arm32: kaslr: Fix clock_gettime and gettimeofday performance degradation when...

arm32: kaslr: Fix clock_gettime and gettimeofday performance degradation when configure CONFIG_RANDOMIZE_BASE

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I8KNA9


CVE: NA

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When we configure CONFIG_RANDOMIZE_BASE we find that:
[XX]$arm-linux-gnueabihf-readelf -s  ./arch/arm/vdso/vdso.so
Symbol table '.dynsym' contains 5 entries:
   Num:    Value  Size Type    Bind   Vis      Ndx Name
	 0: 00000000     0 NOTYPE  LOCAL  DEFAULT  UND
	 1: 00000278     0 SECTION LOCAL  DEFAULT    8
	 2: 00000000     0 OBJECT  GLOBAL DEFAULT  ABS LINUX_2.6

  We can't find __vdso_gettimeofday and __vdso_clock_gettime symbol. So call
clock_gettime and gettimeofday will call system call. This results in
performance degradation.

Signed-off-by: Ye Bin <yebin10@huawei.com>
Signed-off-by: Felix Fu <fuzhen5@huawei.com>