From: Jay Vosburgh Date: Fri, 14 Nov 2014 19:05:06 +0000 (-0800) Subject: Revert "fast_hash: avoid indirect function calls" X-Git-Tag: omap-for-v3.19/fixes-rc1~125^2~187 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a77f9c5dcdf8480a93332792c336fa2bf9d31229;p=pandora-kernel.git Revert "fast_hash: avoid indirect function calls" This reverts commit e5a2c899957659cd1a9f789bc462f9c0b35f5150. Commit e5a2c899 introduced 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 . Signed-off-by: Jay Vosburgh Signed-off-by: David S. Miller --- Reading git-diff-tree failed