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Commit 4809146b authored by Juergen Gross's avatar Juergen Gross Committed by Ingo Molnar
Browse files

x86/ldt: Correct FPU emulation access to LDT 



Commit 37868fe1 ("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: default avatarJuergen Gross <jgross@suse.com>
Reviewed-by: default avatarAndy Lutomirski <luto@kernel.org>
Cc: <stable@vger.kernel.org> # On top of: 37868fe1: 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: default avatarIngo Molnar <mingo@kernel.org>
parent 136d9d83

arch/x86/math-emu/fpu_entry.c

+1 −2
Original line number Diff line number Diff line
@@ -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 */

arch/x86/math-emu/fpu_system.h

+18 −3
Original line number Diff line number Diff line
@@ -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)

arch/x86/math-emu/get_address.c

+1 −2
Original line number Diff line number Diff line
@@ -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