January 2025 - Linux-kselftest-mirror

[PATCH v3 0/2] fix reading ESP during coredump

by Nam Cao

Hi, In /proc/PID/stat, there is the kstkesp field which is the stack pointer of a thread. While the thread is active, this field reads zero. But during a coredump, it should have a valid value. However, at the moment, kstkesp is zero even during coredump. The first commit fixes this problem, and the second commit adds a selftest to detect if this problem appears again in the future. v2..v3 https://lore.kernel.org/lkml/cover.1735550994.git.namcao@linutronix.de/ - Move stackdump file to local directory [Kees] - Always cleanup the stackdump file after the test [Kees] - Remove unused empty function v1..v2 https://lore.kernel.org/lkml/cover.1730883229.git.namcao@linutronix.de/ - Change the fix patch to use PF_POSTCOREDUMP [Oleg] Nam Cao (2): fs/proc: do_task_stat: Fix ESP not readable during coredump selftests: coredump: Add stackdump test fs/proc/array.c | 2 +- tools/testing/selftests/coredump/Makefile | 7 + tools/testing/selftests/coredump/README.rst | 50 ++++++ tools/testing/selftests/coredump/stackdump | 14 ++ .../selftests/coredump/stackdump_test.c | 151 ++++++++++++++++++ 5 files changed, 223 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/coredump/Makefile create mode 100644 tools/testing/selftests/coredump/README.rst create mode 100755 tools/testing/selftests/coredump/stackdump create mode 100644 tools/testing/selftests/coredump/stackdump_test.c -- 2.39.5

4 days, 10 hours

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[PATCH AUTOSEL 6.6 3/3] selftests/alsa: Fix circular dependency involving global-timer

by Sasha Levin

From: Li Zhijian <lizhijian(a)fujitsu.com> [ Upstream commit 55853cb829dc707427c3519f6b8686682a204368 ] The pattern rule `$(OUTPUT)/%: %.c` inadvertently included a circular dependency on the global-timer target due to its inclusion in $(TEST_GEN_PROGS_EXTENDED). This resulted in a circular dependency warning during the build process. To resolve this, the dependency on $(TEST_GEN_PROGS_EXTENDED) has been replaced with an explicit dependency on $(OUTPUT)/libatest.so. This change ensures that libatest.so is built before any other targets that require it, without creating a circular dependency. This fix addresses the following warning: make[4]: Entering directory 'tools/testing/selftests/alsa' make[4]: Circular default_modconfig/kselftest/alsa/global-timer <- default_modconfig/kselftest/alsa/global-timer dependency dropped. make[4]: Nothing to be done for 'all'. make[4]: Leaving directory 'tools/testing/selftests/alsa' Cc: Mark Brown <broonie(a)kernel.org> Cc: Jaroslav Kysela <perex(a)perex.cz> Cc: Takashi Iwai <tiwai(a)suse.com> Cc: Shuah Khan <shuah(a)kernel.org> Signed-off-by: Li Zhijian <lizhijian(a)fujitsu.com> Link: https://patch.msgid.link/20241218025931.914164-1-lizhijian@fujitsu.com Signed-off-by: Takashi Iwai <tiwai(a)suse.de> Signed-off-by: Sasha Levin <sashal(a)kernel.org> --- tools/testing/selftests/alsa/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/testing/selftests/alsa/Makefile b/tools/testing/selftests/alsa/Makefile index 5af9ba8a4645..140c7f821727 100644 --- a/tools/testing/selftests/alsa/Makefile +++ b/tools/testing/selftests/alsa/Makefile @@ -23,5 +23,5 @@ include ../lib.mk $(OUTPUT)/libatest.so: conf.c alsa-local.h $(CC) $(CFLAGS) -shared -fPIC $< $(LDLIBS) -o $@ -$(OUTPUT)/%: %.c $(TEST_GEN_PROGS_EXTENDED) alsa-local.h +$(OUTPUT)/%: %.c $(OUTPUT)/libatest.so alsa-local.h $(CC) $(CFLAGS) $< $(LDLIBS) -latest -o $@ -- 2.39.5

5 days, 2 hours

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[PATCH AUTOSEL 6.12 4/4] selftests/alsa: Fix circular dependency involving global-timer

by Sasha Levin

From: Li Zhijian <lizhijian(a)fujitsu.com> [ Upstream commit 55853cb829dc707427c3519f6b8686682a204368 ] The pattern rule `$(OUTPUT)/%: %.c` inadvertently included a circular dependency on the global-timer target due to its inclusion in $(TEST_GEN_PROGS_EXTENDED). This resulted in a circular dependency warning during the build process. To resolve this, the dependency on $(TEST_GEN_PROGS_EXTENDED) has been replaced with an explicit dependency on $(OUTPUT)/libatest.so. This change ensures that libatest.so is built before any other targets that require it, without creating a circular dependency. This fix addresses the following warning: make[4]: Entering directory 'tools/testing/selftests/alsa' make[4]: Circular default_modconfig/kselftest/alsa/global-timer <- default_modconfig/kselftest/alsa/global-timer dependency dropped. make[4]: Nothing to be done for 'all'. make[4]: Leaving directory 'tools/testing/selftests/alsa' Cc: Mark Brown <broonie(a)kernel.org> Cc: Jaroslav Kysela <perex(a)perex.cz> Cc: Takashi Iwai <tiwai(a)suse.com> Cc: Shuah Khan <shuah(a)kernel.org> Signed-off-by: Li Zhijian <lizhijian(a)fujitsu.com> Link: https://patch.msgid.link/20241218025931.914164-1-lizhijian@fujitsu.com Signed-off-by: Takashi Iwai <tiwai(a)suse.de> Signed-off-by: Sasha Levin <sashal(a)kernel.org> --- tools/testing/selftests/alsa/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/testing/selftests/alsa/Makefile b/tools/testing/selftests/alsa/Makefile index 944279160fed..8dab90ad22bb 100644 --- a/tools/testing/selftests/alsa/Makefile +++ b/tools/testing/selftests/alsa/Makefile @@ -27,5 +27,5 @@ include ../lib.mk $(OUTPUT)/libatest.so: conf.c alsa-local.h $(CC) $(CFLAGS) -shared -fPIC $< $(LDLIBS) -o $@ -$(OUTPUT)/%: %.c $(TEST_GEN_PROGS_EXTENDED) alsa-local.h +$(OUTPUT)/%: %.c $(OUTPUT)/libatest.so alsa-local.h $(CC) $(CFLAGS) $< $(LDLIBS) -latest -o $@ -- 2.39.5

5 days, 2 hours

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[PATCH v7 0/2] selftests: tmpfs: Add kselftest support

by Shivam Chaudhary

This version 7 patch series replace direct error handling methods with ksft macros, which provide better reporting.Currently, when the tmpfs test runs, it does not display any output if it passes,and if it fails (particularly when not run as root),it simply exits without any warning or message. This series of patch adds: 1. Add 'ksft_print_header()' and 'ksft_set_plan()' to structure test outputs more effectively. 2. skip if not run as root. 3. Replace direct error handling with 'ksft_test_result_*', macros for better reporting. v6->v7: - Improve the handling of failure macros. v6 v1: https://lore.kernel.org/all/20241219152929.4005003-2-cvam0000@gmail.com/ v6 v2: https://lore.kernel.org/all/20241219152929.4005003-3-cvam0000@gmail.com/ v5->v6: - Skip if not run as root. v5 v1: https://lore.kernel.org/all/20241112143056.565122-2-cvam0000@gmail.com/ v5 v2: https://lore.kernel.org/all/20241112143056.565122-3-cvam0000@gmail.com/ v4->v5: - Remove unnecessary pass messages. - Remove unnecessary use of KSFT_SKIP. - Add appropriate use of ksft_exit_fail_msg. v4 v1: https://lore.kernel.org/all/8db9feab-0600-440b-b4b2-042695a100b5@linuxfound… v4 v2: https://lore.kernel.org/all/63d5e3bb-9817-4a34-98fe-823a9cac7c16@linuxfound… v3->v4: - Start a patchset - Split patch into smaller patches to make it easy to review. Patch1 Replace 'ksft_test_result_skip' with 'KSFT_SKIP' during root run check. Patch2 Replace 'ksft_test_result_fail' with 'KSFT_SKIP' where fail does not make sense, or failure could be due to not unsupported APIs with appropriate warnings. v3: https://lore.kernel.org/all/20241028185756.111832-1-cvam0000@gmail.com/ v2->v3: - Remove extra ksft_set_plan() - Remove function for unshare() - Fix the comment style v2: https://lore.kernel.org/all/20241026191621.2860376-1-cvam0000@gmail.com/ v1->v2: - Make the commit message more clear. v1: https://lore.kernel.org/all/20241024200228.1075840-1-cvam0000@gmail.com/T/#u thanks Shivam Shivam Chaudhary (2): selftests: tmpfs: Add Test-skip if not run as root selftests: tmpfs: Add kselftest support to tmpfs .../selftests/tmpfs/bug-link-o-tmpfile.c | 40 ++++++++++++------- 1 file changed, 26 insertions(+), 14 deletions(-) -- 2.34.1

5 days, 2 hours

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[PATCH v5 0/3] rust: kunit: Support KUnit tests with a user-space like syntax

by David Gow

Hi all, v5 here is a small set of fixes and a rebase of the previous versions. If there are no major issues, I'd like to land this soon so it can be used and tested ready for 6.14. This series was originally written by José Expósito, and has been modified and updated by Matt Gilbride and myself. The original version can be found here: https://github.com/Rust-for-Linux/linux/pull/950 Add support for writing KUnit tests in Rust. While Rust doctests are already converted to KUnit tests and run, they're really better suited for examples, rather than as first-class unit tests. This series implements a series of direct Rust bindings for KUnit tests, as well as a new macro which allows KUnit tests to be written using a close variant of normal Rust unit test syntax. The only change required is replacing '#[cfg(test)]' with '#[kunit_tests(kunit_test_suite_name)]' An example test would look like: #[kunit_tests(rust_kernel_hid_driver)] mod tests { use super::*; use crate::{c_str, driver, hid, prelude::*}; use core::ptr; struct SimpleTestDriver; impl Driver for SimpleTestDriver { type Data = (); } #[test] fn rust_test_hid_driver_adapter() { let mut hid = bindings::hid_driver::default(); let name = c_str!("SimpleTestDriver"); static MODULE: ThisModule = unsafe { ThisModule::from_ptr(ptr::null_mut()) }; let res = unsafe { <hid::Adapter<SimpleTestDriver> as driver::DriverOps>::register(&mut hid, name, &MODULE) }; assert_eq!(res, Err(ENODEV)); // The mock returns -19 } } Please give this a go, and make sure I haven't broken it! There's almost certainly a lot of improvements which can be made -- and there's a fair case to be made for replacing some of this with generated C code which can use the C macros -- but this is hopefully an adequate implementation for now, and the interface can (with luck) remain the same even if the implementation changes. A few small notable missing features: - Attributes (like the speed of a test) are hardcoded to the default value. - Similarly, the module name attribute is hardcoded to NULL. In C, we use the KBUILD_MODNAME macro, but I couldn't find a way to use this from Rust which wasn't more ugly than just disabling it. - Assertions are not automatically rewritten to use KUnit assertions. --- Changes since v4: https://lore.kernel.org/linux-kselftest/20241101064505.3820737-1-davidgow@g… - Rebased against 6.13-rc1 - Allowed an unused_unsafe warning after the behaviour of addr_of_mut!() changed in Rust 1.82. (Thanks Boqun, Miguel) - "Expect" that the sample assert_eq!(1+1, 2) produces a clippy warning due to a redundant assertion. (Thanks Boqun, Miguel) - Fix some missing safety comments, and remove some unneeded 'unsafe' blocks. (Thanks Boqun) - Fix a couple of minor rustfmt issues which were triggering checkpatch warnings. Changes since v3: https://lore.kernel.org/linux-kselftest/20241030045719.3085147-2-davidgow@g… - The kunit_unsafe_test_suite!() macro now panic!s if the suite name is too long, triggering a compile error. (Thanks, Alice!) - The #[kunit_tests()] macro now preserves span information, so errors can be better reported. (Thanks, Boqun!) - The example tests have been updated to no longer use assert_eq!() with a constant bool argument (which triggered a clippy warning now we have the span info). Changes since v2: https://lore.kernel.org/linux-kselftest/20241029092422.2884505-1-davidgow@g… - Include missing rust/macros/kunit.rs file from v2. (Thanks Boqun!) - The kunit_unsafe_test_suite!() macro will truncate the name of the suite if it is too long. (Thanks Alice!) - The proc macro now emits an error if the suite name is too long. - We no longer needlessly use UnsafeCell<> in kunit_unsafe_test_suite!(). (Thanks Alice!) Changes since v1: https://lore.kernel.org/lkml/20230720-rustbind-v1-0-c80db349e3b5@google.com… - Rebase on top of the latest rust-next (commit 718c4069896c) - Make kunit_case a const fn, rather than a macro (Thanks Boqun) - As a result, the null terminator is now created with kernel::kunit::kunit_case_null() - Use the C kunit_get_current_test() function to implement in_kunit_test(), rather than re-implementing it (less efficiently) ourselves. Changes since the GitHub PR: - Rebased on top of kselftest/kunit - Add const_mut_refs feature This may conflict with https://lore.kernel.org/lkml/20230503090708.2524310-6-nmi@metaspace.dk/ - Add rust/macros/kunit.rs to the KUnit MAINTAINERS entry --- José Expósito (3): rust: kunit: add KUnit case and suite macros rust: macros: add macro to easily run KUnit tests rust: kunit: allow to know if we are in a test MAINTAINERS | 1 + rust/kernel/kunit.rs | 207 +++++++++++++++++++++++++++++++++++++++++++ rust/kernel/lib.rs | 1 + rust/macros/kunit.rs | 168 +++++++++++++++++++++++++++++++++++ rust/macros/lib.rs | 29 ++++++ 5 files changed, 406 insertions(+) create mode 100644 rust/macros/kunit.rs -- 2.47.1.613.gc27f4b7a9f-goog

5 days, 3 hours

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Question about test_xsk.sh

by Alexis Lothoré

Hello all, I was looking at other test candidates for conversion to bpf test_progs framework (to increase automatic testing scope) and found test_xsk.sh, which does not seem to have coverage yet in test_progs. This test validates the AF_XDP socket behavior with different XDP modes (SKB, DRV, zero copy) and socket configuration (normal, busy polling). The testing program looks pretty big, considering all files involved (test_xsk.sh, xskxceiver.c, xsk.c, the different XDP programs) and the matrix of tests it runs. So before really diving into it, I would like to ask: - is it indeed a good/relevant target for integration in test_progs (all tests look like functional tests, so I guess it is) ? - if so, is there anyone already working on this ? - multiple commits on xskxceiver.c hint that the program is also used for testing on real hardware, could someone confirm that it is still the case (similar need has been seen with test_xdp_features.sh for example) ? If so, it means that the current form must be preserved, and it would be an additional integration into test_progs rather a conversion (then most of the code should be shared between the non-test_progs and the test_progs version) Thanks, Alexis -- Alexis Lothoré, Bootlin Embedded Linux and Kernel engineering https://bootlin.com

5 days, 5 hours

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[PATCH net-next 0/4] netconsole: selftest for userdata overflow

by Breno Leitao

Implement comprehensive testing for netconsole userdata entry handling, demonstrating correct behavior when creating maximum entries and preventing unauthorized overflow. Refactor existing test infrastructure to support modular, reusable helper functions that validate strict entry limit enforcement. Also, add a warning if update_userdata() sees more than MAX_USERDATA_ITEMS entries. This shouldn't happen and it is a bug that shouldn't be silently ignored. Signed-off-by: Breno Leitao <leitao(a)debian.org> --- Breno Leitao (4): netconsole: Warn if MAX_USERDATA_ITEMS limit is exceeded netconsole: selftest: Split the helpers from the selftest netconsole: selftest: Delete all userdata keys netconsole: selftest: verify userdata entry limit MAINTAINERS | 3 +- drivers/net/netconsole.c | 2 +- .../selftests/drivers/net/lib/sh/lib_netcons.sh | 225 +++++++++++++++++++++ .../testing/selftests/drivers/net/netcons_basic.sh | 218 +------------------- .../selftests/drivers/net/netcons_overflow.sh | 67 ++++++ 5 files changed, 296 insertions(+), 219 deletions(-) --- base-commit: bb18265c3aba92b91a1355609769f3e967b65dee change-id: 20241204-netcons_overflow_test-eaf735d1f743 Best regards, -- Breno Leitao <leitao(a)debian.org>

5 days, 7 hours

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[PATCH v5 0/3] Add support for the Idle HLT intercept feature

by Manali Shukla

The upcoming new Idle HLT Intercept feature allows for the HLT instruction execution by a vCPU to be intercepted by the hypervisor only if there are no pending V_INTR and V_NMI events for the vCPU. When the vCPU is expected to service the pending V_INTR and V_NMI events, the Idle HLT intercept won’t trigger. The feature allows the hypervisor to determine if the vCPU is actually idle and reduces wasteful VMEXITs. The Idle HLT intercept feature is used for enlightened guests who wish to securely handle the events. When an enlightened guest does a HLT while an interrupt is pending, hypervisor will not have a way to figure out whether the guest needs to be re-entered or not. The Idle HLT intercept feature allows the HLT execution only if there are no pending V_INTR and V_NMI events. Presence of the Idle HLT Intercept feature is indicated via CPUID function Fn8000_000A_EDX[30]. Document for the Idle HLT intercept feature is available at [1]. This series is based on kvm-x86/next (13e98294d7ce) + [2] + [3]. Testing Done: - Tested the functionality for the Idle HLT intercept feature using selftest ipi_hlt_test. - Tested on normal, SEV, SEV-ES, SEV-SNP guest for the Idle HLT intercept functionality. - Tested the Idle HLT intercept functionality on nested guest. v4 -> v5 - Incorporated Sean's review comments on nested Idle HLT intercept support. - Make svm_idle_hlt_test independent of the Idle HLT to run on all hardware. v3 -> v4 - Drop the patches to add vcpu_get_stat() into a new series [2]. - Added nested Idle HLT intercept support. v2 -> v3 - Incorporated Andrew's suggestion to structure vcpu_stat_types in a way that each architecture can share the generic types and also provide its own. v1 -> v2 - Done changes in svm_idle_hlt_test based on the review comments from Sean. - Added an enum based approach to get binary stats in vcpu_get_stat() which doesn't use string to get stat data based on the comments from Sean. - Added safe_halt() and cli() helpers based on the comments from Sean. [1]: AMD64 Architecture Programmer's Manual Pub. 24593, April 2024, Vol 2, 15.9 Instruction Intercepts (Table 15-7: IDLE_HLT). https://bugzilla.kernel.org/attachment.cgi?id=306250 [2]: https://lore.kernel.org/kvm/20241220013906.3518334-1-seanjc@google.com/T/#u [3]: https://lore.kernel.org/kvm/20241220012617.3513898-1-seanjc@google.com/T/#u --- V4: https://lore.kernel.org/kvm/20241022054810.23369-1-manali.shukla@amd.com/ V3: https://lore.kernel.org/kvm/20240528041926.3989-4-manali.shukla@amd.com/T/ V2: https://lore.kernel.org/kvm/20240501145433.4070-1-manali.shukla@amd.com/ V1: https://lore.kernel.org/kvm/20240307054623.13632-1-manali.shukla@amd.com/ Manali Shukla (3): x86/cpufeatures: Add CPUID feature bit for Idle HLT intercept KVM: SVM: Add Idle HLT intercept support KVM: selftests: Add self IPI HLT test arch/x86/include/asm/cpufeatures.h | 1 + arch/x86/include/asm/svm.h | 1 + arch/x86/include/uapi/asm/svm.h | 2 + arch/x86/kvm/svm/svm.c | 13 ++- tools/testing/selftests/kvm/Makefile.kvm | 1 + .../selftests/kvm/include/x86/processor.h | 1 + tools/testing/selftests/kvm/ipi_hlt_test.c | 85 +++++++++++++++++++ 7 files changed, 101 insertions(+), 3 deletions(-) create mode 100644 tools/testing/selftests/kvm/ipi_hlt_test.c base-commit: 13e98294d7cec978e31138d16824f50556a62d17 prerequisite-patch-id: cb345fc0d814a351df2b5788b76eee0eef9de549 prerequisite-patch-id: 71806f400cffe09f47d6231cb072cbdbd540de1b prerequisite-patch-id: 9ea0412aab7ecd8555fcee3e9609dbfe8456d47b prerequisite-patch-id: 3504df50cdd33958456f2e56139d76867273525c prerequisite-patch-id: 674e56729a56cc487cb85be1a64ef561eb7bac8a prerequisite-patch-id: 48e87354f9d6e6bd121ca32ab73cd0d7f1dce74f prerequisite-patch-id: 74daffd7677992995f37e5a5cb784b8d4357e342 prerequisite-patch-id: 509018dc2fc1657debc641544e86f5a92d04bc1a prerequisite-patch-id: 4a50c6a4dc3b3c8c8c640a86072faafb7bae4384 -- 2.34.1

5 days, 11 hours

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[PATCH] rseq/selftests: Fix riscv rseq_offset_deref_addv inline asm

by Stafford Horne

When working on OpenRISC support for restartable sequences I noticed and fixed these two issues with the riscv support bits. 1 The 'inc' argument to RSEQ_ASM_OP_R_DEREF_ADDV was being implicitly passed to the macro. Fix this by adding 'inc' to the list of macro arguments. 2 The inline asm input constraints for 'inc' and 'off' use "er", The riscv gcc port does not have an "e" constraint, this looks to be copied from the x86 port. Fix this by just using an "r" constraint. I have compile tested this only for riscv. However, the same fixes I use in the OpenRISC rseq selftests and everything passes with no issues. Signed-off-by: Stafford Horne <shorne(a)gmail.com> --- tools/testing/selftests/rseq/rseq-riscv-bits.h | 6 +++--- tools/testing/selftests/rseq/rseq-riscv.h | 2 +- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/tools/testing/selftests/rseq/rseq-riscv-bits.h b/tools/testing/selftests/rseq/rseq-riscv-bits.h index de31a0143139..f02f411d550d 100644 --- a/tools/testing/selftests/rseq/rseq-riscv-bits.h +++ b/tools/testing/selftests/rseq/rseq-riscv-bits.h @@ -243,7 +243,7 @@ int RSEQ_TEMPLATE_IDENTIFIER(rseq_offset_deref_addv)(intptr_t *ptr, off_t off, i #ifdef RSEQ_COMPARE_TWICE RSEQ_ASM_CMP_CPU_ID(cpu_id, current_cpu_id, "%l[error1]") #endif - RSEQ_ASM_OP_R_DEREF_ADDV(ptr, off, 3) + RSEQ_ASM_OP_R_DEREF_ADDV(ptr, off, inc, 3) RSEQ_INJECT_ASM(4) RSEQ_ASM_DEFINE_ABORT(4, abort) : /* gcc asm goto does not allow outputs */ @@ -251,8 +251,8 @@ int RSEQ_TEMPLATE_IDENTIFIER(rseq_offset_deref_addv)(intptr_t *ptr, off_t off, i [current_cpu_id] "m" (rseq_get_abi()->RSEQ_TEMPLATE_CPU_ID_FIELD), [rseq_cs] "m" (rseq_get_abi()->rseq_cs.arch.ptr), [ptr] "r" (ptr), - [off] "er" (off), - [inc] "er" (inc) + [off] "r" (off), + [inc] "r" (inc) RSEQ_INJECT_INPUT : "memory", RSEQ_ASM_TMP_REG_1 RSEQ_INJECT_CLOBBER diff --git a/tools/testing/selftests/rseq/rseq-riscv.h b/tools/testing/selftests/rseq/rseq-riscv.h index 37e598d0a365..67d544aaa9a3 100644 --- a/tools/testing/selftests/rseq/rseq-riscv.h +++ b/tools/testing/selftests/rseq/rseq-riscv.h @@ -158,7 +158,7 @@ do { \ "bnez " RSEQ_ASM_TMP_REG_1 ", 222b\n" \ "333:\n" -#define RSEQ_ASM_OP_R_DEREF_ADDV(ptr, off, post_commit_label) \ +#define RSEQ_ASM_OP_R_DEREF_ADDV(ptr, off, inc, post_commit_label) \ "mv " RSEQ_ASM_TMP_REG_1 ", %[" __rseq_str(ptr) "]\n" \ RSEQ_ASM_OP_R_ADD(off) \ REG_L RSEQ_ASM_TMP_REG_1 ", 0(" RSEQ_ASM_TMP_REG_1 ")\n" \ -- 2.47.0

5 days, 15 hours

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[PATCH bpf-next v6 0/5] Support eliding map lookup nullness

by Daniel Xu

This patch allows progs to elide a null check on statically known map lookup keys. In other words, if the verifier can statically prove that the lookup will be in-bounds, allow the prog to drop the null check. This is useful for two reasons: 1. Large numbers of nullness checks (especially when they cannot fail) unnecessarily pushes prog towards BPF_COMPLEXITY_LIMIT_JMP_SEQ. 2. It forms a tighter contract between programmer and verifier. For (1), bpftrace is starting to make heavier use of percpu scratch maps. As a result, for user scripts with large number of unrolled loops, we are starting to hit jump complexity verification errors. These percpu lookups cannot fail anyways, as we only use static key values. Eliding nullness probably results in less work for verifier as well. For (2), percpu scratch maps are often used as a larger stack, as the currrent stack is limited to 512 bytes. In these situations, it is desirable for the programmer to express: "this lookup should never fail, and if it does, it means I messed up the code". By omitting the null check, the programmer can "ask" the verifier to double check the logic. === Changelog === Changes in v6: * Use is_spilled_scalar_reg() helper and remove unnecessary comment * Add back deleted selftest with different helper to dirty dst buffer * Check size of spill is exactly key_size and update selftests * Read slot_type from correct offset into the spi * Rewrite selftests in C where possible * Mark constant map keys as precise Changes in v5: * Dropped all acks * Use s64 instead of long for const_map_key * Ensure stack slot contains spilled reg before accessing spilled_ptr * Ensure spilled reg is a scalar before accessing tnum const value * Fix verifier selftest for 32-bit write to write at 8 byte alignment to ensure spill is tracked * Introduce more precise tracking of helper stack accesses * Do constant map key extraction as part of helper argument processing and then remove duplicated stack checks * Use ret_flag instead of regs[BPF_REG_0].type * Handle STACK_ZERO * Fix bug in bpf_load_hdr_opt() arg annotation Changes in v4: * Only allow for CAP_BPF * Add test for stack growing upwards * Improve comment about stack growing upwards Changes in v3: * Check if stack is (erroneously) growing upwards * Mention in commit message why existing tests needed change Changes in v2: * Added a check for when R2 is not a ptr to stack * Added a check for when stack is uninitialized (no stack slot yet) * Updated existing tests to account for null elision * Added test case for when R2 can be both const and non-const Daniel Xu (5): bpf: verifier: Add missing newline on verbose() call bpf: tcp: Mark bpf_load_hdr_opt() arg2 as read-write bpf: verifier: Refactor helper access type tracking bpf: verifier: Support eliding map lookup nullness bpf: selftests: verifier: Add nullness elision tests kernel/bpf/verifier.c | 139 +++++++++++---- net/core/filter.c | 2 +- .../testing/selftests/bpf/progs/dynptr_fail.c | 6 +- tools/testing/selftests/bpf/progs/iters.c | 14 +- .../selftests/bpf/progs/map_kptr_fail.c | 2 +- .../selftests/bpf/progs/test_global_func10.c | 2 +- .../selftests/bpf/progs/uninit_stack.c | 5 +- .../bpf/progs/verifier_array_access.c | 168 ++++++++++++++++++ .../bpf/progs/verifier_basic_stack.c | 2 +- .../selftests/bpf/progs/verifier_const_or.c | 4 +- .../progs/verifier_helper_access_var_len.c | 12 +- .../selftests/bpf/progs/verifier_int_ptr.c | 2 +- .../selftests/bpf/progs/verifier_map_in_map.c | 2 +- .../selftests/bpf/progs/verifier_mtu.c | 2 +- .../selftests/bpf/progs/verifier_raw_stack.c | 4 +- .../selftests/bpf/progs/verifier_unpriv.c | 2 +- .../selftests/bpf/progs/verifier_var_off.c | 8 +- tools/testing/selftests/bpf/verifier/calls.c | 2 +- .../testing/selftests/bpf/verifier/map_kptr.c | 2 +- 19 files changed, 311 insertions(+), 69 deletions(-) -- 2.47.1

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Linux-kselftest-mirror January 2025