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authorAurelien Jarno <aurelien@aurel32.net>2022-01-17 19:41:40 +0100
committerAurelien Jarno <aurelien@aurel32.net>2022-01-17 19:49:44 +0100
commita51b76b71e8190a50b0e0c0b32f313888b930108 (patch)
tree11f3cb6646f262308a731d7715b08d023262e1be /Makefile.help
parent55b99e9ed07688019609bd4dcd17d3ebf4572948 (diff)
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x86: use default cache size if it cannot be determined [BZ #28784]
In some cases (e.g QEMU, non-Intel/AMD CPU) the cache information can
not be retrieved and the corresponding values are set to 0.

Commit 2d651eb9265d ("x86: Move x86 processor cache info to
cpu_features") changed the behaviour in such case by defining the
__x86_shared_cache_size and __x86_data_cache_size variables to 0 instead
of using the default values. This cause an issue with the i686 SSE2
optimized bzero/routine which assumes that the cache size is at least
128 bytes, and otherwise tries to zero/set the whole address space minus
128 bytes.

Fix that by restoring the original code to only update
__x86_shared_cache_size and __x86_data_cache_size variables if the
corresponding cache sizes are not zero.

Fixes bug 28784
Fixes commit 2d651eb9265d

Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
(cherry picked from commit c242fcce06e3102ca663b2f992611d0bda4f2668)
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