- Linux-kselftest-mirror - lists.linaro.org

[PATCH] rtc: Rename lib_test to rtc_lib_test

by Geert Uytterhoeven

When compiling the RTC library functions test as a module, the module has the non-descriptive name "lib_test.ko". Fix this by adding the subsystem's name as a prefix. Signed-off-by: Geert Uytterhoeven <geert(a)linux-m68k.org> --- drivers/rtc/Makefile | 2 +- drivers/rtc/{lib_test.c => rtc_lib_test.c} | 0 2 files changed, 1 insertion(+), 1 deletion(-) rename drivers/rtc/{lib_test.c => rtc_lib_test.c} (100%) diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile index 489b4ab07068c758..c0ccbbfe2739c1aa 100644 --- a/drivers/rtc/Makefile +++ b/drivers/rtc/Makefile @@ -15,7 +15,7 @@ rtc-core-$(CONFIG_RTC_INTF_DEV) += dev.o rtc-core-$(CONFIG_RTC_INTF_PROC) += proc.o rtc-core-$(CONFIG_RTC_INTF_SYSFS) += sysfs.o -obj-$(CONFIG_RTC_LIB_KUNIT_TEST) += lib_test.o +obj-$(CONFIG_RTC_LIB_KUNIT_TEST) += rtc_lib_test.o # Keep the list ordered. diff --git a/drivers/rtc/lib_test.c b/drivers/rtc/rtc_lib_test.c similarity index 100% rename from drivers/rtc/lib_test.c rename to drivers/rtc/rtc_lib_test.c -- 2.43.0

5 months, 2 weeks

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[PATCH] selftest/mm: va_high_addr_switch: add ppc64 support check

by Li Wang

This patch adds PPC64 Radix MMU support to the va_high_addr_switch.sh by introducing check_supported_ppc64(). The function verifies: - 5-level paging (PGTABLE_LEVELS >= 5) enable in kernel config - Radix MMU (required for PPC64 5-level translation) - HugePages availability (needed for some tests) If any check fails, the test is skipped (ksft_skip). This ensures compatibility with Power9/Power10 systems running in Radix MMU mode. Avoid failures on 4-level paging system: # mmap(NULL, MAP_HUGETLB): 0xffffffffffffffff - FAILED # mmap(LOW_ADDR, MAP_HUGETLB): 0xffffffffffffffff - FAILED # mmap(HIGH_ADDR, MAP_HUGETLB): 0xffffffffffffffff - FAILED # mmap(HIGH_ADDR, MAP_HUGETLB) again: 0xffffffffffffffff - FAILED # mmap(HIGH_ADDR, MAP_FIXED | MAP_HUGETLB): 0xffffffffffffffff - FAILED # mmap(-1, MAP_HUGETLB): 0xffffffffffffffff - FAILED # mmap(-1, MAP_HUGETLB) again: 0xffffffffffffffff - FAILED # mmap(ADDR_SWITCH_HINT - PAGE_SIZE, 2*HUGETLB_SIZE, MAP_HUGETLB): 0xffffffffffffffff - FAILED # mmap(ADDR_SWITCH_HINT , 2*HUGETLB_SIZE, MAP_FIXED | MAP_HUGETLB): 0xffffffffffffffff - FAILED Signed-off-by: Li Wang <liwang(a)redhat.com> --- .../selftests/mm/va_high_addr_switch.sh | 28 +++++++++++++++++++ 1 file changed, 28 insertions(+) diff --git a/tools/testing/selftests/mm/va_high_addr_switch.sh b/tools/testing/selftests/mm/va_high_addr_switch.sh index 2c725773cd79..1f92e8caceac 100755 --- a/tools/testing/selftests/mm/va_high_addr_switch.sh +++ b/tools/testing/selftests/mm/va_high_addr_switch.sh @@ -41,6 +41,31 @@ check_supported_x86_64() fi } +check_supported_ppc64() +{ + local config="/proc/config.gz" + [[ -f "${config}" ]] || config="/boot/config-$(uname -r)" + [[ -f "${config}" ]] || fail "Cannot find kernel config in /proc or /boot" + + local pg_table_levels=$(gzip -dcfq "${config}" | grep PGTABLE_LEVELS | cut -d'=' -f 2) + if [[ "${pg_table_levels}" -lt 5 ]]; then + echo "$0: PGTABLE_LEVELS=${pg_table_levels}, must be >= 5 to run this test" + exit $ksft_skip + fi + + local mmu_support=$(grep -m1 "mmu" /proc/cpuinfo | awk '{print $3}') + if [[ "$mmu_support" != "radix" ]]; then + echo "$0: System does not use Radix MMU, required for 5-level paging" + exit $ksft_skip + fi + + local hugepages_total=$(awk '/HugePages_Total/ {print $2}' /proc/meminfo) + if [[ "${hugepages_total}" -eq 0 ]]; then + echo "$0: HugePages are not enabled, required for some tests" + exit $ksft_skip + fi +} + check_test_requirements() { # The test supports x86_64 and powerpc64. We currently have no useful @@ -50,6 +75,9 @@ check_test_requirements() "x86_64") check_supported_x86_64 ;; + "ppc64le"|"ppc64") + check_supported_ppc64 + ;; *) return 0 ;; -- 2.48.1

5 months, 2 weeks

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[RFC PATCH v3 0/8] PMU partitioning driver support

by Colton Lewis

This series introduces support in the KVM and ARM PMUv3 driver for partitioning PMU counters into two separate ranges by taking advantage of the MDCR_EL2.HPMN register field. The advantage of a partitioned PMU would be to allow KVM guests direct access to a subset of PMU functionality, greatly reducing the overhead of performance monitoring in guests. While this feature could be accepted on its own merits, practically there is a lot more to be done before it will be fully useful, so I'm sending as an RFC for now. v3: * Include cpucap definition for FEAT_HPMN0 to allow for setting HPMN to 0 * Include PMU header cleanup provided by Marc [1] with some minor changes so compilation works * Pull functions out of pmu-emul.c that aren't specific to the emulated PMU. This and the previous item aren't strictly needed but they provide a nicer starting point. * As suggested by Oliver, start a file for partitioned PMU functions and move the reserved_host_counters parameter and MDCR handling into KVM so the driver does not have to know about it and we need fewer hacks to keep the driver working on 32-bit ARM. This was not a complete separation because the driver still needs to start and stop the host counters all at once and needs to toggle MDCR_EL2.HPME to do that. Introduce kvm_pmu_host_counters_{enable,disable}() functions to handle this and define them as no ops on 32-bit ARM. * As suggested by Oliver, don't limit PMCR.N on emulated PMU. This value will be read correctly when the right traps are disabled to use the partitioned PMU v2: https://lore.kernel.org/kvm/20250208020111.2068239-1-coltonlewis@google.com/ v1: https://lore.kernel.org/kvm/20250127222031.3078945-1-coltonlewis@google.com/ [1] https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/log/?… Colton Lewis (7): arm64: cpufeature: Add cap for HPMN0 arm64: Generate sign macro for sysreg Enums KVM: arm64: Reorganize PMU functions KVM: arm64: Introduce module param to partition the PMU perf: arm_pmuv3: Generalize counter bitmasks perf: arm_pmuv3: Keep out of guest counter partition KVM: arm64: selftests: Reword selftests error Marc Zyngier (1): KVM: arm64: Cleanup PMU includes arch/arm/include/asm/arm_pmuv3.h | 2 + arch/arm64/include/asm/arm_pmuv3.h | 2 +- arch/arm64/include/asm/kvm_host.h | 199 +++++++- arch/arm64/include/asm/kvm_pmu.h | 47 ++ arch/arm64/kernel/cpufeature.c | 8 + arch/arm64/kvm/Makefile | 2 +- arch/arm64/kvm/arm.c | 1 - arch/arm64/kvm/debug.c | 10 +- arch/arm64/kvm/hyp/include/hyp/switch.h | 1 + arch/arm64/kvm/pmu-emul.c | 464 +----------------- arch/arm64/kvm/pmu-part.c | 63 +++ arch/arm64/kvm/pmu.c | 454 +++++++++++++++++ arch/arm64/kvm/sys_regs.c | 2 + arch/arm64/tools/cpucaps | 1 + arch/arm64/tools/gen-sysreg.awk | 1 + arch/arm64/tools/sysreg | 6 +- drivers/perf/arm_pmuv3.c | 73 ++- include/kvm/arm_pmu.h | 204 -------- include/linux/perf/arm_pmu.h | 16 +- include/linux/perf/arm_pmuv3.h | 27 +- .../selftests/kvm/arm64/vpmu_counter_access.c | 2 +- virt/kvm/kvm_main.c | 1 + 22 files changed, 882 insertions(+), 704 deletions(-) create mode 100644 arch/arm64/include/asm/kvm_pmu.h create mode 100644 arch/arm64/kvm/pmu-part.c delete mode 100644 include/kvm/arm_pmu.h base-commit: 2014c95afecee3e76ca4a56956a936e23283f05b -- 2.48.1.601.g30ceb7b040-goog

5 months, 2 weeks

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[PATCH v7 0/3] Enable Zicbom in usermode

by Yunhui Cui

v1/v2: There is only the first patch: RISC-V: Enable cbo.clean/flush in usermode, which mainly removes the enabling of cbo.inval in user mode. v3: Add the functionality of Expose Zicbom and selftests for Zicbom. v4: Modify the order of macros, The test_no_cbo_inval function is added separately. v5: 1. Modify the order of RISCV_HWPROBE_KEY_ZICBOM_BLOCK_SIZE in hwprobe.rst 2. "TEST_NO_ZICBOINVAL" -> "TEST_NO_CBO_INVAL" v6: Change hwprobe_ext0_has's second param to u64. v7: Rebase to the latest code of linux-next. Yunhui Cui (3): RISC-V: Enable cbo.clean/flush in usermode RISC-V: hwprobe: Expose Zicbom extension and its block size RISC-V: selftests: Add TEST_ZICBOM into CBO tests Documentation/arch/riscv/hwprobe.rst | 6 ++ arch/riscv/include/asm/hwprobe.h | 2 +- arch/riscv/include/uapi/asm/hwprobe.h | 2 + arch/riscv/kernel/cpufeature.c | 8 +++ arch/riscv/kernel/sys_hwprobe.c | 8 ++- tools/testing/selftests/riscv/hwprobe/cbo.c | 66 +++++++++++++++++---- 6 files changed, 79 insertions(+), 13 deletions(-) -- 2.39.2

5 months, 2 weeks

2
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[PATCH] selftests/filesystems: remove duplicate sys/types.h header

by Chen Ni

Remove duplicate header which is included twice. Signed-off-by: Chen Ni <nichen(a)iscas.ac.cn> --- tools/testing/selftests/filesystems/utils.c | 1 - 1 file changed, 1 deletion(-) diff --git a/tools/testing/selftests/filesystems/utils.c b/tools/testing/selftests/filesystems/utils.c index e553c89c5b19..06419bf4ba19 100644 --- a/tools/testing/selftests/filesystems/utils.c +++ b/tools/testing/selftests/filesystems/utils.c @@ -3,7 +3,6 @@ #define _GNU_SOURCE #endif #include <fcntl.h> -#include <sys/types.h> #include <dirent.h> #include <grp.h> #include <linux/limits.h> -- 2.25.1

5 months, 2 weeks

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[PATCH net-next v2 0/7] selftests/net: Mixed select()+polling mode for TCP-AO tests

by Dmitry Safonov via B4 Relay

Should fix flaky tcp-ao/connect-deny-ipv6 test. Begging pardon for the delay since the report and for sending it this late in the release cycle. To: David S. Miller <davem(a)davemloft.net> To: Eric Dumazet <edumazet(a)google.com> To: Jakub Kicinski <kuba(a)kernel.org> To: Paolo Abeni <pabeni(a)redhat.com> To: Simon Horman <horms(a)kernel.org> To: Shuah Khan <shuah(a)kernel.org> Cc: netdev(a)vger.kernel.org Cc: linux-kselftest(a)vger.kernel.org Cc: linux-kernel(a)vger.kernel.org Signed-off-by: Dmitry Safonov <0x7f454c46(a)gmail.com> Changes in v2: - Base on net-next (Paolo) - Add a missing Fixes tag (Paolo) - Link to v1: https://lore.kernel.org/r/20250312-tcp-ao-selftests-polling-v1-0-72a642b855… --- Dmitry Safonov (7): selftests/net: Print TCP flags in more common format selftests/net: Provide tcp-ao counters comparison helper selftests/net: Fetch and check TCP-MD5 counters selftests/net: Add mixed select()+polling mode to TCP-AO tests selftests/net: Print the testing side in unsigned-md5 selftests/net: Delete timeout from test_connect_socket() selftests/net: Drop timeout argument from test_client_verify() tools/testing/selftests/net/tcp_ao/connect-deny.c | 58 ++-- tools/testing/selftests/net/tcp_ao/connect.c | 22 +- tools/testing/selftests/net/tcp_ao/icmps-discard.c | 17 +- .../testing/selftests/net/tcp_ao/key-management.c | 76 ++--- tools/testing/selftests/net/tcp_ao/lib/aolib.h | 114 ++++++-- .../testing/selftests/net/tcp_ao/lib/ftrace-tcp.c | 7 +- tools/testing/selftests/net/tcp_ao/lib/sock.c | 315 +++++++++++++++------ tools/testing/selftests/net/tcp_ao/restore.c | 75 +++-- tools/testing/selftests/net/tcp_ao/rst.c | 47 ++- tools/testing/selftests/net/tcp_ao/self-connect.c | 18 +- tools/testing/selftests/net/tcp_ao/seq-ext.c | 30 +- tools/testing/selftests/net/tcp_ao/unsigned-md5.c | 118 ++++---- 12 files changed, 552 insertions(+), 345 deletions(-) --- base-commit: 23c9ff659140f97d44bf6fb59f89526a168f2b86 change-id: 20250312-tcp-ao-selftests-polling-21b6bbdf77b6 Best regards, -- Dmitry Safonov <0x7f454c46(a)gmail.com>

5 months, 2 weeks

4
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[PATCH v2 0/2] KVM: selftests: access_tracking_perf_test: skip the test when NUMA balancing is active

by Maxim Levitsky

Due to several issues which are unlikely to be fixed in the near future, the access_tracking_perf_test sanity check for how many pages are still clean after an iteration is not reliable when NUMA balancing is active. This patch series refactors this test to skip this check by default automatically. V2: adopted Sean's suggestions. Best regards, Maxim Levitsky Maxim Levitsky (1): KVM: selftests: access_tracking_perf_test: add option to skip the sanity check Sean Christopherson (1): KVM: selftests: Extract guts of THP accessor to standalone sysfs helpers .../selftests/kvm/access_tracking_perf_test.c | 33 +++++++++++++-- .../testing/selftests/kvm/include/test_util.h | 1 + tools/testing/selftests/kvm/lib/test_util.c | 42 ++++++++++++++----- 3 files changed, 61 insertions(+), 15 deletions(-) -- 2.26.3

5 months, 2 weeks

3
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[PATCH v1] selftests/mm/cow: fix minor memory leak in child_vmsplice_memcmp_fn()

by Malaya Kumar Rout

Static Analyis for cow.c: error Exception branch exits without releasing memory 'old' and 'new' fix the issue by releasing the allocated memory. Signed-off-by: Malaya Kumar Rout <malayarout91(a)gmail.com> --- tools/testing/selftests/mm/cow.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/tools/testing/selftests/mm/cow.c b/tools/testing/selftests/mm/cow.c index 9446673645eb..fdee42850548 100644 --- a/tools/testing/selftests/mm/cow.c +++ b/tools/testing/selftests/mm/cow.c @@ -168,18 +168,18 @@ static int child_vmsplice_memcmp_fn(char *mem, size_t size, memcpy(old, mem, size); if (pipe(fds) < 0) - return -errno; + goto out; /* Trigger a read-only pin. */ transferred = vmsplice(fds[1], &iov, 1, 0); if (transferred < 0) - return -errno; + goto out; if (transferred == 0) return -EINVAL; /* Unmap it from our page tables. */ if (munmap(mem, size) < 0) - return -errno; + goto out; /* Wait until the parent modified it. */ write(comm_pipes->child_ready[1], "0", 1); @@ -190,10 +190,15 @@ static int child_vmsplice_memcmp_fn(char *mem, size_t size, for (total = 0; total < transferred; total += cur) { cur = read(fds[0], new + total, transferred - total); if (cur < 0) - return -errno; + goto out; } return memcmp(old, new, transferred); + +out: + free(old); + free(new); + return -errno; } typedef int (*child_fn)(char *mem, size_t size, struct comm_pipes *comm_pipes); -- 2.43.0

5 months, 2 weeks

2
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[PATCH] selftests: vDSO: vdso_standalone_test_x86: Replace source file with symlink

by Thomas Weißschuh

With the switch over to nolibc the source file vdso_standalone_test_x86.c was intended to be replaced with a symlink to vdso_test_gettimeofday.c. This was the patch that was submitted to LKML, but during application the symlink was replaced by a textual copy of the linked-to file. Having two copies introduces the possibility of divergence and increases maintenance burden, switch back to a symlink. Link: https://lore.kernel.org/lkml/20250226-parse_vdso-nolibc-v2-16-28e14e031ed8@… Fixes: 8770a9183fe1 ("selftests: vDSO: vdso_standalone_test_x86: Switch to nolibc") Signed-off-by: Thomas Weißschuh <thomas.weissschuh(a)linutronix.de> --- If symlinks are problematic an #include shim would also work. These are not handled really well by the kselftests build system though, as #include dependencies are not tracked by it. --- .../selftests/vDSO/vdso_standalone_test_x86.c | 59 +--------------------- 1 file changed, 1 insertion(+), 58 deletions(-) diff --git a/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c b/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c deleted file mode 100644 index 9ce795b806f0992b83cef78c7e16fac0e54750da..0000000000000000000000000000000000000000 --- a/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c +++ /dev/null @@ -1,58 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0-only -/* - * vdso_test_gettimeofday.c: Sample code to test parse_vdso.c and - * vDSO gettimeofday() - * Copyright (c) 2014 Andy Lutomirski - * - * Compile with: - * gcc -std=gnu99 vdso_test_gettimeofday.c parse_vdso_gettimeofday.c - * - * Tested on x86, 32-bit and 64-bit. It may work on other architectures, too. - */ - -#include <stdio.h> -#ifndef NOLIBC -#include <sys/auxv.h> -#include <sys/time.h> -#endif - -#include "../kselftest.h" -#include "parse_vdso.h" -#include "vdso_config.h" -#include "vdso_call.h" - -int main(int argc, char **argv) -{ - const char *version = versions[VDSO_VERSION]; - const char **name = (const char **)&names[VDSO_NAMES]; - - unsigned long sysinfo_ehdr = getauxval(AT_SYSINFO_EHDR); - if (!sysinfo_ehdr) { - printf("AT_SYSINFO_EHDR is not present!\n"); - return KSFT_SKIP; - } - - vdso_init_from_sysinfo_ehdr(getauxval(AT_SYSINFO_EHDR)); - - /* Find gettimeofday. */ - typedef long (*gtod_t)(struct timeval *tv, struct timezone *tz); - gtod_t gtod = (gtod_t)vdso_sym(version, name[0]); - - if (!gtod) { - printf("Could not find %s\n", name[0]); - return KSFT_SKIP; - } - - struct timeval tv; - long ret = VDSO_CALL(gtod, 2, &tv, 0); - - if (ret == 0) { - printf("The time is %lld.%06lld\n", - (long long)tv.tv_sec, (long long)tv.tv_usec); - } else { - printf("%s failed\n", name[0]); - return KSFT_FAIL; - } - - return 0; -} diff --git a/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c b/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c new file mode 120000 index 0000000000000000000000000000000000000000..4d3d96f1e440c965474681a6f35375a60b3921be --- /dev/null +++ b/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c @@ -0,0 +1 @@ +vdso_test_gettimeofday.c \ No newline at end of file --- base-commit: 1e26c5e28ca5821a824e90dd359556f5e9e7b89f change-id: 20250326-vdso-selftests-fix-vdso_standalone_test_x86-c3a77b57ccbd Best regards, -- Thomas Weißschuh <thomas.weissschuh(a)linutronix.de>

5 months, 3 weeks

1
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[PATCH v4 00/30] 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 =================================================== This is what I've referred to as the "Danger Zone" during my LPC24 talk [4]. 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), i.e.: idtentry_func_foo() <--- we're in the kernel irqentry_enter() enter_from_user_mode() __ct_user_exit() ct_kernel_enter_state() ct_work_flush() <--- deferred operation is executed here 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 doing the actual deferral have more detail on this. Patches ======= o Patches 1-2 are standalone objtool cleanups. o Patches 3-4 add an RCU testing feature. o Patches 5-6 add infrastructure for annotating static keys and static calls that may be used in noinstr code (courtesy of Josh). o Patches 7-19 use said annotations on relevant keys / calls. o Patch 20 enforces proper usage of said annotations (courtesy of Josh). o Patches 21-23 fiddle with CT_STATE* within context tracking o Patches 24-29 add the actual IPI deferral faff o Patch 30 adds a freebie: deferring IPIs for NOHZ_IDLE. Not tested that much! if you care about battery-powered devices and energy consumption, go give it a try! Patches are also available at: https://gitlab.com/vschneid/linux.git -b redhat/isolirq/defer/v4 Stuff I'd like eyes and neurons on ================================== Context-tracking vs idle. Patch 22 "improves" the situation by adding an IDLE->KERNEL transition when getting an IRQ while idle, but it leaves the following window: ~> IRQ ct_nmi_enter() state = state + CT_STATE_KERNEL - CT_STATE_IDLE [...] ct_nmi_exit() state = state - CT_STATE_KERNEL + CT_STATE_IDLE [...] /!\ CT_STATE_IDLE here while we're really in kernelspace! /!\ ct_cpuidle_exit() state = state + CT_STATE_KERNEL - CT_STATE_IDLE Said window is contained within cpu_idle_poll() and the cpuidle call within cpuidle_enter_state(), both being noinstr (the former is __cpuidle which is noinstr itself). Thus objtool will consider it as early entry and will warn accordingly of any static key / call misuse, so the damage is somewhat contained, but it's not ideal. I tried fiddling with this but idle polling likes being annoying, as it is shaped like so: ct_cpuidle_enter(); raw_local_irq_enable(); while (!tif_need_resched() && (cpu_idle_force_poll || tick_check_broadcast_expired())) cpu_relax(); raw_local_irq_disable(); ct_cpuidle_exit(); IOW, getting an IRQ that doesn't end up setting NEED_RESCHED while idle-polling doesn't come near ct_cpuidle_exit(), which prevents me from having the outermost ct_nmi_exit() leave the state as CT_STATE_KERNEL (rather than CT_STATE_IDLE). Testing ======= 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 6 hours. v6.13-rc6 # This is the actual IPI count $ trace-cmd report | grep callback | awk '{ print $(NF) }' | sort | uniq -c | sort -nr 531 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 12818 func=do_flush_tlb_all 910 func=do_kernel_range_flush 78 func=do_sync_core v6.13-rc6 + patches: # This is the actual IPI count $ trace-cmd report | grep callback | awk '{ print $(NF) }' | sort | uniq -c | sort -nr # Zilch! # These are the different CSD's that caused IPIs $ trace-cmd report | grep csd_queue | awk '{ print $(NF-1) }' | sort | uniq -c | sort -nr # Nada! Note that tlb_remove_table_smp_sync() showed up during testing of v3, and has gone as mysteriously as it showed up. Yair had a series adressing this [5] which would be worth revisiting. Acknowledgements ================ Special thanks to: o Clark Williams for listening to my ramblings about this and throwing ideas my way o Josh Poimboeuf for all his help with everything objtool-related o All of the folks who attended various (too many?) talks about this and provided precious feedback. 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 [4]: https://lpc.events/event/18/contributions/1889/ [5]: https://lore.kernel.org/lkml/20230620144618.125703-1-ypodemsk@redhat.com/ Revisions ========= RFCv3 -> v4 ++++++++++++++ o Rebased onto v6.13-rc6 o New objtool patches from Josh o More .noinstr static key/call patches o Static calls now handled as well (again thanks to Josh) o Fixed clearing the work bits on kernel exit o Messed with IRQ hitting an idle CPU vs context tracking o Various comment and naming cleanups o Made RCU_DYNTICKS_TORTURE depend on !COMPILE_TEST (PeterZ) o Fixed the CT_STATE_KERNEL check when setting a deferred work (Frederic) o Cleaned up the __flush_tlb_all() mess thanks to PeterZ RFCv2 -> RFCv3 ++++++++++++++ o Rebased onto v6.12-rc6 o Added objtool documentation for the new warning (Josh) o Added low-size RCU watching counter to TREE04 torture scenario (Paul) o Added FORCEFUL jump label and static key types o Added noinstr-compliant helpers for tlb flush deferral 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) o Fixed flush_tlb_kernel_range_deferrable() definition Josh Poimboeuf (3): jump_label: Add annotations for validating noinstr usage static_call: Add read-only-after-init static calls objtool: Add noinstr validation for static branches/calls Peter Zijlstra (1): x86,tlb: Make __flush_tlb_global() noinstr-compliant Valentin Schneider (26): objtool: Make validate_call() recognize indirect calls to pv_ops[] objtool: Flesh out warning related to pv_ops[] calls rcu: Add a small-width RCU watching counter debug option rcutorture: Make TREE04 use CONFIG_RCU_DYNTICKS_TORTURE x86/paravirt: Mark pv_sched_clock static call as __ro_after_init x86/idle: Mark x86_idle static call as __ro_after_init x86/paravirt: Mark pv_steal_clock static call as __ro_after_init riscv/paravirt: Mark pv_steal_clock static call as __ro_after_init loongarch/paravirt: Mark pv_steal_clock static call as __ro_after_init arm64/paravirt: Mark pv_steal_clock static call as __ro_after_init arm/paravirt: Mark pv_steal_clock static call as __ro_after_init perf/x86/amd: Mark perf_lopwr_cb static call as __ro_after_init sched/clock: Mark sched_clock_running key as __ro_after_init x86/speculation/mds: Mark mds_idle_clear key as allowed in .noinstr sched/clock, x86: Mark __sched_clock_stable key as allowed in .noinstr x86/kvm/vmx: Mark vmx_l1d_should flush and vmx_l1d_flush_cond keys as allowed in .noinstr stackleack: Mark stack_erasing_bypass key as allowed in .noinstr context_tracking: Explicitely use CT_STATE_KERNEL where it is missing context_tracking: Exit CT_STATE_IDLE upon irq/nmi entry context_tracking: Turn CT_STATE_* into bits context-tracking: Introduce work deferral infrastructure context_tracking,x86: Defer kernel text patching IPIs x86/tlb: Make __flush_tlb_local() noinstr-compliant x86/tlb: Make __flush_tlb_all() noinstr x86/mm, mm/vmalloc: Defer flush_tlb_kernel_range() targeting NOHZ_FULL CPUs context-tracking: Add a Kconfig to enable IPI deferral for NO_HZ_IDLE arch/Kconfig | 9 ++ arch/arm/kernel/paravirt.c | 2 +- arch/arm64/kernel/paravirt.c | 2 +- arch/loongarch/kernel/paravirt.c | 2 +- arch/riscv/kernel/paravirt.c | 2 +- arch/x86/Kconfig | 1 + arch/x86/events/amd/brs.c | 2 +- arch/x86/include/asm/context_tracking_work.h | 22 ++++ arch/x86/include/asm/invpcid.h | 13 +-- arch/x86/include/asm/paravirt.h | 4 +- arch/x86/include/asm/text-patching.h | 1 + arch/x86/include/asm/tlbflush.h | 3 +- arch/x86/include/asm/xen/hypercall.h | 11 +- arch/x86/kernel/alternative.c | 38 ++++++- arch/x86/kernel/cpu/bugs.c | 9 +- arch/x86/kernel/kprobes/core.c | 4 +- arch/x86/kernel/kprobes/opt.c | 4 +- arch/x86/kernel/module.c | 2 +- arch/x86/kernel/paravirt.c | 4 +- arch/x86/kernel/process.c | 2 +- arch/x86/kvm/vmx/vmx.c | 11 +- arch/x86/mm/tlb.c | 46 ++++++-- arch/x86/xen/mmu_pv.c | 10 +- arch/x86/xen/xen-ops.h | 12 +- include/asm-generic/sections.h | 15 +++ include/linux/context_tracking.h | 21 ++++ include/linux/context_tracking_state.h | 64 +++++++++-- include/linux/context_tracking_work.h | 28 +++++ include/linux/jump_label.h | 30 ++++- include/linux/objtool.h | 7 ++ include/linux/static_call.h | 19 ++++ kernel/context_tracking.c | 98 ++++++++++++++-- kernel/rcu/Kconfig.debug | 15 +++ kernel/sched/clock.c | 7 +- kernel/stackleak.c | 6 +- kernel/time/Kconfig | 19 ++++ mm/vmalloc.c | 35 +++++- tools/objtool/Documentation/objtool.txt | 34 ++++++ tools/objtool/check.c | 106 +++++++++++++++--- tools/objtool/include/objtool/check.h | 1 + tools/objtool/include/objtool/elf.h | 1 + tools/objtool/include/objtool/special.h | 1 + tools/objtool/special.c | 18 ++- .../selftests/rcutorture/configs/rcu/TREE04 | 1 + 44 files changed, 635 insertions(+), 107 deletions(-) create mode 100644 arch/x86/include/asm/context_tracking_work.h create mode 100644 include/linux/context_tracking_work.h -- 2.43.0

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