@@ -1083,6 +1083,14 @@ static __always_inline vma_flags_t __mk_vma_flags(vma_flags_t flags,
#define append_vma_flags(flags, ...) __mk_vma_flags(flags, \
COUNT_ARGS(__VA_ARGS__), (const vma_flag_t []){__VA_ARGS__})
+/* Calculates the number of set bits in the specified VMA flags. */
+static __always_inline int vma_flags_count(const vma_flags_t *flags)
+{
+ const unsigned long *bitmap = flags->__vma_flags;
+
+ return bitmap_weight(bitmap, NUM_VMA_FLAG_BITS);
+}
+
/*
* Test whether a specific VMA flag is set, e.g.:
*
@@ -1158,6 +1166,26 @@ static __always_inline bool vma_flags_test_all_mask(const vma_flags_t *flags,
#define vma_flags_test_all(flags, ...) \
vma_flags_test_all_mask(flags, mk_vma_flags(__VA_ARGS__))
+/*
+ * Helper to test that a flag mask of type vma_flags_t has a SINGLE flag set
+ * (returning false if flagmask has no flags set).
+ *
+ * This is defined to make the semantics clearer when testing an optionally
+ * defined VMA flags mask, e.g.:
+ *
+ * if (vma_flags_test_single_mask(&flags, VMA_DROPPABLE)) { ... }
+ *
+ * When VMA_DROPPABLE is defined if available, or set to EMPTY_VMA_FLAGS
+ * otherwise.
+ */
+static __always_inline bool vma_flags_test_single_mask(const vma_flags_t *flags,
+ vma_flags_t flagmask)
+{
+ VM_WARN_ON_ONCE(vma_flags_count(&flagmask) > 1);
+
+ return vma_flags_test_any_mask(flags, flagmask);
+}
+
/* Set each of the to_set flags in flags, non-atomically. */
static __always_inline void vma_flags_set_mask(vma_flags_t *flags,
vma_flags_t to_set)
@@ -1286,6 +1314,24 @@ static __always_inline bool vma_test_all_mask(const struct vm_area_struct *vma,
#define vma_test_all(vma, ...) \
vma_test_all_mask(vma, mk_vma_flags(__VA_ARGS__))
+/*
+ * Helper to test that a flag mask of type vma_flags_t has a SINGLE flag set
+ * (returning false if flagmask has no flags set).
+ *
+ * This is useful when a flag needs to be either defined or not depending upon
+ * kernel configuration, e.g.:
+ *
+ * if (vma_test_single_mask(vma, VMA_DROPPABLE)) { ... }
+ *
+ * When VMA_DROPPABLE is defined if available, or set to EMPTY_VMA_FLAGS
+ * otherwise.
+ */
+static __always_inline bool
+vma_test_single_mask(const struct vm_area_struct *vma, vma_flags_t flagmask)
+{
+ return vma_flags_test_single_mask(&vma->flags, flagmask);
+}
+
/*
* Helper to set all VMA flags in a VMA.
*
@@ -15,12 +15,6 @@ extern unsigned long dac_mmap_min_addr;
#define dac_mmap_min_addr 0UL
#endif
-#define VM_WARN_ON(_expr) (WARN_ON(_expr))
-#define VM_WARN_ON_ONCE(_expr) (WARN_ON_ONCE(_expr))
-#define VM_WARN_ON_VMG(_expr, _vmg) (WARN_ON(_expr))
-#define VM_BUG_ON(_expr) (BUG_ON(_expr))
-#define VM_BUG_ON_VMA(_expr, _vma) (BUG_ON(_expr))
-
#define TASK_SIZE ((1ul << 47)-PAGE_SIZE)
/*
@@ -905,6 +905,13 @@ static __always_inline vma_flags_t __mk_vma_flags(vma_flags_t flags,
#define append_vma_flags(flags, ...) __mk_vma_flags(flags, \
COUNT_ARGS(__VA_ARGS__), (const vma_flag_t []){__VA_ARGS__})
+static __always_inline int vma_flags_count(const vma_flags_t *flags)
+{
+ const unsigned long *bitmap = flags->__vma_flags;
+
+ return bitmap_weight(bitmap, NUM_VMA_FLAG_BITS);
+}
+
static __always_inline bool vma_flags_test(const vma_flags_t *flags,
vma_flag_t bit)
{
@@ -952,6 +959,14 @@ static __always_inline bool vma_flags_test_all_mask(const vma_flags_t *flags,
#define vma_flags_test_all(flags, ...) \
vma_flags_test_all_mask(flags, mk_vma_flags(__VA_ARGS__))
+static __always_inline bool vma_flags_test_single_mask(const vma_flags_t *flags,
+ vma_flags_t flagmask)
+{
+ VM_WARN_ON_ONCE(vma_flags_count(&flagmask) > 1);
+
+ return vma_flags_test_any_mask(flags, flagmask);
+}
+
static __always_inline void vma_flags_set_mask(vma_flags_t *flags, vma_flags_t to_set)
{
unsigned long *bitmap = flags->__vma_flags;
@@ -1031,6 +1046,12 @@ static __always_inline bool vma_test_all_mask(const struct vm_area_struct *vma,
#define vma_test_all(vma, ...) \
vma_test_all_mask(vma, mk_vma_flags(__VA_ARGS__))
+static __always_inline bool
+vma_test_single_mask(const struct vm_area_struct *vma, vma_flags_t flagmask)
+{
+ return vma_flags_test_single_mask(&vma->flags, flagmask);
+}
+
static __always_inline void vma_set_flags_mask(struct vm_area_struct *vma,
vma_flags_t flags)
{
@@ -51,6 +51,12 @@ typedef unsigned long pgprotval_t;
typedef struct pgprot { pgprotval_t pgprot; } pgprot_t;
typedef __bitwise unsigned int vm_fault_t;
+#define VM_WARN_ON(_expr) (WARN_ON(_expr))
+#define VM_WARN_ON_ONCE(_expr) (WARN_ON_ONCE(_expr))
+#define VM_WARN_ON_VMG(_expr, _vmg) (WARN_ON(_expr))
+#define VM_BUG_ON(_expr) (BUG_ON(_expr))
+#define VM_BUG_ON_VMA(_expr, _vma) (BUG_ON(_expr))
+
#include "include/stubs.h"
#include "include/dup.h"
#include "include/custom.h"
vma_flags_count() determines how many bits are set in VMA flags, using bitmap_weight(). vma_flags_test_single_mask() determines if a vma_flags_t set of flags contains a single flag specified as another vma_flags_t value, or if the sought flag mask is empty, it is defined to return false. This is useful when we want to declare a VMA flag as optionally a single flag in a mask or empty depending on kernel configuration. This allows us to have VM_NONE-like semantics when checking whether the flag is set. In a subsequent patch, we introduce the use of VMA_DROPPABLE of type vma_flags_t using precisely these semantics. It would be actively confusing to use vma_flags_test_any_single_mask() for this (and vma_flags_test_all_mask() is not correct to use here, as it trivially returns true when tested against an empty vma flags mask). We introduce vma_flags_count() to be able to assert that the compared flag mask is singular or empty, checked when CONFIG_DEBUG_VM is enabled. Also update the VMA tests as part of this change. Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org> --- include/linux/mm.h | 46 ++++++++++++++++++++++++++++++ tools/testing/vma/include/custom.h | 6 ---- tools/testing/vma/include/dup.h | 21 ++++++++++++++ tools/testing/vma/vma_internal.h | 6 ++++ 4 files changed, 73 insertions(+), 6 deletions(-)