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/kernel/sys_m68k.c b/arch/m68k/kernel/sys_m68k.c
index 218f441..e3ad2d6 100644
--- 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 @@
: "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;
+}