On Thu, Feb 13, 2025 at 8:42 AM Jiayuan Chen <mr...@163.com> wrote:
>
> On Thu, Feb 13, 2025 at 08:04:05AM -0800, Alexei Starovoitov wrote:
> > On Thu, Feb 13, 2025 at 5:13 AM Jiayuan Chen <mr...@163.com> wrote:
> > >
> > > Add test cases to ensure the maximum stack size can be properly limited to
> > > 512.
> > >
> > > Test result:
> > > echo "0" > /proc/sys/net/core/bpf_jit_enable
> > > ./test_progs -t verifier_stack_ptr
> > > verifier_stack_ptr/PTR_TO_STACK stack size 512 with may_goto with jit:SKIP
> > > verifier_stack_ptr/PTR_TO_STACK stack size 512 with may_goto without
> > > jit:OK
> > >
> > > echo "1" > /proc/sys/net/core/bpf_jit_enable
> > > verifier_stack_ptr/PTR_TO_STACK stack size 512 with may_goto with jit:OK
> > > verifier_stack_ptr/PTR_TO_STACK stack size 512 with may_goto without
> > > jit:SKIP
> >
> > echo '0|1' is not longer necessary ?
> > The commit log seems obsolete?
> >
> > pw-bot: cr
>
> It looks like the problem only arises when CONFIG_BPF_JIT_ALWAYS_ON is
> turned off, and we're only restricting the stack size when
> prog->jit_requested is false. To test this, I simulated different
> scenarios by echoing '0' or '1' to see how the program would behave when
> jit_requested is enabled or disabled.
>
> As expected, when I echoed '0', the program failed verification, and when
> I echoed '1', it ran smoothly.
I misunderstood the tags in patch 2. I thought:
+#define __use_jit() __attribute__((btf_decl_tag("comment:run_mode=jit")))
+#define __use_interp()
__attribute__((btf_decl_tag("comment:run_mode=interpreter")))
"use jit" actually means use jit.
while what it's doing is different:
+ if ((jit_enabled && spec->run_mode & INTERP) ||
+ (!jit_enabled && spec->run_mode & JIT)) {
+ test__skip();
+ return;
+ }
+
The tags should probably be named __load_if_JITed and __load_if_interpreted
or something like that.
