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Subject[PATCH v2 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>
---
arch/arm64/include/asm/stat.h | 63 +++++++++++++++++
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, 291 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..f63a680
--- /dev/null
+++ b/arch/arm64/include/asm/stat.h
@@ -0,0 +1,63 @@
+/*
+ * 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_AARCH32_EMULATION)
+
+#include <asm/compat.h>
+
+/* This matches struct stat64 in glibc2.1, hence the absolutely
+ * insane amounts of padding around dev_t's.
+ * Note: The kernel zero's the padded region because glibc might read them
+ * in the hope that the kernel has stretched to using larger sizes.
+ */
+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 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..b00718c
--- /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_AARCH32_EMULATION)
+#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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