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authorMauro Carvalho Chehab <mchehab@s-opensource.com>2017-09-29 12:24:10 +0300
committerMauro Carvalho Chehab <mchehab@s-opensource.com>2017-09-29 12:24:10 +0300
commitcf09e3c904bf424f8b6a8203958e09bf7d9bcbc0 (patch)
tree5e9936b3de36aa222b52a9bca366a43d98730ffd /include/linux/bitmap.h
parentd5426f4c2ebac8cf05de43988c3fccddbee13d28 (diff)
parente19b205be43d11bff638cad4487008c48d21c103 (diff)
downloadlinux-cf09e3c904bf424f8b6a8203958e09bf7d9bcbc0.tar.xz
Merge tag 'v4.14-rc2' into patchwork
Linux 4.14-rc2 * tag 'v4.14-rc2': (12066 commits) Linux 4.14-rc2 tpm: ibmvtpm: simplify crq initialization and document crq format tpm: replace msleep() with usleep_range() in TPM 1.2/2.0 generic drivers Documentation: tpm: add powered-while-suspended binding documentation tpm: tpm_crb: constify acpi_device_id. tpm: vtpm: constify vio_device_id security: fix description of values returned by cap_inode_need_killpriv x86/asm: Fix inline asm call constraints for Clang objtool: Handle another GCC stack pointer adjustment bug inet: fix improper empty comparison net: use inet6_rcv_saddr to compare sockets net: set tb->fast_sk_family net: orphan frags on stand-alone ptype in dev_queue_xmit_nit MAINTAINERS: update git tree locations for ieee802154 subsystem SMB3: Don't ignore O_SYNC/O_DSYNC and O_DIRECT flags SMB3: handle new statx fields arch: remove unused *_segments() macros/functions parisc: Unbreak bootloader due to gcc-7 optimizations parisc: Reintroduce option to gzip-compress the kernel apparmor: fix apparmorfs DAC access permissions ...
Diffstat (limited to 'include/linux/bitmap.h')
-rw-r--r--include/linux/bitmap.h32
1 files changed, 32 insertions, 0 deletions
diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index 5797ca6fdfe2..700cf5f67118 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -361,6 +361,38 @@ static inline int bitmap_parse(const char *buf, unsigned int buflen,
}
/*
+ * BITMAP_FROM_U64() - Represent u64 value in the format suitable for bitmap.
+ *
+ * Linux bitmaps are internally arrays of unsigned longs, i.e. 32-bit
+ * integers in 32-bit environment, and 64-bit integers in 64-bit one.
+ *
+ * There are four combinations of endianness and length of the word in linux
+ * ABIs: LE64, BE64, LE32 and BE32.
+ *
+ * On 64-bit kernels 64-bit LE and BE numbers are naturally ordered in
+ * bitmaps and therefore don't require any special handling.
+ *
+ * On 32-bit kernels 32-bit LE ABI orders lo word of 64-bit number in memory
+ * prior to hi, and 32-bit BE orders hi word prior to lo. The bitmap on the
+ * other hand is represented as an array of 32-bit words and the position of
+ * bit N may therefore be calculated as: word #(N/32) and bit #(N%32) in that
+ * word. For example, bit #42 is located at 10th position of 2nd word.
+ * It matches 32-bit LE ABI, and we can simply let the compiler store 64-bit
+ * values in memory as it usually does. But for BE we need to swap hi and lo
+ * words manually.
+ *
+ * With all that, the macro BITMAP_FROM_U64() does explicit reordering of hi and
+ * lo parts of u64. For LE32 it does nothing, and for BE environment it swaps
+ * hi and lo words, as is expected by bitmap.
+ */
+#if __BITS_PER_LONG == 64
+#define BITMAP_FROM_U64(n) (n)
+#else
+#define BITMAP_FROM_U64(n) ((unsigned long) ((u64)(n) & ULONG_MAX)), \
+ ((unsigned long) ((u64)(n) >> 32))
+#endif
+
+/*
* bitmap_from_u64 - Check and swap words within u64.
* @mask: source bitmap
* @dst: destination bitmap