linux-kernel - [PATCH v3 1/2] RISC-V: Define sys_riscv_flush

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Date:   Thu,  9 Aug 2018 15:19:51 -0700
From:   Palmer Dabbelt <palmer@...ive.com>
To:     Christoph Hellwig <hch@...radead.org>, linux@...ck-us.net
Cc:     Palmer Dabbelt <palmer@...ive.com>, aou@...s.berkeley.edu,
        tklauser@...tanz.ch, Arnd Bergmann <arnd@...db.de>,
        Andrew Waterman <andrew@...ive.com>,
        linux@...inikbrodowski.net, dan.carpenter@...cle.com,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Christoph Hellwig <hch@...radead.org>
Subject: [PATCH v3 1/2] 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@...radead.org>
CC: Guenter Roeck <linux@...ck-us.net>
In-Reply-To: <20180809055830.GA17533@...radead.org>
In-Reply-To: <20180809132612.GA31058@...ck-us.net>
Signed-off-by: Palmer Dabbelt <palmer@...ive.com>
---
 arch/riscv/include/asm/vdso.h |  2 --
 arch/riscv/kernel/sys_riscv.c | 12 ++++++++++--
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/arch/riscv/include/asm/vdso.h b/arch/riscv/include/asm/vdso.h
index 541544d64c33..ec6180a4b55d 100644
--- 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 f7181ed8aafc..568026ccf6e8 100644
--- 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
-- 
2.16.4