2012-03-05 11:49:33 +00:00
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/*
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* Copyright (C) 2012 ARM Ltd.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef __ASM_SYSCALL_H
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#define __ASM_SYSCALL_H
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2014-07-04 07:28:30 +00:00
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#include <uapi/linux/audit.h>
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#include <linux/compat.h>
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2012-03-05 11:49:33 +00:00
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#include <linux/err.h>
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arm64: implement syscall wrappers
To minimize the risk of userspace-controlled values being used under
speculation, this patch adds pt_regs based syscall wrappers for arm64,
which pass the minimum set of required userspace values to syscall
implementations. For each syscall, a wrapper which takes a pt_regs
argument is automatically generated, and this extracts the arguments
before calling the "real" syscall implementation.
Each syscall has three functions generated:
* __do_<compat_>sys_<name> is the "real" syscall implementation, with
the expected prototype.
* __se_<compat_>sys_<name> is the sign-extension/narrowing wrapper,
inherited from common code. This takes a series of long parameters,
casting each to the requisite types required by the "real" syscall
implementation in __do_<compat_>sys_<name>.
This wrapper *may* not be necessary on arm64 given the AAPCS rules on
unused register bits, but it seemed safer to keep the wrapper for now.
* __arm64_<compat_>_sys_<name> takes a struct pt_regs pointer, and
extracts *only* the relevant register values, passing these on to the
__se_<compat_>sys_<name> wrapper.
The syscall invocation code is updated to handle the calling convention
required by __arm64_<compat_>_sys_<name>, and passes a single struct
pt_regs pointer.
The compiler can fold the syscall implementation and its wrappers, such
that the overhead of this approach is minimized.
Note that we play games with sys_ni_syscall(). It can't be defined with
SYSCALL_DEFINE0() because we must avoid the possibility of error
injection. Additionally, there are a couple of locations where we need
to call it from C code, and we don't (currently) have a
ksys_ni_syscall(). While it has no wrapper, passing in a redundant
pt_regs pointer is benign per the AAPCS.
When ARCH_HAS_SYSCALL_WRAPPER is selected, no prototype is defines for
sys_ni_syscall(). Since we need to treat it differently for in-kernel
calls and the syscall tables, the prototype is defined as-required.
The wrappers are largely the same as their x86 counterparts, but
simplified as we don't have a variety of compat calling conventions that
require separate stubs. Unlike x86, we have some zero-argument compat
syscalls, and must define COMPAT_SYSCALL_DEFINE0() to ensure that these
are also given an __arm64_compat_sys_ prefix.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
2018-07-11 13:56:56 +00:00
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typedef long (*syscall_fn_t)(struct pt_regs *regs);
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2018-07-11 13:56:42 +00:00
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extern const syscall_fn_t sys_call_table[];
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2012-03-05 11:49:33 +00:00
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2018-07-11 13:56:45 +00:00
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#ifdef CONFIG_COMPAT
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extern const syscall_fn_t compat_sys_call_table[];
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#endif
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2012-03-05 11:49:33 +00:00
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static inline int syscall_get_nr(struct task_struct *task,
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struct pt_regs *regs)
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{
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return regs->syscallno;
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}
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static inline void syscall_rollback(struct task_struct *task,
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struct pt_regs *regs)
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{
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regs->regs[0] = regs->orig_x0;
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}
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static inline long syscall_get_error(struct task_struct *task,
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struct pt_regs *regs)
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{
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unsigned long error = regs->regs[0];
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return IS_ERR_VALUE(error) ? error : 0;
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}
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static inline long syscall_get_return_value(struct task_struct *task,
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struct pt_regs *regs)
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{
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return regs->regs[0];
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}
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static inline void syscall_set_return_value(struct task_struct *task,
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struct pt_regs *regs,
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int error, long val)
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{
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regs->regs[0] = (long) error ? error : val;
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}
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#define SYSCALL_MAX_ARGS 6
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static inline void syscall_get_arguments(struct task_struct *task,
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struct pt_regs *regs,
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unsigned long *args)
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{
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2016-11-07 21:26:37 +00:00
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args[0] = regs->orig_x0;
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args++;
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2012-03-05 11:49:33 +00:00
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2016-11-07 21:26:37 +00:00
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memcpy(args, ®s->regs[1], 5 * sizeof(args[0]));
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2012-03-05 11:49:33 +00:00
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}
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static inline void syscall_set_arguments(struct task_struct *task,
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struct pt_regs *regs,
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const unsigned long *args)
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{
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2019-03-28 00:07:31 +00:00
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regs->orig_x0 = args[0];
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args++;
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memcpy(®s->regs[1], args, 5 * sizeof(args[0]));
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2012-03-05 11:49:33 +00:00
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}
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2014-07-04 07:28:30 +00:00
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/*
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* We don't care about endianness (__AUDIT_ARCH_LE bit) here because
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* AArch64 has the same system calls both on little- and big- endian.
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*/
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2019-03-17 23:30:18 +00:00
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static inline int syscall_get_arch(struct task_struct *task)
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2014-07-04 07:28:30 +00:00
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{
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2019-03-17 23:30:18 +00:00
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if (is_compat_thread(task_thread_info(task)))
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2014-07-04 07:28:30 +00:00
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return AUDIT_ARCH_ARM;
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return AUDIT_ARCH_AARCH64;
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}
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2012-03-05 11:49:33 +00:00
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#endif /* __ASM_SYSCALL_H */
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