On Thu, Aug 27, 2020 at 8:42 PM Hao Luo haoluo@google.com wrote:
Thanks for taking a look!
On Fri, Aug 21, 2020 at 8:30 PM Andrii Nakryiko andrii.nakryiko@gmail.com wrote:
On Wed, Aug 19, 2020 at 3:42 PM Hao Luo haoluo@google.com wrote:
Test bpf_per_cpu_ptr(). Test two paths in the kernel. If the base pointer points to a struct, the returned reg is of type PTR_TO_BTF_ID. Direct pointer dereference can be applied on the returned variable. If the base pointer isn't a struct, the returned reg is of type PTR_TO_MEM, which also supports direct pointer dereference.
Signed-off-by: Hao Luo haoluo@google.com
Acked-by: Andrii Nakryiko andriin@fb.com
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__u64 out__runqueues = -1; __u64 out__bpf_prog_active = -1; +__u32 out__rq_cpu = -1; +unsigned long out__process_counts = -1;
try to not use long for variables, it is 32-bit integer in user-space but always 64-bit in BPF. This causes problems when using skeleton on 32-bit architecture.
Ack. I will use another variable of type 'int' instead.
__u64 is fine as well
-extern const struct rq runqueues __ksym; /* struct type global var. */ +extern const struct rq runqueues __ksym; /* struct type percpu var. */ extern const int bpf_prog_active __ksym; /* int type global var. */ +extern const unsigned long process_counts __ksym; /* int type percpu var. */
SEC("raw_tp/sys_enter") int handler(const void *ctx) {
struct rq *rq;unsigned long *count;out__runqueues = (__u64)&runqueues; out__bpf_prog_active = (__u64)&bpf_prog_active;rq = (struct rq *)bpf_per_cpu_ptr(&runqueues, 1);if (rq)out__rq_cpu = rq->cpu;this is awesome!
Are there any per-cpu variables that are arrays? Would be nice to test those too.
There are currently per-cpu arrays, but not common. There is a 'pmc_prev_left' in arch/x86, I can add that in this test.
arch-specific variables are bad, because selftests will be failing on other architectures; let's not do this then.
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