MIPS: asm: spinlock: Replace "sub" instruction with "addiu"

"sub $reg, imm" is not a real MIPS instruction. The assembler can
replace that with "addi $reg, -imm". However, addi has been removed
from R6, so we replace the "sub" instruction with the "addiu" one.

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

1 files changed, 2 insertions, 5 deletions

diff --git a/arch/mips/include/asm/spinlock.h b/arch/mips/include/asm/spinlock.h
index b5238404c059..b4548690ade9 100644
--- a/arch/mips/include/asm/spinlock.h
+++ b/arch/mips/include/asm/spinlock.h
@@ -254,9 +254,6 @@ static inline void arch_read_lock(arch_rwlock_t *rw)
         smp_llsc_mb();
 }
 
-/* Note the use of sub, not subu which will make the kernel die with an
-   overflow exception if we ever try to unlock an rwlock that is already
-   unlocked or is being held by a writer.  */
 static inline void arch_read_unlock(arch_rwlock_t *rw)
 {
         unsigned int tmp;
@@ -266,7 +263,7 @@ static inline void arch_read_unlock(arch_rwlock_t *rw)
         if (R10000_LLSC_WAR) {
                 __asm__ __volatile__(
                 "1:     ll      %1, %2          # arch_read_unlock      \n"
-                "       sub     %1, 1                                   \n"
+                "       addiu   %1, 1                                   \n"
                 "       sc      %1, %0                                  \n"
                 "       beqzl   %1, 1b                                  \n"
                 : "=" GCC_OFF_SMALL_ASM() (rw->lock), "=&r" (tmp)
@@ -276,7 +273,7 @@ static inline void arch_read_unlock(arch_rwlock_t *rw)
                 do {
                         __asm__ __volatile__(
                         "1:     ll      %1, %2  # arch_read_unlock      \n"
-                        "       sub     %1, 1                           \n"
+                        "       addiu   %1, -1                          \n"
                         "       sc      %1, %0                          \n"
                         : "=" GCC_OFF_SMALL_ASM() (rw->lock), "=&r" (tmp)
                         : GCC_OFF_SMALL_ASM() (rw->lock)