On 8/15/22 12:29 AM, Jiri Olsa wrote:
On Sun, Aug 14, 2022 at 10:29:11PM -0700, Yonghong Song wrote:
On 8/14/22 1:24 PM, Jiri Olsa wrote:
On Thu, Aug 11, 2022 at 10:24:35PM -0700, Yonghong Song wrote:
SNIP
}
static int invoke_bpf_prog(const struct btf_func_model *m, u8 **pprog,
@@ -2020,6 +2081,7 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i
struct bpf_tramp_links *fentry = &tlinks[BPF_TRAMP_FENTRY];
struct bpf_tramp_links *fexit = &tlinks[BPF_TRAMP_FEXIT];
struct bpf_tramp_links *fmod_ret = &tlinks[BPF_TRAMP_MODIFY_RETURN];
+ int struct_val_off, extra_nregs = 0;
u8 **branches = NULL;
u8 *prog;
bool save_ret;
@@ -2028,6 +2090,20 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i
if (nr_args > 6)
return -ENOTSUPP;
+ for (i = 0; i < MAX_BPF_FUNC_ARGS; i++) {
+ if (m->arg_flags[i] & BTF_FMODEL_STRUCT_ARG) {
+ /* Only support up to 16 bytes struct which should keep
+ * values in registers.
+ */
it seems that if the struct contains 'double' field, it's passed in
SSE register, which we don't support is save/restore
That is right.
we should probably check struct's BTF in btf_distill_func_proto and
fail if we found anything else than regular regs types?
The reason I didn't add float/double checking is that I didn't actually
find any float/double struct members in either vmlinux.h or in
arch/x86 directory. Could you help double check as well?
ok I checked on fedora's BTF and could not find any
still the check might be good or at least mention
that in comment
I will mention in the comment. thanks!
+ if (m->arg_size[i] > 16)
+ return -ENOTSUPP;
+
+ extra_nregs += (m->arg_size[i] + 7) / 8 - 1;
+ }
+ }
+ if (nr_args + extra_nregs > 6)
should this value be minus the number of actually found struct arguments?
In the above we have
extra_nregs += (m->arg_size[i] + 7) / 8 - 1;
already did the 'minus' part.
there it is ;-) ok
jirka
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