Commit 6de5a8a5 authored by Eli Cooper's avatar Eli Cooper Committed by Richard Weinberger
Browse files

um: fix FPU state preservation around signal handlers 



This patch makes UML saves/restores FPU state from/to the fpstate in
pt_regs when setting up or returning from a signal stack, rather than
calling ptrace directly. This ensures that FPU state is correctly
preserved around signal handlers in a multi-threaded scenario.

Signed-off-by: default avatarEli Cooper <elicooper@gmx.com>
parent 44549e8f

arch/x86/um/signal.c

+3 −15
Original line number Diff line number Diff line
@@ -225,20 +225,10 @@ static int copy_sc_from_user(struct pt_regs *regs, 
	} else

#endif

	{

		struct user_i387_struct fp;



		err = copy_from_user(&fp, (void *)sc.fpstate,

		err = copy_from_user(regs->regs.fp, (void *)sc.fpstate,

				     sizeof(struct user_i387_struct));

		if (err)

			return 1;



		err = restore_fp_registers(pid, (unsigned long *) &fp);

		if (err < 0) {

			printk(KERN_ERR "copy_sc_from_user - "

			       "restore_fp_registers failed, errno = %d\n",

			       -err);

			return 1;

		}

	}

	return 0;

}
@@ -325,10 +315,8 @@ static int copy_sc_to_user(struct sigcontext __user *to, 
	} else

#endif

	{

		struct user_i387_struct fp;



		err = save_fp_registers(pid, (unsigned long *) &fp);

		if (copy_to_user(to_fp, &fp, sizeof(struct user_i387_struct)))

		if (copy_to_user(to_fp, regs->regs.fp,

				 sizeof(struct user_i387_struct)))

			return 1;

	}