1cf5b23988
This patch makes structs and unions, emitted through BTF dump, automatically CO-RE-relocatable (unless disabled with `#define BPF_NO_PRESERVE_ACCESS_INDEX`, specified before including generated header file). This effectivaly turns usual bpf_probe_read() call into equivalent of bpf_core_read(), by automatically applying builtin_preserve_access_index to any field accesses of types in generated C types header. This is especially useful for tp_btf/fentry/fexit BPF program types. They allow direct memory access, so BPF C code just uses straightfoward a->b->c access pattern to read data from kernel. But without kernel structs marked as CO-RE relocatable through preserve_access_index attribute, one has to enclose all the data reads into a special __builtin_preserve_access_index code block, like so: __builtin_preserve_access_index(({ x = p->pid; /* where p is struct task_struct *, for example */ })); This is very inconvenient and obscures the logic quite a bit. By marking all auto-generated types with preserve_access_index attribute the above code is reduced to just a clean and natural `x = p->pid;`. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200113073143.1779940-5-andriin@fb.com |
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.. | ||
accounting | ||
arch | ||
bpf | ||
build | ||
cgroup | ||
debugging | ||
firewire | ||
firmware | ||
gpio | ||
hv | ||
iio | ||
include | ||
io_uring | ||
kvm/kvm_stat | ||
laptop | ||
leds | ||
lib | ||
memory-model | ||
nfsd | ||
objtool | ||
pci | ||
pcmcia | ||
perf | ||
power | ||
scripts | ||
spi | ||
testing | ||
thermal/tmon | ||
time | ||
usb | ||
virtio | ||
vm | ||
wmi | ||
Makefile |