a77f9c5dcd
This reverts commite5a2c89995. Commite5a2c899introduced an alternative_call, arch_fast_hash2, that selects between __jhash2 and __intel_crc4_2_hash based on the X86_FEATURE_XMM4_2. Unfortunately, the alternative_call system does not appear to be suitable for use with C functions, as register usage is not handled properly for the called functions. The __jhash2 function in particular clobbers registers that are not preserved when called via alternative_call, resulting in a panic for direct callers of arch_fast_hash2 on older CPUs lacking sse4_2. It is possible that __intel_crc4_2_hash works merely by chance because it uses fewer registers. This commit was suggested as the source of the problem by Jesse Gross <jesse@nicira.com>. Signed-off-by: Jay Vosburgh <jay.vosburgh@canonical.com> Signed-off-by: David S. Miller <davem@davemloft.net>
40 lines
1 KiB
C
40 lines
1 KiB
C
/* General purpose hashing library
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*
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* That's a start of a kernel hashing library, which can be extended
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* with further algorithms in future. arch_fast_hash{2,}() will
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* eventually resolve to an architecture optimized implementation.
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*
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* Copyright 2013 Francesco Fusco <ffusco@redhat.com>
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* Copyright 2013 Daniel Borkmann <dborkman@redhat.com>
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* Copyright 2013 Thomas Graf <tgraf@redhat.com>
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* Licensed under the GNU General Public License, version 2.0 (GPLv2)
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*/
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#include <linux/jhash.h>
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#include <linux/hash.h>
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#include <linux/cache.h>
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static struct fast_hash_ops arch_hash_ops __read_mostly = {
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.hash = jhash,
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.hash2 = jhash2,
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};
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u32 arch_fast_hash(const void *data, u32 len, u32 seed)
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{
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return arch_hash_ops.hash(data, len, seed);
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}
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EXPORT_SYMBOL_GPL(arch_fast_hash);
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u32 arch_fast_hash2(const u32 *data, u32 len, u32 seed)
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{
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return arch_hash_ops.hash2(data, len, seed);
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}
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EXPORT_SYMBOL_GPL(arch_fast_hash2);
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static int __init hashlib_init(void)
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{
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setup_arch_fast_hash(&arch_hash_ops);
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return 0;
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}
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early_initcall(hashlib_init);
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