From 4809146b86c3d41ce588fdb767d021e2a80600dd Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Thu, 6 Aug 2015 19:54:34 +0200 Subject: x86/ldt: Correct FPU emulation access to LDT Commit 37868fe113ff ("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 Reviewed-by: Andy Lutomirski Cc: # On top of: 37868fe113ff: x86/ldt: Make modify_ldt synchronous Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner 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 --- arch/x86/math-emu/fpu_system.h | 21 ++++++++++++++++++--- 1 file changed, 18 insertions(+), 3 deletions(-) (limited to 'arch/x86/math-emu/fpu_system.h') diff --git a/arch/x86/math-emu/fpu_system.h b/arch/x86/math-emu/fpu_system.h index 9ccecb61a4fa..5e044d506b7a 100644 --- a/arch/x86/math-emu/fpu_system.h +++ b/arch/x86/math-emu/fpu_system.h @@ -16,9 +16,24 @@ #include #include -/* 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 +#include + +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(¤t->mm->context.lock); + if (current->mm->context.ldt && seg < current->mm->context.ldt->size) + ret = current->mm->context.ldt->entries[seg]; + mutex_unlock(¤t->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) -- cgit v1.2.3