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x86/vdso: Introduce helper functions for CPU and node number

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Clean up the CPU/node number related code a bit, to make it more apparent
how we are encoding/extracting the CPU and node fields from the
segment limit.

No change in functionality intended.

[ mingo: Wrote new changelog. ]

Suggested-by: Andy Lutomirski <luto@kernel.org>
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Markus T Metzger <markus.t.metzger@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Shankar <ravi.v.shankar@intel.com>
Cc: Rik van Riel <riel@surriel.com>
Link: http://lkml.kernel.org/r/1537312139-5580-8-git-send-email-chang.seok.bae@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Chang S. Bae
2018-09-18 16:08:58 -07:00
committed by Ingo Molnar
parent c4755613a1
commit ffebbaedc8
4 changed files with 50 additions and 47 deletions
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41
arch/x86/include/asm/segment.h
View File

@@ -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 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" (__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__
/*