Increase maximum frames in our fork. (#64)

This makes it so we can't support 4.19 series kernels (which are EOL anyway...) but bumps the number of frames we can support from 120 to 240, which is necessary due to the deeply nested stacks in certain Rust libraries (e.g. Tokio and Axum).

Author: umanwizard

.github/workflows/unit-test-on-pull-request.yml

@@ -138,7 +138,7 @@ jobs:
           # https://github.com/cilium/ci-kernels/pkgs/container/ci-kernels/versions?filters%5Bversion_type%5D=tagged
 
           # AMD64
-          - { target_arch: amd64, kernel: 4.19.314 }
+          # - { target_arch: amd64, kernel: 4.19.314 }
           - { target_arch: amd64, kernel: 5.4.276 }
           - { target_arch: amd64, kernel: 5.10.217 }
           - { target_arch: amd64, kernel: 5.15.159 }

support/ebpf/native_stack_trace.ebpf.c

@@ -50,7 +50,7 @@ bpf_map_def SEC("maps") unwind_info_array = {
 };
 
 // The number of native frames to unwind per frame-unwinding eBPF program.
-#define NATIVE_FRAMES_PER_PROGRAM 4
+#define NATIVE_FRAMES_PER_PROGRAM 8
 
 // The decision whether to unwind native stacks or interpreter stacks is made by checking if a given
 // PC address falls into the "interpreter loop" of an interpreter. This map helps identify such

support/ebpf/tracer.ebpf.debug.amd64

@@ -386,7 +386,7 @@ typedef enum TraceOrigin {
 // MAX_FRAME_UNWINDS defines the maximum number of frames per
 // Trace we can unwind and respect the limit of eBPF instructions,
 // limit of tail calls and limit of stack size per eBPF program.
-#define MAX_FRAME_UNWINDS 128
+#define MAX_FRAME_UNWINDS 256
 
 // MAX_NON_ERROR_FRAME_UNWINDS defines the maximum number of frames
 // to be pushed by unwinders while still leaving space for an error frame.