freebsd-dev/sys/arm/include/proc.h
Ed Schouten fa878ec311 Make it possible to safely use TPIDRURW from userspace.
On amd64, arm64 and i386, we have the possibility to switch between TLS
areas in userspace. The nice thing about this is that it makes it easier
to do light-weight threading, if we ever feel like doing that. On armv6,
let's go into the same direction by making it possible to safely use the
TPIDRURW register, which is intended for this purpose.

Clean up the ARMv6 code to remove md_tp entirely. Simply add a dedicated
field to the PCB to hold the value of TPIDRURW across context switches,
like we do for any other register. As userspace currently uses the
read-only TPIDRURO register, simply ensure that we keep both values in
sync where possible. The system calls for modifying the read-only
register will simply write the intended value into both registers, so
that it lazily ends up in the PCB during the next context switch.

Reviewed by:	https://reviews.freebsd.org/D7951
Approved by:	andrew
Reviewed by:	imp
Differential Revision:	https://reviews.freebsd.org/D7951
2016-09-22 08:14:59 +00:00

88 lines
3.0 KiB
C

/*-
* Copyright (c) 1991 Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* from: @(#)proc.h 7.1 (Berkeley) 5/15/91
* from: FreeBSD: src/sys/i386/include/proc.h,v 1.11 2001/06/29
* $FreeBSD$
*/
#ifndef _MACHINE_PROC_H_
#define _MACHINE_PROC_H_
#include <machine/utrap.h>
struct md_utrap {
utrap_entry_t *ut_precise[UT_MAX]; /* must be first */
int ut_refcnt;
};
struct mdthread {
int md_spinlock_count; /* (k) */
register_t md_saved_cspr; /* (k) */
register_t md_spurflt_addr; /* (k) Spurious page fault address. */
int md_ptrace_instr;
int md_ptrace_addr;
int md_ptrace_instr_alt;
int md_ptrace_addr_alt;
#if __ARM_ARCH < 6
register_t md_tp;
void *md_ras_start;
void *md_ras_end;
#endif
};
struct mdproc {
struct md_utrap *md_utrap;
void *md_sigtramp;
};
#define KINFO_PROC_SIZE 816
#define MAXARGS 8
/*
* This holds the syscall state for a single system call.
* As some syscall arguments may be 64-bit aligned we need to ensure the
* args value is 64-bit aligned. The ABI will then ensure any 64-bit
* arguments are already correctly aligned, even if they were passed in
* via registers, we just need to make sure we copy them to an aligned
* buffer.
*/
struct syscall_args {
u_int code;
struct sysent *callp;
register_t args[MAXARGS];
int narg;
u_int nap;
} __aligned(8);
#endif /* !_MACHINE_PROC_H_ */