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Commit 762a1f43 authored by Paul Burton's avatar Paul Burton Committed by Ralf Baechle
Browse files

MIPS: disable preemption whilst initialising MSA 



Preemption must be disabled throughout the process of enabling the FPU,
enabling MSA & initialising the vector registers. Without doing so it
is possible to lose the FPU or MSA whilst initialising them causing
that initialisation to fail.

Signed-off-by: default avatarPaul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7307/


Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent 3587ea88

arch/mips/include/asm/fpu.h

+0 −4
Original line number Diff line number Diff line
@@ -164,8 +164,6 @@ static inline int init_fpu(void) 
{

	int ret = 0;



	preempt_disable();



	if (cpu_has_fpu) {

		ret = __own_fpu();

		if (!ret)
@@ -173,8 +171,6 @@ static inline int init_fpu(void) 
	} else

		fpu_emulator_init_fpu();



	preempt_enable();



	return ret;

}

arch/mips/kernel/traps.c

+11 −3
Original line number Diff line number Diff line
@@ -1093,6 +1093,7 @@ static int enable_restore_fp_context(int msa) 


	if (!used_math()) {

		/* First time FP context user. */

		preempt_disable();

		err = init_fpu();

		if (msa && !err) {

			enable_msa();
@@ -1100,6 +1101,7 @@ static int enable_restore_fp_context(int msa) 
			set_thread_flag(TIF_USEDMSA);

			set_thread_flag(TIF_MSA_CTX_LIVE);

		}

		preempt_enable();

		if (!err)

			set_used_math();

		return err;
@@ -1139,10 +1141,11 @@ static int enable_restore_fp_context(int msa) 
	 * This task is using or has previously used MSA. Thus we require

	 * that Status.FR == 1.

	 */

	preempt_disable();

	was_fpu_owner = is_fpu_owner();

	err = own_fpu(0);

	err = own_fpu_inatomic(0);

	if (err)

		return err;

		goto out;



	enable_msa();

	write_msa_csr(current->thread.fpu.msacsr);
@@ -1158,7 +1161,8 @@ static int enable_restore_fp_context(int msa) 
	prior_msa = test_and_set_thread_flag(TIF_MSA_CTX_LIVE);

	if (!prior_msa && was_fpu_owner) {

		_init_msa_upper();

		return 0;



		goto out;

	}



	if (!prior_msa) {
@@ -1182,6 +1186,10 @@ static int enable_restore_fp_context(int msa) 
		if (!was_fpu_owner)

			asm volatile("ctc1 %0, $31" : : "r"(current->thread.fpu.fcr31));

	}



out:

	preempt_enable();



	return 0;

}