Re: [PATCH bpf-next v6 1/4] bpf: add bpf_get_cpu_cycles kfunc

[kernel test robot <lkp@intel.com>]

Hi Vadim,

kernel test robot noticed the following build errors:

[auto build test ERROR on bpf-next/master]

url:    https://github.com/intel-lab-lkp/linux/commits/Vadim-Fedorenko/bpf-add-bpf_get_cpu_cycles-kfunc/20241117-002106
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
patch link:    https://lore.kernel.org/r/20241115194841.2108634-2-vadfed%40meta.com
patch subject: [PATCH bpf-next v6 1/4] bpf: add bpf_get_cpu_cycles kfunc
config: x86_64-randconfig-075-20241117 (https://download.01.org/0day-ci/archive/20241118/202411180657.c0eoNysc-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20241118/202411180657.c0eoNysc-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202411180657.c0eoNysc-lkp@intel.com/

All errors (new ones prefixed by >>):

   ld: vmlinux.o: in function `vread_pvclock':
>> arch/x86/include/asm/vdso/gettimeofday.h:198: undefined reference to `pvclock_page'
>> ld: arch/x86/include/asm/vdso/gettimeofday.h:198: undefined reference to `pvclock_page'
   ld: vmlinux.o: in function `pvclock_read_begin':
>> arch/x86/include/asm/pvclock.h:25: undefined reference to `pvclock_page'
   ld: vmlinux.o: in function `vread_pvclock':
   arch/x86/include/asm/vdso/gettimeofday.h:228: undefined reference to `pvclock_page'
   ld: vmlinux.o: in function `__pvclock_read_cycles':
   arch/x86/include/asm/pvclock.h:86: undefined reference to `pvclock_page'
   ld: vmlinux.o:arch/x86/include/asm/pvclock.h:88: more undefined references to `pvclock_page' follow
   ld: .tmp_vmlinux1: hidden symbol `pvclock_page' isn't defined
   ld: final link failed: bad value


vim +198 arch/x86/include/asm/vdso/gettimeofday.h

7ac8707479886c Vincenzo Frascino 2019-06-21  195  
7ac8707479886c Vincenzo Frascino 2019-06-21  196  #ifdef CONFIG_PARAVIRT_CLOCK
7ac8707479886c Vincenzo Frascino 2019-06-21  197  static u64 vread_pvclock(void)
7ac8707479886c Vincenzo Frascino 2019-06-21 @198  {
ecf9db3d1f1a8f Andy Lutomirski   2019-06-22  199  	const struct pvclock_vcpu_time_info *pvti = &pvclock_page.pvti;
7ac8707479886c Vincenzo Frascino 2019-06-21  200  	u32 version;
7ac8707479886c Vincenzo Frascino 2019-06-21  201  	u64 ret;
7ac8707479886c Vincenzo Frascino 2019-06-21  202  
7ac8707479886c Vincenzo Frascino 2019-06-21  203  	/*
7ac8707479886c Vincenzo Frascino 2019-06-21  204  	 * Note: The kernel and hypervisor must guarantee that cpu ID
7ac8707479886c Vincenzo Frascino 2019-06-21  205  	 * number maps 1:1 to per-CPU pvclock time info.
7ac8707479886c Vincenzo Frascino 2019-06-21  206  	 *
7ac8707479886c Vincenzo Frascino 2019-06-21  207  	 * Because the hypervisor is entirely unaware of guest userspace
7ac8707479886c Vincenzo Frascino 2019-06-21  208  	 * preemption, it cannot guarantee that per-CPU pvclock time
7ac8707479886c Vincenzo Frascino 2019-06-21  209  	 * info is updated if the underlying CPU changes or that that
7ac8707479886c Vincenzo Frascino 2019-06-21  210  	 * version is increased whenever underlying CPU changes.
7ac8707479886c Vincenzo Frascino 2019-06-21  211  	 *
7ac8707479886c Vincenzo Frascino 2019-06-21  212  	 * On KVM, we are guaranteed that pvti updates for any vCPU are
7ac8707479886c Vincenzo Frascino 2019-06-21  213  	 * atomic as seen by *all* vCPUs.  This is an even stronger
7ac8707479886c Vincenzo Frascino 2019-06-21  214  	 * guarantee than we get with a normal seqlock.
7ac8707479886c Vincenzo Frascino 2019-06-21  215  	 *
7ac8707479886c Vincenzo Frascino 2019-06-21  216  	 * On Xen, we don't appear to have that guarantee, but Xen still
7ac8707479886c Vincenzo Frascino 2019-06-21  217  	 * supplies a valid seqlock using the version field.
7ac8707479886c Vincenzo Frascino 2019-06-21  218  	 *
7ac8707479886c Vincenzo Frascino 2019-06-21  219  	 * We only do pvclock vdso timing at all if
7ac8707479886c Vincenzo Frascino 2019-06-21  220  	 * PVCLOCK_TSC_STABLE_BIT is set, and we interpret that bit to
7ac8707479886c Vincenzo Frascino 2019-06-21  221  	 * mean that all vCPUs have matching pvti and that the TSC is
7ac8707479886c Vincenzo Frascino 2019-06-21  222  	 * synced, so we can just look at vCPU 0's pvti.
7ac8707479886c Vincenzo Frascino 2019-06-21  223  	 */
7ac8707479886c Vincenzo Frascino 2019-06-21  224  
7ac8707479886c Vincenzo Frascino 2019-06-21  225  	do {
7ac8707479886c Vincenzo Frascino 2019-06-21  226  		version = pvclock_read_begin(pvti);
7ac8707479886c Vincenzo Frascino 2019-06-21  227  
7ac8707479886c Vincenzo Frascino 2019-06-21  228  		if (unlikely(!(pvti->flags & PVCLOCK_TSC_STABLE_BIT)))
7ac8707479886c Vincenzo Frascino 2019-06-21  229  			return U64_MAX;
7ac8707479886c Vincenzo Frascino 2019-06-21  230  
7ac8707479886c Vincenzo Frascino 2019-06-21  231  		ret = __pvclock_read_cycles(pvti, rdtsc_ordered());
7ac8707479886c Vincenzo Frascino 2019-06-21  232  	} while (pvclock_read_retry(pvti, version));
7ac8707479886c Vincenzo Frascino 2019-06-21  233  
77750f78b0b324 Peter Zijlstra    2023-05-19  234  	return ret & S64_MAX;
7ac8707479886c Vincenzo Frascino 2019-06-21  235  }
7ac8707479886c Vincenzo Frascino 2019-06-21  236  #endif
7ac8707479886c Vincenzo Frascino 2019-06-21  237  

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