diff options
Diffstat (limited to 'arch/x86/include/asm/segment.h')
| -rw-r--r-- | arch/x86/include/asm/segment.h | 48 |
1 files changed, 44 insertions, 4 deletions
diff --git a/arch/x86/include/asm/segment.h b/arch/x86/include/asm/segment.h index e293c122d0d5..ac3892920419 100644 --- a/arch/x86/include/asm/segment.h +++ b/arch/x86/include/asm/segment.h @@ -186,8 +186,7 @@ #define GDT_ENTRY_TLS_MIN 12 #define GDT_ENTRY_TLS_MAX 14 -/* Abused to load per CPU data from limit */ -#define GDT_ENTRY_PER_CPU 15 +#define GDT_ENTRY_CPUNODE 15 /* * Number of entries in the GDT table: @@ -207,11 +206,11 @@ #define __USER_DS (GDT_ENTRY_DEFAULT_USER_DS*8 + 3) #define __USER32_DS __USER_DS #define __USER_CS (GDT_ENTRY_DEFAULT_USER_CS*8 + 3) -#define __PER_CPU_SEG (GDT_ENTRY_PER_CPU*8 + 3) +#define __CPUNODE_SEG (GDT_ENTRY_CPUNODE*8 + 3) #endif -#ifndef CONFIG_PARAVIRT +#ifndef CONFIG_PARAVIRT_XXL # define get_kernel_rpl() 0 #endif @@ -225,6 +224,47 @@ #define GDT_ENTRY_TLS_ENTRIES 3 #define TLS_SIZE (GDT_ENTRY_TLS_ENTRIES* 8) +#ifdef CONFIG_X86_64 + +/* Bit size and mask of CPU number stored in the per CPU data (and TSC_AUX) */ +#define VDSO_CPUNODE_BITS 12 +#define VDSO_CPUNODE_MASK 0xfff + +#ifndef __ASSEMBLY__ + +/* Helper functions to store/load CPU and node numbers */ + +static inline unsigned long vdso_encode_cpunode(int cpu, unsigned long node) +{ + return (node << VDSO_CPUNODE_BITS) | cpu; +} + +static inline void vdso_read_cpunode(unsigned *cpu, unsigned *node) +{ + unsigned int p; + + /* + * Load CPU and node number from the GDT. LSL is faster than RDTSCP + * and works on all CPUs. This is volatile so that it orders + * correctly with respect to barrier() and to keep GCC from cleverly + * hoisting it out of the calling function. + * + * If RDPID is available, use it. + */ + alternative_io ("lsl %[seg],%[p]", + ".byte 0xf3,0x0f,0xc7,0xf8", /* RDPID %eax/rax */ + X86_FEATURE_RDPID, + [p] "=a" (p), [seg] "r" (__CPUNODE_SEG)); + + if (cpu) + *cpu = (p & VDSO_CPUNODE_MASK); + if (node) + *node = (p >> VDSO_CPUNODE_BITS); +} + +#endif /* !__ASSEMBLY__ */ +#endif /* CONFIG_X86_64 */ + #ifdef __KERNEL__ /* |