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| Started by | Thomas Gleixner <tglx@linutronix.de> |
|---|---|
| First post | 2017-08-28 09:00 +0200 |
| Last post | 2017-08-29 13:30 +0200 |
| Articles | 2 — 2 participants |
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[patch V3 26/44] x86/gdt: Use bitfields for initialization Thomas Gleixner <tglx@linutronix.de> - 2017-08-28 09:00 +0200
[tip:x86/apic] x86/gdt: Use bitfields for initialization tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-08-29 13:30 +0200
| From | Thomas Gleixner <tglx@linutronix.de> |
|---|---|
| Date | 2017-08-28 09:00 +0200 |
| Subject | [patch V3 26/44] x86/gdt: Use bitfields for initialization |
| Message-ID | <ujmbG-2dY-59@gated-at.bofh.it> |
The GDT entry related code uses partially bitfields and macros which
initialize the two 16 bit parts of the entry by magic shift and mask
operations.
Clean it up and use the bitfields to initialize and access entries.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
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(-)
--- 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 */
--- 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_
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(struc
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
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
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
--- 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,
--- 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
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)
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| From | tip-bot for Thomas Gleixner <tipbot@zytor.com> |
|---|---|
| Date | 2017-08-29 13:30 +0200 |
| Subject | [tip:x86/apic] x86/gdt: Use bitfields for initialization |
| Message-ID | <ujMSx-1Zf-77@gated-at.bofh.it> |
| In reply to | #1721088 |
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)
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