m68k: Add NPTL support

This patch adds several syscalls, that provide necessary
functionality to support NPTL on m68k/ColdFire.
The syscalls are get_thread_area, set_thread_area, atomic_cmpxchg_32 and
atomic_barrier.
The cmpxchg syscall is required for ColdFire as it doesn't support 'cas'
instruction.

Also a ptrace call PTRACE_GET_THREAD_AREA is added to allow debugger to
inspect the TLS storage.

Signed-off-by: Maxim Kuvyrkov <maxim@codesourcery.com>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

diff --git a/arch/m68k/include/asm/ptrace.h b/arch/m68k/include/asm/ptrace.h
index ee4011c..21605c7 100644 (file)
--- a/arch/m68k/include/asm/ptrace.h
+++ b/arch/m68k/include/asm/ptrace.h
@@ -71,6 +71,8 @@ struct switch_stack {
 #define PTRACE_GETFPREGS          14
 #define PTRACE_SETFPREGS          15
 
+#define PTRACE_GET_THREAD_AREA    25
+
 #define PTRACE_SINGLEBLOCK     33      /* resume execution until next branch */
 
 #ifdef __KERNEL__

diff --git a/arch/m68k/include/asm/thread_info_mm.h b/arch/m68k/include/asm/thread_info_mm.h
index 167e518..67266c6 100644 (file)
--- a/arch/m68k/include/asm/thread_info_mm.h
+++ b/arch/m68k/include/asm/thread_info_mm.h
@@ -16,6 +16,7 @@ struct thread_info {
        struct exec_domain      *exec_domain;   /* execution domain */
        int                     preempt_count;  /* 0 => preemptable, <0 => BUG */
        __u32 cpu; /* should always be 0 on m68k */
+       unsigned long           tp_value;       /* thread pointer */
        struct restart_block    restart_block;
 };
 #endif /* __ASSEMBLY__ */

diff --git a/arch/m68k/include/asm/unistd.h b/arch/m68k/include/asm/unistd.h
index 48b87f5..d72a71d 100644 (file)
--- a/arch/m68k/include/asm/unistd.h
+++ b/arch/m68k/include/asm/unistd.h
@@ -336,10 +336,14 @@
 #define __NR_pwritev           330
 #define __NR_rt_tgsigqueueinfo 331
 #define __NR_perf_event_open   332
+#define __NR_get_thread_area   333
+#define __NR_set_thread_area   334
+#define __NR_atomic_cmpxchg_32 335
+#define __NR_atomic_barrier    336
 
 #ifdef __KERNEL__
 
-#define NR_syscalls            333
+#define NR_syscalls            337
 
 #define __ARCH_WANT_IPC_PARSE_VERSION
 #define __ARCH_WANT_OLD_READDIR

diff --git a/arch/m68k/kernel/entry.S b/arch/m68k/kernel/entry.S
index 77fc7c1..e136b8c 100644 (file)
--- a/arch/m68k/kernel/entry.S
+++ b/arch/m68k/kernel/entry.S
@@ -761,4 +761,8 @@ sys_call_table:
        .long sys_pwritev               /* 330 */
        .long sys_rt_tgsigqueueinfo
        .long sys_perf_event_open
+       .long sys_get_thread_area
+       .long sys_set_thread_area
+       .long sys_atomic_cmpxchg_32     /* 335 */
+       .long sys_atomic_barrier
 

diff --git a/arch/m68k/kernel/process.c b/arch/m68k/kernel/process.c
index 0529659..17c3f32 100644 (file)
--- a/arch/m68k/kernel/process.c
+++ b/arch/m68k/kernel/process.c
@@ -251,6 +251,10 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
 
        p->thread.usp = usp;
        p->thread.ksp = (unsigned long)childstack;
+
+       if (clone_flags & CLONE_SETTLS)
+               task_thread_info(p)->tp_value = regs->d5;
+
        /*
         * Must save the current SFC/DFC value, NOT the value when
         * the parent was last descheduled - RGH  10-08-96

diff --git a/arch/m68k/kernel/ptrace.c b/arch/m68k/kernel/ptrace.c
index 1fc217e..616e597 100644 (file)
--- a/arch/m68k/kernel/ptrace.c
+++ b/arch/m68k/kernel/ptrace.c
@@ -245,6 +245,11 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data)
                        ret = -EFAULT;
                break;
 
+       case PTRACE_GET_THREAD_AREA:
+               ret = put_user(task_thread_info(child)->tp_value,
+                              (unsigned long __user *)data);
+               break;
+
        default:
                ret = ptrace_request(child, request, addr, data);
                break;

diff --git a/arch/m68k/kernel/sys_m68k.c b/arch/m68k/kernel/sys_m68k.c
index 218f441..e3ad2d6 100644 (file)
--- a/arch/m68k/kernel/sys_m68k.c
+++ b/arch/m68k/kernel/sys_m68k.c
@@ -28,6 +28,11 @@
 #include <asm/traps.h>
 #include <asm/page.h>
 #include <asm/unistd.h>
+#include <linux/elf.h>
+#include <asm/tlb.h>
+
+asmlinkage int do_page_fault(struct pt_regs *regs, unsigned long address,
+                            unsigned long error_code);
 
 asmlinkage long sys_mmap2(unsigned long addr, unsigned long len,
        unsigned long prot, unsigned long flags,
@@ -595,3 +600,79 @@ int kernel_execve(const char *filename, char *const argv[], char *const envp[])
                        : "d" (__a), "d" (__b), "d" (__c));
        return __res;
 }
+
+asmlinkage unsigned long sys_get_thread_area(void)
+{
+       return current_thread_info()->tp_value;
+}
+
+asmlinkage int sys_set_thread_area(unsigned long tp)
+{
+       current_thread_info()->tp_value = tp;
+       return 0;
+}
+
+/* This syscall gets its arguments in A0 (mem), D2 (oldval) and
+   D1 (newval).  */
+asmlinkage int
+sys_atomic_cmpxchg_32(unsigned long newval, int oldval, int d3, int d4, int d5,
+                     unsigned long __user * mem)
+{
+       /* This was borrowed from ARM's implementation.  */
+       for (;;) {
+               struct mm_struct *mm = current->mm;
+               pgd_t *pgd;
+               pmd_t *pmd;
+               pte_t *pte;
+               spinlock_t *ptl;
+               unsigned long mem_value;
+
+               down_read(&mm->mmap_sem);
+               pgd = pgd_offset(mm, (unsigned long)mem);
+               if (!pgd_present(*pgd))
+                       goto bad_access;
+               pmd = pmd_offset(pgd, (unsigned long)mem);
+               if (!pmd_present(*pmd))
+                       goto bad_access;
+               pte = pte_offset_map_lock(mm, pmd, (unsigned long)mem, &ptl);
+               if (!pte_present(*pte) || !pte_dirty(*pte)
+                   || !pte_write(*pte)) {
+                       pte_unmap_unlock(pte, ptl);
+                       goto bad_access;
+               }
+
+               mem_value = *mem;
+               if (mem_value == oldval)
+                       *mem = newval;
+
+               pte_unmap_unlock(pte, ptl);
+               up_read(&mm->mmap_sem);
+               return mem_value;
+
+             bad_access:
+               up_read(&mm->mmap_sem);
+               /* This is not necessarily a bad access, we can get here if
+                  a memory we're trying to write to should be copied-on-write.
+                  Make the kernel do the necessary page stuff, then re-iterate.
+                  Simulate a write access fault to do that.  */
+               {
+                       /* The first argument of the function corresponds to
+                          D1, which is the first field of struct pt_regs.  */
+                       struct pt_regs *fp = (struct pt_regs *)&newval;
+
+                       /* '3' is an RMW flag.  */
+                       if (do_page_fault(fp, (unsigned long)mem, 3))
+                               /* If the do_page_fault() failed, we don't
+                                  have anything meaningful to return.
+                                  There should be a SIGSEGV pending for
+                                  the process.  */
+                               return 0xdeadbeef;
+               }
+       }
+}
+
+asmlinkage int sys_atomic_barrier(void)
+{
+       /* no code needed for uniprocs */
+       return 0;
+}