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RISC-V: Don't use a global include guard for uapi/asm/syscalls.h

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This file is expected to be included multiple times in the same file in
order to allow the __SYSCALL macro to generate system call tables.  With
a global include guard we end up missing __NR_riscv_flush_icache in the
syscall table, which results in icache flushes that escape the vDSO call
to not actually do anything.

The fix is to move to per-#define include guards, which allows the
system call tables to actually be populated.  Thanks to Macrus Comstedt
for finding and fixing the bug!

Cc: Marcus Comstedt <marcus@mc.pp.se>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
This commit is contained in:
Palmer Dabbelt 2018-08-03 12:27:19 -07:00
parent 7847e7052f
commit e45c7aca49
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GPG key ID: EF4CA1502CCBAB41
2 changed files with 13 additions and 5 deletions
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5
arch/riscv/include/asm/unistd.h
View file

@ -11,6 +11,11 @@
* GNU General Public License for more details.
*/
/*
* There is explicitly no include guard here because this file is expected to
* be included multiple times. See uapi/asm/syscalls.h for more info.
*/
#define __ARCH_WANT_SYS_CLONE
#include <uapi/asm/unistd.h>
#include <uapi/asm/syscalls.h>

13
arch/riscv/include/uapi/asm/syscalls.h
View file

@ -1,10 +1,13 @@
/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (C) 2017 SiFive
* Copyright (C) 2017-2018 SiFive
*/
#ifndef _ASM__UAPI__SYSCALLS_H
#define _ASM__UAPI__SYSCALLS_H
/*
* 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
@ -20,7 +23,7 @@
* 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)
__SYSCALL(__NR_riscv_flush_icache, sys_riscv_flush_icache)
#endif
__SYSCALL(__NR_riscv_flush_icache, sys_riscv_flush_icache)