Commit c4755613 authored by Chang S. Bae's avatar Chang S. Bae Committed by Ingo Molnar
Browse files

x86/segments/64: Rename the GDT PER_CPU entry to CPU_NUMBER 



The old 'per CPU' naming was misleading: 64-bit kernels don't use this
GDT entry for per CPU data, but to store the CPU (and node) ID.

[ mingo: Wrote new changelog. ]

Suggested-by: default avatarH. Peter Anvin <hpa@zytor.com>
Signed-off-by: default avatarChang S. Bae <chang.seok.bae@intel.com>
Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarAndy Lutomirski <luto@kernel.org>
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: 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/1537312139-5580-7-git-send-email-chang.seok.bae@intel.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent f4550b52

arch/x86/entry/vdso/vma.c

+1 −1
Original line number Diff line number Diff line
@@ -359,7 +359,7 @@ static void vgetcpu_cpu_init(void *arg) 
	d.p = 1;		/* Present */

	d.d = 1;		/* 32-bit */



	write_gdt_entry(get_cpu_gdt_rw(cpu), GDT_ENTRY_PER_CPU, &d, DESCTYPE_S);

	write_gdt_entry(get_cpu_gdt_rw(cpu), GDT_ENTRY_CPU_NUMBER, &d, DESCTYPE_S);

}



static int vgetcpu_online(unsigned int cpu)

arch/x86/include/asm/segment.h

+2 −3
Original line number Diff line number Diff line
@@ -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_CPU_NUMBER		15



/*

 * Number of entries in the GDT table:
@@ -207,7 +206,7 @@ 
#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 __CPU_NUMBER_SEG		(GDT_ENTRY_CPU_NUMBER*8 + 3)



#endif

arch/x86/include/asm/vgtod.h

+4 −4
Original line number Diff line number Diff line
@@ -86,9 +86,9 @@ static inline unsigned int __getcpu(void) 
	unsigned int p;



	/*

	 * Load per CPU data 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

	 * 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.
@@ -96,7 +96,7 @@ static inline unsigned int __getcpu(void) 
	alternative_io ("lsl %[seg],%[p]",

			".byte 0xf3,0x0f,0xc7,0xf8", /* RDPID %eax/rax */

			X86_FEATURE_RDPID,

			[p] "=a" (p), [seg] "r" (__PER_CPU_SEG));

			[p] "=a" (p), [seg] "r" (__CPU_NUMBER_SEG));



	return p;

}

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