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

[PATCH v4 00/38] Mediated vPMU 4.0 for x86

by Mingwei Zhang

With joint effort from the upstream KVM community, we come up with the 4th version of mediated vPMU for x86. We have made the following changes on top of the previous RFC v3. v3 -> v4 - Rebase whole patchset on 6.14-rc3 base. - Address Peter's comments on Perf part. - Address Sean's comments on KVM part. * Change key word "passthrough" to "mediated" in all patches * Change static enabling to user space dynamic enabling via KVM_CAP_PMU_CAPABILITY. * Only support GLOBAL_CTRL save/restore with VMCS exec_ctrl, drop the MSR save/retore list support for GLOBAL_CTRL, thus the support of mediated vPMU is constrained to SapphireRapids and later CPUs on Intel side. * Merge some small changes into a single patch. - Address Sandipan's comment on invalid pmu pointer. - Add back "eventsel_hw" and "fixed_ctr_ctrl_hw" to avoid to directly manipulate pmc->eventsel and pmu->fixed_ctr_ctrl. Testing (Intel side): - Perf-based legacy vPMU (force emulation on/off) * Kselftests pmu_counters_test, pmu_event_filter_test and vmx_pmu_caps_test pass. * KUT PMU tests pmu, pmu_lbr, pmu_pebs pass. * Basic perf counting/sampling tests in 3 scenarios, guest-only, host-only and host-guest coexistence all pass. - Mediated vPMU (force emulation on/off) * Kselftests pmu_counters_test, pmu_event_filter_test and vmx_pmu_caps_test pass. * KUT PMU tests pmu, pmu_lbr, pmu_pebs pass. * Basic perf counting/sampling tests in 3 scenarios, guest-only, host-only and host-guest coexistence all pass. - Failures. All above tests passed on Intel Granite Rapids as well except a failure on KUT/pmu_pebs. * GP counter 0 (0xfffffffffffe): PEBS record (written seq 0) is verified (including size, counters and cfg). * The pebs_data_cfg (0xb500000000) doesn't match with the effective MSR_PEBS_DATA_CFG (0x0). * This failure has nothing to do with this mediated vPMU patch set. The failure is caused by Granite Rapids supported timed PEBS which needs extra support on Qemu and KUT/pmu_pebs. These extra support would be sent in separate patches later. Testing (AMD side): - Kselftests pmu_counters_test, pmu_event_filter_test and vmx_pmu_caps_test all pass - legacy guest with KUT/pmu: * qmeu option: -cpu host, -perfctr-core * when set force_emulation_prefix=1, passes * when set force_emulation_prefix=0, passes - perfmon-v1 guest with KUT/pmu: * qmeu option: -cpu host, -perfmon-v2 * when set force_emulation_prefix=1, passes * when set force_emulation_prefix=0, passes - perfmon-v2 guest with KUT/pmu: * qmeu option: -cpu host * when set force_emulation_prefix=1, passes * when set force_emulation_prefix=0, passes - perf_fuzzer (perfmon-v2): * fails with soft lockup in guest in current version. * culprit could be between 6.13 ~ 6.14-rc3 within KVM * Series tested on 6.12 and 6.13 without issue. Note: a QEMU series is needed to run mediated vPMU v4: - https://lore.kernel.org/all/20250324123712.34096-1-dapeng1.mi@linux.intel.c… History: - RFC v3: https://lore.kernel.org/all/20240801045907.4010984-1-mizhang@google.com/ - RFC v2: https://lore.kernel.org/all/20240506053020.3911940-1-mizhang@google.com/ - RFC v1: https://lore.kernel.org/all/20240126085444.324918-1-xiong.y.zhang@linux.int… Dapeng Mi (18): KVM: x86/pmu: Introduce enable_mediated_pmu global parameter KVM: x86/pmu: Check PMU cpuid configuration from user space KVM: x86: Rename vmx_vmentry/vmexit_ctrl() helpers KVM: x86/pmu: Add perf_capabilities field in struct kvm_host_values{} KVM: x86/pmu: Move PMU_CAP_{FW_WRITES,LBR_FMT} into msr-index.h header KVM: VMX: Add macros to wrap around {secondary,tertiary}_exec_controls_changebit() KVM: x86/pmu: Check if mediated vPMU can intercept rdpmc KVM: x86/pmu/vmx: Save/load guest IA32_PERF_GLOBAL_CTRL with vm_exit/entry_ctrl KVM: x86/pmu: Optimize intel/amd_pmu_refresh() helpers KVM: x86/pmu: Setup PMU MSRs' interception mode KVM: x86/pmu: Handle PMU MSRs interception and event filtering KVM: x86/pmu: Switch host/guest PMU context at vm-exit/vm-entry KVM: x86/pmu: Handle emulated instruction for mediated vPMU KVM: nVMX: Add macros to simplify nested MSR interception setting KVM: selftests: Add mediated vPMU supported for pmu tests KVM: Selftests: Support mediated vPMU for vmx_pmu_caps_test KVM: Selftests: Fix pmu_counters_test error for mediated vPMU KVM: x86/pmu: Expose enable_mediated_pmu parameter to user space Kan Liang (8): perf: Support get/put mediated PMU interfaces perf: Skip pmu_ctx based on event_type perf: Clean up perf ctx time perf: Add a EVENT_GUEST flag perf: Add generic exclude_guest support perf: Add switch_guest_ctx() interface perf/x86: Support switch_guest_ctx interface perf/x86/intel: Support PERF_PMU_CAP_MEDIATED_VPMU Mingwei Zhang (5): perf/x86: Forbid PMI handler when guest own PMU perf/x86/core: Plumb mediated PMU capability from x86_pmu to x86_pmu_cap KVM: x86/pmu: Exclude PMU MSRs in vmx_get_passthrough_msr_slot() KVM: x86/pmu: introduce eventsel_hw to prepare for pmu event filtering KVM: nVMX: Add nested virtualization support for mediated PMU Sandipan Das (4): perf/x86/core: Do not set bit width for unavailable counters KVM: x86/pmu: Add AMD PMU registers to direct access list KVM: x86/pmu/svm: Set GuestOnly bit and clear HostOnly bit when guest write to event selectors perf/x86/amd: Support PERF_PMU_CAP_MEDIATED_VPMU for AMD host Xiong Zhang (3): x86/irq: Factor out common code for installing kvm irq handler perf: core/x86: Register a new vector for KVM GUEST PMI KVM: x86/pmu: Register KVM_GUEST_PMI_VECTOR handler arch/x86/events/amd/core.c | 2 + arch/x86/events/core.c | 40 +- arch/x86/events/intel/core.c | 5 + arch/x86/include/asm/hardirq.h | 1 + arch/x86/include/asm/idtentry.h | 1 + arch/x86/include/asm/irq.h | 2 +- arch/x86/include/asm/irq_vectors.h | 5 +- arch/x86/include/asm/kvm-x86-pmu-ops.h | 2 + arch/x86/include/asm/kvm_host.h | 10 + arch/x86/include/asm/msr-index.h | 18 +- arch/x86/include/asm/perf_event.h | 1 + arch/x86/include/asm/vmx.h | 1 + arch/x86/kernel/idt.c | 1 + arch/x86/kernel/irq.c | 39 +- arch/x86/kvm/cpuid.c | 15 + arch/x86/kvm/pmu.c | 254 ++++++++- arch/x86/kvm/pmu.h | 45 ++ arch/x86/kvm/svm/pmu.c | 148 ++++- arch/x86/kvm/svm/svm.c | 26 + arch/x86/kvm/svm/svm.h | 2 +- arch/x86/kvm/vmx/capabilities.h | 11 +- arch/x86/kvm/vmx/nested.c | 68 ++- arch/x86/kvm/vmx/pmu_intel.c | 224 ++++++-- arch/x86/kvm/vmx/vmx.c | 89 +-- arch/x86/kvm/vmx/vmx.h | 11 +- arch/x86/kvm/x86.c | 63 ++- arch/x86/kvm/x86.h | 2 + include/linux/perf_event.h | 47 +- kernel/events/core.c | 519 ++++++++++++++---- .../beauty/arch/x86/include/asm/irq_vectors.h | 5 +- .../selftests/kvm/include/kvm_test_harness.h | 13 + .../testing/selftests/kvm/include/kvm_util.h | 3 + .../selftests/kvm/include/x86/processor.h | 8 + tools/testing/selftests/kvm/lib/kvm_util.c | 23 + .../selftests/kvm/x86/pmu_counters_test.c | 24 +- .../selftests/kvm/x86/pmu_event_filter_test.c | 8 +- .../selftests/kvm/x86/vmx_pmu_caps_test.c | 2 +- 37 files changed, 1480 insertions(+), 258 deletions(-) base-commit: 0ad2507d5d93f39619fc42372c347d6006b64319 -- 2.49.0.395.g12beb8f557-goog

3 months, 2 weeks

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[PATCH net] selftests: net: packetdrill: xfail all problems on slow machines

by Jakub Kicinski

We keep seeing flakes on packetdrill on debug kernels, while non-debug kernels are stable, not a single flake in 200 runs. Time to give up, debug kernels appear to suffer from 10msec latency spikes and any timing-sensitive test is bound to flake. Signed-off-by: Jakub Kicinski <kuba(a)kernel.org> --- CC: shuah(a)kernel.org CC: willemb(a)google.com CC: matttbe(a)kernel.org CC: linux-kselftest(a)vger.kernel.org --- .../selftests/net/packetdrill/ksft_runner.sh | 19 +------------------ 1 file changed, 1 insertion(+), 18 deletions(-) diff --git a/tools/testing/selftests/net/packetdrill/ksft_runner.sh b/tools/testing/selftests/net/packetdrill/ksft_runner.sh index c5b01e1bd4c7..a7e790af38ff 100755 --- a/tools/testing/selftests/net/packetdrill/ksft_runner.sh +++ b/tools/testing/selftests/net/packetdrill/ksft_runner.sh @@ -35,24 +35,7 @@ failfunc=ktap_test_fail if [[ -n "${KSFT_MACHINE_SLOW}" ]]; then optargs+=('--tolerance_usecs=14000') - - # xfail tests that are known flaky with dbg config, not fixable. - # still run them for coverage (and expect 100% pass without dbg). - declare -ar xfail_list=( - "tcp_blocking_blocking-connect.pkt" - "tcp_blocking_blocking-read.pkt" - "tcp_eor_no-coalesce-retrans.pkt" - "tcp_fast_recovery_prr-ss.*.pkt" - "tcp_sack_sack-route-refresh-ip-tos.pkt" - "tcp_slow_start_slow-start-after-win-update.pkt" - "tcp_timestamping.*.pkt" - "tcp_user_timeout_user-timeout-probe.pkt" - "tcp_zerocopy_cl.*.pkt" - "tcp_zerocopy_epoll_.*.pkt" - "tcp_tcp_info_tcp-info-.*-limited.pkt" - ) - readonly xfail_regex="^($(printf '%s|' "${xfail_list[@]}"))$" - [[ "$script" =~ ${xfail_regex} ]] && failfunc=ktap_test_xfail + failfunc=ktap_test_xfail fi ktap_print_header -- 2.50.1

3 months, 2 weeks

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[PATCH v2] selftests/proc: Fix string literal warning in proc-maps-race.c

by Sukrut Heroorkar

This change resolves non literal string format warning invoked for proc-maps-race.c while compiling. proc-maps-race.c:205:17: warning: format not a string literal and no format arguments [-Wformat-security] 205 | printf(text); | ^~~~~~ proc-maps-race.c:209:17: warning: format not a string literal and no format arguments [-Wformat-security] 209 | printf(text); | ^~~~~~ proc-maps-race.c: In function ‘print_last_lines’: proc-maps-race.c:224:9: warning: format not a string literal and no format arguments [-Wformat-security] 224 | printf(start); | ^~~~~~ Added string format specifier %s for the printf calls in both print_first_lines() and print_last_lines() thus resolving the warnings invoked. The test executes fine after this change thus causing no affect to the functional behavior of the test. Fixes: aadc099c480f ("selftests/proc: add verbose mode for /proc/pid/maps tearing tests") Signed-off-by: Sukrut Heroorkar <hsukrut3(a)gmail.com> Acked-by: Suren Baghdasaryan <surenb(a)google.com> --- Changes since v1: - Added Fixes tag - Included Acked-by Suren Baghdasaryan https://lore.kernel.org/all/CAHCkknoxpKV80-S3jByY1xnRXd1Pr=v=D2a0ZcgnY0-Hny… tools/testing/selftests/proc/proc-maps-race.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/tools/testing/selftests/proc/proc-maps-race.c b/tools/testing/selftests/proc/proc-maps-race.c index 66773685a047..94bba4553130 100644 --- a/tools/testing/selftests/proc/proc-maps-race.c +++ b/tools/testing/selftests/proc/proc-maps-race.c @@ -202,11 +202,11 @@ static void print_first_lines(char *text, int nr) int offs = end - text; text[offs] = '\0'; - printf(text); + printf("%s", text); text[offs] = '\n'; printf("\n"); } else { - printf(text); + printf("%s", text); } } @@ -221,7 +221,7 @@ static void print_last_lines(char *text, int nr) nr--; start--; } - printf(start); + printf("%s", start); } static void print_boundaries(const char *title, FIXTURE_DATA(proc_maps_race) *self) -- 2.43.0

3 months, 2 weeks

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[PATCH] selftests/proc: Fix string literal warning in proc-maps-race.c

by Sukrut Heroorkar

This change resolves non literal string format warning invoked for proc-maps-race.c while compiling. proc-maps-race.c:205:17: warning: format not a string literal and no format arguments [-Wformat-security] 205 | printf(text); | ^~~~~~ proc-maps-race.c:209:17: warning: format not a string literal and no format arguments [-Wformat-security] 209 | printf(text); | ^~~~~~ proc-maps-race.c: In function ‘print_last_lines’: proc-maps-race.c:224:9: warning: format not a string literal and no format arguments [-Wformat-security] 224 | printf(start); | ^~~~~~ Added string format specifier %s for the printf calls in both print_first_lines() and print_last_lines() thus resolving the warnings invoked. The test executes fine after this change thus causing no affect to the functional behavior of the test. Signed-off-by: Sukrut Heroorkar <hsukrut3(a)gmail.com> --- tools/testing/selftests/proc/proc-maps-race.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/tools/testing/selftests/proc/proc-maps-race.c b/tools/testing/selftests/proc/proc-maps-race.c index 66773685a047..94bba4553130 100644 --- a/tools/testing/selftests/proc/proc-maps-race.c +++ b/tools/testing/selftests/proc/proc-maps-race.c @@ -202,11 +202,11 @@ static void print_first_lines(char *text, int nr) int offs = end - text; text[offs] = '\0'; - printf(text); + printf("%s", text); text[offs] = '\n'; printf("\n"); } else { - printf(text); + printf("%s", text); } } @@ -221,7 +221,7 @@ static void print_last_lines(char *text, int nr) nr--; start--; } - printf(start); + printf("%s", start); } static void print_boundaries(const char *title, FIXTURE_DATA(proc_maps_race) *self) -- 2.43.0

3 months, 2 weeks

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[PATCH] selftests: bpf: crypto: Improved clarity in test output message

by Noorain Eqbal

In 'crypto_setup()' the error message for invalid buffer size was updated for grammar and clarity This change does not affect the test behaviour but improve the quality of test output Signed-off-by: Noorain Eqbal <nooraineqbal(a)gmail.com> --- tools/testing/selftests/bpf/benchs/bench_bpf_crypto.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/testing/selftests/bpf/benchs/bench_bpf_crypto.c b/tools/testing/selftests/bpf/benchs/bench_bpf_crypto.c index 2845edaba8db..ac91cb224373 100644 --- a/tools/testing/selftests/bpf/benchs/bench_bpf_crypto.c +++ b/tools/testing/selftests/bpf/benchs/bench_bpf_crypto.c @@ -83,7 +83,7 @@ static void crypto_setup(void) sz = args.crypto_len; if (!sz || sz > sizeof(ctx.skel->bss->dst)) { - fprintf(stderr, "invalid encrypt buffer size (source %zu, target %zu)\n", + fprintf(stderr, "invalid encryption buffer size: source %zu, target %zu\n", sz, sizeof(ctx.skel->bss->dst)); exit(1); } -- 2.50.1

3 months, 2 weeks

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[PATCH v11 iproute2-next 0/1] DUALPI2 iproute2 patch

by chia-yu.chang＠nokia-bell-labs.com

From: Chia-Yu Chang <chia-yu.chang(a)nokia-bell-labs.com> Hello, Please find DUALPI2 iproute2 patch v11. For more details of DualPI2, please refer IETF RFC9332 (https://datatracker.ietf.org/doc/html/rfc9332). Best Regards, Chia-Yu --- v11 (18-Jul-2025) - Replace TCA_DUALPI2 prefix with TC_DUALPI2 prefix for enums (Jakub Kicinski <kuba(a)kernel.org>) v10 (02-Jul-2025) - Replace STEP_THRESH and STEP_PACKETS w/ STEP_THRESH_PKTS and STEP_THRESH_US of net-next patch (Jakub Kicinski <kuba(a)kernel.org>) v9 (13-Jun-2025) - Fix space issue and typos (ALOK TIWARI <alok.a.tiwari(a)oracle.com>) - Change 'rtt_typical' to 'typical_rtt' in tc/q_dualpi2.c (ALOK TIWARI <alok.a.tiwari(a)oracle.com>) - Add the num of enum used by DualPI2 in pkt_sched.h v8 (09-May-2025) - Update pkt_sched.h with the one in nex-next - Correct a typo in the comment within pkt_sched.h (ALOK TIWARI <alok.a.tiwari(a)oracle.com>) - Update manual content in man/man8/tc-dualpi2.8 (ALOK TIWARI <alok.a.tiwari(a)oracle.com>) - Update tc/q_dualpi2.c to fix missing blank lines and add missing case (ALOK TIWARI <alok.a.tiwari(a)oracle.com>) v7 (05-May-2025) - Align pkt_sched.h with the v14 version of net-next due to spec modification in tc.yaml - Reorganize dualpi2_print_opt() to match the order in tc.yaml - Remove credit-queue in PRINT_JSON v6 (26-Apr-2025) - Update JSON file output due to spec modification in tc.yaml of net-next v5 (25-Mar-2025) - Use matches() to replace current strcmp() (Stephen Hemminger <stephen(a)networkplumber.org>) - Use general parse_percent() for handling scaled percentage values (Stephen Hemminger <stephen(a)networkplumber.org>) - Add print function for JSON of dualpi2 stats (Stephen Hemminger <stephen(a)networkplumber.org>) v4 (16-Mar-2025) - Add min_qlen_step to the dualpi2 attribute as the minimum queue length in number of packets in the L-queue to start step marking. v3 (21-Feb-2025) - Add memlimit to the dualpi2 attribute, and add memory_used, max_memory_used, and memory_limit in dualpi2 stats (Dave Taht <dave.taht(a)gmail.com>) - Update the manual to align with the latest implementation and clarify the queue naming and default unit - Use common "get_scaled_alpha_beta" and clean print_opt for Dualpi2 v2 (23-Oct-2024) - Rename get_float in dualpi2 to get_float_min_max in utils.c - Move get_float from iplink_can.c in utils.c (Stephen Hemminger <stephen(a)networkplumber.org>) - Add print function for JSON of dualpi2 (Stephen Hemminger <stephen(a)networkplumber.org>) --- Chia-Yu Chang (1): tc: add dualpi2 scheduler module bash-completion/tc | 11 +- include/uapi/linux/pkt_sched.h | 68 +++++ include/utils.h | 2 + ip/iplink_can.c | 14 - lib/utils.c | 30 ++ man/man8/tc-dualpi2.8 | 249 ++++++++++++++++ tc/Makefile | 1 + tc/q_dualpi2.c | 528 +++++++++++++++++++++++++++++++++ 8 files changed, 888 insertions(+), 15 deletions(-) create mode 100644 man/man8/tc-dualpi2.8 create mode 100644 tc/q_dualpi2.c -- 2.34.1

3 months, 2 weeks

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[PATCH v3 0/4] signal handling support for nolibc

by Benjamin Berg

From: Benjamin Berg <benjamin.berg(a)intel.com> Hi, This patchset adds signal handling to nolibc. Initially, I would like to use this for tests. But in the long run, the goal is to use nolibc for the UML kernel itself. In both cases, signal handling will be needed. With v3 everything is now included in nolibc instead of trying to use the messy kernel headers. Benjamin Benjamin Berg (4): selftests/nolibc: fix EXPECT_NZ macro selftests/nolibc: remove outdated comment about construct order tools/nolibc: add more generic bitmask macros for FD_* tools/nolibc: add signal support tools/include/nolibc/Makefile | 1 + tools/include/nolibc/arch-s390.h | 4 +- tools/include/nolibc/asm-signal.h | 237 +++++++++++++++++++ tools/include/nolibc/signal.h | 179 ++++++++++++++ tools/include/nolibc/sys.h | 2 +- tools/include/nolibc/sys/wait.h | 1 + tools/include/nolibc/time.h | 2 +- tools/include/nolibc/types.h | 81 ++++--- tools/testing/selftests/nolibc/nolibc-test.c | 139 ++++++++++- 9 files changed, 608 insertions(+), 38 deletions(-) create mode 100644 tools/include/nolibc/asm-signal.h -- 2.50.1

3 months, 3 weeks

3
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[PATCH] selftests/mm: link with thp_settings when necessary

by Wei Yang

Currently all test cases are linked with thp_settings, while only 6 out of 50+ targets rely on it. Instead of making thp_settings as a common dependency, link it only when necessary. Signed-off-by: Wei Yang <richard.weiyang(a)gmail.com> Cc: Ryan Roberts <ryan.roberts(a)arm.com> --- tools/testing/selftests/mm/Makefile | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/tools/testing/selftests/mm/Makefile b/tools/testing/selftests/mm/Makefile index d4f19f87053b..eea4881c918a 100644 --- a/tools/testing/selftests/mm/Makefile +++ b/tools/testing/selftests/mm/Makefile @@ -158,14 +158,19 @@ TEST_FILES += write_hugetlb_memory.sh include ../lib.mk -$(TEST_GEN_PROGS): vm_util.c thp_settings.c -$(TEST_GEN_FILES): vm_util.c thp_settings.c +$(TEST_GEN_PROGS): vm_util.c +$(TEST_GEN_FILES): vm_util.c $(OUTPUT)/uffd-stress: uffd-common.c $(OUTPUT)/uffd-unit-tests: uffd-common.c -$(OUTPUT)/uffd-wp-mremap: uffd-common.c +$(OUTPUT)/uffd-wp-mremap: uffd-common.c thp_settings.c $(OUTPUT)/protection_keys: pkey_util.c $(OUTPUT)/pkey_sighandler_tests: pkey_util.c +$(OUTPUT)/cow: thp_settings.c +$(OUTPUT)/migration: thp_settings.c +$(OUTPUT)/khugepaged: thp_settings.c +$(OUTPUT)/ksm_tests: thp_settings.c +$(OUTPUT)/soft-dirty: thp_settings.c ifeq ($(ARCH),x86_64) BINARIES_32 := $(patsubst %,$(OUTPUT)/%,$(BINARIES_32)) -- 2.34.1

3 months, 3 weeks

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[PATCH v5 0/2] libbpf: fix USDT SIB argument handling causing unrecognized register error

by Jiawei Zhao

When using GCC on x86-64 to compile an usdt prog with -O1 or higher optimization, the compiler will generate SIB addressing mode for global array and PC-relative addressing mode for global variable, e.g. "1@-96(%rbp,%rax,8)" and "-1@4+t1(%rip)". The current USDT implementation in libbpf cannot parse these two formats, causing `bpf_program__attach_usdt()` to fail with -ENOENT (unrecognized register). This patch series adds support for SIB addressing mode in USDT probes. The main changes include: - add correct handling logic for SIB-addressed arguments in `parse_usdt_arg`. - force -O2 optimization for usdt.test.o to generate SIB addressing usdt argument spec. - change the global variable t1 to a local variable, to avoid compiler generating PC-relative addressing mode for it. Testing shows that the SIB probe correctly generates 8@(%rcx,%rax,8) argument spec and passes all validation checks. The modification history of this patch series: Change since v1: - refactor the code to make it more readable - modify the commit message to explain why and how Change since v2: - fix the `scale` uninitialized error Change since v3: - force -O2 optimization for usdt.test.o to generate SIB addressing usdt and pass all test cases. Change since v4: - split the patch into two parts, one for the fix and the other for the test Do we need to add support for PC-relative USDT argument spec handling in libbpf? I have some interest in this question, but currently have no ideas. Getting offsets based on symbols requires dependency on the symbol table. However, once the binary file is stripped, the symtab will also be removed, which will cause this approach to fail. Does anyone have any thoughts on this? Jiawei Zhao (2): libbpf: fix USDT SIB argument handling causing unrecognized register error selftests/bpf: Force -O2 for USDT selftests to cover SIB handling logic tools/lib/bpf/usdt.bpf.h | 33 +++++++++++++- tools/lib/bpf/usdt.c | 43 ++++++++++++++++--- tools/testing/selftests/bpf/Makefile | 5 +++ tools/testing/selftests/bpf/prog_tests/usdt.c | 18 +++++--- 4 files changed, 86 insertions(+), 13 deletions(-) -- 2.43.0

3 months, 3 weeks

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[PATCH v4 0/1] libbpf: fix USDT SIB argument handling causing unrecognized register error

by Jiawei Zhao

When using GCC on x86-64 to compile an usdt prog with -O1 or higher optimization, the compiler will generate SIB addressing mode for global array and PC-relative addressing mode for global variable, e.g. "1@-96(%rbp,%rax,8)" and "-1@4+t1(%rip)". The current USDT implementation in libbpf cannot parse these two formats, causing `bpf_program__attach_usdt()` to fail with -ENOENT (unrecognized register). This patch series adds support for SIB addressing mode in USDT probes. The main changes include: - add correct handling logic for SIB-addressed arguments in `parse_usdt_arg`. - force -O2 optimization for usdt.test.o to generate SIB addressing usdt argument spec. - change the global variable t1 to a local variable, to avoid compiler generating PC-relative addressing mode for it. Testing shows that the SIB probe correctly generates 8@(%rcx,%rax,8) argument spec and passes all validation checks. The modification history of this patch series: Change since v1: - refactor the code to make it more readable - modify the commit message to explain why and how Change since v2: - fix the `scale` uninitialized error Change since v3: - force -O2 optimization for usdt.test.o to generate SIB addressing usdt and pass all test cases. Do we need to add support for PC-relative USDT argument spec handling in libbpf? I have some interest in this question, but currently have no ideas. Getting offsets based on symbols requires dependency on the symbol table. However, once the binary file is stripped, the symtab will also be removed, which will cause this approach to fail. Does anyone have any thoughts on this? Jiawei Zhao (1): libbpf: fix USDT SIB argument handling causing unrecognized register error tools/lib/bpf/usdt.bpf.h | 33 +++++++++++++- tools/lib/bpf/usdt.c | 43 ++++++++++++++++--- tools/testing/selftests/bpf/Makefile | 5 +++ tools/testing/selftests/bpf/prog_tests/usdt.c | 18 +++++--- 4 files changed, 86 insertions(+), 13 deletions(-) -- 2.43.0

3 months, 3 weeks

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2025

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