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Colin Ian KingandPeter Zijlstra
32d35c4a96
The 64 bit value read from MSR_ARCH_PERFMON_FIXED_CTR_CTRL is being bit-wise masked with the value (0x03 << i*4). However, the shifted value is evaluated using 32 bit arithmetic, so will UB when i > 8. Fix this by making 0x03 a ULL so that the shift is performed using 64 bit arithmetic. This makes the arithmetic internally consistent and preparers for the day when hardware provides 8<num_fixed_counters<16. Signed-off-by: Colin Ian King <colin.king@canonical.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20210420142907.382417-1-colin.king@canonical.com
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.