[PATCH 07/16] powerpc: mm: Support MAP_BELOW_HINT

[Charlie Jenkins]

Add support for MAP_BELOW_HINT to arch_get_mmap_base() and
arch_get_mmap_end().

Signed-off-by: Charlie Jenkins <charlie at rivosinc.com>
---
 arch/powerpc/include/asm/task_size_64.h | 36 +++++++++++++++++++++++++++------
 1 file changed, 30 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/include/asm/task_size_64.h b/arch/powerpc/include/asm/task_size_64.h
index 239b363841aa..a37a5a81365d 100644
--- a/arch/powerpc/include/asm/task_size_64.h
+++ b/arch/powerpc/include/asm/task_size_64.h
@@ -72,12 +72,36 @@
 #define STACK_TOP_MAX TASK_SIZE_USER64
 #define STACK_TOP (is_32bit_task() ? STACK_TOP_USER32 : STACK_TOP_USER64)
 
-#define arch_get_mmap_base(addr, len, base, flags) \
-	(((addr) > DEFAULT_MAP_WINDOW) ? (base) + TASK_SIZE - DEFAULT_MAP_WINDOW : (base))
+#define arch_get_mmap_base(addr, len, base, flags)					\
+({											\
+	unsigned long mmap_base;							\
+	typeof(flags) _flags = (flags);							\
+	typeof(addr) _addr = (addr);							\
+	typeof(base) _base = (base);							\
+	typeof(len) _len = (len);							\
+	unsigned long rnd_gap = DEFAULT_MAP_WINDOW - (_base);				\
+	if (_flags & MAP_BELOW_HINT && _addr != 0 && ((_addr + _len) > BIT(VA_BITS - 1)))\
+		mmap_base = (_addr + _len) - rnd_gap;					\
+	else										\
+		mmap_end = ((_addr > DEFAULT_MAP_WINDOW) ?				\
+				_base + TASK_SIZE - DEFAULT_MAP_WINDOW :		\
+				_base);							\
+	mmap_end;									\
+})
 
-#define arch_get_mmap_end(addr, len, flags) \
-	(((addr) > DEFAULT_MAP_WINDOW) || \
-	 (((flags) & MAP_FIXED) && ((addr) + (len) > DEFAULT_MAP_WINDOW)) ? TASK_SIZE : \
-									    DEFAULT_MAP_WINDOW)
+#define arch_get_mmap_end(addr, len, flags)							\
+({												\
+	unsigned long mmap_end;									\
+	typeof(flags) _flags = (flags);								\
+	typeof(addr) _addr = (addr);								\
+	typeof(len) _len = (len);								\
+	if (_flags & MAP_BELOW_HINT && _addr != 0 && ((_addr + _len) > BIT(VA_BITS - 1)))	\
+		mmap_end = (_addr + _len);							\
+	else											\
+		mmap_end = (((_addr) > DEFAULT_MAP_WINDOW) ||					\
+				(((_flags) & MAP_FIXED) && ((_addr) + (_len) > DEFAULT_MAP_WINDOW))\
+				? TASK_SIZE : DEFAULT_MAP_WINDOW)				\
+	mmap_end;										\
+})
 
 #endif /* _ASM_POWERPC_TASK_SIZE_64_H */

-- 
2.45.0