xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

x86,vdso: Use LSL unconditionally for vgetcpu

Browse Source 
LSL is faster than RDTSCP and works everywhere; there's no need to
switch between them depending on CPU.

Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Cc: Andi Kleen <andi@firstfloor.org>
Link: http://lkml.kernel.org/r/72f73d5ec4514e02bba345b9759177ef03742efb.1414706021.git.luto@amacapital.net
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Andy Lutomirski
2014-10-30 14:58:01 -07:00
committed by Thomas Gleixner
parent a92f101bc9
commit e76b027e64
6 changed files with 19 additions and 43 deletions
Download Patch File Download Diff File Expand all files Collapse all files

29
arch/x86/include/asm/vsyscall.h
View File

@@ -4,15 +4,6 @@
#include <linux/seqlock.h>
#include <uapi/asm/vsyscall.h>
#define VGETCPU_RDTSCP 1
#define VGETCPU_LSL 2
/* kernel space (writeable) */
extern int vgetcpu_mode;
extern struct timezone sys_tz;
#include <asm/vvar.h>
extern void map_vsyscall(void);
/*
@@ -21,24 +12,4 @@ extern void map_vsyscall(void);
*/
extern bool emulate_vsyscall(struct pt_regs *regs, unsigned long address);
#ifdef CONFIG_X86_64
#define VGETCPU_CPU_MASK 0xfff
static inline unsigned int __getcpu(void)
{
unsigned int p;
if (VVAR(vgetcpu_mode) == VGETCPU_RDTSCP) {
/* Load per CPU data from RDTSCP */
native_read_tscp(&p);
} else {
/* Load per CPU data from GDT */
asm("lsl %1,%0" : "=r" (p) : "r" (__PER_CPU_SEG));
}
return p;
}
#endif /* CONFIG_X86_64 */
#endif /* _ASM_X86_VSYSCALL_H */