linux-kernel - [PATCH] riscv: restore asm/syscalls.h UAPI header

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Message-Id: <20181211080935.20856-1-david.abdurachmanov@gmail.com>
Date:   Tue, 11 Dec 2018 09:09:35 +0100
From:   David Abdurachmanov <david.abdurachmanov@...il.com>
To:     palmer@...ive.com, aou@...s.berkeley.edu,
        linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org
Cc:     David Abdurachmanov <david.abdurachmanov@...il.com>
Subject: [PATCH] riscv: restore asm/syscalls.h UAPI header

UAPI header asm/syscalls.h was merged into UAPI asm/unistd.h header,
which did resolve issue with missing syscalls macros resulting in
glibc (2.28) build failure. It also broke glibc in a different way:
asm/syscalls.h is being used by glibc. I noticed this while doing
Fedora 30/Rawhide mass rebuild.

The patch returns asm/syscalls.h header and incl. it into asm/unistd.h.
I plan to send a patch to glibc to use asm/unistd.h instead of
asm/syscalls.h

Signed-off-by: David Abdurachmanov <david.abdurachmanov@...il.com>
Fixes: 27f8899d6002 ("riscv: add asm/unistd.h UAPI header")
---
 arch/riscv/include/uapi/asm/syscalls.h | 29 ++++++++++++++++++++++++++
 arch/riscv/include/uapi/asm/unistd.h   | 20 +-----------------
 2 files changed, 30 insertions(+), 19 deletions(-)
 create mode 100644 arch/riscv/include/uapi/asm/syscalls.h

diff --git a/arch/riscv/include/uapi/asm/syscalls.h b/arch/riscv/include/uapi/asm/syscalls.h
new file mode 100644
index 000000000000..206dc4b0f6ea
--- /dev/null
+++ b/arch/riscv/include/uapi/asm/syscalls.h
@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2017-2018 SiFive
+ */
+
+/*
+ * There is explicitly no include guard here because this file is expected to
+ * be included multiple times in order to define the syscall macros via
+ * __SYSCALL.
+ */
+
+/*
+ * Allows the instruction cache to be flushed from userspace.  Despite RISC-V
+ * having a direct 'fence.i' instruction available to userspace (which we
+ * can't trap!), that's not actually viable when running on Linux because the
+ * kernel might schedule a process on another hart.  There is no way for
+ * userspace to handle this without invoking the kernel (as it doesn't know the
+ * thread->hart mappings), so we've defined a RISC-V specific system call to
+ * flush the instruction cache.
+ *
+ * __NR_riscv_flush_icache is defined to flush the instruction cache over an
+ * address range, with the flush applying to either all threads or just the
+ * caller.  We don't currently do anything with the address range, that's just
+ * in there for forwards compatibility.
+ */
+#ifndef __NR_riscv_flush_icache
+#define __NR_riscv_flush_icache (__NR_arch_specific_syscall + 15)
+#endif
+__SYSCALL(__NR_riscv_flush_icache, sys_riscv_flush_icache)
diff --git a/arch/riscv/include/uapi/asm/unistd.h b/arch/riscv/include/uapi/asm/unistd.h
index 1f3bd3ebbb0d..06103139db50 100644
--- a/arch/riscv/include/uapi/asm/unistd.h
+++ b/arch/riscv/include/uapi/asm/unistd.h
@@ -20,22 +20,4 @@
 #endif /* __LP64__ */
 
 #include <asm-generic/unistd.h>
-
-/*
- * Allows the instruction cache to be flushed from userspace.  Despite RISC-V
- * having a direct 'fence.i' instruction available to userspace (which we
- * can't trap!), that's not actually viable when running on Linux because the
- * kernel might schedule a process on another hart.  There is no way for
- * userspace to handle this without invoking the kernel (as it doesn't know the
- * thread->hart mappings), so we've defined a RISC-V specific system call to
- * flush the instruction cache.
- *
- * __NR_riscv_flush_icache is defined to flush the instruction cache over an
- * address range, with the flush applying to either all threads or just the
- * caller.  We don't currently do anything with the address range, that's just
- * in there for forwards compatibility.
- */
-#ifndef __NR_riscv_flush_icache
-#define __NR_riscv_flush_icache (__NR_arch_specific_syscall + 15)
-#endif
-__SYSCALL(__NR_riscv_flush_icache, sys_riscv_flush_icache)
+#include <asm/syscalls.h>
-- 
2.19.2