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From: tip-bot for Thomas Gleixner <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: jpoimboe@redhat.com, tglx@linutronix.de, dvlasenk@redhat.com,
	linux-kernel@vger.kernel.org, brgerst@gmail.com,
	rostedt@goodmis.org, luto@kernel.org, peterz@infradead.org,
	torvalds@linux-foundation.org, mingo@kernel.org, hpa@zytor.com,
	bp@alien8.de
Subject: [tip:x86/apic] x86/gdt: Use bitfields for initialization
Date: Tue, 29 Aug 2017 04:14:21 -0700	[thread overview]
Message-ID: <tip-38e9e81f4c81c75799b002d5811de7241b307676@git.kernel.org> (raw)
In-Reply-To: <20170828064958.197673367@linutronix.de>

Commit-ID:  38e9e81f4c81c75799b002d5811de7241b307676
Gitweb:     http://git.kernel.org/tip/38e9e81f4c81c75799b002d5811de7241b307676
Author:     Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Mon, 28 Aug 2017 08:47:41 +0200
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 29 Aug 2017 12:07:25 +0200

x86/gdt: Use bitfields for initialization

The GDT entry related code uses two ways to access entries via
union fields:

 - bitfields

 - macros which initialize the two 16-bit parts of the entry
   by magic shift and mask operations.

Clean it up and only use the bitfields to initialize and access entries.

( The old access patterns were partly done due to GCC optimizing bitfield
  accesses in a horrible way - that's mostly fixed these days and clarity
  of code in such low level accessors is very important. )

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20170828064958.197673367@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/entry/vdso/vma.c        |  2 +-
 arch/x86/include/asm/desc.h      | 26 +++++++++++++++---------
 arch/x86/include/asm/desc_defs.h | 44 ++++++++++++++++++----------------------
 arch/x86/math-emu/fpu_system.h   |  2 +-
 4 files changed, 38 insertions(+), 36 deletions(-)

diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index 726355c..1911310 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -351,7 +351,7 @@ static void vgetcpu_cpu_init(void *arg)
 	 * and 8 bits for the node)
 	 */
 	d.limit0 = cpu | ((node & 0xf) << 12);
-	d.limit = node >> 4;
+	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/desc.h b/arch/x86/include/asm/desc.h
index 0731064..2090cd2 100644
--- a/arch/x86/include/asm/desc.h
+++ b/arch/x86/include/asm/desc.h
@@ -23,7 +23,7 @@ static inline void fill_ldt(struct desc_struct *desc, const struct user_desc *in
 	desc->s			= 1;
 	desc->dpl		= 0x3;
 	desc->p			= info->seg_not_present ^ 1;
-	desc->limit		= (info->limit & 0xf0000) >> 16;
+	desc->limit1		= (info->limit & 0xf0000) >> 16;
 	desc->avl		= info->useable;
 	desc->d			= info->seg_32bit;
 	desc->g			= info->limit_in_pages;
@@ -170,14 +170,20 @@ static inline void pack_descriptor(struct desc_struct *desc, unsigned long base,
 				   unsigned long limit, unsigned char type,
 				   unsigned char flags)
 {
-	desc->a = ((base & 0xffff) << 16) | (limit & 0xffff);
-	desc->b = (base & 0xff000000) | ((base & 0xff0000) >> 16) |
-		(limit & 0x000f0000) | ((type & 0xff) << 8) |
-		((flags & 0xf) << 20);
-	desc->p = 1;
+	desc->limit0		= (u16) limit;
+	desc->base0		= (u16) base;
+	desc->base1		= (base >> 16) & 0xFF;
+	desc->type		= type & 0x0F;
+	desc->s			= 0;
+	desc->dpl		= 0;
+	desc->p			= 1;
+	desc->limit1		= (limit >> 16) & 0xF;
+	desc->avl		= (flags >> 0) & 0x01;
+	desc->l			= (flags >> 1) & 0x01;
+	desc->d			= (flags >> 2) & 0x01;
+	desc->g			= (flags >> 3) & 0x01;
 }
 
-
 static inline void set_tssldt_descriptor(void *d, unsigned long addr,
 					 unsigned type, unsigned size)
 {
@@ -195,7 +201,7 @@ static inline void set_tssldt_descriptor(void *d, unsigned long addr,
 	desc->base2		= (addr >> 24) & 0xFF;
 	desc->base3		= (u32) (addr >> 32);
 #else
-	pack_descriptor((struct desc_struct *)d, addr, size, 0x80 | type, 0);
+	pack_descriptor((struct desc_struct *)d, addr, size, type, 0);
 #endif
 }
 
@@ -395,13 +401,13 @@ static inline void set_desc_base(struct desc_struct *desc, unsigned long base)
 
 static inline unsigned long get_desc_limit(const struct desc_struct *desc)
 {
-	return desc->limit0 | (desc->limit << 16);
+	return desc->limit0 | (desc->limit1 << 16);
 }
 
 static inline void set_desc_limit(struct desc_struct *desc, unsigned long limit)
 {
 	desc->limit0 = limit & 0xffff;
-	desc->limit = (limit >> 16) & 0xf;
+	desc->limit1 = (limit >> 16) & 0xf;
 }
 
 #ifdef CONFIG_X86_64
diff --git a/arch/x86/include/asm/desc_defs.h b/arch/x86/include/asm/desc_defs.h
index d684bee..1b9494e 100644
--- a/arch/x86/include/asm/desc_defs.h
+++ b/arch/x86/include/asm/desc_defs.h
@@ -11,34 +11,30 @@
 
 #include <linux/types.h>
 
-/*
- * FIXME: Accessing the desc_struct through its fields is more elegant,
- * and should be the one valid thing to do. However, a lot of open code
- * still touches the a and b accessors, and doing this allow us to do it
- * incrementally. We keep the signature as a struct, rather than a union,
- * so we can get rid of it transparently in the future -- glommer
- */
 /* 8 byte segment descriptor */
 struct desc_struct {
-	union {
-		struct {
-			unsigned int a;
-			unsigned int b;
-		};
-		struct {
-			u16 limit0;
-			u16 base0;
-			unsigned base1: 8, type: 4, s: 1, dpl: 2, p: 1;
-			unsigned limit: 4, avl: 1, l: 1, d: 1, g: 1, base2: 8;
-		};
-	};
+	u16	limit0;
+	u16	base0;
+	u16	base1: 8, type: 4, s: 1, dpl: 2, p: 1;
+	u16	limit1: 4, avl: 1, l: 1, d: 1, g: 1, base2: 8;
 } __attribute__((packed));
 
-#define GDT_ENTRY_INIT(flags, base, limit) { { { \
-		.a = ((limit) & 0xffff) | (((base) & 0xffff) << 16), \
-		.b = (((base) & 0xff0000) >> 16) | (((flags) & 0xf0ff) << 8) | \
-			((limit) & 0xf0000) | ((base) & 0xff000000), \
-	} } }
+#define GDT_ENTRY_INIT(flags, base, limit)			\
+	{							\
+		.limit0		= (u16) (limit),		\
+		.limit1		= ((limit) >> 16) & 0x0F,	\
+		.base0		= (u16) (base),			\
+		.base1		= ((base) >> 16) & 0xFF,	\
+		.base2		= ((base) >> 24) & 0xFF,	\
+		.type		= (flags & 0x0f),		\
+		.s		= (flags >> 4) & 0x01,		\
+		.dpl		= (flags >> 5) & 0x03,		\
+		.p		= (flags >> 7) & 0x01,		\
+		.avl		= (flags >> 12) & 0x01,		\
+		.l		= (flags >> 13) & 0x01,		\
+		.d		= (flags >> 14) & 0x01,		\
+		.g		= (flags >> 15) & 0x01,		\
+	}
 
 enum {
 	GATE_INTERRUPT = 0xE,
diff --git a/arch/x86/math-emu/fpu_system.h b/arch/x86/math-emu/fpu_system.h
index 2319a25..699f329 100644
--- a/arch/x86/math-emu/fpu_system.h
+++ b/arch/x86/math-emu/fpu_system.h
@@ -49,7 +49,7 @@ static inline unsigned long seg_get_base(struct desc_struct *d)
 
 static inline unsigned long seg_get_limit(struct desc_struct *d)
 {
-	return ((unsigned long)d->limit << 16) | d->limit0;
+	return ((unsigned long)d->limit1 << 16) | d->limit0;
 }
 
 static inline unsigned long seg_get_granularity(struct desc_struct *d)

  reply	other threads:[~2017-08-29 11:20 UTC|newest]

Thread overview: 95+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-08-28  6:47 [patch V3 00/44] x86: Cleanup IDT code Thomas Gleixner
2017-08-28  6:47 ` [patch V3 01/44] x86/irq: Remove vector_used_by_percpu_irq() Thomas Gleixner
2017-08-29 11:04   ` [tip:x86/apic] " tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 02/44] x86/irq: Unexport used_vectors Thomas Gleixner
2017-08-29 11:04   ` [tip:x86/apic] x86/irq: Unexport used_vectors[] tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 03/44] x86/irq: Get rid of the first_system_vector bogisity Thomas Gleixner
2017-08-29 11:04   ` [tip:x86/apic] x86/irq: Get rid of the 'first_system_vector' indirection bogosity tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 04/44] x86/irq: Remove duplicated used_vectors definition Thomas Gleixner
2017-08-29 11:05   ` [tip:x86/apic] " tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 05/44] x86/boot: Move EISA setup to a proper place Thomas Gleixner
2017-08-29 11:05   ` [tip:x86/apic] x86/boot: Move EISA setup to a separate file tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 06/44] x86/tracing: Introduce a static key for exception tracing Thomas Gleixner
2017-08-29 11:06   ` [tip:x86/apic] " tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 07/44] x86/traps: Simplify pagefault tracing logic Thomas Gleixner
2017-08-29 11:06   ` [tip:x86/apic] " tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 08/44] x86/apic: Remove the duplicated tracing version of local_timer_interrupt Thomas Gleixner
2017-08-29 11:07   ` [tip:x86/apic] x86/apic: Remove the duplicated tracing version of local_timer_interrupt() tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 09/44] x86/apic: Use this_cpu_ptr in local_timer_interrupt Thomas Gleixner
2017-08-29 11:07   ` [tip:x86/apic] x86/apic: Use this_cpu_ptr() in local_timer_interrupt() tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 10/44] x86/irq: Get rid of duplicated trace_x86_platform_ipi() code Thomas Gleixner
2017-08-29 11:07   ` [tip:x86/apic] " tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 11/44] x86/apic: Remove the duplicated tracing versions of interrupts Thomas Gleixner
2017-08-29 11:08   ` [tip:x86/apic] " tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 12/44] x86/irqwork: Get rid of duplicated tracing interrupt code Thomas Gleixner
2017-08-29 11:08   ` [tip:x86/apic] " tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 13/44] x86/mce: Remove " Thomas Gleixner
2017-08-29 11:08   ` [tip:x86/apic] " tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 14/44] x86/smp: Remove pointless duplicated " Thomas Gleixner
2017-08-29 11:09   ` [tip:x86/apic] " tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 15/44] x86/smp: Use static key for reschedule interrupt tracing Thomas Gleixner
2017-08-29 11:09   ` [tip:x86/apic] " tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 16/44] x86/idt: Remove tracing idt completely Thomas Gleixner
2017-08-29 11:10   ` [tip:x86/apic] x86/idt: Remove the tracing IDT completely tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 17/44] x86/idt: Cleanup the i386 low level entry macros Thomas Gleixner
2017-08-29 11:10   ` [tip:x86/apic] x86/idt: Clean up " tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 18/44] x86/tracing: Disentangle pagefault and resched IPI tracing key Thomas Gleixner
2017-08-29 11:10   ` [tip:x86/apic] " tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 19/44] x86/ipi: Make platform IPI depend on APIC Thomas Gleixner
2017-08-29 11:11   ` [tip:x86/apic] " tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 20/44] x86/irq_work: Make it " Thomas Gleixner
2017-08-29 11:11   ` [tip:x86/apic] " tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 21/44] x86/tracing: Build tracepoints only when they are used Thomas Gleixner
2017-08-29 11:12   ` [tip:x86/apic] " tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 22/44] x86/idt: Unify gate_struct handling for 32/64bit Thomas Gleixner
2017-08-29 11:12   ` [tip:x86/apic] x86/idt: Unify gate_struct handling for 32/64-bit kernels tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 23/44] x86/percpu: Use static initializer for GDT entry Thomas Gleixner
2017-08-29 11:13   ` [tip:x86/apic] " tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 24/44] x86/fpu: Use bitfield accessors for desc_struct Thomas Gleixner
2017-08-29 11:13   ` [tip:x86/apic] " tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 25/44] x86: Replace access to desc_struct:a/b fields Thomas Gleixner
2017-08-29 11:13   ` [tip:x86/apic] x86/asm: " tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 26/44] x86/gdt: Use bitfields for initialization Thomas Gleixner
2017-08-29 11:14   ` tip-bot for Thomas Gleixner [this message]
2017-08-28  6:47 ` [patch V3 27/44] x86/ldttss: Cleanup 32bit descriptors Thomas Gleixner
2017-08-29 11:14   ` [tip:x86/apic] x86/ldttss: Clean up 32-bit descriptors tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 28/44] x86/idt: Create file for IDT related code Thomas Gleixner
2017-08-29 11:15   ` [tip:x86/apic] " tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 29/44] x86/idt: Move 32bit idt_descr to C code Thomas Gleixner
2017-08-29 11:15   ` [tip:x86/apic] x86/idt: Move 32-bit " tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 30/44] x86/idt: Remove unused set_trap_gate() Thomas Gleixner
2017-08-29 11:16   ` [tip:x86/apic] " tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 31/44] x86/idt: Consolidate IDT invalidation Thomas Gleixner
2017-08-29 11:16   ` [tip:x86/apic] " tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 32/44] x86/idt: Move early IDT handler setup to IDT code Thomas Gleixner
2017-08-29 11:16   ` [tip:x86/apic] " tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 33/44] x86/idt: Move early IDT setup out of 32bit asm Thomas Gleixner
2017-08-29 11:17   ` [tip:x86/apic] x86/idt: Move early IDT setup out of 32-bit asm tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 34/44] x86/idt: Prepare for table based init Thomas Gleixner
2017-08-29 11:17   ` [tip:x86/apic] " tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 35/44] x86/idt: Switch early trap init to IDT tables Thomas Gleixner
2017-08-29 11:18   ` [tip:x86/apic] " tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 36/44] x86/idt: Move debug stack init to table based Thomas Gleixner
2017-08-29 11:18   ` [tip:x86/apic] " tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 37/44] x86/idt: Move ist stack based traps to table init Thomas Gleixner
2017-08-29 11:18   ` [tip:x86/apic] x86/idt: Move IST " tip-bot for Thomas Gleixner
2017-09-01  6:28     ` Andrei Vagin
2017-09-01  8:26       ` [PATCH] x86/idt: Fix the X86_TRAP_BP gate Ingo Molnar
2017-09-01  8:59         ` Thomas Gleixner
2017-09-01  9:09         ` [tip:x86/apic] " tip-bot for Ingo Molnar
2017-09-01 14:39         ` [PATCH] " Andrei Vagin
2017-08-28  6:47 ` [patch V3 38/44] x86/idt: Move regular trap init to tables Thomas Gleixner
2017-08-29 11:19   ` [tip:x86/apic] " tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 39/44] x86/idt: Move APIC gate initialization " Thomas Gleixner
2017-08-29 11:19   ` [tip:x86/apic] " tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 40/44] x86/idt: Move interrupt gate initialization to IDT code Thomas Gleixner
2017-08-29 11:20   ` [tip:x86/apic] " tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 41/44] x86/idt: Remove unused functions/inlines Thomas Gleixner
2017-08-29 11:20   ` [tip:x86/apic] " tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 42/44] x86/idt: Deinline setup functions Thomas Gleixner
2017-08-29 11:20   ` [tip:x86/apic] " tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 43/44] x86/idt: Simplify alloc_intr_gate Thomas Gleixner
2017-08-28 14:35   ` KY Srinivasan
2017-08-29 11:21   ` [tip:x86/apic] x86/idt: Simplify alloc_intr_gate() tip-bot for Thomas Gleixner
2017-08-28  6:47 ` [patch V3 44/44] x86/idt: Hide set_intr_gate() Thomas Gleixner
2017-08-29 11:21   ` [tip:x86/apic] " tip-bot for Thomas Gleixner

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