perf test amd ibs: avoid using executable heap

Making [parts of] the heap executable is dangerous and is blocked by
SELinux on Fedora/RHEL even for an unconfined user. Replace the malloc()
+ mprotect() combo with just mmap(), creating a private anonymous rwx
mapping, which only requires the more commonly allowed "execmem"
permission under SELinux (things like JIT or regex compilation need it
as well). mmap() with MAP_ANONYMOUS will give us a zeroed mapping that
begins on a page boundary, so the result is equivalent to the original
code even without a memset() or the page-alignment dance.

Verified that the test still passes on a machine with an AMD CPU that
has the "ibs" CPU flag.

Fixes: 35db59fa8ea2 ("perf test amd ibs: Add sample period unit test")
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Reviewed-by: Ravi Bangoria <ravi.bangoria@amd.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

0 files changed, 0 insertions, 0 deletions