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Commit e49d3848 authored by Maciej W. Rozycki's avatar Maciej W. Rozycki Committed by Ralf Baechle
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MIPS: MSA: Fix a link error on `_init_msa_upper' with older GCC 



Fix a build regression from commit c9017757 ("MIPS: init upper 64b
of vector registers when MSA is first used"):

arch/mips/built-in.o: In function `enable_restore_fp_context':
traps.c:(.text+0xbb90): undefined reference to `_init_msa_upper'
traps.c:(.text+0xbb90): relocation truncated to fit: R_MIPS_26 against `_init_msa_upper'
traps.c:(.text+0xbef0): undefined reference to `_init_msa_upper'
traps.c:(.text+0xbef0): relocation truncated to fit: R_MIPS_26 against `_init_msa_upper'

to !CONFIG_CPU_HAS_MSA configurations with older GCC versions, which are
unable to figure out that calls to `_init_msa_upper' are indeed dead.
Of the many ways to tackle this failure choose the approach we have
already taken in `thread_msa_context_live'.

[ralf@linux-mips.org: Drop patch segment to junk file.]

Signed-off-by: default avatarMaciej W. Rozycki <macro@imgtec.com>
Cc: stable@vger.kernel.org # v3.16+
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/13271/


Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent 0868971a

arch/mips/include/asm/msa.h

+13 −0
Original line number Original line Diff line number Diff line
@@ -147,6 +147,19 @@ static inline void restore_msa(struct task_struct *t) 
		_restore_msa(t);

		_restore_msa(t);

}

}





static inline void init_msa_upper(void)

{

	/*

	 * Check cpu_has_msa only if it's a constant. This will allow the

	 * compiler to optimise out code for CPUs without MSA without adding

	 * an extra redundant check for CPUs with MSA.

	 */

	if (__builtin_constant_p(cpu_has_msa) && !cpu_has_msa)

		return;



	_init_msa_upper();

}



#ifdef TOOLCHAIN_SUPPORTS_MSA

#ifdef TOOLCHAIN_SUPPORTS_MSA





#define __BUILD_MSA_CTL_REG(name, cs)				\

#define __BUILD_MSA_CTL_REG(name, cs)				\

arch/mips/kernel/traps.c

+3 −3
Original line number Original line Diff line number Diff line
@@ -1246,7 +1246,7 @@ static int enable_restore_fp_context(int msa) 
		err = init_fpu();

		err = init_fpu();

		if (msa && !err) {

		if (msa && !err) {

			enable_msa();

			enable_msa();

			_init_msa_upper();

			init_msa_upper();

			set_thread_flag(TIF_USEDMSA);

			set_thread_flag(TIF_USEDMSA);

			set_thread_flag(TIF_MSA_CTX_LIVE);

			set_thread_flag(TIF_MSA_CTX_LIVE);

		}

		}
@@ -1309,7 +1309,7 @@ static int enable_restore_fp_context(int msa) 
	 */

	 */

	prior_msa = test_and_set_thread_flag(TIF_MSA_CTX_LIVE);

	prior_msa = test_and_set_thread_flag(TIF_MSA_CTX_LIVE);

	if (!prior_msa && was_fpu_owner) {

	if (!prior_msa && was_fpu_owner) {

		_init_msa_upper();

		init_msa_upper();





		goto out;

		goto out;

	}

	}
@@ -1326,7 +1326,7 @@ static int enable_restore_fp_context(int msa) 
		 * of each vector register such that it cannot see data left

		 * of each vector register such that it cannot see data left

		 * behind by another task.

		 * behind by another task.

		 */

		 */

		_init_msa_upper();

		init_msa_upper();

	} else {

	} else {

		/* We need to restore the vector context. */

		/* We need to restore the vector context. */

		restore_msa(current);

		restore_msa(current);