10 files changed, 33 insertions, 157 deletions

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 15ac18a56c93..20b688c81956 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -7,6 +7,8 @@ config ARM64
         select GENERIC_IOMAP
         select GENERIC_IRQ_PROBE
         select GENERIC_IRQ_SHOW
+        select GENERIC_KERNEL_EXECVE
+        select GENERIC_KERNEL_THREAD
         select GENERIC_SMP_IDLE_THREAD
         select GENERIC_TIME_VSYSCALL
         select HARDIRQS_SW_RESEND
diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
index 77f696c14339..ab239b2c456f 100644
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -128,11 +128,6 @@ unsigned long get_wchan(struct task_struct *p);
 extern struct task_struct *cpu_switch_to(struct task_struct *prev,
                                          struct task_struct *next);
 
-/*
- * Create a new kernel thread
- */
-extern int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
-
 #define task_pt_regs(p) \
         ((struct pt_regs *)(THREAD_START_SP + task_stack_page(p)) - 1)
 
diff --git a/arch/arm64/include/asm/syscalls.h b/arch/arm64/include/asm/syscalls.h
index 09ff33572aab..81680a0ae913 100644
--- a/arch/arm64/include/asm/syscalls.h
+++ b/arch/arm64/include/asm/syscalls.h
@@ -23,9 +23,6 @@
 /*
  * 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,
diff --git a/arch/arm64/include/asm/unistd.h b/arch/arm64/include/asm/unistd.h
index 68aff2816e86..43064a8bd99e 100644
--- a/arch/arm64/include/asm/unistd.h
+++ b/arch/arm64/include/asm/unistd.h
@@ -25,4 +25,5 @@
 #define __ARCH_WANT_COMPAT_SYS_RT_SIGSUSPEND
 #define __ARCH_WANT_COMPAT_SYS_SENDFILE
 #endif
+#define __ARCH_WANT_SYS_EXECVE
 #include <uapi/asm/unistd.h>
diff --git a/arch/arm64/include/asm/unistd32.h b/arch/arm64/include/asm/unistd32.h
index 6d909faebf28..9035e6add3e4 100644
--- a/arch/arm64/include/asm/unistd32.h
+++ b/arch/arm64/include/asm/unistd32.h
@@ -32,7 +32,7 @@ __SYSCALL(7,   sys_ni_syscall)			/* 7 was sys_waitpid */
 __SYSCALL(8,   sys_creat)
 __SYSCALL(9,   sys_link)
 __SYSCALL(10,  sys_unlink)
-__SYSCALL(11,  compat_sys_execve_wrapper)
+__SYSCALL(11,  compat_sys_execve)
 __SYSCALL(12,  sys_chdir)
 __SYSCALL(13,  sys_ni_syscall)                  /* 13 was sys_time */
 __SYSCALL(14,  sys_mknod)
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index a6f3f7da6880..616531862d52 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -594,7 +594,7 @@ work_resched:
 /*
  * "slow" syscall return path.
  */
-ENTRY(ret_to_user)
+ret_to_user:
         disable_irq                             // disable interrupts
         ldr     x1, [tsk, #TI_FLAGS]
         and     x2, x1, #_TIF_WORK_MASK
@@ -611,7 +611,10 @@ ENDPROC(ret_to_user)
  */
 ENTRY(ret_from_fork)
         bl      schedule_tail
-        get_thread_info tsk
+        cbz     x19, 1f                         // not a kernel thread
+        mov     x0, x20
+        blr     x19
+1:      get_thread_info tsk
         b       ret_to_user
 ENDPROC(ret_from_fork)
 
@@ -673,11 +676,6 @@ __sys_trace_return:
 /*
  * Special system call wrappers.
  */
-ENTRY(sys_execve_wrapper)
-        mov     x3, sp
-        b       sys_execve
-ENDPROC(sys_execve_wrapper)
-
 ENTRY(sys_clone_wrapper)
         mov     x5, sp
         b       sys_clone
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index e04cebdbb47f..a430b5cad308 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -240,27 +240,35 @@ int copy_thread(unsigned long clone_flags, unsigned long stack_start,
         struct pt_regs *childregs = task_pt_regs(p);
         unsigned long tls = p->thread.tp_value;
 
-        *childregs = *regs;
-        childregs->regs[0] = 0;
+        memset(&p->thread.cpu_context, 0, sizeof(struct cpu_context));
 
-        if (is_compat_thread(task_thread_info(p)))
-                childregs->compat_sp = stack_start;
-        else {
+        if (likely(regs)) {
+                *childregs = *regs;
+                childregs->regs[0] = 0;
+                if (is_compat_thread(task_thread_info(p))) {
+                        childregs->compat_sp = stack_start;
+                } else {
+                        /*
+                         * Read the current TLS pointer from tpidr_el0 as it may be
+                         * out-of-sync with the saved value.
+                         */
+                        asm("mrs %0, tpidr_el0" : "=r" (tls));
+                        childregs->sp = stack_start;
+                }
                 /*
-                 * Read the current TLS pointer from tpidr_el0 as it may be
-                 * out-of-sync with the saved value.
+                 * If a TLS pointer was passed to clone (4th argument), use it
+                 * for the new thread.
                  */
-                asm("mrs %0, tpidr_el0" : "=r" (tls));
-                childregs->sp = stack_start;
+                if (clone_flags & CLONE_SETTLS)
+                        tls = regs->regs[3];
+        } else {
+                memset(childregs, 0, sizeof(struct pt_regs));
+                childregs->pstate = PSR_MODE_EL1h;
+                p->thread.cpu_context.x19 = stack_start;
+                p->thread.cpu_context.x20 = stk_sz;
         }
-
-        memset(&p->thread.cpu_context, 0, sizeof(struct cpu_context));
-        p->thread.cpu_context.sp = (unsigned long)childregs;
         p->thread.cpu_context.pc = (unsigned long)ret_from_fork;
-
-        /* If a TLS pointer was passed to clone, use that for the new thread. */
-        if (clone_flags & CLONE_SETTLS)
-                tls = regs->regs[3];
+        p->thread.cpu_context.sp = (unsigned long)childregs;
         p->thread.tp_value = tls;
 
         ptrace_hw_copy_thread(p);
@@ -309,43 +317,6 @@ struct task_struct *__switch_to(struct task_struct *prev,
         return last;
 }
 
-/*
- * Shuffle the argument into the correct register before calling the
- * thread function.  x1 is the thread argument, x2 is the pointer to
- * the thread function, and x3 points to the exit function.
- */
-extern void kernel_thread_helper(void);
-asm(    ".section .text\n"
-"       .align\n"
-"       .type   kernel_thread_helper, #function\n"
-"kernel_thread_helper:\n"
-"       mov     x0, x1\n"
-"       mov     x30, x3\n"
-"       br      x2\n"
-"       .size   kernel_thread_helper, . - kernel_thread_helper\n"
-"       .previous");
-
-#define kernel_thread_exit      do_exit
-
-/*
- * Create a kernel thread.
- */
-pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
-{
-        struct pt_regs regs;
-
-        memset(&regs, 0, sizeof(regs));
-
-        regs.regs[1] = (unsigned long)arg;
-        regs.regs[2] = (unsigned long)fn;
-        regs.regs[3] = (unsigned long)kernel_thread_exit;
-        regs.pc = (unsigned long)kernel_thread_helper;
-        regs.pstate = PSR_MODE_EL1h;
-
-        return do_fork(flags|CLONE_VM|CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
-}
-EXPORT_SYMBOL(kernel_thread);
-
 unsigned long get_wchan(struct task_struct *p)
 {
         struct stackframe frame;
diff --git a/arch/arm64/kernel/sys.c b/arch/arm64/kernel/sys.c
index b120df37de35..9c77c0bacc1d 100644
--- a/arch/arm64/kernel/sys.c
+++ b/arch/arm64/kernel/sys.c
@@ -41,70 +41,6 @@ asmlinkage long sys_clone(unsigned long clone_flags, unsigned long newsp,
         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;
-        struct filename *filename;
-
-        filename = getname(filenamei);
-        error = PTR_ERR(filename);
-        if (IS_ERR(filename))
-                goto out;
-        error = do_execve(filename->name, 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)
@@ -118,7 +54,6 @@ asmlinkage long sys_mmap(unsigned long addr, unsigned long len,
 /*
  * 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
diff --git a/arch/arm64/kernel/sys32.S b/arch/arm64/kernel/sys32.S
index 54c4aec47a08..92145d402cf1 100644
--- a/arch/arm64/kernel/sys32.S
+++ b/arch/arm64/kernel/sys32.S
@@ -36,11 +36,6 @@ compat_sys_vfork_wrapper:
         b       compat_sys_vfork
 ENDPROC(compat_sys_vfork_wrapper)
 
-compat_sys_execve_wrapper:
-        mov     x3, sp
-        b       compat_sys_execve
-ENDPROC(compat_sys_execve_wrapper)
-
 compat_sys_clone_wrapper:
         mov     x5, sp
         b       compat_sys_clone
diff --git a/arch/arm64/kernel/sys_compat.c b/arch/arm64/kernel/sys_compat.c
index 906e3bd270b0..d140b73a8bc4 100644
--- a/arch/arm64/kernel/sys_compat.c
+++ b/arch/arm64/kernel/sys_compat.c
@@ -49,24 +49,6 @@ asmlinkage int compat_sys_vfork(struct pt_regs *regs)
                        regs, 0, NULL, NULL);
 }
 
-asmlinkage int compat_sys_execve(const char __user *filenamei,
-                                 compat_uptr_t argv, compat_uptr_t envp,
-                                 struct pt_regs *regs)
-{
-        int error;
-        struct filename *filename;
-
-        filename = getname(filenamei);
-        error = PTR_ERR(filename);
-        if (IS_ERR(filename))
-                goto out;
-        error = compat_do_execve(filename->name, compat_ptr(argv),
-                                        compat_ptr(envp), regs);
-        putname(filename);
-out:
-        return error;
-}
-
 asmlinkage int compat_sys_sched_rr_get_interval(compat_pid_t pid,
                                                 struct compat_timespec __user *interval)
 {