kernel/tools/testing/selftests/vDSO/parse_vdso.c, branch linux-rolling-stable

Merge tag 'timers-vdso-2025-03-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2025-03-25T18:30:42Z

Pull VDSO infrastructure updates from Thomas Gleixner: - Consolidate the VDSO storage The VDSO data storage and data layout has been largely architecture specific for historical reasons. That increases the maintenance effort and causes inconsistencies over and over. There is no real technical reason for architecture specific layouts and implementations. The architecture specific details can easily be integrated into a generic layout, which also reduces the amount of duplicated code for managing the mappings. Convert all architectures over to a unified layout and common mapping infrastructure. This splits the VDSO data layout into subsystem specific blocks, timekeeping, random and architecture parts, which provides a better structure and allows to improve and update the functionalities without conflict and interaction. - Rework the timekeeping data storage The current implementation is designed for exposing system timekeeping accessors, which was good enough at the time when it was designed. PTP and Time Sensitive Networking (TSN) change that as there are requirements to expose independent PTP clocks, which are not related to system timekeeping. Replace the monolithic data storage by a structured layout, which allows to add support for independent PTP clocks on top while reusing both the data structures and the time accessor implementations. * tag 'timers-vdso-2025-03-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (55 commits) sparc/vdso: Always reject undefined references during linking x86/vdso: Always reject undefined references during linking vdso: Rework struct vdso_time_data and introduce struct vdso_clock vdso: Move architecture related data before basetime data powerpc/vdso: Prepare introduction of struct vdso_clock arm64/vdso: Prepare introduction of struct vdso_clock x86/vdso: Prepare introduction of struct vdso_clock time/namespace: Prepare introduction of struct vdso_clock vdso/namespace: Rename timens_setup_vdso_data() to reflect new vdso_clock struct vdso/vsyscall: Prepare introduction of struct vdso_clock vdso/gettimeofday: Prepare helper functions for introduction of struct vdso_clock vdso/gettimeofday: Prepare do_coarse_timens() for introduction of struct vdso_clock vdso/gettimeofday: Prepare do_coarse() for introduction of struct vdso_clock vdso/gettimeofday: Prepare do_hres_timens() for introduction of struct vdso_clock vdso/gettimeofday: Prepare do_hres() for introduction of struct vdso_clock vdso/gettimeofday: Prepare introduction of struct vdso_clock vdso/helpers: Prepare introduction of struct vdso_clock vdso/datapage: Define vdso_clock to prepare for multiple PTP clocks vdso: Make vdso_time_data cacheline aligned arm64: Make asm/cache.h compatible with vDSO ...

selftests/vDSO: Fix GNU hash table entry size for s390x

2025-03-04T16:15:18Z

Commit 14be4e6f3522 ("selftests: vDSO: fix ELF hash table entry size for s390x") changed the type of the ELF hash table entries to 64bit on s390x. However the *GNU* hash tables entries are always 32bit. The "bucket" pointer is shared between both hash algorithms. On s390, this caused the GNU hash algorithm to access its 32-bit entries as if they were 64-bit, triggering compiler warnings (assignment between "Elf64_Xword *" and "Elf64_Word *") and runtime crashes. Introduce a new dedicated "gnu_bucket" pointer which is used by the GNU hash. Fixes: e0746bde6f82 ("selftests/vDSO: support DT_GNU_HASH") Reviewed-by: Jens Remus Signed-off-by: Thomas Weißschuh Acked-by: Shuah Khan Link: https://lore.kernel.org/r/20250217-selftests-vdso-s390-gnu-hash-v2-1-f6c2532ffe2a@linutronix.de Signed-off-by: Vasily Gorbik

selftests: vDSO: parse_vdso: Test __SIZEOF_LONG__ instead of ULONG_MAX

2025-03-03T19:00:13Z

According to limits.h(2) ULONG_MAX is only guaranteed to expand to an expression, not a symbolic constant which can be evaluated by the preprocessor. Specifically the definition of ULONG_MAX from nolibc can not be evaluated by the preprocessor. To provide compatibility with nolibc, check with __SIZEOF_LONG__ instead, with is provided directly by the preprocessor and therefore always a symbolic constant. Signed-off-by: Thomas Weißschuh Signed-off-by: Thomas Gleixner Reviewed-by: Vincenzo Frascino Acked-by: Shuah Khan Link: https://lore.kernel.org/all/20250226-parse_vdso-nolibc-v2-13-28e14e031ed8@linutronix.de

selftests: vDSO: parse_vdso: Use UAPI headers instead of libc headers

2025-03-03T19:00:12Z

To allow the usage of parse_vdso.c together with a limited libc like nolibc, use the kernels own elf.h and auxvec.h headers. Signed-off-by: Thomas Weißschuh Signed-off-by: Thomas Gleixner Reviewed-by: Vincenzo Frascino Acked-by: Shuah Khan Link: https://lore.kernel.org/all/20250226-parse_vdso-nolibc-v2-12-28e14e031ed8@linutronix.de

selftests: vDSO: parse_vdso: Drop vdso_init_from_auxv()

2025-03-03T19:00:12Z

There are no users left. This also removes the usage of ElfXX_auxv_t, which is not formally standardized. Signed-off-by: Thomas Weißschuh Signed-off-by: Thomas Gleixner Reviewed-by: Vincenzo Frascino Acked-by: Shuah Khan Link: https://lore.kernel.org/all/20250226-parse_vdso-nolibc-v2-11-28e14e031ed8@linutronix.de

selftests/vDSO: support DT_GNU_HASH

2025-01-15T00:06:31Z

glibc added support for DT_GNU_HASH in 2006 and DT_HASH has been obsoleted for more than one decade in many Linux distributions. Many vDSOs support DT_GNU_HASH. This patch adds selftests support. Link: https://lore.kernel.org/r/20241206130724.7944-2-xry111@xry111.site Signed-off-by: Fangrui Song Tested-by: Xi Ruoyao Signed-off-by: Xi Ruoyao # rebase Signed-off-by: Shuah Khan

powerpc/vdso: Flag VDSO64 entry points as functions

2024-10-16T02:37:37Z

On powerpc64 as shown below by readelf, vDSO functions symbols have type NOTYPE. $ powerpc64-linux-gnu-readelf -a arch/powerpc/kernel/vdso/vdso64.so.dbg ELF Header: Magic: 7f 45 4c 46 02 02 01 00 00 00 00 00 00 00 00 00 Class: ELF64 Data: 2's complement, big endian Version: 1 (current) OS/ABI: UNIX - System V ABI Version: 0 Type: DYN (Shared object file) Machine: PowerPC64 Version: 0x1 ... Symbol table '.dynsym' contains 12 entries: Num: Value Size Type Bind Vis Ndx Name ... 1: 0000000000000524 84 NOTYPE GLOBAL DEFAULT 8 __[...]@@LINUX_2.6.15 ... 4: 0000000000000000 0 OBJECT GLOBAL DEFAULT ABS LINUX_2.6.15 5: 00000000000006c0 48 NOTYPE GLOBAL DEFAULT 8 __[...]@@LINUX_2.6.15 Symbol table '.symtab' contains 56 entries: Num: Value Size Type Bind Vis Ndx Name ... 45: 0000000000000000 0 OBJECT GLOBAL DEFAULT ABS LINUX_2.6.15 46: 00000000000006c0 48 NOTYPE GLOBAL DEFAULT 8 __kernel_getcpu 47: 0000000000000524 84 NOTYPE GLOBAL DEFAULT 8 __kernel_clock_getres To overcome that, commit ba83b3239e65 ("selftests: vDSO: fix vDSO symbols lookup for powerpc64") was applied to have selftests also look for NOTYPE symbols, but the correct fix should be to flag VDSO entry points as functions. The original commit that brought VDSO support into powerpc/64 has the following explanation: Note that the symbols exposed by the vDSO aren't "normal" function symbols, apps can't be expected to link against them directly, the vDSO's are both seen as if they were linked at 0 and the symbols just contain offsets to the various functions. This is done on purpose to avoid a relocation step (ppc64 functions normally have descriptors with abs addresses in them). When glibc uses those functions, it's expected to use it's own trampolines that know how to reach them. The descriptors it's talking about are the OPD function descriptors used on ABI v1 (big endian). But it would be more correct for a text symbol to have type function, even if there's no function descriptor for it. glibc has a special case already for handling the VDSO symbols which creates a fake opd pointing at the kernel symbol. So changing the VDSO symbol type to function shouldn't affect that. For ABI v2, there is no function descriptors and VDSO functions can safely have function type. So lets flag VDSO entry points as functions and revert the selftest change. Link: https://github.com/mpe/linux-fullhistory/commit/5f2dd691b62da9d9cc54b938f8b29c22c93cb805 Fixes: ba83b3239e65 ("selftests: vDSO: fix vDSO symbols lookup for powerpc64") Signed-off-by: Christophe Leroy Reviewed-By: Segher Boessenkool Signed-off-by: Michael Ellerman Link: https://patch.msgid.link/b6ad2f1ee9887af3ca5ecade2a56f4acda517a85.1728512263.git.christophe.leroy@csgroup.eu

selftests: vDSO: fix ELF hash table entry size for s390x

2024-09-13T15:28:36Z

The vDSO self tests fail on s390x for a vDSO linked with the GNU linker ld as follows: # ./vdso_test_gettimeofday Floating point exception (core dumped) On s390x the ELF hash table entries are 64 bits instead of 32 bits in size (see Glibc sysdeps/unix/sysv/linux/s390/bits/elfclass.h). Fixes: 40723419f407 ("kselftest: Enable vDSO test on non x86 platforms") Reported-by: Heiko Carstens Tested-by: Heiko Carstens Signed-off-by: Jens Remus Signed-off-by: Heiko Carstens Signed-off-by: Jason A. Donenfeld

selftests: vDSO: fix vDSO symbols lookup for powerpc64

2024-08-30T13:48:45Z

On powerpc64, following tests fail locating vDSO functions: ~ # ./vdso_test_abi TAP version 13 1..16 # [vDSO kselftest] VDSO_VERSION: LINUX_2.6.15 # Couldn't find __kernel_gettimeofday ok 1 # SKIP __kernel_gettimeofday # clock_id: CLOCK_REALTIME # Couldn't find __kernel_clock_gettime ok 2 # SKIP __kernel_clock_gettime CLOCK_REALTIME # Couldn't find __kernel_clock_getres ok 3 # SKIP __kernel_clock_getres CLOCK_REALTIME ... # Couldn't find __kernel_time ok 16 # SKIP __kernel_time # Totals: pass:0 fail:0 xfail:0 xpass:0 skip:16 error:0 ~ # ./vdso_test_getrandom __kernel_getrandom is missing! ~ # ./vdso_test_gettimeofday Could not find __kernel_gettimeofday ~ # ./vdso_test_getcpu Could not find __kernel_getcpu On powerpc64, as shown below by readelf, vDSO functions symbols have type NOTYPE, so also accept that type when looking for symbols. $ powerpc64-linux-gnu-readelf -a arch/powerpc/kernel/vdso/vdso64.so.dbg ELF Header: Magic: 7f 45 4c 46 02 02 01 00 00 00 00 00 00 00 00 00 Class: ELF64 Data: 2's complement, big endian Version: 1 (current) OS/ABI: UNIX - System V ABI Version: 0 Type: DYN (Shared object file) Machine: PowerPC64 Version: 0x1 ... Symbol table '.dynsym' contains 12 entries: Num: Value Size Type Bind Vis Ndx Name 0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND 1: 0000000000000524 84 NOTYPE GLOBAL DEFAULT 8 __[...]@@LINUX_2.6.15 2: 00000000000005f0 36 NOTYPE GLOBAL DEFAULT 8 __[...]@@LINUX_2.6.15 3: 0000000000000578 68 NOTYPE GLOBAL DEFAULT 8 __[...]@@LINUX_2.6.15 4: 0000000000000000 0 OBJECT GLOBAL DEFAULT ABS LINUX_2.6.15 5: 00000000000006c0 48 NOTYPE GLOBAL DEFAULT 8 __[...]@@LINUX_2.6.15 6: 0000000000000614 172 NOTYPE GLOBAL DEFAULT 8 __[...]@@LINUX_2.6.15 7: 00000000000006f0 84 NOTYPE GLOBAL DEFAULT 8 __[...]@@LINUX_2.6.15 8: 000000000000047c 84 NOTYPE GLOBAL DEFAULT 8 __[...]@@LINUX_2.6.15 9: 0000000000000454 12 NOTYPE GLOBAL DEFAULT 8 __[...]@@LINUX_2.6.15 10: 00000000000004d0 84 NOTYPE GLOBAL DEFAULT 8 __[...]@@LINUX_2.6.15 11: 00000000000005bc 52 NOTYPE GLOBAL DEFAULT 8 __[...]@@LINUX_2.6.15 Symbol table '.symtab' contains 56 entries: Num: Value Size Type Bind Vis Ndx Name ... 45: 0000000000000000 0 OBJECT GLOBAL DEFAULT ABS LINUX_2.6.15 46: 00000000000006c0 48 NOTYPE GLOBAL DEFAULT 8 __kernel_getcpu 47: 0000000000000524 84 NOTYPE GLOBAL DEFAULT 8 __kernel_clock_getres 48: 00000000000005f0 36 NOTYPE GLOBAL DEFAULT 8 __kernel_get_tbfreq 49: 000000000000047c 84 NOTYPE GLOBAL DEFAULT 8 __kernel_gettimeofday 50: 0000000000000614 172 NOTYPE GLOBAL DEFAULT 8 __kernel_sync_dicache 51: 00000000000006f0 84 NOTYPE GLOBAL DEFAULT 8 __kernel_getrandom 52: 0000000000000454 12 NOTYPE GLOBAL DEFAULT 8 __kernel_sigtram[...] 53: 0000000000000578 68 NOTYPE GLOBAL DEFAULT 8 __kernel_time 54: 00000000000004d0 84 NOTYPE GLOBAL DEFAULT 8 __kernel_clock_g[...] 55: 00000000000005bc 52 NOTYPE GLOBAL DEFAULT 8 __kernel_get_sys[...] Fixes: 98eedc3a9dbf ("Document the vDSO and add a reference parser") Signed-off-by: Christophe Leroy Acked-by: Shuah Khan Signed-off-by: Jason A. Donenfeld

selftests/vDSO: fix clang build errors and warnings

2024-07-05T20:12:23Z

When building with clang, via: make LLVM=1 -C tools/testing/selftests ...there are several warnings, and an error. This fixes all of those and allows these tests to run and pass. 1. Fix linker error (undefined reference to memcpy) by providing a local version of memcpy. 2. clang complains about using this form: if (g = h & 0xf0000000) ...so factor out the assignment into a separate step. 3. The code is passing a signed const char* to elf_hash(), which expects a const unsigned char *. There are several callers, so fix this at the source by allowing the function to accept a signed argument, and then converting to unsigned operations, once inside the function. 4. clang doesn't have __attribute__((externally_visible)) and generates a warning to that effect. Fortunately, gcc 12 and gcc 13 do not seem to require that attribute in order to build, run and pass tests here, so remove it. Reviewed-by: Carlos Llamas Reviewed-by: Edward Liaw Reviewed-by: Muhammad Usama Anjum Tested-by: Muhammad Usama Anjum Signed-off-by: John Hubbard Signed-off-by: Shuah Khan