3.19.8-ckt23 -stable review patch. If anyone has any objections, please let me
know.
---8<------------------------------------------------------------
From: "Maciej W. Rozycki" <ma...@imgtec.com>
commit e49d38488515057dba8f0c2ba4cfde5be4a7281f upstream.
Fix a build regression from commit c9017757c532 ("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'.
[r...@linux-mips.org: Drop patch segment to junk file.]
Signed-off-by: Maciej W. Rozycki <ma...@imgtec.com>
Cc: linux-m...@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/13271/
Signed-off-by: Ralf Baechle <r...@linux-mips.org>
Signed-off-by: Kamal Mostafa <ka...@canonical.com>
---
arch/mips/include/asm/msa.h | 13 +++++++++++++
arch/mips/kernel/traps.c | 6 +++---
2 files changed, 16 insertions(+), 3 deletions(-)
diff --git a/arch/mips/include/asm/msa.h b/arch/mips/include/asm/msa.h
index af5638b..38bbeda 100644
--- a/arch/mips/include/asm/msa.h
+++ b/arch/mips/include/asm/msa.h
@@ -67,6 +67,19 @@ static inline void restore_msa(struct task_struct *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
#define __BUILD_MSA_CTL_REG(name, cs) \
diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index af1475f..e3b5fe1 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -1150,7 +1150,7 @@ static int enable_restore_fp_context(int msa)
err = init_fpu();
if (msa && !err) {
enable_msa();
- _init_msa_upper();
+ init_msa_upper();
set_thread_flag(TIF_USEDMSA);
set_thread_flag(TIF_MSA_CTX_LIVE);
}
@@ -1213,7 +1213,7 @@ 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();
+ init_msa_upper();
goto out;
}
@@ -1230,7 +1230,7 @@ static int enable_restore_fp_context(int msa)
* of each vector register such that it cannot see data left
* behind by another task.
*/
- _init_msa_upper();
+ init_msa_upper();
} else {
/* We need to restore the vector context. */
restore_msa(current);
--
2.7.4
