249dbe74d3
The epoll_wait() system call wrapper is one of the remaining users of the set_fs() infrasturcture for Arm. Changing it to not require set_fs() is rather complex unfortunately. The approach I'm taking here is to allow architectures to override the code that copies the output to user space, and let the oabi-compat implementation check whether it is getting called from an EABI or OABI system call based on the thread_info->syscall value. The in_oabi_syscall() check here mirrors the in_compat_syscall() and in_x32_syscall() helpers for 32-bit compat implementations on other architectures. Overall, the amount of code goes down, at least with the newly added sys_oabi_epoll_pwait() helper getting removed again. The downside is added complexity in the source code for the native implementation. There should be no difference in runtime performance except for Arm kernels with CONFIG_OABI_COMPAT enabled that now have to go through an external function call to check which of the two variants to use. Acked-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
96 lines
2.2 KiB
C
96 lines
2.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Access to user system call parameters and results
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*
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* See asm-generic/syscall.h for descriptions of what we must do here.
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*/
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#ifndef _ASM_ARM_SYSCALL_H
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#define _ASM_ARM_SYSCALL_H
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#include <uapi/linux/audit.h> /* for AUDIT_ARCH_* */
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#include <linux/elf.h> /* for ELF_EM */
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#include <linux/err.h>
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#include <linux/sched.h>
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#include <asm/unistd.h>
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#define NR_syscalls (__NR_syscalls)
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extern const unsigned long sys_call_table[];
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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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if (IS_ENABLED(CONFIG_AEABI) && !IS_ENABLED(CONFIG_OABI_COMPAT))
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return task_thread_info(task)->abi_syscall;
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return task_thread_info(task)->abi_syscall & __NR_SYSCALL_MASK;
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}
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static inline bool __in_oabi_syscall(struct task_struct *task)
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{
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return IS_ENABLED(CONFIG_OABI_COMPAT) &&
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(task_thread_info(task)->abi_syscall & __NR_OABI_SYSCALL_BASE);
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}
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static inline bool in_oabi_syscall(void)
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{
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return __in_oabi_syscall(current);
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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->ARM_r0 = regs->ARM_ORIG_r0;
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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->ARM_r0;
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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->ARM_r0;
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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->ARM_r0 = (long) error ? error : val;
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}
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#define SYSCALL_MAX_ARGS 7
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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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args[0] = regs->ARM_ORIG_r0;
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args++;
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memcpy(args, ®s->ARM_r0 + 1, 5 * sizeof(args[0]));
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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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regs->ARM_ORIG_r0 = args[0];
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args++;
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memcpy(®s->ARM_r0 + 1, args, 5 * sizeof(args[0]));
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}
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static inline int syscall_get_arch(struct task_struct *task)
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{
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/* ARM tasks don't change audit architectures on the fly. */
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return AUDIT_ARCH_ARM;
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}
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#endif /* _ASM_ARM_SYSCALL_H */
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