[NFC] Rename some PALs to make the naming more consistent.

src/pal/pal_freebsd_kernel.h

@@ -0,0 +1,95 @@
+#pragma once
+
+#include "../ds/bits.h"
+#include "../mem/allocconfig.h"
+
+#if defined(FreeBSD_KERNEL)
+extern "C"
+{
+#  include <sys/vmem.h>
+#  include <vm/vm.h>
+#  include <vm/vm_extern.h>
+#  include <vm/vm_kern.h>
+#  include <vm/vm_object.h>
+#  include <vm/vm_param.h>
+}
+
+namespace snmalloc
+{
+  class PALFreeBSDKernel
+  {
+    vm_offset_t get_vm_offset(uint_ptr_t p)
+    {
+      return static_cast<vm_offset_t>(reinterpret_cast<uintptr_t>(p));
+    }
+
+  public:
+    /**
+     * Bitmap of PalFeatures flags indicating the optional features that this
+     * PAL supports.
+     */
+    static constexpr uint64_t pal_features = AlignedAllocation;
+    void error(const char* const str)
+    {
+      panic("snmalloc error: %s", str);
+    }
+
+    /// Notify platform that we will not be using these pages
+    void notify_not_using(void* p, size_t size)
+    {
+      vm_offset_t addr = get_vm_offset(p);
+      kmem_unback(kernel_object, addr, size);
+    }
+
+    /// Notify platform that we will be using these pages
+    template<ZeroMem zero_mem>
+    void notify_using(void* p, size_t size)
+    {
+      vm_offset_t addr = get_vm_offset(p);
+      int flags = M_WAITOK | ((zero_mem == YesZero) ? M_ZERO : 0);
+      if (kmem_back(kernel_object, addr, size, flags) != KERN_SUCCESS)
+      {
+        error("Out of memory");
+      }
+    }
+
+    /// OS specific function for zeroing memory
+    template<bool page_aligned = false>
+    void zero(void* p, size_t size)
+    {
+      ::bzero(p, size);
+    }
+
+    template<bool committed>
+    void* reserve(size_t* size, size_t align)
+    {
+      size_t request = *size;
+      vm_offset_t addr;
+      if (vmem_xalloc(
+            kernel_arena,
+            request,
+            align,
+            0,
+            0,
+            VMEM_ADDR_MIN,
+            VMEM_ADDR_MAX,
+            M_BESTFIT,
+            &addr))
+      {
+        return nullptr;
+      }
+      if (committed)
+      {
+        if (
+          kmem_back(kernel_object, addr, request, M_ZERO | M_WAITOK) !=
+          KERN_SUCCESS)
+        {
+          vmem_xfree(kernel_arena, addr, request);
+          return nullptr;
+        }
+      }
+      return get_vm_offset(addr);
+    }
+  };
+}
+#endif