m68k: sanitize copy_thread(), fork/vfork/clone wrappers, switch to generic fork/vfork
Al Viro [Sun, 21 Oct 2012 20:41:46 +0000 (16:41 -0400)]
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

arch/m68k/include/asm/unistd.h
arch/m68k/kernel/entry.S
arch/m68k/kernel/process.c
arch/m68k/kernel/syscalltable.S

index 0aa1654..a021d67 100644 (file)
@@ -32,6 +32,8 @@
 #define __ARCH_WANT_SYS_RT_SIGACTION
 #define __ARCH_WANT_SYS_RT_SIGSUSPEND
 #define __ARCH_WANT_SYS_EXECVE
+#define __ARCH_WANT_SYS_FORK
+#define __ARCH_WANT_SYS_VFORK
 
 /*
  * "Conditional" syscalls
index 45b2f29..a78f564 100644 (file)
 
 .globl system_call, buserr, trap, resume
 .globl sys_call_table
-.globl sys_fork, sys_clone, sys_vfork
+.globl __sys_fork, __sys_clone, __sys_vfork
 .globl ret_from_interrupt, bad_interrupt
 .globl auto_irqhandler_fixup
 .globl user_irqvec_fixup
 
 .text
-ENTRY(sys_fork)
+ENTRY(__sys_fork)
        SAVE_SWITCH_STACK
-       pea     %sp@(SWITCH_STACK_SIZE)
-       jbsr    m68k_fork
-       addql   #4,%sp
-       RESTORE_SWITCH_STACK
+       jbsr    sys_fork
+       lea     %sp@(24),%sp
        rts
 
-ENTRY(sys_clone)
+ENTRY(__sys_clone)
        SAVE_SWITCH_STACK
        pea     %sp@(SWITCH_STACK_SIZE)
        jbsr    m68k_clone
-       addql   #4,%sp
-       RESTORE_SWITCH_STACK
+       lea     %sp@(28),%sp
        rts
 
-ENTRY(sys_vfork)
+ENTRY(__sys_vfork)
        SAVE_SWITCH_STACK
-       pea     %sp@(SWITCH_STACK_SIZE)
-       jbsr    m68k_vfork
-       addql   #4,%sp
-       RESTORE_SWITCH_STACK
+       jbsr    sys_vfork
+       lea     %sp@(24),%sp
        rts
 
 ENTRY(sys_sigreturn)
index c51bb17..aa9b110 100644 (file)
@@ -136,57 +136,36 @@ void flush_thread(void)
 }
 
 /*
- * "m68k_fork()".. By the time we get here, the
- * non-volatile registers have also been saved on the
- * stack. We do some ugly pointer stuff here.. (see
- * also copy_thread)
+ * Why not generic sys_clone, you ask?  m68k passes all arguments on stack.
+ * And we need all registers saved, which means a bunch of stuff pushed
+ * on top of pt_regs, which means that sys_clone() arguments would be
+ * buried.  We could, of course, copy them, but it's too costly for no
+ * good reason - generic clone() would have to copy them *again* for
+ * do_fork() anyway.  So in this case it's actually better to pass pt_regs *
+ * and extract arguments for do_fork() from there.  Eventually we might
+ * go for calling do_fork() directly from the wrapper, but only after we
+ * are finished with do_fork() prototype conversion.
  */
-
-asmlinkage int m68k_fork(struct pt_regs *regs)
-{
-#ifdef CONFIG_MMU
-       return do_fork(SIGCHLD, rdusp(), regs, 0, NULL, NULL);
-#else
-       return -EINVAL;
-#endif
-}
-
-asmlinkage int m68k_vfork(struct pt_regs *regs)
-{
-       return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, rdusp(), regs, 0,
-                      NULL, NULL);
-}
-
 asmlinkage int m68k_clone(struct pt_regs *regs)
 {
-       unsigned long clone_flags;
-       unsigned long newsp;
-       int __user *parent_tidptr, *child_tidptr;
-
-       /* syscall2 puts clone_flags in d1 and usp in d2 */
-       clone_flags = regs->d1;
-       newsp = regs->d2;
-       parent_tidptr = (int __user *)regs->d3;
-       child_tidptr = (int __user *)regs->d4;
-       if (!newsp)
-               newsp = rdusp();
-       return do_fork(clone_flags, newsp, regs, 0,
-                      parent_tidptr, child_tidptr);
+       /* regs will be equal to current_pt_regs() */
+       return do_fork(regs->d1, regs->d2, regs, 0,
+                      (int __user *)regs->d3, (int __user *)regs->d4);
 }
 
 int copy_thread(unsigned long clone_flags, unsigned long usp,
                 unsigned long arg,
-                struct task_struct * p, struct pt_regs * regs)
+                struct task_struct * p, struct pt_regs * unused)
 {
-       struct pt_regs * childregs;
-       struct switch_stack *childstack;
+       struct fork_frame {
+               struct switch_stack sw;
+               struct pt_regs regs;
+       } *frame;
 
-       childregs = (struct pt_regs *) (task_stack_page(p) + THREAD_SIZE) - 1;
-       childstack = ((struct switch_stack *) childregs) - 1;
+       frame = (struct fork_frame *) (task_stack_page(p) + THREAD_SIZE) - 1;
 
-       p->thread.usp = usp;
-       p->thread.ksp = (unsigned long)childstack;
-       p->thread.esp0 = (unsigned long)childregs;
+       p->thread.ksp = (unsigned long)frame;
+       p->thread.esp0 = (unsigned long)&frame->regs;
 
        /*
         * Must save the current SFC/DFC value, NOT the value when
@@ -194,25 +173,24 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
         */
        p->thread.fs = get_fs().seg;
 
-       if (unlikely(!regs)) {
+       if (unlikely(p->flags & PF_KTHREAD)) {
                /* kernel thread */
-               memset(childstack, 0,
-                       sizeof(struct switch_stack) + sizeof(struct pt_regs));
-               childregs->sr = PS_S;
-               childstack->a3 = usp; /* function */
-               childstack->d7 = arg;
-               childstack->retpc = (unsigned long)ret_from_kernel_thread;
+               memset(frame, 0, sizeof(struct fork_frame));
+               frame->regs.sr = PS_S;
+               frame->sw.a3 = usp; /* function */
+               frame->sw.d7 = arg;
+               frame->sw.retpc = (unsigned long)ret_from_kernel_thread;
                p->thread.usp = 0;
                return 0;
        }
-       *childregs = *regs;
-       childregs->d0 = 0;
-
-       *childstack = ((struct switch_stack *) regs)[-1];
-       childstack->retpc = (unsigned long)ret_from_fork;
+       memcpy(frame, container_of(current_pt_regs(), struct fork_frame, regs),
+               sizeof(struct fork_frame));
+       frame->regs.d0 = 0;
+       frame->sw.retpc = (unsigned long)ret_from_fork;
+       p->thread.usp = usp ?: rdusp();
 
        if (clone_flags & CLONE_SETTLS)
-               task_thread_info(p)->tp_value = regs->d5;
+               task_thread_info(p)->tp_value = frame->regs.d5;
 
 #ifdef CONFIG_FPU
        if (!FPU_IS_EMU) {
index 4fc2e29..c30da5b 100644 (file)
@@ -22,7 +22,7 @@ ALIGN
 ENTRY(sys_call_table)
        .long sys_restart_syscall       /* 0 - old "setup()" system call, used for restarting */
        .long sys_exit
-       .long sys_fork
+       .long __sys_fork
        .long sys_read
        .long sys_write
        .long sys_open                  /* 5 */
@@ -140,7 +140,7 @@ ENTRY(sys_call_table)
        .long sys_ipc
        .long sys_fsync
        .long sys_sigreturn
-       .long sys_clone                 /* 120 */
+       .long __sys_clone               /* 120 */
        .long sys_setdomainname
        .long sys_newuname
        .long sys_cacheflush            /* modify_ldt for i386 */
@@ -210,7 +210,7 @@ ENTRY(sys_call_table)
        .long sys_sendfile
        .long sys_ni_syscall            /* streams1 */
        .long sys_ni_syscall            /* streams2 */
-       .long sys_vfork                 /* 190 */
+       .long __sys_vfork               /* 190 */
        .long sys_getrlimit
        .long sys_mmap2
        .long sys_truncate64