[PATCH v4 06/36] mm: enumerate all gfp flags

Suren Baghdasaryan
2024-02-21T19:41:10Z

Introduce GFP bits enumeration to let compiler track the number of used
bits (which depends on the config options) instead of hardcoding them.
That simplifies __GFP_BITS_SHIFT calculation.

Suggested-by: Petr Tesařík <petr@tesarici.cz>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
---
include/linux/gfp_types.h | 90 +++++++++++++++++++++++++++------------
1 file changed, 62 insertions(+), 28 deletions(-)

diff --git a/include/linux/gfp_types.h b/include/linux/gfp_types.h
index 1b6053da8754..868c8fb1bbc1 100644
--- a/include/linux/gfp_types.h
+++ b/include/linux/gfp_types.h
@@ -21,44 +21,78 @@ typedef unsigned int __bitwise gfp_t;
* include/trace/events/mmflags.h and tools/perf/builtin-kmem.c
*/

+enum {
+ ___GFP_DMA_BIT,
+ ___GFP_HIGHMEM_BIT,
+ ___GFP_DMA32_BIT,
+ ___GFP_MOVABLE_BIT,
+ ___GFP_RECLAIMABLE_BIT,
+ ___GFP_HIGH_BIT,
+ ___GFP_IO_BIT,
+ ___GFP_FS_BIT,
+ ___GFP_ZERO_BIT,
+ ___GFP_UNUSED_BIT, /* 0x200u unused */
+ ___GFP_DIRECT_RECLAIM_BIT,
+ ___GFP_KSWAPD_RECLAIM_BIT,
+ ___GFP_WRITE_BIT,
+ ___GFP_NOWARN_BIT,
+ ___GFP_RETRY_MAYFAIL_BIT,
+ ___GFP_NOFAIL_BIT,
+ ___GFP_NORETRY_BIT,
+ ___GFP_MEMALLOC_BIT,
+ ___GFP_COMP_BIT,
+ ___GFP_NOMEMALLOC_BIT,
+ ___GFP_HARDWALL_BIT,
+ ___GFP_THISNODE_BIT,
+ ___GFP_ACCOUNT_BIT,
+ ___GFP_ZEROTAGS_BIT,
+#ifdef CONFIG_KASAN_HW_TAGS
+ ___GFP_SKIP_ZERO_BIT,
+ ___GFP_SKIP_KASAN_BIT,
+#endif
+#ifdef CONFIG_LOCKDEP
+ ___GFP_NOLOCKDEP_BIT,
+#endif
+ ___GFP_LAST_BIT
+};
+
/* Plain integer GFP bitmasks. Do not use this directly. */
-#define ___GFP_DMA 0x01u
-#define ___GFP_HIGHMEM 0x02u
-#define ___GFP_DMA32 0x04u
-#define ___GFP_MOVABLE 0x08u
-#define ___GFP_RECLAIMABLE 0x10u
-#define ___GFP_HIGH 0x20u
-#define ___GFP_IO 0x40u
-#define ___GFP_FS 0x80u
-#define ___GFP_ZERO 0x100u
+#define ___GFP_DMA BIT(___GFP_DMA_BIT)
+#define ___GFP_HIGHMEM BIT(___GFP_HIGHMEM_BIT)
+#define ___GFP_DMA32 BIT(___GFP_DMA32_BIT)
+#define ___GFP_MOVABLE BIT(___GFP_MOVABLE_BIT)
+#define ___GFP_RECLAIMABLE BIT(___GFP_RECLAIMABLE_BIT)
+#define ___GFP_HIGH BIT(___GFP_HIGH_BIT)
+#define ___GFP_IO BIT(___GFP_IO_BIT)
+#define ___GFP_FS BIT(___GFP_FS_BIT)
+#define ___GFP_ZERO BIT(___GFP_ZERO_BIT)
/* 0x200u unused */
-#define ___GFP_DIRECT_RECLAIM 0x400u
-#define ___GFP_KSWAPD_RECLAIM 0x800u
-#define ___GFP_WRITE 0x1000u
-#define ___GFP_NOWARN 0x2000u
-#define ___GFP_RETRY_MAYFAIL 0x4000u
-#define ___GFP_NOFAIL 0x8000u
-#define ___GFP_NORETRY 0x10000u
-#define ___GFP_MEMALLOC 0x20000u
-#define ___GFP_COMP 0x40000u
-#define ___GFP_NOMEMALLOC 0x80000u
-#define ___GFP_HARDWALL 0x100000u
-#define ___GFP_THISNODE 0x200000u
-#define ___GFP_ACCOUNT 0x400000u
-#define ___GFP_ZEROTAGS 0x800000u
+#define ___GFP_DIRECT_RECLAIM BIT(___GFP_DIRECT_RECLAIM_BIT)
+#define ___GFP_KSWAPD_RECLAIM BIT(___GFP_KSWAPD_RECLAIM_BIT)
+#define ___GFP_WRITE BIT(___GFP_WRITE_BIT)
+#define ___GFP_NOWARN BIT(___GFP_NOWARN_BIT)
+#define ___GFP_RETRY_MAYFAIL BIT(___GFP_RETRY_MAYFAIL_BIT)
+#define ___GFP_NOFAIL BIT(___GFP_NOFAIL_BIT)
+#define ___GFP_NORETRY BIT(___GFP_NORETRY_BIT)
+#define ___GFP_MEMALLOC BIT(___GFP_MEMALLOC_BIT)
+#define ___GFP_COMP BIT(___GFP_COMP_BIT)
+#define ___GFP_NOMEMALLOC BIT(___GFP_NOMEMALLOC_BIT)
+#define ___GFP_HARDWALL BIT(___GFP_HARDWALL_BIT)
+#define ___GFP_THISNODE BIT(___GFP_THISNODE_BIT)
+#define ___GFP_ACCOUNT BIT(___GFP_ACCOUNT_BIT)
+#define ___GFP_ZEROTAGS BIT(___GFP_ZEROTAGS_BIT)
#ifdef CONFIG_KASAN_HW_TAGS
-#define ___GFP_SKIP_ZERO 0x1000000u
-#define ___GFP_SKIP_KASAN 0x2000000u
+#define ___GFP_SKIP_ZERO BIT(___GFP_SKIP_ZERO_BIT)
+#define ___GFP_SKIP_KASAN BIT(___GFP_SKIP_KASAN_BIT)
#else
#define ___GFP_SKIP_ZERO 0
#define ___GFP_SKIP_KASAN 0
#endif
#ifdef CONFIG_LOCKDEP
-#define ___GFP_NOLOCKDEP 0x4000000u
+#define ___GFP_NOLOCKDEP BIT(___GFP_NOLOCKDEP_BIT)
#else
#define ___GFP_NOLOCKDEP 0
#endif
-/* If the above are modified, __GFP_BITS_SHIFT may need updating */

/*
* Physical address zone modifiers (see linux/mmzone.h - low four bits)
@@ -249,7 +283,7 @@ typedef unsigned int __bitwise gfp_t;
#define __GFP_NOLOCKDEP ((__force gfp_t)___GFP_NOLOCKDEP)

/* Room for N __GFP_FOO bits */
-#define __GFP_BITS_SHIFT (26 + IS_ENABLED(CONFIG_LOCKDEP))
+#define __GFP_BITS_SHIFT ___GFP_LAST_BIT
#define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1))

/**
--
2.44.0.rc0.258.g7320e95886-goog