RDPID is a new instruction in unspecified future Intel processors (sigh) that returns MSR_TSC_AUX. This will finally let the vDSO stop using LSL.
Patch 1 is the meat and patch 2 is the test. Megha has kindly tested them for me, since I don't own an unspecified Intel processor :) Andy Lutomirski (2): x86/vdso: Use RDPID in preference to LSL when available selftests/x86: Add test_vdso to test getcpu arch/x86/include/asm/cpufeatures.h | 1 + arch/x86/include/asm/vgtod.h | 7 +- tools/testing/selftests/x86/Makefile | 2 +- tools/testing/selftests/x86/test_vdso.c | 123 ++++++++++++++++++++++++++++++++ 4 files changed, 131 insertions(+), 2 deletions(-) create mode 100644 tools/testing/selftests/x86/test_vdso.c -- 2.7.4
