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Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

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Merge x86 fixes from Ingo Molnar:
 "Two followup fixes related to the previous LDT fix"

Also applied a further FPU emulation fix from Andy Lutomirski to the
branch before actually merging it.

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
  x86/ldt: Further fix FPU emulation
  x86/ldt: Correct FPU emulation access to LDT
  x86/ldt: Correct LDT access in single stepping logic
This commit is contained in:
Linus Torvalds 2015-08-16 15:11:25 -07:00
commit 01565479e9
4 changed files with 22 additions and 9 deletions
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4
arch/x86/kernel/step.c
View File

@ -28,11 +28,11 @@ unsigned long convert_ip_to_linear(struct task_struct *child, struct pt_regs *re
struct desc_struct *desc;
unsigned long base;
seg &= ~7UL;
seg >>= 3;
mutex_lock(&child->mm->context.lock);
if (unlikely(!child->mm->context.ldt ||
(seg >> 3) >= child->mm->context.ldt->size))
seg >= child->mm->context.ldt->size))
addr = -1L; /* bogus selector, access would fault */
else {
desc = &child->mm->context.ldt->entries[seg];

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(addr->selector);
base_address = SEG_BASE_ADDR(descriptor);
address = base_address + offset;
limit = base_address