blaster4385/linux-IllusionX/tools/testing/selftests/vDSO, branch v6.12.10

powerpc/vdso: Flag VDSO64 entry points as functions

2024-12-05T13:02:03Z

[ Upstream commit 0161bd38c24312853ed5ae9a425a1c41c4ac674a ] 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 Signed-off-by: Sasha Levin

selftests: vDSO: Explicitly include sched.h

2024-10-08T21:48:09Z

The previous commit introduced the use of CLONE_NEWTIME without including which contains its definition. Add an explicit include of to ensure that CLONE_NEWTIME is correctly defined before it is used. Fixes: 2aec90036dcd ("selftests: vDSO: ensure vgetrandom works in a time namespace") Signed-off-by: Yu Liao Signed-off-by: Shuah Khan

selftests: vDSO: improve getrandom and chacha error messages

2024-10-08T21:21:52Z

Improve the error and skip condition messages to let the developer know precisely where a test has failed. Also make better use of the ksft api for this. Signed-off-by: Jason A. Donenfeld Signed-off-by: Shuah Khan

selftests: vDSO: unconditionally build getrandom test

2024-10-08T21:21:36Z

Rather than building on supported archs, build on all archs, and then use the presence of the symbol in the vDSO to either skip the test or move forward with it. Note that this means that this test no longer checks whether the symbol was correctly added to the kernel. But hopefully this will be clear enough to developers and we'll cross our fingers that symbols aren't removed by accident and not caught after this change. Signed-off-by: Jason A. Donenfeld Signed-off-by: Shuah Khan

selftests: vDSO: unconditionally build chacha test

2024-10-08T21:21:29Z

Rather than using symlinks to find the vgetrandom-chacha.S file for each arch, store this in a file that uses the compiler to determine architecture, and then make use of weak symbols to skip the test on architectures that don't provide the code. Signed-off-by: Jason A. Donenfeld Signed-off-by: Shuah Khan

selftests: vDSO: align getrandom states to cache line

2024-10-01T14:30:58Z

This prevents false sharing, which makes a large difference on machines with several NUMA nodes, such as on a dual socket Intel(R) Xeon(R) Gold 6338 CPU @ 2.00GHz, where the "bench-multi" test goes from 2.7s down to 1.9s. While this is just test code, it also forms the basis of how folks will wind up implementing this in libraries, so we should implement this simple cache alignment improvement here. Suggested-by: Florian Weimer Cc: Adhemerval Zanella Signed-off-by: Jason A. Donenfeld Signed-off-by: Shuah Khan

Merge tag 'linux_kselftest-next-6.12-rc1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest

2024-09-29T15:37:03Z

Pull kselftest fix from Shuah Khan: "One urgent fix to vDSO as automated testing is failing due to this bug" * tag 'linux_kselftest-next-6.12-rc1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest: selftests: vDSO: align stack for O2-optimized memcpy

selftests: vDSO: align stack for O2-optimized memcpy

2024-09-27T18:17:12Z

When switching on -O2, gcc generates SSE2 instructions that assume a 16-byte aligned stack, which the standalone test's start point wasn't aligning. Fix this with the usual alignment sequence. Fixes: ecb8bd70d51 ("selftests: vDSO: build tests with O2 optimization") Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-lkp/202409241558.98e13f6f-oliver.sang@intel.com Signed-off-by: Jason A. Donenfeld Signed-off-by: Shuah Khan

selftests: vDSO: check cpu caps before running chacha test

2024-09-16T11:22:04Z

Some archs -- arm64 and s390x -- implemented chacha using instructions that are available most places, but aren't always available. The kernel handles this just fine, but the selftest does not. Check the hwcaps before running, and skip the test if the cpu doesn't support it. As well, on s390x, always emit the fallback instructions of an alternative block, to ensure maximum compatibility. Co-developed-by: Heiko Carstens Signed-off-by: Heiko Carstens Signed-off-by: Jason A. Donenfeld

s390/vdso: Wire up getrandom() vdso implementation

2024-09-13T18:57:31Z

Provide the s390 specific vdso getrandom() architecture backend. _vdso_rng_data required data is placed within the _vdso_data vvar page, by using a hardcoded offset larger than vdso_data. As required the chacha20 implementation does not write to the stack. The implementation follows more or less the arm64 implementations and makes use of vector instructions. It has a fallback to the getrandom() system call for machines where the vector facility is not installed. The check if the vector facility is installed, as well as an optimization for machines with the vector-enhancements facility 2, is implemented with alternatives, avoiding runtime checks. Note that __kernel_getrandom() is implemented without the vdso user wrapper which would setup a stack frame for odd cases (aka very old glibc variants) where the caller has not done that. All callers of __kernel_getrandom() are required to setup a stack frame, like the C ABI requires it. The vdso testcases vdso_test_getrandom and vdso_test_chacha pass. Benchmark on a z16: $ ./vdso_test_getrandom bench-single vdso: 25000000 times in 0.493703559 seconds syscall: 25000000 times in 6.584025337 seconds Signed-off-by: Heiko Carstens Reviewed-by: Harald Freudenberger Signed-off-by: Jason A. Donenfeld