xen/common: Use enhanced ASSERT_ALLOC_CONTEXT in xmalloc()

xmalloc() will use a pool for allocation smaller than a page.
The pool is extended only when there are no more space. At which
point, alloc_xenheap_pages() is called to add more memory.

xmalloc() must be protected by ASSERT_ALLOC_CONTEXT. It should not
rely on pool expanding to trigger the ASSERT_ALLOC_CONTEXT in
alloc_xenheap_pages(). Hence, this commit moves the definition of
ASSERT_ALLOC_CONTEXT to header and uses the ASSERT_ALLOC_CONTEXT
to replace the original assertion in xmalloc().

For consistency, the same assertion should be used in xfree(),
and the position of the assertion should be at the beginning of
the xfree().

Also take the opportunity to enhance the non-static functions
xmem_pool_{alloc,free}() with the same assertion so that future
callers of these two functions can be benefited.

Reported-by: Wei Chen <Wei.Chen@arm.com>
Suggested-by: Julien Grall <jgrall@amazon.com>
Signed-off-by: Henry Wang <Henry.Wang@arm.com>
Tested-by: Julien Grall <jgrall@amazon.com>
Acked-by: Julien Grall <jgrall@amazon.com>

xen/common/page_alloc.c

@@ -162,13 +162,6 @@
 static char __initdata opt_badpage[100] = "";
 string_param("badpage", opt_badpage);
 
-/*
- * Heap allocations may need TLB flushes which may require IRQs to be
- * enabled (except when only 1 PCPU is online).
- */
-#define ASSERT_ALLOC_CONTEXT() \
-    ASSERT(!in_irq() && (local_irq_is_enabled() || num_online_cpus() <= 1))
-
 /*
  * no-bootscrub -> Free pages are not zeroed during boot.
  */

xen/common/xmalloc_tlsf.c

@@ -378,6 +378,8 @@ void *xmem_pool_alloc(unsigned long size, struct xmem_pool *pool)
     int fl, sl;
     unsigned long tmp_size;
 
+    ASSERT_ALLOC_CONTEXT();
+
     if ( size < MIN_BLOCK_SIZE )
         size = MIN_BLOCK_SIZE;
     else
@@ -456,6 +458,8 @@ void xmem_pool_free(void *ptr, struct xmem_pool *pool)
     struct bhdr *b, *tmp_b;
     int fl = 0, sl = 0;
 
+    ASSERT_ALLOC_CONTEXT();
+
     if ( unlikely(ptr == NULL) )
         return;
 
@@ -594,7 +598,7 @@ void *_xmalloc(unsigned long size, unsigned long align)
 {
     void *p = NULL;
 
-    ASSERT(!in_irq());
+    ASSERT_ALLOC_CONTEXT();
 
     if ( !size )
         return ZERO_BLOCK_PTR;
@@ -697,11 +701,11 @@ void *_xrealloc(void *ptr, unsigned long size, unsigned long align)
 
 void xfree(void *p)
 {
+    ASSERT_ALLOC_CONTEXT();
+
     if ( p == NULL || p == ZERO_BLOCK_PTR )
         return;
 
-    ASSERT(!in_irq());
-
     if ( !((unsigned long)p & (PAGE_SIZE - 1)) )
     {
         unsigned long size = PFN_ORDER(virt_to_page(p));

xen/include/xen/irq.h

@@ -10,6 +10,13 @@
 #include <asm/hardirq.h>
 #include <public/event_channel.h>
 
+/*
+ * Heap allocations may need TLB flushes which may require IRQs to be
+ * enabled (except when only 1 PCPU is online).
+ */
+#define ASSERT_ALLOC_CONTEXT() \
+    ASSERT(!in_irq() && (local_irq_is_enabled() || num_online_cpus() <= 1))
+
 struct irqaction {
     void (*handler)(int, void *, struct cpu_user_regs *);
     const char *name;