MIPS: End spinlocks with .insn

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@imgtec.com>
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Reviewed-by: Maciej W. Rozycki <macro@imgtec.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Cc: <stable@vger.kernel.org>
Patchwork: https://patchwork.linux-mips.org/patch/15325/
Signed-off-by: James Hogan <james.hogan@imgtec.com>

diff --git a/arch/mips/include/asm/spinlock.h b/arch/mips/include/asm/spinlock.h
index f485afe..a8df44d 100644 (file)
--- a/arch/mips/include/asm/spinlock.h
+++ b/arch/mips/include/asm/spinlock.h
@@ -127,7 +127,7 @@ static inline void arch_spin_lock(arch_spinlock_t *lock)
                "       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"
@@ -202,7 +202,7 @@ static inline unsigned int arch_spin_trylock(arch_spinlock_t *lock)
                "       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"
@@ -382,7 +382,7 @@ static inline int arch_read_trylock(arch_rwlock_t *rw)
                "       .set    reorder                                 \n"
                __WEAK_LLSC_MB
                "       li      %2, 1                                   \n"
-               "2:                                                     \n"
+               "2:     .insn                                           \n"
                : "=" GCC_OFF_SMALL_ASM() (rw->lock), "=&r" (tmp), "=&r" (ret)
                : GCC_OFF_SMALL_ASM() (rw->lock)
                : "memory");
@@ -422,7 +422,7 @@ static inline int arch_write_trylock(arch_rwlock_t *rw)
                        "       lui     %1, 0x8000                      \n"
                        "       sc      %1, %0                          \n"
                        "       li      %2, 1                           \n"
-                       "2:                                             \n"
+                       "2:     .insn                                   \n"
                        : "=" GCC_OFF_SMALL_ASM() (rw->lock), "=&r" (tmp),
                          "=&r" (ret)
                        : GCC_OFF_SMALL_ASM() (rw->lock)