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x86/ldt: Correct FPU emulation access to LDT 

Commit 37868fe113 ("x86/ldt: Make modify_ldt synchronous")
introduced a new struct ldt_struct anchored at mm->context.ldt.

Adapt the x86 fpu emulation code to use that new structure.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Cc: <stable@vger.kernel.org> # On top of: 37868fe113ff: x86/ldt: Make modify_ldt synchronous
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: billm@melbpc.org.au
Link: http://lkml.kernel.org/r/1438883674-1240-1-git-send-email-jgross@suse.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Juergen Gross 2015-08-06 19:54:34 +02:00 committed by Ingo Molnar
parent 136d9d83c0
commit 4809146b86
3 changed files with 20 additions and 7 deletions
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3
arch/x86/math-emu/fpu_entry.c
View File

@ -29,7 +29,6 @@
#include <asm/uaccess.h>
#include <asm/traps.h>
#include <asm/desc.h>
#include <asm/user.h>
#include <asm/fpu/internal.h>
@ -181,7 +180,7 @@ void math_emulate(struct math_emu_info *info)
math_abort(FPU_info, SIGILL);
}
code_descriptor = LDT_DESCRIPTOR(FPU_CS);
code_descriptor = FPU_get_ldt_descriptor(FPU_CS);
if (SEG_D_SIZE(code_descriptor)) {
/* The above test may be wrong, the book is not clear */
/* Segmented 32 bit protected mode */

21
arch/x86/math-emu/fpu_system.h
View File

@ -16,9 +16,24 @@
#include <linux/kernel.h>
#include <linux/mm.h>
/* s is always from a cpu register, and the cpu does bounds checking
* during register load --> no further bounds checks needed */
#define LDT_DESCRIPTOR(s) (((struct desc_struct *)current->mm->context.ldt)[(s) >> 3])
#include <asm/desc.h>
#include <asm/mmu_context.h>
static inline struct desc_struct FPU_get_ldt_descriptor(unsigned seg)
{
static struct desc_struct zero_desc;
struct desc_struct ret = zero_desc;
#ifdef CONFIG_MODIFY_LDT_SYSCALL
seg >>= 3;
mutex_lock(&current->mm->context.lock);
if (current->mm->context.ldt && seg < current->mm->context.ldt->size)
ret = current->mm->context.ldt->entries[seg];
mutex_unlock(&current->mm->context.lock);
#endif
return ret;
}
#define SEG_D_SIZE(x) ((x).b & (3 << 21))
#define SEG_G_BIT(x) ((x).b & (1 << 23))
#define SEG_GRANULARITY(x) (((x).b & (1 << 23)) ? 4096 : 1)

3
arch/x86/math-emu/get_address.c
View File

@ -20,7 +20,6 @@
#include <linux/stddef.h>
#include <asm/uaccess.h>
#include <asm/desc.h>
#include "fpu_system.h"
#include "exception.h"
@ -158,7 +157,7 @@ static long pm_address(u_char FPU_modrm, u_char segment,
addr->selector = PM_REG_(segment);
}
descriptor = LDT_DESCRIPTOR(PM_REG_(segment));
descriptor = FPU_get_ldt_descriptor(segment);
base_address = SEG_BASE_ADDR(descriptor);
address = base_address + offset;
limit = base_address