16 files changed, 116 insertions, 205 deletions

diff --git a/arch/tile/Kconfig b/arch/tile/Kconfig
index 875d008828b8..ea7f61e8bc9e 100644
--- a/arch/tile/Kconfig
+++ b/arch/tile/Kconfig
@@ -21,6 +21,8 @@ config TILE
         select ARCH_HAVE_NMI_SAFE_CMPXCHG
         select GENERIC_CLOCKEVENTS
         select MODULES_USE_ELF_RELA
+        select GENERIC_KERNEL_THREAD
+        select GENERIC_KERNEL_EXECVE
 
 # FIXME: investigate whether we need/want these options.
 #       select HAVE_IOREMAP_PROT
diff --git a/arch/tile/include/asm/compat.h b/arch/tile/include/asm/compat.h
index 3063e6fc8daa..ca61fb4296b3 100644
--- a/arch/tile/include/asm/compat.h
+++ b/arch/tile/include/asm/compat.h
@@ -275,18 +275,14 @@ extern int compat_setup_rt_frame(int sig, struct k_sigaction *ka,
 struct compat_sigaction;
 struct compat_siginfo;
 struct compat_sigaltstack;
-long compat_sys_execve(const char __user *path,
-                       compat_uptr_t __user *argv,
-                       compat_uptr_t __user *envp, struct pt_regs *);
 long compat_sys_rt_sigaction(int sig, struct compat_sigaction __user *act,
                              struct compat_sigaction __user *oact,
                              size_t sigsetsize);
 long compat_sys_rt_sigqueueinfo(int pid, int sig,
                                 struct compat_siginfo __user *uinfo);
-long compat_sys_rt_sigreturn(struct pt_regs *);
+long compat_sys_rt_sigreturn(void);
 long compat_sys_sigaltstack(const struct compat_sigaltstack __user *uss_ptr,
-                            struct compat_sigaltstack __user *uoss_ptr,
-                            struct pt_regs *);
+                            struct compat_sigaltstack __user *uoss_ptr);
 long compat_sys_truncate64(char __user *filename, u32 dummy, u32 low, u32 high);
 long compat_sys_ftruncate64(unsigned int fd, u32 dummy, u32 low, u32 high);
 long compat_sys_pread64(unsigned int fd, char __user *ubuf, size_t count,
@@ -303,12 +299,7 @@ long compat_sys_fallocate(int fd, int mode,
 long compat_sys_sched_rr_get_interval(compat_pid_t pid,
                                       struct compat_timespec __user *interval);
 
-/* These are the intvec_64.S trampolines. */
-long _compat_sys_execve(const char __user *path,
-                        const compat_uptr_t __user *argv,
-                        const compat_uptr_t __user *envp);
-long _compat_sys_sigaltstack(const struct compat_sigaltstack __user *uss_ptr,
-                            struct compat_sigaltstack __user *uoss_ptr);
+/* Assembly trampoline to avoid clobbering r0. */
 long _compat_sys_rt_sigreturn(void);
 
 #endif /* _ASM_TILE_COMPAT_H */
diff --git a/arch/tile/include/asm/elf.h b/arch/tile/include/asm/elf.h
index f8ccf08f6934..b73e1039c911 100644
--- a/arch/tile/include/asm/elf.h
+++ b/arch/tile/include/asm/elf.h
@@ -148,6 +148,7 @@ extern int arch_setup_additional_pages(struct linux_binprm *bprm,
 #define compat_start_thread(regs, ip, usp) do { \
                 regs->pc = ptr_to_compat_reg((void *)(ip)); \
                 regs->sp = ptr_to_compat_reg((void *)(usp)); \
+                single_step_execve();   \
         } while (0)
 
 /*
diff --git a/arch/tile/include/asm/processor.h b/arch/tile/include/asm/processor.h
index 8c4dd9ff91eb..2b70dfb1442e 100644
--- a/arch/tile/include/asm/processor.h
+++ b/arch/tile/include/asm/processor.h
@@ -211,6 +211,7 @@ static inline void start_thread(struct pt_regs *regs,
 {
         regs->pc = pc;
         regs->sp = usp;
+        single_step_execve();
 }
 
 /* Free all resources held by a thread. */
@@ -219,8 +220,6 @@ static inline void release_thread(struct task_struct *dead_task)
         /* Nothing for now */
 }
 
-extern int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
-
 extern int do_work_pending(struct pt_regs *regs, u32 flags);
 
 
@@ -239,6 +238,9 @@ unsigned long get_wchan(struct task_struct *p);
 #define KSTK_TOP(task)  (task_ksp0(task) - STACK_TOP_DELTA)
 #define task_pt_regs(task) \
   ((struct pt_regs *)(task_ksp0(task) - KSTK_PTREGS_GAP) - 1)
+#define current_pt_regs()                                   \
+  ((struct pt_regs *)((stack_pointer | (THREAD_SIZE - 1)) - \
+                      (KSTK_PTREGS_GAP - 1)) - 1)
 #define task_sp(task)   (task_pt_regs(task)->sp)
 #define task_pc(task)   (task_pt_regs(task)->pc)
 /* Aliases for pc and sp (used in fs/proc/array.c) */
diff --git a/arch/tile/include/asm/switch_to.h b/arch/tile/include/asm/switch_to.h
index 1d48c5fee8b7..b8f888cbe6b0 100644
--- a/arch/tile/include/asm/switch_to.h
+++ b/arch/tile/include/asm/switch_to.h
@@ -68,7 +68,10 @@ extern unsigned long get_switch_to_pc(void);
 /* Support function for forking a new task. */
 void ret_from_fork(void);
 
-/* Called from ret_from_fork() when a new process starts up. */
+/* Support function for forking a new kernel thread. */
+void ret_from_kernel_thread(void *fn, void *arg);
+
+/* Called from ret_from_xxx() when a new process starts up. */
 struct task_struct *sim_notify_fork(struct task_struct *prev);
 
 #endif /* !__ASSEMBLY__ */
diff --git a/arch/tile/include/asm/syscalls.h b/arch/tile/include/asm/syscalls.h
index 06f0464cfed9..4c8462a62cb6 100644
--- a/arch/tile/include/asm/syscalls.h
+++ b/arch/tile/include/asm/syscalls.h
@@ -51,8 +51,7 @@ long sys_cacheflush(unsigned long addr, unsigned long len,
 
 #ifndef __tilegx__
 /* mm/fault.c */
-long sys_cmpxchg_badaddr(unsigned long address, struct pt_regs *);
-long _sys_cmpxchg_badaddr(unsigned long address);
+long sys_cmpxchg_badaddr(unsigned long address);
 #endif
 
 #ifdef CONFIG_COMPAT
@@ -63,14 +62,16 @@ long sys_truncate64(const char __user *path, loff_t length);
 long sys_ftruncate64(unsigned int fd, loff_t length);
 #endif
 
+/* Provide versions of standard syscalls that use current_pt_regs(). */
+long sys_rt_sigreturn(void);
+long sys_sigaltstack(const stack_t __user *, stack_t __user *);
+#define sys_rt_sigreturn sys_rt_sigreturn
+#define sys_sigaltstack sys_sigaltstack
+
 /* These are the intvec*.S trampolines. */
-long _sys_sigaltstack(const stack_t __user *, stack_t __user *);
 long _sys_rt_sigreturn(void);
 long _sys_clone(unsigned long clone_flags, unsigned long newsp,
                 void __user *parent_tid, void __user *child_tid);
-long _sys_execve(const char __user *filename,
-                 const char __user *const __user *argv,
-                 const char __user *const __user *envp);
 
 #include <asm-generic/syscalls.h>
 
diff --git a/arch/tile/include/asm/unistd.h b/arch/tile/include/asm/unistd.h
index 6e032a0a268e..b51c6ee3cd6c 100644
--- a/arch/tile/include/asm/unistd.h
+++ b/arch/tile/include/asm/unistd.h
@@ -16,4 +16,6 @@
 #define __ARCH_WANT_SYS_LLSEEK
 #endif
 #define __ARCH_WANT_SYS_NEWFSTATAT
+#define __ARCH_WANT_SYS_EXECVE
+#define __ARCH_WANT_SYS_CLONE
 #include <uapi/asm/unistd.h>
diff --git a/arch/tile/kernel/compat.c b/arch/tile/kernel/compat.c
index d67459b9ac2a..9cd7cb6041c0 100644
--- a/arch/tile/kernel/compat.c
+++ b/arch/tile/kernel/compat.c
@@ -102,9 +102,7 @@ long compat_sys_sched_rr_get_interval(compat_pid_t pid,
 #define compat_sys_fadvise64_64 sys32_fadvise64_64
 #define compat_sys_readahead sys32_readahead
 
-/* Call the trampolines to manage pt_regs where necessary. */
-#define compat_sys_execve _compat_sys_execve
-#define compat_sys_sigaltstack _compat_sys_sigaltstack
+/* Call the assembly trampolines where necessary. */
 #define compat_sys_rt_sigreturn _compat_sys_rt_sigreturn
 #define sys_clone _sys_clone
 
diff --git a/arch/tile/kernel/compat_signal.c b/arch/tile/kernel/compat_signal.c
index 08b4fe1717bb..2e4cc69224a6 100644
--- a/arch/tile/kernel/compat_signal.c
+++ b/arch/tile/kernel/compat_signal.c
@@ -197,8 +197,7 @@ int copy_siginfo_from_user32(siginfo_t *to, struct compat_siginfo __user *from)
 }
 
 long compat_sys_sigaltstack(const struct compat_sigaltstack __user *uss_ptr,
-                            struct compat_sigaltstack __user *uoss_ptr,
-                            struct pt_regs *regs)
+                            struct compat_sigaltstack __user *uoss_ptr)
 {
         stack_t uss, uoss;
         int ret;
@@ -219,7 +218,7 @@ long compat_sys_sigaltstack(const struct compat_sigaltstack __user *uss_ptr,
         set_fs(KERNEL_DS);
         ret = do_sigaltstack(uss_ptr ? (stack_t __user __force *)&uss : NULL,
                              (stack_t __user __force *)&uoss,
-                             (unsigned long)compat_ptr(regs->sp));
+                             (unsigned long)compat_ptr(current_pt_regs()->sp));
         set_fs(seg);
         if (ret >= 0 && uoss_ptr)  {
                 if (!access_ok(VERIFY_WRITE, uoss_ptr, sizeof(*uoss_ptr)) ||
@@ -232,8 +231,9 @@ long compat_sys_sigaltstack(const struct compat_sigaltstack __user *uss_ptr,
 }
 
 /* The assembly shim for this function arranges to ignore the return value. */
-long compat_sys_rt_sigreturn(struct pt_regs *regs)
+long compat_sys_rt_sigreturn(void)
 {
+        struct pt_regs *regs = current_pt_regs();
         struct compat_rt_sigframe __user *frame =
                 (struct compat_rt_sigframe __user *) compat_ptr(regs->sp);
         sigset_t set;
@@ -248,7 +248,7 @@ long compat_sys_rt_sigreturn(struct pt_regs *regs)
         if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
                 goto badframe;
 
-        if (compat_sys_sigaltstack(&frame->uc.uc_stack, NULL, regs) != 0)
+        if (compat_sys_sigaltstack(&frame->uc.uc_stack, NULL) == -EFAULT)
                 goto badframe;
 
         return 0;
diff --git a/arch/tile/kernel/entry.S b/arch/tile/kernel/entry.S
index c31637baff28..f116cb0bce20 100644
--- a/arch/tile/kernel/entry.S
+++ b/arch/tile/kernel/entry.S
@@ -28,17 +28,6 @@ STD_ENTRY(current_text_addr)
         STD_ENDPROC(current_text_addr)
 
 /*
- * Implement execve().  The i386 code has a note that forking from kernel
- * space results in no copy on write until the execve, so we should be
- * careful not to write to the stack here.
- */
-STD_ENTRY(kernel_execve)
-        moveli TREG_SYSCALL_NR_NAME, __NR_execve
-        swint1
-        jrp lr
-        STD_ENDPROC(kernel_execve)
-
-/*
  * We don't run this function directly, but instead copy it to a page
  * we map into every user process.  See vdso_setup().
  *
diff --git a/arch/tile/kernel/intvec_32.S b/arch/tile/kernel/intvec_32.S
index 6943515100f8..f212bf7cea86 100644
--- a/arch/tile/kernel/intvec_32.S
+++ b/arch/tile/kernel/intvec_32.S
@@ -1291,6 +1291,21 @@ STD_ENTRY(ret_from_fork)
         }
         STD_ENDPROC(ret_from_fork)
 
+STD_ENTRY(ret_from_kernel_thread)
+        jal     sim_notify_fork
+        jal     schedule_tail
+        FEEDBACK_REENTER(ret_from_fork)
+        {
+         move   r0, r31
+         jalr   r30
+        }
+        FEEDBACK_REENTER(ret_from_kernel_thread)
+        {
+         movei  r30, 0               /* not an NMI */
+         j      .Lresume_userspace   /* jump into middle of interrupt_return */
+        }
+        STD_ENDPROC(ret_from_kernel_thread)
+
         /*
          * Code for ill interrupt.
          */
@@ -1437,15 +1452,6 @@ STD_ENTRY_LOCAL(bad_intr)
         panic   "Unhandled interrupt %#x: PC %#lx"
         STD_ENDPROC(bad_intr)
 
-/* Put address of pt_regs in reg and jump. */
-#define PTREGS_SYSCALL(x, reg)                          \
-        STD_ENTRY(_##x);                                \
-        {                                               \
-         PTREGS_PTR(reg, PTREGS_OFFSET_BASE);           \
-         j      x                                       \
-        };                                              \
-        STD_ENDPROC(_##x)
-
 /*
  * Special-case sigreturn to not write r0 to the stack on return.
  * This is technically more efficient, but it also avoids difficulties
@@ -1461,12 +1467,9 @@ STD_ENTRY_LOCAL(bad_intr)
         };                                              \
         STD_ENDPROC(_##x)
 
-PTREGS_SYSCALL(sys_execve, r3)
-PTREGS_SYSCALL(sys_sigaltstack, r2)
 PTREGS_SYSCALL_SIGRETURN(sys_rt_sigreturn, r0)
-PTREGS_SYSCALL(sys_cmpxchg_badaddr, r1)
 
-/* Save additional callee-saves to pt_regs, put address in r4 and jump. */
+/* Save additional callee-saves to pt_regs and jump to standard function. */
 STD_ENTRY(_sys_clone)
         push_extra_callee_saves r4
         j       sys_clone
diff --git a/arch/tile/kernel/intvec_64.S b/arch/tile/kernel/intvec_64.S
index 7c06d597ffd0..54bc9a6678e8 100644
--- a/arch/tile/kernel/intvec_64.S
+++ b/arch/tile/kernel/intvec_64.S
@@ -1150,6 +1150,21 @@ STD_ENTRY(ret_from_fork)
         }
         STD_ENDPROC(ret_from_fork)
 
+STD_ENTRY(ret_from_kernel_thread)
+        jal     sim_notify_fork
+        jal     schedule_tail
+        FEEDBACK_REENTER(ret_from_fork)
+        {
+         move   r0, r31
+         jalr   r30
+        }
+        FEEDBACK_REENTER(ret_from_kernel_thread)
+        {
+         movei  r30, 0               /* not an NMI */
+         j      .Lresume_userspace   /* jump into middle of interrupt_return */
+        }
+        STD_ENDPROC(ret_from_kernel_thread)
+
 /* Various stub interrupt handlers and syscall handlers */
 
 STD_ENTRY_LOCAL(_kernel_double_fault)
@@ -1166,15 +1181,6 @@ STD_ENTRY_LOCAL(bad_intr)
         panic   "Unhandled interrupt %#x: PC %#lx"
         STD_ENDPROC(bad_intr)
 
-/* Put address of pt_regs in reg and jump. */
-#define PTREGS_SYSCALL(x, reg)                          \
-        STD_ENTRY(_##x);                                \
-        {                                               \
-         PTREGS_PTR(reg, PTREGS_OFFSET_BASE);           \
-         j      x                                       \
-        };                                              \
-        STD_ENDPROC(_##x)
-
 /*
  * Special-case sigreturn to not write r0 to the stack on return.
  * This is technically more efficient, but it also avoids difficulties
@@ -1190,16 +1196,12 @@ STD_ENTRY_LOCAL(bad_intr)
         };                                              \
         STD_ENDPROC(_##x)
 
-PTREGS_SYSCALL(sys_execve, r3)
-PTREGS_SYSCALL(sys_sigaltstack, r2)
 PTREGS_SYSCALL_SIGRETURN(sys_rt_sigreturn, r0)
 #ifdef CONFIG_COMPAT
-PTREGS_SYSCALL(compat_sys_execve, r3)
-PTREGS_SYSCALL(compat_sys_sigaltstack, r2)
 PTREGS_SYSCALL_SIGRETURN(compat_sys_rt_sigreturn, r0)
 #endif
 
-/* Save additional callee-saves to pt_regs, put address in r4 and jump. */
+/* Save additional callee-saves to pt_regs and jump to standard function. */
 STD_ENTRY(_sys_clone)
         push_extra_callee_saves r4
         j       sys_clone
diff --git a/arch/tile/kernel/process.c b/arch/tile/kernel/process.c
index 307d010696c9..0e5661e7d00d 100644
--- a/arch/tile/kernel/process.c
+++ b/arch/tile/kernel/process.c
@@ -157,24 +157,43 @@ void arch_release_thread_info(struct thread_info *info)
 static void save_arch_state(struct thread_struct *t);
 
 int copy_thread(unsigned long clone_flags, unsigned long sp,
-                unsigned long stack_size,
-                struct task_struct *p, struct pt_regs *regs)
+                unsigned long arg, struct task_struct *p)
 {
-        struct pt_regs *childregs;
+        struct pt_regs *childregs = task_pt_regs(p), *regs = current_pt_regs();
         unsigned long ksp;
+        unsigned long *callee_regs;
 
         /*
-         * When creating a new kernel thread we pass sp as zero.
-         * Assign it to a reasonable value now that we have the stack.
+         * Set up the stack and stack pointer appropriately for the
+         * new child to find itself woken up in __switch_to().
+         * The callee-saved registers must be on the stack to be read;
+         * the new task will then jump to assembly support to handle
+         * calling schedule_tail(), etc., and (for userspace tasks)
+         * returning to the context set up in the pt_regs.
          */
-        if (sp == 0 && regs->ex1 == PL_ICS_EX1(KERNEL_PL, 0))
-                sp = KSTK_TOP(p);
+        ksp = (unsigned long) childregs;
+        ksp -= C_ABI_SAVE_AREA_SIZE;   /* interrupt-entry save area */
+        ((long *)ksp)[0] = ((long *)ksp)[1] = 0;
+        ksp -= CALLEE_SAVED_REGS_COUNT * sizeof(unsigned long);
+        callee_regs = (unsigned long *)ksp;
+        ksp -= C_ABI_SAVE_AREA_SIZE;   /* __switch_to() save area */
+        ((long *)ksp)[0] = ((long *)ksp)[1] = 0;
+        p->thread.ksp = ksp;
 
-        /*
-         * Do not clone step state from the parent; each thread
-         * must make its own lazily.
-         */
-        task_thread_info(p)->step_state = NULL;
+        /* Record the pid of the task that created this one. */
+        p->thread.creator_pid = current->pid;
+
+        if (unlikely(p->flags & PF_KTHREAD)) {
+                /* kernel thread */
+                memset(childregs, 0, sizeof(struct pt_regs));
+                memset(&callee_regs[2], 0,
+                       (CALLEE_SAVED_REGS_COUNT - 2) * sizeof(unsigned long));
+                callee_regs[0] = sp;   /* r30 = function */
+                callee_regs[1] = arg;  /* r31 = arg */
+                childregs->ex1 = PL_ICS_EX1(KERNEL_PL, 0);
+                p->thread.pc = (unsigned long) ret_from_kernel_thread;
+                return 0;
+        }
 
         /*
          * Start new thread in ret_from_fork so it schedules properly
@@ -182,46 +201,33 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
          */
         p->thread.pc = (unsigned long) ret_from_fork;
 
-        /* Save user stack top pointer so we can ID the stack vm area later. */
-        p->thread.usp0 = sp;
-
-        /* Record the pid of the process that created this one. */
-        p->thread.creator_pid = current->pid;
+        /*
+         * Do not clone step state from the parent; each thread
+         * must make its own lazily.
+         */
+        task_thread_info(p)->step_state = NULL;
 
         /*
          * Copy the registers onto the kernel stack so the
          * return-from-interrupt code will reload it into registers.
          */
-        childregs = task_pt_regs(p);
-        *childregs = *regs;
+        *childregs = *current_pt_regs();
         childregs->regs[0] = 0;         /* return value is zero */
-        childregs->sp = sp;  /* override with new user stack pointer */
+        if (sp)
+                childregs->sp = sp;  /* override with new user stack pointer */
+        memcpy(callee_regs, &childregs->regs[CALLEE_SAVED_FIRST_REG],
+               CALLEE_SAVED_REGS_COUNT * sizeof(unsigned long));
+
+        /* Save user stack top pointer so we can ID the stack vm area later. */
+        p->thread.usp0 = childregs->sp;
 
         /*
          * If CLONE_SETTLS is set, set "tp" in the new task to "r4",
          * which is passed in as arg #5 to sys_clone().
          */
         if (clone_flags & CLONE_SETTLS)
-                childregs->tp = regs->regs[4];
+                childregs->tp = childregs->regs[4];
 
-        /*
-         * Copy the callee-saved registers from the passed pt_regs struct
-         * into the context-switch callee-saved registers area.
-         * This way when we start the interrupt-return sequence, the
-         * callee-save registers will be correctly in registers, which
-         * is how we assume the compiler leaves them as we start doing
-         * the normal return-from-interrupt path after calling C code.
-         * Zero out the C ABI save area to mark the top of the stack.
-         */
-        ksp = (unsigned long) childregs;
-        ksp -= C_ABI_SAVE_AREA_SIZE;   /* interrupt-entry save area */
-        ((long *)ksp)[0] = ((long *)ksp)[1] = 0;
-        ksp -= CALLEE_SAVED_REGS_COUNT * sizeof(unsigned long);
-        memcpy((void *)ksp, &regs->regs[CALLEE_SAVED_FIRST_REG],
-               CALLEE_SAVED_REGS_COUNT * sizeof(unsigned long));
-        ksp -= C_ABI_SAVE_AREA_SIZE;   /* __switch_to() save area */
-        ((long *)ksp)[0] = ((long *)ksp)[1] = 0;
-        p->thread.ksp = ksp;
 
 #if CHIP_HAS_TILE_DMA()
         /*
@@ -577,62 +583,6 @@ int do_work_pending(struct pt_regs *regs, u32 thread_info_flags)
         panic("work_pending: bad flags %#x\n", thread_info_flags);
 }
 
-/* Note there is an implicit fifth argument if (clone_flags & CLONE_SETTLS). */
-SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
-                void __user *, parent_tidptr, void __user *, child_tidptr,
-                struct pt_regs *, regs)
-{
-        if (!newsp)
-                newsp = regs->sp;
-        return do_fork(clone_flags, newsp, regs, 0,
-                       parent_tidptr, child_tidptr);
-}
-
-/*
- * sys_execve() executes a new program.
- */
-SYSCALL_DEFINE4(execve, const char __user *, path,
-                const char __user *const __user *, argv,
-                const char __user *const __user *, envp,
-                struct pt_regs *, regs)
-{
-        long error;
-        struct filename *filename;
-
-        filename = getname(path);
-        error = PTR_ERR(filename);
-        if (IS_ERR(filename))
-                goto out;
-        error = do_execve(filename->name, argv, envp, regs);
-        putname(filename);
-        if (error == 0)
-                single_step_execve();
-out:
-        return error;
-}
-
-#ifdef CONFIG_COMPAT
-long compat_sys_execve(const char __user *path,
-                       compat_uptr_t __user *argv,
-                       compat_uptr_t __user *envp,
-                       struct pt_regs *regs)
-{
-        long error;
-        struct filename *filename;
-
-        filename = getname(path);
-        error = PTR_ERR(filename);
-        if (IS_ERR(filename))
-                goto out;
-        error = compat_do_execve(filename->name, argv, envp, regs);
-        putname(filename);
-        if (error == 0)
-                single_step_execve();
-out:
-        return error;
-}
-#endif
-
 unsigned long get_wchan(struct task_struct *p)
 {
         struct KBacktraceIterator kbt;
@@ -650,37 +600,6 @@ unsigned long get_wchan(struct task_struct *p)
         return 0;
 }
 
-/*
- * We pass in lr as zero (cleared in kernel_thread) and the caller
- * part of the backtrace ABI on the stack also zeroed (in copy_thread)
- * so that backtraces will stop with this function.
- * Note that we don't use r0, since copy_thread() clears it.
- */
-static void start_kernel_thread(int dummy, int (*fn)(int), int arg)
-{
-        do_exit(fn(arg));
-}
-
-/*
- * Create a kernel thread
- */
-int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
-{
-        struct pt_regs regs;
-
-        memset(&regs, 0, sizeof(regs));
-        regs.ex1 = PL_ICS_EX1(KERNEL_PL, 0);  /* run at kernel PL, no ICS */
-        regs.pc = (long) start_kernel_thread;
-        regs.flags = PT_FLAGS_CALLER_SAVES;   /* need to restore r1 and r2 */
-        regs.regs[1] = (long) fn;             /* function pointer */
-        regs.regs[2] = (long) arg;            /* parameter register */
-
-        /* Ok, create the new process.. */
-        return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs,
-                       0, NULL, NULL);
-}
-EXPORT_SYMBOL(kernel_thread);
-
 /* Flush thread state. */
 void flush_thread(void)
 {
diff --git a/arch/tile/kernel/signal.c b/arch/tile/kernel/signal.c
index 67efb656d104..657a7ace4ab4 100644
--- a/arch/tile/kernel/signal.c
+++ b/arch/tile/kernel/signal.c
@@ -37,10 +37,10 @@
 
 #define DEBUG_SIG 0
 
-SYSCALL_DEFINE3(sigaltstack, const stack_t __user *, uss,
-                stack_t __user *, uoss, struct pt_regs *, regs)
+SYSCALL_DEFINE2(sigaltstack, const stack_t __user *, uss,
+                stack_t __user *, uoss)
 {
-        return do_sigaltstack(uss, uoss, regs->sp);
+        return do_sigaltstack(uss, uoss, current_pt_regs()->sp);
 }
 
 
@@ -83,8 +83,9 @@ void signal_fault(const char *type, struct pt_regs *regs,
 }
 
 /* The assembly shim for this function arranges to ignore the return value. */
-SYSCALL_DEFINE1(rt_sigreturn, struct pt_regs *, regs)
+SYSCALL_DEFINE0(rt_sigreturn)
 {
+        struct pt_regs *regs = current_pt_regs();
         struct rt_sigframe __user *frame =
                 (struct rt_sigframe __user *)(regs->sp);
         sigset_t set;
diff --git a/arch/tile/kernel/sys.c b/arch/tile/kernel/sys.c
index b08095b402d6..b881a7be24bd 100644
--- a/arch/tile/kernel/sys.c
+++ b/arch/tile/kernel/sys.c
@@ -106,14 +106,10 @@ SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
 #define sys_readahead sys32_readahead
 #endif
 
-/* Call the trampolines to manage pt_regs where necessary. */
-#define sys_execve _sys_execve
-#define sys_sigaltstack _sys_sigaltstack
+/* Call the assembly trampolines where necessary. */
+#undef sys_rt_sigreturn
 #define sys_rt_sigreturn _sys_rt_sigreturn
 #define sys_clone _sys_clone
-#ifndef __tilegx__
-#define sys_cmpxchg_badaddr _sys_cmpxchg_badaddr
-#endif
 
 /*
  * Note that we can't include <linux/unistd.h> here since the header
diff --git a/arch/tile/mm/fault.c b/arch/tile/mm/fault.c
index fe811fa5f1b9..3d2b81c163a6 100644
--- a/arch/tile/mm/fault.c
+++ b/arch/tile/mm/fault.c
@@ -70,9 +70,10 @@ static noinline void force_sig_info_fault(const char *type, int si_signo,
  * Synthesize the fault a PL0 process would get by doing a word-load of
  * an unaligned address or a high kernel address.
  */
-SYSCALL_DEFINE2(cmpxchg_badaddr, unsigned long, address,
-                struct pt_regs *, regs)
+SYSCALL_DEFINE1(cmpxchg_badaddr, unsigned long, address)
 {
+        struct pt_regs *regs = current_pt_regs();
+
         if (address >= PAGE_OFFSET)
                 force_sig_info_fault("atomic segfault", SIGSEGV, SEGV_MAPERR,
                                      address, INT_DTLB_MISS, current, regs);