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From: "tip-bot for Chang S. Bae" <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: markus.t.metzger@intel.com, hpa@zytor.com,
	ravi.v.shankar@intel.com, dvlasenk@redhat.com,
	linux-kernel@vger.kernel.org, riel@surriel.com,
	dave.hansen@linux.intel.com, torvalds@linux-foundation.org,
	brgerst@gmail.com, luto@kernel.org, luto@amacapital.net,
	mingo@kernel.org, chang.seok.bae@intel.com, bp@alien8.de,
	peterz@infradead.org, tglx@linutronix.de
Subject: [tip:x86/asm] x86/segments/64: Rename the GDT PER_CPU entry to CPU_NUMBER
Date: Mon, 8 Oct 2018 02:57:41 -0700	[thread overview]
Message-ID: <tip-c4755613a1339ea77dbb15de75c9f74217209265@git.kernel.org> (raw)
In-Reply-To: <1537312139-5580-7-git-send-email-chang.seok.bae@intel.com>

Commit-ID:  c4755613a1339ea77dbb15de75c9f74217209265
Gitweb:     https://git.kernel.org/tip/c4755613a1339ea77dbb15de75c9f74217209265
Author:     Chang S. Bae <chang.seok.bae@intel.com>
AuthorDate: Tue, 18 Sep 2018 16:08:57 -0700
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Mon, 8 Oct 2018 10:41:10 +0200

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: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Andy 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: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/entry/vdso/vma.c      | 2 +-
 arch/x86/include/asm/segment.h | 5 ++---
 arch/x86/include/asm/vgtod.h   | 8 ++++----
 3 files changed, 7 insertions(+), 8 deletions(-)

diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index 5b8b556dbb12..0b114aafcedc 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -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)
diff --git a/arch/x86/include/asm/segment.h b/arch/x86/include/asm/segment.h
index e293c122d0d5..e3e788ea52e5 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_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
 
diff --git a/arch/x86/include/asm/vgtod.h b/arch/x86/include/asm/vgtod.h
index 53748541c487..4e81ea920722 100644
--- a/arch/x86/include/asm/vgtod.h
+++ b/arch/x86/include/asm/vgtod.h
@@ -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;
 }

  reply	other threads:[~2018-10-08  9:58 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-18 23:08 [PATCH v6 0/8] x86: infrastructure to enable FSGSBASE Chang S. Bae
2018-09-18 23:08 ` [PATCH v6 1/8] x86/arch_prctl/64: Make ptrace read FS/GS base accurately Chang S. Bae
2018-10-08  9:54   ` [tip:x86/asm] x86/fsgsbase/64: Fix ptrace() to read the " tip-bot for Andy Lutomirski
2018-10-08  9:59   ` [tip:x86/asm] x86/segments: Introduce the 'CPUNODE' naming to better document the segment limit CPU/node NR trick tip-bot for Ingo Molnar
2018-10-08  9:59   ` [tip:x86/asm] x86/fsgsbase/64: Clean up various details tip-bot for Ingo Molnar
2018-09-18 23:08 ` [PATCH v6 2/8] x86/fsgsbase/64: Introduce FS/GS base helper functions Chang S. Bae
2018-10-08  9:55   ` [tip:x86/asm] " tip-bot for Chang S. Bae
2018-10-24 19:01   ` [regression in -rc1] Re: [PATCH v6 2/8] " Andy Lutomirski
2018-10-24 19:13     ` Bae, Chang Seok
2018-10-24 19:22       ` Andy Lutomirski
2018-10-24 19:29         ` Bae, Chang Seok
2018-10-24 19:43           ` Andy Lutomirski
2018-10-24 22:50             ` Bae, Chang Seok
2018-10-25 22:37     ` Andy Lutomirski
2018-09-18 23:08 ` [PATCH v6 3/8] x86/fsgsbase/64: Make ptrace use correct FS/GS base helpers Chang S. Bae
2018-10-08  9:56   ` [tip:x86/asm] x86/fsgsbase/64: Make ptrace use the new " tip-bot for Chang S. Bae
2018-09-18 23:08 ` [PATCH v6 4/8] x86/fsgsbase/64: Use FS/GS base helpers in core dump Chang S. Bae
2018-10-08  9:56   ` [tip:x86/asm] x86/fsgsbase/64: Convert the ELF core dump code to the new FSGSBASE helpers tip-bot for Chang S. Bae
2018-09-18 23:08 ` [PATCH v6 5/8] x86/fsgsbase/64: Factor out load FS/GS segments from __switch_to() Chang S. Bae
2018-10-08  9:57   ` [tip:x86/asm] x86/fsgsbase/64: Factor out FS/GS segment loading " tip-bot for Chang S. Bae
2018-09-18 23:08 ` [PATCH v6 6/8] x86/segments/64: Rename PER_CPU segment to CPU_NUMBER Chang S. Bae
2018-10-08  9:57   ` tip-bot for Chang S. Bae [this message]
2018-09-18 23:08 ` [PATCH v6 7/8] x86/vdso: Introduce helper functions for CPU and node number Chang S. Bae
2018-10-08  9:58   ` [tip:x86/asm] " tip-bot for Chang S. Bae
2018-09-18 23:08 ` [PATCH v6 8/8] x86/vdso: Move out the CPU initialization Chang S. Bae
2018-10-08  8:36   ` Ingo Molnar
2018-10-08  9:58   ` [tip:x86/asm] x86/vdso: Initialize the CPU/node NR segment descriptor earlier tip-bot for Chang S. Bae

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