hexagon: kernel_thread()/kernel_execve() conversion

introduce sane current_pt_regs(), use it in syscalls where needed.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/arch/hexagon/Kconfig b/arch/hexagon/Kconfig
index 0744f7d..e418803 100644 (file)
--- a/arch/hexagon/Kconfig
+++ b/arch/hexagon/Kconfig
@@ -31,6 +31,8 @@ config HEXAGON
        select GENERIC_CLOCKEVENTS
        select GENERIC_CLOCKEVENTS_BROADCAST
        select MODULES_USE_ELF_RELA
+       select GENERIC_KERNEL_THREAD
+       select GENERIC_KERNEL_EXECVE
        ---help---
          Qualcomm Hexagon is a processor architecture designed for high
          performance and low power across a wide variety of applications.

diff --git a/arch/hexagon/include/asm/processor.h b/arch/hexagon/include/asm/processor.h
index e8ea459..8483b49 100644 (file)
--- a/arch/hexagon/include/asm/processor.h
+++ b/arch/hexagon/include/asm/processor.h
@@ -34,7 +34,6 @@
 struct task_struct;
 
 /*  this is defined in arch/process.c  */
-extern pid_t kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
 extern unsigned long thread_saved_pc(struct task_struct *tsk);
 
 extern void start_thread(struct pt_regs *, unsigned long, unsigned long);

diff --git a/arch/hexagon/include/asm/ptrace.h b/arch/hexagon/include/asm/ptrace.h
index 3d2f607..7e1e374 100644 (file)
--- a/arch/hexagon/include/asm/ptrace.h
+++ b/arch/hexagon/include/asm/ptrace.h
@@ -32,4 +32,8 @@
 extern int regs_query_register_offset(const char *name);
 extern const char *regs_query_register_name(unsigned int offset);
 
+#define current_pt_regs() \
+       ((struct pt_regs *) \
+        ((unsigned long)current_thread_info() + THREAD_SIZE) - 1)
+
 #endif

diff --git a/arch/hexagon/kernel/process.c b/arch/hexagon/kernel/process.c
index af51de6..8a016f7 100644 (file)
--- a/arch/hexagon/kernel/process.c
+++ b/arch/hexagon/kernel/process.c
@@ -25,33 +25,6 @@
 #include <linux/uaccess.h>
 #include <linux/slab.h>
 
-/*
- * Kernel thread creation.  The desired kernel function is "wrapped"
- * in the kernel_thread_helper function, which does cleanup
- * afterwards.
- */
-static void __noreturn kernel_thread_helper(void *arg, int (*fn)(void *))
-{
-       do_exit(fn(arg));
-}
-
-int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
-{
-       struct pt_regs regs;
-
-       memset(&regs, 0, sizeof(regs));
-       /*
-        * Yes, we're exploting illicit knowledge of the ABI here.
-        */
-       regs.r00 = (unsigned long) arg;
-       regs.r01 = (unsigned long) fn;
-       pt_set_elr(&regs, (unsigned long)kernel_thread_helper);
-       pt_set_kmode(&regs);
-
-       return do_fork(flags|CLONE_VM|CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
-}
-EXPORT_SYMBOL(kernel_thread);
-
 /*
  * Program thread launch.  Often defined as a macro in processor.h,
  * but we're shooting for a small footprint and it's not an inner-loop
@@ -114,7 +87,7 @@ unsigned long thread_saved_pc(struct task_struct *tsk)
  * Copy architecture-specific thread state
  */
 int copy_thread(unsigned long clone_flags, unsigned long usp,
-               unsigned long unused, struct task_struct *p,
+               unsigned long arg, struct task_struct *p,
                struct pt_regs *regs)
 {
        struct thread_info *ti = task_thread_info(p);
@@ -125,61 +98,50 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
        childregs = (struct pt_regs *) (((unsigned long) ti + THREAD_SIZE) -
                                        sizeof(*childregs));
 
-       memcpy(childregs, regs, sizeof(*childregs));
        ti->regs = childregs;
 
        /*
         * Establish kernel stack pointer and initial PC for new thread
+        * Note that unlike the usual situation, we do not copy the
+        * parent's callee-saved here; those are in pt_regs and whatever
+        * we leave here will be overridden on return to userland.
         */
        ss = (struct hexagon_switch_stack *) ((unsigned long) childregs -
                                                    sizeof(*ss));
        ss->lr = (unsigned long)ret_from_fork;
        p->thread.switch_sp = ss;
-
-       /* If User mode thread, set pt_reg stack pointer as per parameter */
-       if (user_mode(childregs)) {
-               pt_set_rte_sp(childregs, usp);
-
-               /* Child sees zero return value */
-               childregs->r00 = 0;
-
-               /*
-                * The clone syscall has the C signature:
-                * int [r0] clone(int flags [r0],
-                *           void *child_frame [r1],
-                *           void *parent_tid [r2],
-                *           void *child_tid [r3],
-                *           void *thread_control_block [r4]);
-                * ugp is used to provide TLS support.
-                */
-               if (clone_flags & CLONE_SETTLS)
-                       childregs->ugp = childregs->r04;
-
-               /*
-                * Parent sees new pid -- not necessary, not even possible at
-                * this point in the fork process
-                * Might also want to set things like ti->addr_limit
-                */
-       } else {
-               /*
-                * If kernel thread, resume stack is kernel stack base.
-                * Note that this is pointer arithmetic on pt_regs *
-                */
-               pt_set_rte_sp(childregs, (unsigned long)(childregs + 1));
-               /*
-                * We need the current thread_info fast path pointer
-                * set up in pt_regs.  The register to be used is
-                * parametric for assembler code, but the mechanism
-                * doesn't drop neatly into C.  Needs to be fixed.
-                */
-               childregs->THREADINFO_REG = (unsigned long) ti;
+       if (unlikely(p->flags & PF_KTHREAD)) {
+               memset(childregs, 0, sizeof(struct pt_regs));
+               /* r24 <- fn, r25 <- arg */
+               ss->r2524 = usp | ((u64)arg << 32);
+               pt_set_kmode(childregs);
+               return 0;
        }
+       memcpy(childregs, regs, sizeof(*childregs));
+       ss->r2524 = 0;
+
+       pt_set_rte_sp(childregs, usp);
+
+       /* Child sees zero return value */
+       childregs->r00 = 0;
+
+       /*
+        * The clone syscall has the C signature:
+        * int [r0] clone(int flags [r0],
+        *           void *child_frame [r1],
+        *           void *parent_tid [r2],
+        *           void *child_tid [r3],
+        *           void *thread_control_block [r4]);
+        * ugp is used to provide TLS support.
+        */
+       if (clone_flags & CLONE_SETTLS)
+               childregs->ugp = childregs->r04;
 
        /*
-        * thread_info pointer is pulled out of task_struct "stack"
-        * field on switch_to.
+        * Parent sees new pid -- not necessary, not even possible at
+        * this point in the fork process
+        * Might also want to set things like ti->addr_limit
         */
-       p->stack = (void *)ti;
 
        return 0;
 }

diff --git a/arch/hexagon/kernel/signal.c b/arch/hexagon/kernel/signal.c
index 1ea16be..28b9e26 100644 (file)
--- a/arch/hexagon/kernel/signal.c
+++ b/arch/hexagon/kernel/signal.c
@@ -249,14 +249,14 @@ void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags)
  */
 asmlinkage int sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
 {
-       struct pt_regs *regs = current_thread_info()->regs;
+       struct pt_regs *regs = current_pt_regs();
 
        return do_sigaltstack(uss, uoss, regs->r29);
 }
 
 asmlinkage int sys_rt_sigreturn(void)
 {
-       struct pt_regs *regs = current_thread_info()->regs;
+       struct pt_regs *regs = current_pt_regs();
        struct rt_sigframe __user *frame;
        sigset_t blocked;
 

diff --git a/arch/hexagon/kernel/syscall.c b/arch/hexagon/kernel/syscall.c
index 25a9bfe..120f1a5 100644 (file)
--- a/arch/hexagon/kernel/syscall.c
+++ b/arch/hexagon/kernel/syscall.c
@@ -39,7 +39,7 @@ asmlinkage int sys_execve(char __user *ufilename,
                          const char __user *const __user *argv,
                          const char __user *const __user *envp)
 {
-       struct pt_regs *pregs = current_thread_info()->regs;
+       struct pt_regs *pregs = current_pt_regs();
        struct filename *filename;
        int retval;
 
@@ -57,33 +57,10 @@ asmlinkage int sys_execve(char __user *ufilename,
 asmlinkage int sys_clone(unsigned long clone_flags, unsigned long newsp,
                         unsigned long parent_tidp, unsigned long child_tidp)
 {
-       struct pt_regs *pregs = current_thread_info()->regs;
+       struct pt_regs *pregs = current_pt_regs();
 
        if (!newsp)
                newsp = pregs->SP;
        return do_fork(clone_flags, newsp, pregs, 0, (int __user *)parent_tidp,
                       (int __user *)child_tidp);
 }
-
-/*
- * Do a system call from the kernel, so as to have a proper pt_regs
- * and recycle the sys_execvpe infrustructure.
- */
-int kernel_execve(const char *filename,
-                 const char *const argv[], const char *const envp[])
-{
-       register unsigned long __a0 asm("r0") = (unsigned long) filename;
-       register unsigned long __a1 asm("r1") = (unsigned long) argv;
-       register unsigned long __a2 asm("r2") = (unsigned long) envp;
-       int retval;
-
-       __asm__ volatile(
-               "       R6 = #%4;\n"
-               "       trap0(#1);\n"
-               "       %0 = R0;\n"
-               : "=r" (retval)
-               : "r" (__a0), "r" (__a1), "r" (__a2), "i" (__NR_execve)
-       );
-
-       return retval;
-}

diff --git a/arch/hexagon/kernel/vm_entry.S b/arch/hexagon/kernel/vm_entry.S
index 5b99066..1a7fcf5 100644 (file)
--- a/arch/hexagon/kernel/vm_entry.S
+++ b/arch/hexagon/kernel/vm_entry.S
@@ -266,4 +266,8 @@ _K_enter_machcheck:
        .globl ret_from_fork
 ret_from_fork:
        call schedule_tail
+       P0 = cmp.eq(R24, #0);
+       if P0 jump return_from_syscall
+       R0 = R25;
+       callr R24
        jump return_from_syscall