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    Subject[PATCH v3 17/31] arm64: System calls handling
    Date
    This patch adds support for system calls coming from 64-bit
    applications. It uses the asm-generic/unistd.h definitions with the
    canonical set of system calls. The private system calls are only used
    for 32-bit (compat) applications as 64-bit ones can set the TLS and
    flush the caches entirely from user space.

    The sys_call_table is just an array defined in a C file and it contains
    pointers to the syscall functions. The array is 4KB aligned to allow the
    use of the ADRP instruction (longer range ADR) in entry.S.

    Signed-off-by: Will Deacon <will.deacon@arm.com>
    Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
    Acked-by: Tony Lindgren <tony@atomide.com>
    ---
    arch/arm64/include/asm/stat.h | 62 +++++++++++++++++
    arch/arm64/include/asm/statfs.h | 23 ++++++
    arch/arm64/include/asm/syscalls.h | 40 +++++++++++
    arch/arm64/include/asm/unistd.h | 27 +++++++
    arch/arm64/kernel/sys.c | 138 +++++++++++++++++++++++++++++++++++++
    5 files changed, 290 insertions(+), 0 deletions(-)
    create mode 100644 arch/arm64/include/asm/stat.h
    create mode 100644 arch/arm64/include/asm/statfs.h
    create mode 100644 arch/arm64/include/asm/syscalls.h
    create mode 100644 arch/arm64/include/asm/unistd.h
    create mode 100644 arch/arm64/kernel/sys.c

    diff --git a/arch/arm64/include/asm/stat.h b/arch/arm64/include/asm/stat.h
    new file mode 100644
    index 0000000..d87225c
    --- /dev/null
    +++ b/arch/arm64/include/asm/stat.h
    @@ -0,0 +1,62 @@
    +/*
    + * Copyright (C) 2012 ARM Ltd.
    + *
    + * 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_STAT_H
    +#define __ASM_STAT_H
    +
    +#include <asm-generic/stat.h>
    +
    +#if defined(__KERNEL__) && defined(CONFIG_COMPAT)
    +
    +#include <asm/compat.h>
    +
    +/*
    + * struct stat64 is needed for compat tasks only. Its definition is different
    + * from the generic struct stat64.
    + */
    +struct stat64 {
    + compat_u64 st_dev;
    + unsigned char __pad0[4];
    +
    +#define STAT64_HAS_BROKEN_ST_INO 1
    + compat_ulong_t __st_ino;
    + compat_uint_t st_mode;
    + compat_uint_t st_nlink;
    +
    + compat_ulong_t st_uid;
    + compat_ulong_t st_gid;
    +
    + compat_u64 st_rdev;
    + unsigned char __pad3[4];
    +
    + compat_s64 st_size;
    + compat_ulong_t st_blksize;
    + compat_u64 st_blocks; /* Number of 512-byte blocks allocated. */
    +
    + compat_ulong_t st_atime;
    + compat_ulong_t st_atime_nsec;
    +
    + compat_ulong_t st_mtime;
    + compat_ulong_t st_mtime_nsec;
    +
    + compat_ulong_t st_ctime;
    + compat_ulong_t st_ctime_nsec;
    +
    + compat_u64 st_ino;
    +};
    +
    +#endif
    +
    +#endif
    diff --git a/arch/arm64/include/asm/statfs.h b/arch/arm64/include/asm/statfs.h
    new file mode 100644
    index 0000000..6f62190
    --- /dev/null
    +++ b/arch/arm64/include/asm/statfs.h
    @@ -0,0 +1,23 @@
    +/*
    + * Copyright (C) 2012 ARM Ltd.
    + *
    + * 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_STATFS_H
    +#define __ASM_STATFS_H
    +
    +#define ARCH_PACK_COMPAT_STATFS64 __attribute__((packed,aligned(4)))
    +
    +#include <asm-generic/statfs.h>
    +
    +#endif
    diff --git a/arch/arm64/include/asm/syscalls.h b/arch/arm64/include/asm/syscalls.h
    new file mode 100644
    index 0000000..09ff335
    --- /dev/null
    +++ b/arch/arm64/include/asm/syscalls.h
    @@ -0,0 +1,40 @@
    +/*
    + * Copyright (C) 2012 ARM Ltd.
    + *
    + * 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_SYSCALLS_H
    +#define __ASM_SYSCALLS_H
    +
    +#include <linux/linkage.h>
    +#include <linux/compiler.h>
    +#include <linux/signal.h>
    +
    +/*
    + * System call wrappers implemented in kernel/entry.S.
    + */
    +asmlinkage long sys_execve_wrapper(const char __user *filename,
    + const char __user *const __user *argv,
    + const char __user *const __user *envp);
    +asmlinkage long sys_clone_wrapper(unsigned long clone_flags,
    + unsigned long newsp,
    + void __user *parent_tid,
    + unsigned long tls_val,
    + void __user *child_tid);
    +asmlinkage long sys_rt_sigreturn_wrapper(void);
    +asmlinkage long sys_sigaltstack_wrapper(const stack_t __user *uss,
    + stack_t __user *uoss);
    +
    +#include <asm-generic/syscalls.h>
    +
    +#endif /* __ASM_SYSCALLS_H */
    diff --git a/arch/arm64/include/asm/unistd.h b/arch/arm64/include/asm/unistd.h
    new file mode 100644
    index 0000000..fe18a68
    --- /dev/null
    +++ b/arch/arm64/include/asm/unistd.h
    @@ -0,0 +1,27 @@
    +/*
    + * Copyright (C) 2012 ARM Ltd.
    + *
    + * 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/>.
    + */
    +#if !defined(__ASM_UNISTD_H) || defined(__SYSCALL)
    +#define __ASM_UNISTD_H
    +
    +#ifndef __SYSCALL_COMPAT
    +#include <asm-generic/unistd.h>
    +#endif
    +
    +#if defined(__KERNEL__) && defined(CONFIG_COMPAT)
    +#include <asm/unistd32.h>
    +#endif
    +
    +#endif /* __ASM_UNISTD_H */
    diff --git a/arch/arm64/kernel/sys.c b/arch/arm64/kernel/sys.c
    new file mode 100644
    index 0000000..905fcfb
    --- /dev/null
    +++ b/arch/arm64/kernel/sys.c
    @@ -0,0 +1,138 @@
    +/*
    + * AArch64-specific system calls implementation
    + *
    + * Copyright (C) 2012 ARM Ltd.
    + * Author: Catalin Marinas <catalin.marinas@arm.com>
    + *
    + * 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/>.
    + */
    +
    +#include <linux/compiler.h>
    +#include <linux/errno.h>
    +#include <linux/fs.h>
    +#include <linux/mm.h>
    +#include <linux/export.h>
    +#include <linux/sched.h>
    +#include <linux/slab.h>
    +#include <linux/syscalls.h>
    +
    +/*
    + * Clone a task - this clones the calling program thread.
    + */
    +asmlinkage long sys_clone(unsigned long clone_flags, unsigned long newsp,
    + int __user *parent_tidptr, unsigned long tls_val,
    + int __user *child_tidptr, struct pt_regs *regs)
    +{
    + if (!newsp)
    + newsp = regs->sp;
    + /* 16-byte aligned stack mandatory on AArch64 */
    + if (newsp & 15)
    + return -EINVAL;
    + return do_fork(clone_flags, newsp, regs, 0, parent_tidptr, child_tidptr);
    +}
    +
    +/*
    + * sys_execve() executes a new program.
    + */
    +asmlinkage long sys_execve(const char __user *filenamei,
    + const char __user *const __user *argv,
    + const char __user *const __user *envp,
    + struct pt_regs *regs)
    +{
    + long error;
    + char * filename;
    +
    + filename = getname(filenamei);
    + error = PTR_ERR(filename);
    + if (IS_ERR(filename))
    + goto out;
    + error = do_execve(filename, argv, envp, regs);
    + putname(filename);
    +out:
    + return error;
    +}
    +
    +int kernel_execve(const char *filename,
    + const char *const argv[],
    + const char *const envp[])
    +{
    + struct pt_regs regs;
    + int ret;
    +
    + memset(&regs, 0, sizeof(struct pt_regs));
    + ret = do_execve(filename,
    + (const char __user *const __user *)argv,
    + (const char __user *const __user *)envp, &regs);
    + if (ret < 0)
    + goto out;
    +
    + /*
    + * Save argc to the register structure for userspace.
    + */
    + regs.regs[0] = ret;
    +
    + /*
    + * We were successful. We won't be returning to our caller, but
    + * instead to user space by manipulating the kernel stack.
    + */
    + asm( "add x0, %0, %1\n\t"
    + "mov x1, %2\n\t"
    + "mov x2, %3\n\t"
    + "bl memmove\n\t" /* copy regs to top of stack */
    + "mov x27, #0\n\t" /* not a syscall */
    + "mov x28, %0\n\t" /* thread structure */
    + "mov sp, x0\n\t" /* reposition stack pointer */
    + "b ret_to_user"
    + :
    + : "r" (current_thread_info()),
    + "Ir" (THREAD_START_SP - sizeof(regs)),
    + "r" (&regs),
    + "Ir" (sizeof(regs))
    + : "x0", "x1", "x2", "x27", "x28", "x30", "memory");
    +
    + out:
    + return ret;
    +}
    +EXPORT_SYMBOL(kernel_execve);
    +
    +asmlinkage long sys_mmap(unsigned long addr, unsigned long len,
    + unsigned long prot, unsigned long flags,
    + unsigned long fd, off_t off)
    +{
    + if (offset_in_page(off) != 0)
    + return -EINVAL;
    +
    + return sys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT);
    +}
    +
    +/*
    + * Wrappers to pass the pt_regs argument.
    + */
    +#define sys_execve sys_execve_wrapper
    +#define sys_clone sys_clone_wrapper
    +#define sys_rt_sigreturn sys_rt_sigreturn_wrapper
    +#define sys_sigaltstack sys_sigaltstack_wrapper
    +
    +#include <asm/syscalls.h>
    +
    +#undef __SYSCALL
    +#define __SYSCALL(nr, sym) [nr] = sym,
    +
    +/*
    + * The sys_call_table array must be 4K aligned to be accessible from
    + * kernel/entry.S.
    + */
    +void *sys_call_table[__NR_syscalls] __aligned(4096) = {
    + [0 ... __NR_syscalls - 1] = sys_ni_syscall,
    +#include <asm/unistd.h>
    +};


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