RISC-V: Define sys_riscv_flush_icache when SMP=n

This would be necessary to make non-SMP builds work, but there is
another error in the implementation of our syscall linkage that actually
just causes sys_riscv_flush_icache to never build.  I've build tested
this on allnoconfig and allnoconfig+SMP=y, as well as defconfig like
normal.

CC: Christoph Hellwig <hch@infradead.org>
CC: Guenter Roeck <linux@roeck-us.net>
In-Reply-To: <20180809055830.GA17533@infradead.org>
In-Reply-To: <20180809132612.GA31058@roeck-us.net>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>

diff --git a/arch/riscv/include/asm/vdso.h b/arch/riscv/include/asm/vdso.h
index 541544d..ec6180a 100644 (file)
--- a/arch/riscv/include/asm/vdso.h
+++ b/arch/riscv/include/asm/vdso.h
@@ -38,8 +38,6 @@ struct vdso_data {
        (void __user *)((unsigned long)(base) + __vdso_##name);                 \
 })
 
-#ifdef CONFIG_SMP
 asmlinkage long sys_riscv_flush_icache(uintptr_t, uintptr_t, uintptr_t);
-#endif
 
 #endif /* _ASM_RISCV_VDSO_H */

diff --git a/arch/riscv/kernel/sys_riscv.c b/arch/riscv/kernel/sys_riscv.c
index f7181ed..568026c 100644 (file)
--- a/arch/riscv/kernel/sys_riscv.c
+++ b/arch/riscv/kernel/sys_riscv.c
@@ -48,7 +48,6 @@ SYSCALL_DEFINE6(mmap2, unsigned long, addr, unsigned long, len,
 }
 #endif /* !CONFIG_64BIT */
 
-#ifdef CONFIG_SMP
 /*
  * Allows the instruction cache to be flushed from userspace.  Despite RISC-V
  * having a direct 'fence.i' instruction available to userspace (which we
@@ -66,15 +65,24 @@ SYSCALL_DEFINE6(mmap2, unsigned long, addr, unsigned long, len,
 SYSCALL_DEFINE3(riscv_flush_icache, uintptr_t, start, uintptr_t, end,
        uintptr_t, flags)
 {
+#ifdef CONFIG_SMP
        struct mm_struct *mm = current->mm;
        bool local = (flags & SYS_RISCV_FLUSH_ICACHE_LOCAL) != 0;
+#endif
 
        /* Check the reserved flags. */
        if (unlikely(flags & ~SYS_RISCV_FLUSH_ICACHE_ALL))
                return -EINVAL;
 
+       /*
+        * Without CONFIG_SMP flush_icache_mm is a just a flush_icache_all(),
+        * which generates unused variable warnings all over this function.
+        */
+#ifdef CONFIG_SMP
        flush_icache_mm(mm, local);
+#else
+       flush_icache_all();
+#endif
 
        return 0;
 }
-#endif