Commit ca750649 authored by Leonid Yegoshin's avatar Leonid Yegoshin Committed by Ralf Baechle
Browse files

MIPS: kernel: signal: Prevent save/restore FPU context in user memory 



EVA does not have FPU specific instructions for reading or writing
FPU registers from userspace memory.

Signed-off-by: default avatarLeonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: default avatarMarkos Chandras <markos.chandras@imgtec.com>
parent c2d85bc1

arch/mips/kernel/signal.c

+32 −0
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ 
 * Copyright (C) 1991, 1992  Linus Torvalds

 * Copyright (C) 1994 - 2000  Ralf Baechle

 * Copyright (C) 1999, 2000 Silicon Graphics, Inc.

 * Copyright (C) 2014, Imagination Technologies Ltd.

 */

#include <linux/cache.h>

#include <linux/context_tracking.h>
@@ -140,6 +141,7 @@ static int protected_save_fp_context(struct sigcontext __user *sc, 
{

	int err;

	bool save_msa = cpu_has_msa && (used_math & USEDMATH_MSA);

#ifndef CONFIG_EVA

	while (1) {

		lock_fpu_owner();

		if (is_fpu_owner()) {
@@ -162,6 +164,17 @@ static int protected_save_fp_context(struct sigcontext __user *sc, 
		if (err)

			break;	/* really bad sigcontext */

	}

#else

	/*

	 * EVA does not have FPU EVA instructions so saving fpu context directly

	 * does not work.

	 */

	disable_msa();

	lose_fpu(1);

	err = save_fp_context(sc); /* this might fail */

	if (save_msa && !err)

		err = copy_msa_to_sigcontext(sc);

#endif

	return err;

}
@@ -170,6 +183,7 @@ static int protected_restore_fp_context(struct sigcontext __user *sc, 
{

	int err, tmp __maybe_unused;

	bool restore_msa = cpu_has_msa && (used_math & USEDMATH_MSA);

#ifndef CONFIG_EVA

	while (1) {

		lock_fpu_owner();

		if (is_fpu_owner()) {
@@ -197,6 +211,17 @@ static int protected_restore_fp_context(struct sigcontext __user *sc, 
		if (err)

			break;	/* really bad sigcontext */

	}

#else

	/*

	 * EVA does not have FPU EVA instructions so restoring fpu context

	 * directly does not work.

	 */

	enable_msa();

	lose_fpu(0);

	err = restore_fp_context(sc); /* this might fail */

	if (restore_msa && !err)

		err = copy_msa_from_sigcontext(sc);

#endif

	return err;

}
@@ -685,6 +710,7 @@ asmlinkage void do_notify_resume(struct pt_regs *regs, void *unused, 
}



#ifdef CONFIG_SMP

#ifndef CONFIG_EVA

static int smp_save_fp_context(struct sigcontext __user *sc)

{

	return raw_cpu_has_fpu
@@ -698,10 +724,12 @@ static int smp_restore_fp_context(struct sigcontext __user *sc) 
	       ? _restore_fp_context(sc)

	       : copy_fp_from_sigcontext(sc);

}

#endif /* CONFIG_EVA */

#endif



static int signal_setup(void)

{

#ifndef CONFIG_EVA

#ifdef CONFIG_SMP

	/* For now just do the cpu_has_fpu check when the functions are invoked */

	save_fp_context = smp_save_fp_context;
@@ -714,6 +742,10 @@ static int signal_setup(void) 
		save_fp_context = copy_fp_from_sigcontext;

		restore_fp_context = copy_fp_to_sigcontext;

	}

#endif /* CONFIG_SMP */

#else

	save_fp_context = copy_fp_from_sigcontext;;

	restore_fp_context = copy_fp_to_sigcontext;

#endif



	return 0;