The CPU initialization in vDSO is now a bit cleaned up by the new helper functions. The helper functions will take care of combining CPU and node number and reading each from the combined value.
Suggested-by: Andy Lutomirski <[email protected]> Suggested-by: Thomas Gleixner <[email protected]> Signed-off-by: Chang S. Bae <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Andi Kleen <[email protected]> Cc: Dave Hansen <[email protected]> --- arch/x86/entry/vdso/vgetcpu.c | 9 +-------- arch/x86/entry/vdso/vma.c | 19 +++++++------------ arch/x86/include/asm/segment.h | 41 +++++++++++++++++++++++++++++++++++++++++ arch/x86/include/asm/vgtod.h | 26 -------------------------- 4 files changed, 49 insertions(+), 46 deletions(-) diff --git a/arch/x86/entry/vdso/vgetcpu.c b/arch/x86/entry/vdso/vgetcpu.c index 8ec3d1f..de78fc9 100644 --- a/arch/x86/entry/vdso/vgetcpu.c +++ b/arch/x86/entry/vdso/vgetcpu.c @@ -13,14 +13,7 @@ notrace long __vdso_getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *unused) { - unsigned int p; - - p = __getcpu(); - - if (cpu) - *cpu = p & VGETCPU_CPU_MASK; - if (node) - *node = p >> 12; + vdso_read_cpu_node(cpu, node); return 0; } diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c index 0b114aa..378732a 100644 --- a/arch/x86/entry/vdso/vma.c +++ b/arch/x86/entry/vdso/vma.c @@ -339,20 +339,15 @@ static void vgetcpu_cpu_init(void *arg) { int cpu = smp_processor_id(); struct desc_struct d = { }; - unsigned long node = 0; -#ifdef CONFIG_NUMA - node = cpu_to_node(cpu); -#endif + unsigned long cpudata = vdso_encode_cpu_node(cpu, cpu_to_node(cpu)); + if (static_cpu_has(X86_FEATURE_RDTSCP)) - write_rdtscp_aux((node << 12) | cpu); + write_rdtscp_aux(cpudata); + + /* Store cpu and node number in limit */ + d.limit0 = cpudata; + d.limit1 = cpudata >> 16; - /* - * Store cpu number in limit so that it can be loaded - * quickly in user space in vgetcpu. (12 bits for the CPU - * and 8 bits for the node) - */ - d.limit0 = cpu | ((node & 0xf) << 12); - d.limit1 = node >> 4; d.type = 5; /* RO data, expand down, accessed */ d.dpl = 3; /* Visible to user code */ d.s = 1; /* Not a system segment */ diff --git a/arch/x86/include/asm/segment.h b/arch/x86/include/asm/segment.h index e3e788ea..25a2588 100644 --- a/arch/x86/include/asm/segment.h +++ b/arch/x86/include/asm/segment.h @@ -224,6 +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_CPU_SIZE 12 +#define VDSO_CPU_MASK 0xfff + +#ifndef __ASSEMBLY__ + +/* Helper functions to store/load CPU and node numbers */ + +static inline unsigned long vdso_encode_cpu_node(int cpu, unsigned long node) +{ + return ((node << VDSO_CPU_SIZE) | cpu); +} + +static inline void vdso_read_cpu_node(unsigned *cpu, unsigned *node) +{ + unsigned int p; + + /* + * Load CPU and node number from GDT. LSL is faster than RDTSCP + * and works on all CPUs. This is volatile so that it orders + * correctly wrt barrier() and to keep gcc from cleverly + * hoisting it out of the calling function. + * + * If RDPID is available, use it. + */ + alternative_io ("lsl %[p],%[seg]", + ".byte 0xf3,0x0f,0xc7,0xf8", /* RDPID %eax/rax */ + X86_FEATURE_RDPID, + [p] "=a" (p), [seg] "r" (__CPU_NUMBER_SEG)); + + if (cpu) + *cpu = (p & VDSO_CPU_MASK); + if (node) + *node = (p >> VDSO_CPU_SIZE); +} + +#endif /* !__ASSEMBLY__ */ +#endif /* CONFIG_X86_64 */ + #ifdef __KERNEL__ /* diff --git a/arch/x86/include/asm/vgtod.h b/arch/x86/include/asm/vgtod.h index dd58a2e..056a61c 100644 --- a/arch/x86/include/asm/vgtod.h +++ b/arch/x86/include/asm/vgtod.h @@ -77,30 +77,4 @@ static inline void gtod_write_end(struct vsyscall_gtod_data *s) ++s->seq; } -#ifdef CONFIG_X86_64 - -#define VGETCPU_CPU_MASK 0xfff - -static inline unsigned int __getcpu(void) -{ - unsigned int p; - - /* - * Load CPU (and node) number from GDT. LSL is faster than RDTSCP - * and works on all CPUs. This is volatile so that it orders - * correctly wrt barrier() and to keep gcc from cleverly - * hoisting it out of the calling function. - * - * If RDPID is available, use it. - */ - alternative_io ("lsl %[p],%[seg]", - ".byte 0xf3,0x0f,0xc7,0xf8", /* RDPID %eax/rax */ - X86_FEATURE_RDPID, - [p] "=a" (p), [seg] "r" (__CPU_NUMBER_SEG)); - - return p; -} - -#endif /* CONFIG_X86_64 */ - #endif /* _ASM_X86_VGTOD_H */ -- 2.7.4
