Commit 43b287b3 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

x86/fpu: Add debugging checks to all copy_kernel_to_*() functions 



Copying from in-kernel FPU context buffers to FPU registers are
never supposed to fault.

Add debugging checks to copy_kernel_to_fxregs() and copy_kernel_to_fregs()
to double check this assumption.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Bobby Powers <bobbypowers@gmail.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent ce2a1e67

arch/x86/include/asm/fpu/internal.h

+20 −8
Original line number Diff line number Diff line
@@ -143,14 +143,22 @@ static inline int copy_fxregs_to_user(struct fxregs_state __user *fx) 


static inline int copy_kernel_to_fxregs(struct fxregs_state *fx)

{

	if (config_enabled(CONFIG_X86_32))

		return check_insn(fxrstor %[fx], "=m" (*fx), [fx] "m" (*fx));

	else if (config_enabled(CONFIG_AS_FXSAVEQ))

		return check_insn(fxrstorq %[fx], "=m" (*fx), [fx] "m" (*fx));

	int err;



	if (config_enabled(CONFIG_X86_32)) {

		err = check_insn(fxrstor %[fx], "=m" (*fx), [fx] "m" (*fx));

	} else {

		if (config_enabled(CONFIG_AS_FXSAVEQ)) {

			err = check_insn(fxrstorq %[fx], "=m" (*fx), [fx] "m" (*fx));

		} else {

			/* See comment in copy_fxregs_to_kernel() below. */

	return check_insn(rex64/fxrstor (%[fx]), "=m" (*fx), [fx] "R" (fx),

			  "m" (*fx));

			err = check_insn(rex64/fxrstor (%[fx]), "=m" (*fx), [fx] "R" (fx), "m" (*fx));

		}

	}

	/* Copying from a kernel buffer to FPU registers should never fail: */

	WARN_ON_FPU(err);



	return err;

}



static inline int copy_user_to_fxregs(struct fxregs_state __user *fx)
@@ -167,7 +175,11 @@ static inline int copy_user_to_fxregs(struct fxregs_state __user *fx) 


static inline int copy_kernel_to_fregs(struct fregs_state *fx)

{

	return check_insn(frstor %[fx], "=m" (*fx), [fx] "m" (*fx));

	int err = check_insn(frstor %[fx], "=m" (*fx), [fx] "m" (*fx));



	WARN_ON_FPU(err);



	return err;

}



static inline int copy_user_to_fregs(struct fregs_state __user *fx)

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