On 1/12/21 7:43 AM, Daniel Borkmann wrote:
On 1/12/21 4:35 PM, Gilad Reti wrote:
On Tue, Jan 12, 2021 at 4:56 PM KP Singh <kpsingh@xxxxxxxxxx> wrote:
On Tue, Jan 12, 2021 at 10:16 AM Gilad Reti <gilad.reti@xxxxxxxxx>
wrote:
Add test to check that the verifier is able to recognize spilling of
PTR_TO_MEM registers.
It would be nice to have some explanation of what the test does to
recognize the spilling of the PTR_TO_MEM registers in the commit
log as well.
Would it be possible to augment an existing test_progs
program like tools/testing/selftests/bpf/progs/test_ringbuf.c to test
this functionality?
How would you guarantee that LLVM generates the spill/fill, via inline asm?
You can make the following change to force the return value ("sample"
here) of bpf_ringbuf_reserve() to spill on the stack.
diff --git a/tools/testing/selftests/bpf/progs/test_ringbuf.c
b/tools/testing/selftests/bpf/progs/test_ringbuf.c
index 8ba9959b036b..011521170856 100644
--- a/tools/testing/selftests/bpf/progs/test_ringbuf.c
+++ b/tools/testing/selftests/bpf/progs/test_ringbuf.c
@@ -40,7 +40,7 @@ SEC("tp/syscalls/sys_enter_getpgid")
int test_ringbuf(void *ctx)
{
int cur_pid = bpf_get_current_pid_tgid() >> 32;
- struct sample *sample;
+ struct sample * volatile sample;
int zero = 0;
if (cur_pid != pid)
This change will cause verifier failure without Patch #1.
It may be possible, but from what I understood from Daniel's comment here
https://lore.kernel.org/bpf/17629073-4fab-a922-ecc3-25b019960f44@xxxxxxxxxxxxx/
the test should be a part of the verifier tests (which is reasonable
to me since it is
a verifier bugfix)
Yeah, the test_verifier case as you have is definitely the most straight
forward way to add coverage in this case.
