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perf test amd ibs: avoid using executable heap

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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: 35db59fa8e ("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>
This commit is contained in:
Ondrej Mosnacek
2026-07-01 08:23:21 +02:00
committed by Namhyung Kim
parent ca0e19074b
commit e34006e743
1 changed files with 6 additions and 14 deletions
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20
tools/perf/arch/x86/tests/amd-ibs-period.c
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@@ -46,7 +46,6 @@ static int dummy_workload_1(unsigned long count)
{
int (*func)(void);
int ret = 0;
char *p;
char insn1[] = {
0xb8, 0x01, 0x00, 0x00, 0x00, /* mov 1,%eax */
0xc3, /* ret */
@@ -59,18 +58,11 @@ static int dummy_workload_1(unsigned long count)
0xcc, /* int 3 */
};
p = calloc(2, page_size);
if (!p) {
printf("malloc() failed. %m");
return 1;
}
func = (void *)((unsigned long)(p + page_size - 1) & ~(page_size - 1));
ret = mprotect(func, page_size, PROT_READ | PROT_WRITE | PROT_EXEC);
if (ret) {
printf("mprotect() failed. %m");
goto out;
func = mmap(NULL, page_size, PROT_READ | PROT_WRITE | PROT_EXEC,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (func == MAP_FAILED) {
pr_debug("mmap() failed. %m\n");
return -1;
}
if (count < 100000)
@@ -93,7 +85,7 @@ static int dummy_workload_1(unsigned long count)
}
out:
free(p);
munmap(func, page_size);
return ret;
}