On 12/16/20 12:12 PM, Claudio Imbrenda wrote:
The new function page_alloc_set_default_flags can be used to set the
default flags for allocations. The passed value will be ORed with the
flags argument passed to the allocator at each allocation.
The default value for the default flags is FLAG_ZERO, which means that
by default all allocated memory is now zeroed, restoring the default
behaviour that had been accidentally removed by a previous commit.
If needed, a testcase can call page_alloc_set_default_flags(0) in order
to get non-zeroed pages from the allocator. For example, if the
testcase will need fresh memory, the zero flag should be removed from
the default.
Fixes: 8131e91a4b61 ("lib/alloc_page: complete rewrite of the page allocator")
Reported-by: Nadav Amit<nadav.amit@xxxxxxxxx>
Signed-off-by: Claudio Imbrenda<imbrenda@xxxxxxxxxxxxx>
---
lib/alloc_page.h | 3 +++
lib/alloc_page.c | 8 ++++++++
2 files changed, 11 insertions(+)
diff --git a/lib/alloc_page.h b/lib/alloc_page.h
index 1039814..8b53a58 100644
--- a/lib/alloc_page.h
+++ b/lib/alloc_page.h
@@ -22,6 +22,9 @@
/* Returns true if the page allocator has been initialized */
bool page_alloc_initialized(void);
+/* Sets the default flags for the page allocator, the default is FLAG_ZERO */
+void page_alloc_set_default_flags(unsigned int flags);
+
/*
* Initializes a memory area.
* n is the number of the area to initialize
diff --git a/lib/alloc_page.c b/lib/alloc_page.c
index 4d5722f..08e0d05 100644
--- a/lib/alloc_page.c
+++ b/lib/alloc_page.c
@@ -54,12 +54,19 @@ static struct mem_area areas[MAX_AREAS];
static unsigned int areas_mask;
/* Protects areas and areas mask */
static struct spinlock lock;
+/* Default behaviour: zero allocated pages */
+static unsigned int default_flags = FLAG_ZERO;
bool page_alloc_initialized(void)
{
return areas_mask != 0;
}
+void page_alloc_set_default_flags(unsigned int flags)
+{
+ default_flags = flags;
Who calls this functions ?
Just wondering if default flag should be a static set of flag values
which the caller can override based on needs rather than the caller
setting the default flag.
+}
+
/*
* Each memory area contains an array of metadata entries at the very
* beginning. The usable memory follows immediately afterwards.
@@ -394,6 +401,7 @@ static void *page_memalign_order_flags(u8 ord, u8 al, u32 flags)
void *res = NULL;
int i, area, fresh;
+ flags |= default_flags;
fresh = !!(flags & FLAG_FRESH);
spin_lock(&lock);
area = (flags & AREA_MASK) ? flags & areas_mask : areas_mask;
