Commit 37868fe113ff ("x86/ldt: Make modify_ldt synchronous") introduced
a new struct ldt_struct anchored at mm->context.ldt.
Adapt the x86 fpu emulation to use that new structure.
Cc: <stable@xxxxxxxxxxxxxxx> # 37868fe113ff: x86/ldt: Make modify_ldt synchronous
Cc: <stable@xxxxxxxxxxxxxxx> # a5b9e5a2f14f: x86/ldt: Make modify_ldt optional
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
arch/x86/math-emu/fpu_entry.c | 3 +--
arch/x86/math-emu/fpu_system.h | 18 +++++++++++++++---
arch/x86/math-emu/get_address.c | 3 +--
3 files changed, 17 insertions(+), 7 deletions(-)
diff --git a/arch/x86/math-emu/fpu_entry.c b/arch/x86/math-emu/fpu_entry.c
index f37e84a..203318a 100644
--- a/arch/x86/math-emu/fpu_entry.c
+++ b/arch/x86/math-emu/fpu_entry.c
@@ -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 */
diff --git a/arch/x86/math-emu/fpu_system.h b/arch/x86/math-emu/fpu_system.h
index 9ccecb6..9330583 100644
--- a/arch/x86/math-emu/fpu_system.h
+++ b/arch/x86/math-emu/fpu_system.h
@@ -16,9 +16,21 @@
#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;
+
+#ifdef CONFIG_MODIFY_LDT_SYSCALL
+ seg >>= 3;
+ if (seg < current->mm->context.ldt->size)
+ return current->mm->context.ldt->entries + seg;
+#endif
+ return &zero_desc;
+}
+
#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)
diff --git a/arch/x86/math-emu/get_address.c b/arch/x86/math-emu/get_address.c
index 6ef5e99..f912edd 100644
--- a/arch/x86/math-emu/get_address.c
+++ b/arch/x86/math-emu/get_address.c
@@ -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
--
2.1.4
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