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Unverified Commit 9e49a4ed authored by Palmer Dabbelt's avatar Palmer Dabbelt
Browse files

RISC-V: Make __NR_riscv_flush_icache visible to userspace 



We were hoping to avoid making this visible to userspace, but it looks
like we're going to have to because QEMU's user-mode emulation doesn't
want to emulate a vDSO.  Having vDSO-only system calls was a bit
unothodox anyway, so I think in this case it's OK to just make the
actual system call number public.

This patch simply moves the definition of __NR_riscv_flush_icache
availiable to userspace, which results in the deletion of the now empty
vdso-syscalls.h.

Changes since v1:

* I've moved the definition into uapi/asm/syscalls.h rathen than
  uapi/asm/unistd.h.  This allows me to keep asm/unistd.h, so we can
  keep the syscall table macros sane.
* As a side effect of the above, this no longer disables all system
  calls on RISC-V.  Whoops!

Signed-off-by: default avatarPalmer Dabbelt <palmer@sifive.com>
parent 33c57c0d

arch/riscv/include/asm/unistd.h

+1 −0
Original line number Diff line number Diff line
@@ -14,3 +14,4 @@ 
#define __ARCH_HAVE_MMU

#define __ARCH_WANT_SYS_CLONE

#include <uapi/asm/unistd.h>

#include <uapi/asm/syscalls.h>

arch/riscv/include/asm/vdso-syscalls.h

deleted100644 → 0
+0 −28
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2017 SiFive

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program.  If not, see <http://www.gnu.org/licenses/>.

 */



#ifndef _ASM_RISCV_VDSO_SYSCALLS_H

#define _ASM_RISCV_VDSO_SYSCALLS_H



#ifdef CONFIG_SMP



/* These syscalls are only used by the vDSO and are not in the uapi. */

#define __NR_riscv_flush_icache (__NR_arch_specific_syscall + 15)

__SYSCALL(__NR_riscv_flush_icache, sys_riscv_flush_icache)



#endif



#endif /* _ASM_RISCV_VDSO_H */

arch/riscv/include/uapi/asm/syscalls.h

0 → 100644
+26 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

/*

 * Copyright (C) 2017 SiFive

 */



#ifndef _ASM__UAPI__SYSCALLS_H

#define _ASM__UAPI__SYSCALLS_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.

 */

#define __NR_riscv_flush_icache (__NR_arch_specific_syscall + 15)

__SYSCALL(__NR_riscv_flush_icache, sys_riscv_flush_icache)



#endif

arch/riscv/kernel/syscall_table.c

+0 −1
Original line number Diff line number Diff line
@@ -23,5 +23,4 @@ 
void *sys_call_table[__NR_syscalls] = {

	[0 ... __NR_syscalls - 1] = sys_ni_syscall,

#include <asm/unistd.h>

#include <asm/vdso-syscalls.h>

};

arch/riscv/kernel/vdso/flush_icache.S

+0 −1
Original line number Diff line number Diff line
@@ -13,7 +13,6 @@ 


#include <linux/linkage.h>

#include <asm/unistd.h>

#include <asm/vdso-syscalls.h>



	.text

/* int __vdso_flush_icache(void *start, void *end, unsigned long flags); */