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x86/entry/vm86: Clean up saved_fs/gs

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There is no need to save FS and non-lazy GS outside the 32-bit
regs.  Lazy GS still needs to be saved because it wasn't saved
on syscall entry.  Save it in the gs slot of regs32, which is
present but unused.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1437354550-25858-2-git-send-email-brgerst@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Brian Gerst 2015-07-19 21:09:04 -04:00 • committed by Ingo Molnar
parent bf9f2ee28d
commit 0233606ce5
2 changed files with 2 additions and 6 deletions
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2
arch/x86/include/asm/processor.h
View file

@ -410,8 +410,6 @@ struct thread_struct {
unsigned long v86flags;
unsigned long v86mask;
unsigned long saved_sp0;
unsigned int saved_fs;
unsigned int saved_gs;
#endif
/* IO permissions: */
unsigned long *io_bitmap_ptr;

6
arch/x86/kernel/vm86_32.c
View file

@ -159,8 +159,7 @@ struct pt_regs *save_v86_state(struct kernel_vm86_regs *regs)
ret = KVM86->regs32;
ret->fs = current->thread.saved_fs;
set_user_gs(ret, current->thread.saved_gs);
lazy_load_gs(ret->gs);
return ret;
}
@ -315,8 +314,7 @@ static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk
*/
info->regs32->ax = VM86_SIGNAL;
tsk->thread.saved_sp0 = tsk->thread.sp0;
tsk->thread.saved_fs = info->regs32->fs;
tsk->thread.saved_gs = get_user_gs(info->regs32);
lazy_save_gs(info->regs32->gs);
tss = &per_cpu(cpu_tss, get_cpu());
tsk->thread.sp0 = (unsigned long) &info->VM86_TSS_ESP0;