[PATCH 3.16 020/178] MIPS: End spinlocks with .insn

From: Ben Hutchings
Date: Sun Jul 16 2017 - 10:09:48 EST


3.16.46-rc1 review patch. If anyone has any objections, please let me know.

------------------

From: Paul Burton <paul.burton@xxxxxxxxxx>

commit 4b5347a24a0f2d3272032c120664b484478455de upstream.

When building for microMIPS we need to ensure that the assembler always
knows that there is code at the target of a branch or jump. Recent
toolchains will fail to link a microMIPS kernel when this isn't the case
due to what it thinks is a branch to non-microMIPS code.

mips-mti-linux-gnu-ld kernel/built-in.o: .spinlock.text+0x2fc: Unsupported branch between ISA modes.
mips-mti-linux-gnu-ld final link failed: Bad value

This is due to inline assembly labels in spinlock.h not being followed
by an instruction mnemonic, either due to a .subsection pseudo-op or the
end of the inline asm block.

Fix this with a .insn direction after such labels.

Signed-off-by: Paul Burton <paul.burton@xxxxxxxxxx>
Signed-off-by: James Hogan <james.hogan@xxxxxxxxxx>
Reviewed-by: Maciej W. Rozycki <macro@xxxxxxxxxx>
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: linux-mips@xxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Patchwork: https://patchwork.linux-mips.org/patch/15325/
Signed-off-by: James Hogan <james.hogan@xxxxxxxxxx>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
arch/mips/include/asm/spinlock.h | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

--- a/arch/mips/include/asm/spinlock.h
+++ b/arch/mips/include/asm/spinlock.h
@@ -73,7 +73,7 @@ static inline void arch_spin_lock(arch_s
" andi %[ticket], %[ticket], 0xffff \n"
" bne %[ticket], %[my_ticket], 4f \n"
" subu %[ticket], %[my_ticket], %[ticket] \n"
- "2: \n"
+ "2: .insn \n"
" .subsection 2 \n"
"4: andi %[ticket], %[ticket], 0xffff \n"
" sll %[ticket], 5 \n"
@@ -181,7 +181,7 @@ static inline unsigned int arch_spin_try
" sc %[ticket], %[ticket_ptr] \n"
" beqz %[ticket], 1b \n"
" li %[ticket], 1 \n"
- "2: \n"
+ "2: .insn \n"
" .subsection 2 \n"
"3: b 2b \n"
" li %[ticket], 0 \n"
@@ -364,7 +364,7 @@ static inline int arch_read_trylock(arch
" .set reorder \n"
__WEAK_LLSC_MB
" li %2, 1 \n"
- "2: \n"
+ "2: .insn \n"
: "=m" (rw->lock), "=&r" (tmp), "=&r" (ret)
: "m" (rw->lock)
: "memory");
@@ -404,7 +404,7 @@ static inline int arch_write_trylock(arc
" lui %1, 0x8000 \n"
" sc %1, %0 \n"
" li %2, 1 \n"
- "2: \n"
+ "2: .insn \n"
: "=m" (rw->lock), "=&r" (tmp), "=&r" (ret)
: "m" (rw->lock)
: "memory");