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authorArnaldo Carvalho de Melo <acme@redhat.com>2023-08-21 16:40:09 +0300
committerArnaldo Carvalho de Melo <acme@redhat.com>2023-08-21 16:48:58 +0300
commit262b54b6c9396823ab06df46a1be475c44b28b5f (patch)
tree40fe2b2dba872825d41b9cefa7892eb88f66783d /tools
parenta50b8db3ea358b01f3c83e1e1c063e75352dcb3b (diff)
downloadlinux-262b54b6c9396823ab06df46a1be475c44b28b5f.tar.xz
perf bpf augmented_raw_syscalls: Add an assert to make sure sizeof(saddr) is a power of two.
We're using the BPF verifier suggestion: 22: (85) call bpf_probe_read#4 R2 min value is negative, either use unsigned or 'var &= const' That works only when const is a (power of two - 1) so add an assert to make sure that that is the case. Suggested-by: Ian Rogers <irogers@google.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Link: https://lore.kernel.org/lkml/ZONrFmJBNlQpSpZj@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools')
-rw-r--r--tools/perf/util/bpf_skel/augmented_raw_syscalls.bpf.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/tools/perf/util/bpf_skel/augmented_raw_syscalls.bpf.c b/tools/perf/util/bpf_skel/augmented_raw_syscalls.bpf.c
index 9c1d0b271b20..43549b63b433 100644
--- a/tools/perf/util/bpf_skel/augmented_raw_syscalls.bpf.c
+++ b/tools/perf/util/bpf_skel/augmented_raw_syscalls.bpf.c
@@ -10,6 +10,16 @@
#include <bpf/bpf_helpers.h>
#include <linux/limits.h>
+/**
+ * is_power_of_2() - check if a value is a power of two
+ * @n: the value to check
+ *
+ * Determine whether some value is a power of two, where zero is *not*
+ * considered a power of two. Return: true if @n is a power of 2, otherwise
+ * false.
+ */
+#define is_power_of_2(n) (n != 0 && ((n & (n - 1)) == 0))
+
#define MAX_CPUS 4096
// FIXME: These should come from system headers
@@ -187,6 +197,7 @@ int sys_enter_connect(struct syscall_enter_args *args)
if (augmented_args == NULL)
return 1; /* Failure: don't filter */
+ _Static_assert(is_power_of_2(sizeof(augmented_args->saddr)), "sizeof(augmented_args->saddr) needs to be a power of two");
socklen &= sizeof(augmented_args->saddr) - 1;
bpf_probe_read(&augmented_args->saddr, socklen, sockaddr_arg);