ print $(NF) }' | sort | uniq -c | sort -nr 2 callback=generic_smp_call_function_single_interrupt+0x0 # These are the different CSD's that caused IPIs $ trace-cmd report | grep csd_queue | awk '{ print $(NF-1) }' | sort | uniq -c | sort -nr 2 func=nohz_full_kick_func The incriminating IPIs are all gone, but note that on the machine I used to test v1 there were still some do_flush_tlb_all() IPIs caused by pcpu_balance_workfn(), since only vmalloc is affected by the deferral mechanism. Acknowledgements ================ Special thanks to: o Clark Williams for listening to my ramblings about this and throwing ideas my way o Josh Poimboeuf for his guidance regarding objtool and hinting at the .data..ro_after_init section. Links ===== [1]: https://lore.kernel.org/all/20210929151723.162004989@infradead.org/ [2]: https://github.com/vianpl/linux.git -b ct-work-defer-wip [3]: https://youtu.be/0vjE6fjoVVE Revisions ========= RFCv1 -> RFCv2 ++++++++++++++ o Rebased onto v6.5-rc1 o Updated the trace filter patches (Steven) o Fixed __ro_after_init keys used in modules (Peter) o Dropped the extra context_tracking atomic, squashed the new bits in the existing .state field (Peter, Frederic) o Added an RCU_EXPERT config for the RCU dynticks counter size, and added an rcutorture case for a low-size counter (Paul) The new TREE11 case with a 2-bit dynticks counter seems to pass when ran against this series. o Fixed flush_tlb_kernel_range_deferrable() definition Peter Zijlstra (1): jump_label,module: Don't alloc static_key_mod for __ro_after_init keys Valentin Schneider (19): tracing/filters: Dynamically allocate filter_pred.regex tracing/filters: Enable filtering a cpumask field by another cpumask tracing/filters: Enable filtering a scalar field by a cpumask tracing/filters: Enable filtering the CPU common field by a cpumask tracing/filters: Optimise cpumask vs cpumask filtering when user mask is a single CPU tracing/filters: Optimise scalar vs cpumask filtering when the user mask is a single CPU tracing/filters: Optimise CPU vs cpumask filtering when the user mask is a single CPU tracing/filters: Further optimise scalar vs cpumask comparison tracing/filters: Document cpumask filtering objtool: Flesh out warning related to pv_ops[] calls objtool: Warn about non __ro_after_init static key usage in .noinstr context_tracking: Make context_tracking_key __ro_after_init x86/kvm: Make kvm_async_pf_enabled __ro_after_init context-tracking: Introduce work deferral infrastructure rcu: Make RCU dynticks counter size configurable rcutorture: Add a test config to torture test low RCU_DYNTICKS width context_tracking,x86: Defer kernel text patching IPIs context_tracking,x86: Add infrastructure to defer kernel TLBI x86/mm, mm/vmalloc: Defer flush_tlb_kernel_range() targeting NOHZ_FULL CPUs Documentation/trace/events.rst | 14 + arch/Kconfig | 9 + arch/x86/Kconfig | 1 + arch/x86/include/asm/context_tracking_work.h | 20 ++ arch/x86/include/asm/text-patching.h | 1 + arch/x86/include/asm/tlbflush.h | 2 + arch/x86/kernel/alternative.c | 24 +- arch/x86/kernel/kprobes/core.c | 4 +- arch/x86/kernel/kprobes/opt.c | 4 +- arch/x86/kernel/kvm.c | 2 +- arch/x86/kernel/module.c | 2 +- arch/x86/mm/tlb.c | 40 ++- include/asm-generic/sections.h | 5 + include/linux/context_tracking.h | 26 ++ include/linux/context_tracking_state.h | 65 +++- include/linux/context_tracking_work.h | 28 ++ include/linux/jump_label.h | 1 + include/linux/trace_events.h | 1 + init/main.c | 1 + kernel/context_tracking.c | 53 ++- kernel/jump_label.c | 49 +++ kernel/rcu/Kconfig | 33 ++ kernel/time/Kconfig | 5 + kernel/trace/trace_events_filter.c | 302 ++++++++++++++++-- mm/vmalloc.c | 19 +- tools/objtool/check.c | 22 +- tools/objtool/include/objtool/check.h | 1 + tools/objtool/include/objtool/special.h | 2 + tools/objtool/special.c | 3 + .../selftests/rcutorture/configs/rcu/TREE11 | 19 ++ .../rcutorture/configs/rcu/TREE11.boot | 1 + 31 files changed, 695 insertions(+), 64 deletions(-) create mode 100644 arch/x86/include/asm/context_tracking_work.h create mode 100644 include/linux/context_tracking_work.h create mode 100644 tools/testing/selftests/rcutorture/configs/rcu/TREE11 create mode 100644 tools/testing/selftests/rcutorture/configs/rcu/TREE11.boot -- 2.31.1

2 years

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[PATCH] Documentation: kselftests: Remove references to bpf tests

by Marcos Paulo de Souza

Currently the bpf selftests are skipped by default, so is someone would like to run the tests one would need to run: $ make TARGETS=bpf SKIP_TARGETS="" kselftest To overwrite the SKIP_TARGETS that defines bpf by default. Also, following the BPF instructions[1], to run the bpf selftests one would need to enter in the tools/testing/selftests/bpf/ directory, and then run make, which is not the standard way to run selftests per it's documentation. For the reasons above stop mentioning bpf in the kselftests as examples of how to run a test suite. [1]: Documentation/bpf/bpf_devel_QA.rst Signed-off-by: Marcos Paulo de Souza <mpdesouza(a)suse.com> --- Documentation/dev-tools/kselftest.rst | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/Documentation/dev-tools/kselftest.rst b/Documentation/dev-tools/kselftest.rst index deede972f254..ab376b316c36 100644 --- a/Documentation/dev-tools/kselftest.rst +++ b/Documentation/dev-tools/kselftest.rst @@ -112,7 +112,7 @@ You can specify multiple tests to skip:: You can also specify a restricted list of tests to run together with a dedicated skiplist:: - $ make TARGETS="bpf breakpoints size timers" SKIP_TARGETS=bpf kselftest + $ make TARGETS="breakpoints size timers" SKIP_TARGETS=size kselftest See the top-level tools/testing/selftests/Makefile for the list of all possible targets. @@ -165,7 +165,7 @@ To see the list of available tests, the `-l` option can be used:: The `-c` option can be used to run all the tests from a test collection, or the `-t` option for specific single tests. Either can be used multiple times:: - $ ./run_kselftest.sh -c bpf -c seccomp -t timers:posix_timers -t timer:nanosleep + $ ./run_kselftest.sh -c size -c seccomp -t timers:posix_timers -t timer:nanosleep For other features see the script usage output, seen with the `-h` option. @@ -210,7 +210,7 @@ option is supported, such as:: tests by using variables specified in `Running a subset of selftests`_ section:: - $ make -C tools/testing/selftests gen_tar TARGETS="bpf" FORMAT=.xz + $ make -C tools/testing/selftests gen_tar TARGETS="size" FORMAT=.xz .. _tar's auto-compress: https://www.gnu.org/software/tar/manual/html_node/gzip.html#auto_002dcompre… -- 2.42.0

2 years

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[PATCH v6 00/38] arm64/gcs: Provide support for GCS in userspace

by Mark Brown

The arm64 Guarded Control Stack (GCS) feature provides support for hardware protected stacks of return addresses, intended to provide hardening against return oriented programming (ROP) attacks and to make it easier to gather call stacks for applications such as profiling. When GCS is active a secondary stack called the Guarded Control Stack is maintained, protected with a memory attribute which means that it can only be written with specific GCS operations. The current GCS pointer can not be directly written to by userspace. When a BL is executed the value stored in LR is also pushed onto the GCS, and when a RET is executed the top of the GCS is popped and compared to LR with a fault being raised if the values do not match. GCS operations may only be performed on GCS pages, a data abort is generated if they are not. The combination of hardware enforcement and lack of extra instructions in the function entry and exit paths should result in something which has less overhead and is more difficult to attack than a purely software implementation like clang's shadow stacks. This series implements support for use of GCS by userspace, along with support for use of GCS within KVM guests. It does not enable use of GCS by either EL1 or EL2, this will be implemented separately. Executables are started without GCS and must use a prctl() to enable it, it is expected that this will be done very early in application execution by the dynamic linker or other startup code. For dynamic linking this will be done by checking that everything in the executable is marked as GCS compatible. x86 has an equivalent feature called shadow stacks, this series depends on the x86 patches for generic memory management support for the new guarded/shadow stack page type and shares APIs as much as possible. As there has been extensive discussion with the wider community around the ABI for shadow stacks I have as far as practical kept implementation decisions close to those for x86, anticipating that review would lead to similar conclusions in the absence of strong reasoning for divergence. The main divergence I am concious of is that x86 allows shadow stack to be enabled and disabled repeatedly, freeing the shadow stack for the thread whenever disabled, while this implementation keeps the GCS allocated after disable but refuses to reenable it. This is to avoid races with things actively walking the GCS during a disable, we do anticipate that some systems will wish to disable GCS at runtime but are not aware of any demand for subsequently reenabling it. x86 uses an arch_prctl() to manage enable and disable, since only x86 and S/390 use arch_prctl() a generic prctl() was proposed[1] as part of a patch set for the equivalent RISC-V zisslpcfi feature which I initially adopted fairly directly but following review feedback has been revised quite a bit. There is an open issue with support for CRIU, on x86 this required the ability to set the GCS mode via ptrace. This series supports configuring mode bits other than enable/disable via ptrace but it needs to be confirmed if this is sufficient. There's a few bits where I'm not convinced with where I've placed things, in particular the GCS write operation is in the GCS header not in uaccess.h, I wasn't sure what was clearest there and am probably too close to the code to have a clear opinion. The reporting of GCS in /proc/PID/smaps is also a bit awkward. The series depends on the x86 shadow stack support: https://lore.kernel.org/lkml/20230227222957.24501-1-rick.p.edgecombe@intel.… I've rebased this onto v6.5-rc4 but not included it in the series in order to avoid confusion with Rick's work and cut down the size of the series, you can see the branch at: https://git.kernel.org/pub/scm/linux/kernel/git/broonie/misc.git arm64-gcs [1] https://lore.kernel.org/lkml/20230213045351.3945824-1-debug@rivosinc.com/ Pending feedback from Catalin: - Use clone3() paramaters to size/place the GCS. - Switch copy_to_user_gcs() to be put_user_gcs(). Signed-off-by: Mark Brown <broonie(a)kernel.org> --- Changes in v6: - Rebase onto v6.6-rc3. - Add some more gcsb_dsync() barriers following spec clarifications. - Due to ongoing discussion around clone()/clone3() I've not updated anything there, the behaviour is the same as on previous versions. - Link to v5: https://lore.kernel.org/r/20230822-arm64-gcs-v5-0-9ef181dd6324@kernel.org Changes in v5: - Don't map any permissions for user GCSs, we always use EL0 accessors or use a separate mapping of the page. - Reduce the standard size of the GCS to RLIMIT_STACK/2. - Enforce a PAGE_SIZE alignment requirement on map_shadow_stack(). - Clarifications and fixes to documentation. - More tests. - Link to v4: https://lore.kernel.org/r/20230807-arm64-gcs-v4-0-68cfa37f9069@kernel.org Changes in v4: - Implement flags for map_shadow_stack() allowing the cap and end of stack marker to be enabled independently or not at all. - Relax size and alignment requirements for map_shadow_stack(). - Add more blurb explaining the advantages of hardware enforcement. - Link to v3: https://lore.kernel.org/r/20230731-arm64-gcs-v3-0-cddf9f980d98@kernel.org Changes in v3: - Rebase onto v6.5-rc4. - Add a GCS barrier on context switch. - Add a GCS stress test. - Link to v2: https://lore.kernel.org/r/20230724-arm64-gcs-v2-0-dc2c1d44c2eb@kernel.org Changes in v2: - Rebase onto v6.5-rc3. - Rework prctl() interface to allow each bit to be locked independently. - map_shadow_stack() now places the cap token based on the size requested by the caller not the actual space allocated. - Mode changes other than enable via ptrace are now supported. - Expand test coverage. - Various smaller fixes and adjustments. - Link to v1: https://lore.kernel.org/r/20230716-arm64-gcs-v1-0-bf567f93bba6@kernel.org --- Mark Brown (38): arm64/mm: Restructure arch_validate_flags() for extensibility prctl: arch-agnostic prctl for shadow stack mman: Add map_shadow_stack() flags arm64: Document boot requirements for Guarded Control Stacks arm64/gcs: Document the ABI for Guarded Control Stacks arm64/sysreg: Add new system registers for GCS arm64/sysreg: Add definitions for architected GCS caps arm64/gcs: Add manual encodings of GCS instructions arm64/gcs: Provide copy_to_user_gcs() arm64/cpufeature: Runtime detection of Guarded Control Stack (GCS) arm64/mm: Allocate PIE slots for EL0 guarded control stack mm: Define VM_SHADOW_STACK for arm64 when we support GCS arm64/mm: Map pages for guarded control stack KVM: arm64: Manage GCS registers for guests arm64/gcs: Allow GCS usage at EL0 and EL1 arm64/idreg: Add overrride for GCS arm64/hwcap: Add hwcap for GCS arm64/traps: Handle GCS exceptions arm64/mm: Handle GCS data aborts arm64/gcs: Context switch GCS state for EL0 arm64/gcs: Allocate a new GCS for threads with GCS enabled arm64/gcs: Implement shadow stack prctl() interface arm64/mm: Implement map_shadow_stack() arm64/signal: Set up and restore the GCS context for signal handlers arm64/signal: Expose GCS state in signal frames arm64/ptrace: Expose GCS via ptrace and core files arm64: Add Kconfig for Guarded Control Stack (GCS) kselftest/arm64: Verify the GCS hwcap kselftest/arm64: Add GCS as a detected feature in the signal tests kselftest/arm64: Add framework support for GCS to signal handling tests kselftest/arm64: Allow signals tests to specify an expected si_code kselftest/arm64: Always run signals tests with GCS enabled kselftest/arm64: Add very basic GCS test program kselftest/arm64: Add a GCS test program built with the system libc kselftest/arm64: Add test coverage for GCS mode locking selftests/arm64: Add GCS signal tests kselftest/arm64: Add a GCS stress test kselftest/arm64: Enable GCS for the FP stress tests Documentation/admin-guide/kernel-parameters.txt | 6 + Documentation/arch/arm64/booting.rst | 22 + Documentation/arch/arm64/elf_hwcaps.rst | 3 + Documentation/arch/arm64/gcs.rst | 233 +++++++ Documentation/arch/arm64/index.rst | 1 + Documentation/filesystems/proc.rst | 2 +- arch/arm64/Kconfig | 19 + arch/arm64/include/asm/cpufeature.h | 6 + arch/arm64/include/asm/el2_setup.h | 17 + arch/arm64/include/asm/esr.h | 28 +- arch/arm64/include/asm/exception.h | 2 + arch/arm64/include/asm/gcs.h | 106 +++ arch/arm64/include/asm/hwcap.h | 1 + arch/arm64/include/asm/kvm_arm.h | 4 +- arch/arm64/include/asm/kvm_host.h | 12 + arch/arm64/include/asm/mman.h | 23 +- arch/arm64/include/asm/pgtable-prot.h | 14 +- arch/arm64/include/asm/processor.h | 7 + arch/arm64/include/asm/sysreg.h | 20 + arch/arm64/include/asm/uaccess.h | 42 ++ arch/arm64/include/uapi/asm/hwcap.h | 1 + arch/arm64/include/uapi/asm/ptrace.h | 8 + arch/arm64/include/uapi/asm/sigcontext.h | 9 + arch/arm64/kernel/cpufeature.c | 19 + arch/arm64/kernel/cpuinfo.c | 1 + arch/arm64/kernel/entry-common.c | 23 + arch/arm64/kernel/idreg-override.c | 2 + arch/arm64/kernel/process.c | 92 +++ arch/arm64/kernel/ptrace.c | 59 ++ arch/arm64/kernel/signal.c | 237 ++++++- arch/arm64/kernel/traps.c | 11 + arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h | 17 + arch/arm64/kvm/sys_regs.c | 22 + arch/arm64/mm/Makefile | 1 + arch/arm64/mm/fault.c | 79 ++- arch/arm64/mm/gcs.c | 228 +++++++ arch/arm64/mm/mmap.c | 13 +- arch/arm64/tools/cpucaps | 1 + arch/arm64/tools/sysreg | 55 ++ arch/x86/include/uapi/asm/mman.h | 3 - fs/proc/task_mmu.c | 3 + include/linux/mm.h | 16 +- include/uapi/asm-generic/mman.h | 4 + include/uapi/asm-generic/unistd.h | 5 +- include/uapi/linux/elf.h | 1 + include/uapi/linux/prctl.h | 22 + kernel/sys.c | 30 + tools/testing/selftests/arm64/Makefile | 2 +- tools/testing/selftests/arm64/abi/hwcap.c | 19 + tools/testing/selftests/arm64/fp/assembler.h | 15 + tools/testing/selftests/arm64/fp/fpsimd-test.S | 2 + tools/testing/selftests/arm64/fp/sve-test.S | 2 + tools/testing/selftests/arm64/fp/za-test.S | 2 + tools/testing/selftests/arm64/fp/zt-test.S | 2 + tools/testing/selftests/arm64/gcs/.gitignore | 5 + tools/testing/selftests/arm64/gcs/Makefile | 24 + tools/testing/selftests/arm64/gcs/asm-offsets.h | 0 tools/testing/selftests/arm64/gcs/basic-gcs.c | 356 ++++++++++ tools/testing/selftests/arm64/gcs/gcs-locking.c | 200 ++++++ .../selftests/arm64/gcs/gcs-stress-thread.S | 311 +++++++++ tools/testing/selftests/arm64/gcs/gcs-stress.c | 532 +++++++++++++++ tools/testing/selftests/arm64/gcs/gcs-util.h | 100 +++ tools/testing/selftests/arm64/gcs/libc-gcs.c | 742 +++++++++++++++++++++ tools/testing/selftests/arm64/signal/.gitignore | 1 + .../testing/selftests/arm64/signal/test_signals.c | 17 +- .../testing/selftests/arm64/signal/test_signals.h | 6 + .../selftests/arm64/signal/test_signals_utils.c | 32 +- .../selftests/arm64/signal/test_signals_utils.h | 39 ++ .../arm64/signal/testcases/gcs_exception_fault.c | 59 ++ .../selftests/arm64/signal/testcases/gcs_frame.c | 78 +++ .../arm64/signal/testcases/gcs_write_fault.c | 67 ++ .../selftests/arm64/signal/testcases/testcases.c | 7 + .../selftests/arm64/signal/testcases/testcases.h | 1 + 73 files changed, 4110 insertions(+), 41 deletions(-) --- base-commit: 6465e260f48790807eef06b583b38ca9789b6072 change-id: 20230303-arm64-gcs-e311ab0d8729 Best regards, -- Mark Brown <broonie(a)kernel.org>

2 years

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Re: [RFC PATCH 1/7] net: skbuff: Add tun_vnet_hash flag

by Willem de Bruijn

On Sun, Oct 8, 2023 at 7:22 AM Akihiko Odaki <akihiko.odaki(a)daynix.com> wrote: > > tun_vnet_hash can use this flag to indicate it stored virtio-net hash > cache to cb. > > Signed-off-by: Akihiko Odaki <akihiko.odaki(a)daynix.com> > --- > include/linux/skbuff.h | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h > index 4174c4b82d13..e638f157c13c 100644 > --- a/include/linux/skbuff.h > +++ b/include/linux/skbuff.h > @@ -837,6 +837,7 @@ typedef unsigned char *sk_buff_data_t; > * @truesize: Buffer size > * @users: User count - see {datagram,tcp}.c > * @extensions: allocated extensions, valid if active_extensions is nonzero > + * @tun_vnet_hash: tun stored virtio-net hash cache to cb > */ > > struct sk_buff { > @@ -989,6 +990,7 @@ struct sk_buff { > #if IS_ENABLED(CONFIG_IP_SCTP) > __u8 csum_not_inet:1; > #endif > + __u8 tun_vnet_hash:1; sk_buff space is very limited. No need to extend it, especially for code that stays within a single subsystem (tun). To a lesser extent the same point applies to the qdisc_skb_cb.

2 years

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Re: [RFC PATCH 0/7] tun: Introduce virtio-net hashing feature

by Willem de Bruijn

On Sun, Oct 8, 2023 at 7:21 AM Akihiko Odaki <akihiko.odaki(a)daynix.com> wrote: > > virtio-net have two usage of hashes: one is RSS and another is hash > reporting. Conventionally the hash calculation was done by the VMM. > However, computing the hash after the queue was chosen defeats the > purpose of RSS. > > Another approach is to use eBPF steering program. This approach has > another downside: it cannot report the calculated hash due to the > restrictive nature of eBPF. > > Introduce the code to compute hashes to the kernel in order to overcome > thse challenges. > > An alternative solution is to extend the eBPF steering program so that it > will be able to report to the userspace, but it makes little sense to > allow to implement different hashing algorithms with eBPF since the hash > value reported by virtio-net is strictly defined by the specification. But using the existing BPF steering may have the benefit of requiring a lot less new code. There is ample precedence for BPF programs that work this way. The flow dissector comes to mind.

2 years

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[PATCH] tools/nolibc: drop test for getauxval(AT_PAGESZ)

by Thomas Weißschuh

The test will not work for systems with pagesize != 4096 like aarch64 and some others. Other testcases are already testing the same functionality: * auxv_AT_UID tests getauxval() in general. * test_getpagesize() tests pagesize() which directly calls getauxval(AT_PAGESZ). Fixes: 48967b73f8fe ("selftests/nolibc: add testcases for startup code") Cc: stable(a)vger.kernel.org Signed-off-by: Thomas Weißschuh <linux(a)weissschuh.net> --- Note: This should probably also make it into 6.6. --- tools/testing/selftests/nolibc/nolibc-test.c | 1 - 1 file changed, 1 deletion(-) diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c index a3ee4496bf0a..7e3936c182dc 100644 --- a/tools/testing/selftests/nolibc/nolibc-test.c +++ b/tools/testing/selftests/nolibc/nolibc-test.c @@ -630,7 +630,6 @@ int run_startup(int min, int max) CASE_TEST(environ_HOME); EXPECT_PTRNZ(1, getenv("HOME")); break; CASE_TEST(auxv_addr); EXPECT_PTRGT(test_auxv != (void *)-1, test_auxv, brk); break; CASE_TEST(auxv_AT_UID); EXPECT_EQ(1, getauxval(AT_UID), getuid()); break; - CASE_TEST(auxv_AT_PAGESZ); EXPECT_GE(1, getauxval(AT_PAGESZ), 4096); break; case __LINE__: return ret; /* must be last */ /* note: do not set any defaults so as to permit holes above */ --- base-commit: ab663cc32912914258bc8a2fbd0e753f552ee9d8 change-id: 20231007-nolibc-auxval-pagesz-05f5ff79c4c4 Best regards, -- Thomas Weißschuh <linux(a)weissschuh.net>

2 years

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[PATCH v2] tools/nolibc: add support for constructors and destructors

by Thomas Weißschuh

With the startup code moved to C, implementing support for constructors and deconstructors is fairly easy to implement. Examples for code size impact: text data bss dec hex filename 21837 104 88 22029 560d nolibc-test.before 22135 120 88 22343 5747 nolibc-test.after 21970 104 88 22162 5692 nolibc-test.after-only-crt.h-changes The sections are defined by [0]. [0] https://refspecs.linuxfoundation.org/elf/gabi4+/ch5.dynamic.html Signed-off-by: Thomas Weißschuh <linux(a)weissschuh.net> --- Changes in v2: - Drop RFC status. - Add comment to constructor test that execution in definition-order is expected. (Willy) - Rework destructor loop to avoid underflow if __fini_array_end is not provided by the linker. - Link to v1: https://lore.kernel.org/r/20231005-nolibc-constructors-v1-1-776d56bbe917@we… --- tools/include/nolibc/crt.h | 23 ++++++++++++++++++++++- tools/testing/selftests/nolibc/nolibc-test.c | 17 +++++++++++++++++ 2 files changed, 39 insertions(+), 1 deletion(-) diff --git a/tools/include/nolibc/crt.h b/tools/include/nolibc/crt.h index a5f33fef1672..b84f5fbb7b58 100644 --- a/tools/include/nolibc/crt.h +++ b/tools/include/nolibc/crt.h @@ -13,11 +13,22 @@ const unsigned long *_auxv __attribute__((weak)); static void __stack_chk_init(void); static void exit(int); +extern void (*const __preinit_array_start[])(void) __attribute__((weak)); +extern void (*const __preinit_array_end[])(void) __attribute__((weak)); + +extern void (*const __init_array_start[])(void) __attribute__((weak)); +extern void (*const __init_array_end[])(void) __attribute__((weak)); + +extern void (*const __fini_array_start[])(void) __attribute__((weak)); +extern void (*const __fini_array_end[])(void) __attribute__((weak)); + void _start_c(long *sp) { long argc; char **argv; char **envp; + int exitcode; + void (* const *func)(void); const unsigned long *auxv; /* silence potential warning: conflicting types for 'main' */ int _nolibc_main(int, char **, char **) __asm__ ("main"); @@ -54,8 +65,18 @@ void _start_c(long *sp) ; _auxv = auxv; + for (func = __preinit_array_start; func < __preinit_array_end; func++) + (*func)(); + for (func = __init_array_start; func < __init_array_end; func++) + (*func)(); + /* go to application */ - exit(_nolibc_main(argc, argv, envp)); + exitcode = _nolibc_main(argc, argv, envp); + + for (func = __fini_array_end; func > __fini_array_start;) + (*--func)(); + + exit(exitcode); } #endif /* _NOLIBC_CRT_H */ diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c index a3ee4496bf0a..88ea8e06e596 100644 --- a/tools/testing/selftests/nolibc/nolibc-test.c +++ b/tools/testing/selftests/nolibc/nolibc-test.c @@ -57,6 +57,9 @@ static int test_argc; /* will be used by some test cases as readable file, please don't write it */ static const char *argv0; +/* will be used by constructor tests */ +static int constructor_test_value; + /* definition of a series of tests */ struct test { const char *name; /* test name */ @@ -594,6 +597,19 @@ int expect_strne(const char *expr, int llen, const char *cmp) #define CASE_TEST(name) \ case __LINE__: llen += printf("%d %s", test, #name); +/* constructors validate that they are executed in definition order */ +__attribute__((constructor)) +static void constructor1(void) +{ + constructor_test_value = 1; +} + +__attribute__((constructor)) +static void constructor2(void) +{ + constructor_test_value *= 2; +} + int run_startup(int min, int max) { int test; @@ -631,6 +647,7 @@ int run_startup(int min, int max) CASE_TEST(auxv_addr); EXPECT_PTRGT(test_auxv != (void *)-1, test_auxv, brk); break; CASE_TEST(auxv_AT_UID); EXPECT_EQ(1, getauxval(AT_UID), getuid()); break; CASE_TEST(auxv_AT_PAGESZ); EXPECT_GE(1, getauxval(AT_PAGESZ), 4096); break; + CASE_TEST(constructor); EXPECT_EQ(1, constructor_test_value, 2); break; case __LINE__: return ret; /* must be last */ /* note: do not set any defaults so as to permit holes above */ --- base-commit: ab663cc32912914258bc8a2fbd0e753f552ee9d8 change-id: 20231005-nolibc-constructors-b2aebffe9b65 Best regards, -- Thomas Weißschuh <linux(a)weissschuh.net>

2 years

2
1
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[PATCH 0/4] kunit: Fix indentation of parameterized tests messages

by Michal Wajdeczko

The indentation of parameterized tests messages is currently broken in kunit. Try to fix that by introducing a test level attribute, that will be increased during nested parameterized tests execution, and use it to generate correct indent at the runtime when printing message or writing them to the log. Also improve kunit by providing test plan for the parameterized tests. Cc: David Gow <davidgow(a)google.com> Cc: Rae Moar <rmoar(a)google.com> Michal Wajdeczko (4): kunit: Drop redundant text from suite init failure message kunit: Fix indentation level of suite messages kunit: Fix indentation of parameterized tests messages kunit: Prepare test plan for parameterized subtests include/kunit/test.h | 25 ++++++++++++-- lib/kunit/test.c | 79 +++++++++++++++++++++++--------------------- 2 files changed, 65 insertions(+), 39 deletions(-) -- 2.25.1

2 years

3
16
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[PATCH] kunit: Reset suite counter right before running tests

by Michal Wajdeczko

Today we reset the suite counter as part of the suite cleanup, called from the module exit callback, but it might not work that well as one can try to collect results without unloading a previous test (either unintentionally or due to dependencies). For easy reproduction try to load the kunit-test.ko and then collect and parse results from the kunit-example-test.ko load. Parser will complain about mismatch of expected test number: [ ] KTAP version 1 [ ] 1..1 [ ] # example: initializing suite [ ] KTAP version 1 [ ] # Subtest: example .. [ ] # example: pass:5 fail:0 skip:4 total:9 [ ] # Totals: pass:6 fail:0 skip:6 total:12 [ ] ok 7 example [ ] [ERROR] Test: example: Expected test number 1 but found 7 [ ] ===================== [PASSED] example ===================== [ ] ============================================================ [ ] Testing complete. Ran 12 tests: passed: 6, skipped: 6, errors: 1 Since we are now printing suite test plan on every module load, right before running suite tests, we should make sure that suite counter will also start from 1. Easiest solution seems to be move counter reset to the __kunit_test_suites_init() function. Signed-off-by: Michal Wajdeczko <michal.wajdeczko(a)intel.com> Cc: David Gow <davidgow(a)google.com> Cc: Rae Moar <rmoar(a)google.com> --- lib/kunit/test.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/lib/kunit/test.c b/lib/kunit/test.c index f2eb71f1a66c..9325d309ed82 100644 --- a/lib/kunit/test.c +++ b/lib/kunit/test.c @@ -670,6 +670,8 @@ int __kunit_test_suites_init(struct kunit_suite * const * const suites, int num_ return 0; } + kunit_suite_counter = 1; + static_branch_inc(&kunit_running); for (i = 0; i < num_suites; i++) { @@ -696,8 +698,6 @@ void __kunit_test_suites_exit(struct kunit_suite **suites, int num_suites) for (i = 0; i < num_suites; i++) kunit_exit_suite(suites[i]); - - kunit_suite_counter = 1; } EXPORT_SYMBOL_GPL(__kunit_test_suites_exit); -- 2.25.1

2 years

2
1
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[PATCH RFC] tools/nolibc: add support for constructors and destructors

by Thomas Weißschuh

With the startup code moved to C, implementing support for constructors and deconstructors is fairly easy to implement. Examples for code size impact: text data bss dec hex filename 21837 104 88 22029 560d nolibc-test.before 22135 120 88 22343 5747 nolibc-test.after 21970 104 88 22162 5692 nolibc-test.after-only-crt.h-changes The sections are defined by [0]. [0] https://refspecs.linuxfoundation.org/elf/gabi4+/ch5.dynamic.html Signed-off-by: Thomas Weißschuh <linux(a)weissschuh.net> --- Note: This is only an RFC as I'm not 100% sure it belong into nolibc. But at least the code is visible as an example. Also it is one prerequisite for full ksefltest_harness.h support in nolibc, should we want that. --- tools/include/nolibc/crt.h | 23 ++++++++++++++++++++++- tools/testing/selftests/nolibc/nolibc-test.c | 16 ++++++++++++++++ 2 files changed, 38 insertions(+), 1 deletion(-) diff --git a/tools/include/nolibc/crt.h b/tools/include/nolibc/crt.h index a5f33fef1672..c1176611d9a9 100644 --- a/tools/include/nolibc/crt.h +++ b/tools/include/nolibc/crt.h @@ -13,11 +13,22 @@ const unsigned long *_auxv __attribute__((weak)); static void __stack_chk_init(void); static void exit(int); +extern void (*const __preinit_array_start[])(void) __attribute__((weak)); +extern void (*const __preinit_array_end[])(void) __attribute__((weak)); + +extern void (*const __init_array_start[])(void) __attribute__((weak)); +extern void (*const __init_array_end[])(void) __attribute__((weak)); + +extern void (*const __fini_array_start[])(void) __attribute__((weak)); +extern void (*const __fini_array_end[])(void) __attribute__((weak)); + void _start_c(long *sp) { long argc; char **argv; char **envp; + int exitcode; + void (* const *func)(void); const unsigned long *auxv; /* silence potential warning: conflicting types for 'main' */ int _nolibc_main(int, char **, char **) __asm__ ("main"); @@ -54,8 +65,18 @@ void _start_c(long *sp) ; _auxv = auxv; + for (func = __preinit_array_start; func < __preinit_array_end; func++) + (*func)(); + for (func = __init_array_start; func < __init_array_end; func++) + (*func)(); + /* go to application */ - exit(_nolibc_main(argc, argv, envp)); + exitcode = _nolibc_main(argc, argv, envp); + + for (func = __fini_array_end - 1; func >= __fini_array_start; func--) + (*func)(); + + exit(exitcode); } #endif /* _NOLIBC_CRT_H */ diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c index a3ee4496bf0a..f166b425613a 100644 --- a/tools/testing/selftests/nolibc/nolibc-test.c +++ b/tools/testing/selftests/nolibc/nolibc-test.c @@ -57,6 +57,9 @@ static int test_argc; /* will be used by some test cases as readable file, please don't write it */ static const char *argv0; +/* will be used by constructor tests */ +static int constructor_test_value; + /* definition of a series of tests */ struct test { const char *name; /* test name */ @@ -594,6 +597,18 @@ int expect_strne(const char *expr, int llen, const char *cmp) #define CASE_TEST(name) \ case __LINE__: llen += printf("%d %s", test, #name); +__attribute__((constructor)) +static void constructor1(void) +{ + constructor_test_value = 1; +} + +__attribute__((constructor)) +static void constructor2(void) +{ + constructor_test_value *= 2; +} + int run_startup(int min, int max) { int test; @@ -631,6 +646,7 @@ int run_startup(int min, int max) CASE_TEST(auxv_addr); EXPECT_PTRGT(test_auxv != (void *)-1, test_auxv, brk); break; CASE_TEST(auxv_AT_UID); EXPECT_EQ(1, getauxval(AT_UID), getuid()); break; CASE_TEST(auxv_AT_PAGESZ); EXPECT_GE(1, getauxval(AT_PAGESZ), 4096); break; + CASE_TEST(constructor); EXPECT_EQ(1, constructor_test_value, 2); break; case __LINE__: return ret; /* must be last */ /* note: do not set any defaults so as to permit holes above */ --- base-commit: ab663cc32912914258bc8a2fbd0e753f552ee9d8 change-id: 20231005-nolibc-constructors-b2aebffe9b65 Best regards, -- Thomas Weißschuh <linux(a)weissschuh.net>

2 years

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