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Add BPFTRACE_STACK_MODE env variable
Summary: This is so users can more easily set the global output for their stacks rather than repeating the same string for every invocation of ustack or kstack Test Plan: Tested locally. ``` BPFTRACE_STACK_MODE=tomato sudo ./src/bpftrace -e 'kprobe:do_nanosleep { printf("Jordan\n%s\n", ustack()); }' ERROR: Env var 'BPFTRACE_STACK_MODE' did not contain a valid StackMode: tomato ``` ``` BPFTRACE_STACK_MODE=perf sudo ./src/bpftrace -e 'kprobe:do_nanosleep { printf("Jordan\n%s\n", ustack()); }' Attaching 1 probe... Jordan 7f088cae85b3 __clock_nanosleep+99 (/usr/local/fbcode/platform010-compat/lib/libc.so.6) 7f088caed253 __nanosleep+19 (/usr/local/fbcode/platform010-compat/lib/libc.so.6) 1f3418b scribe::common::sink::QueueSink::sendLoop(scribe::common::sink::detail::BatchQueue*, int)+2971 (/usr/local/fbprojects/scribe/bin/scribed) 6187e12 folly::ThreadedExecutor::work(folly::Function<void ()>&)+82 (/usr/local/fbprojects/scribe/bin/scribed) 7f088cedf2e5 execute_native_thread_routine+21 (/usr/local/fbcode/platform010-compat/lib/libstdc++.so.6.0.29) 7f088ca979bf start_thread+559 (/usr/local/fbcode/platform010-compat/lib/libc.so.6) 7f088cb288ac __GI___clone3+44 (/usr/local/fbcode/platform010-compat/lib/libc.so.6) ``` Reviewers: Subscribers: Tasks: Tags:
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‎docs/reference_guide.md

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@@ -176,6 +176,7 @@ ENVIRONMENT:
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BPFTRACE_CACHE_USER_SYMBOLS [default: auto] enable user symbol cache
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BPFTRACE_VMLINUX [default: none] vmlinux path used for kernel symbol resolution
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BPFTRACE_BTF [default: none] BTF file
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BPFTRACE_STACK_MODE [default: bpftrace] Output format for ustack and kstack builtins
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EXAMPLES:
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bpftrace -l '*sleep*'
@@ -553,6 +554,12 @@ Default: `..`
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Trailer to add to strings that were truncated. Set to empty string to disable truncation trailers.
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### 9.11 `BPFTRACE_STACK_MODE`
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Default: bpftrace
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Output format for ustack and kstack builtins. Available modes/formats: `bpftrace`, `perf`, and `raw`.
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This can be overwritten at the call site.
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## 10. Clang Environment Variables
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‎man/adoc/bpftrace.adoc

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@@ -258,6 +258,13 @@ Default: `..`
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Trailer to add to strings that were truncated. Set to empty string to disable truncation trailers.
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=== BPFTRACE_STACK_MODE
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Default: bpftrace
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Output format for ustack and kstack builtins. Available modes/formats: `bpftrace`, `perf`, and `raw`.
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This can be overwritten at the call site.
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////
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!
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!

‎src/ast/passes/semantic_analyser.cpp

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@@ -1417,6 +1417,12 @@ void SemanticAnalyser::check_stack_call(Call &call, bool kernel)
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}
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StackType stack_type;
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if (bpftrace_.stack_mode_.has_value())
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{
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stack_type.mode = *bpftrace_.stack_mode_;
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}
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if (call.vargs)
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{
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switch (call.vargs->size())

‎src/bpftrace.h

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@@ -195,6 +195,7 @@ class BPFtrace
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bool usdt_file_activation_ = false;
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int helper_check_level_ = 0;
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uint64_t ast_max_nodes_ = 0; // Maximum AST nodes allowed for fuzzing
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std::optional<StackMode> stack_mode_;
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std::optional<struct timespec> boottime_;
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static void sort_by_key(

‎src/main.cpp

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@@ -128,6 +128,7 @@ void usage()
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std::cerr << " BPFTRACE_VMLINUX [default: none] vmlinux path used for kernel symbol resolution" << std::endl;
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std::cerr << " BPFTRACE_BTF [default: none] BTF file" << std::endl;
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std::cerr << " BPFTRACE_STR_TRUNC_TRAILER [default: '..'] string truncation trailer" << std::endl;
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std::cerr << " BPFTRACE_STACK_MODE [default: bpftrace] Output format for ustack and kstack builtins" << std::endl;
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std::cerr << std::endl;
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std::cerr << "EXAMPLES:" << std::endl;
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std::cerr << "bpftrace -l '*sleep*'" << std::endl;
@@ -334,6 +335,21 @@ static std::optional<struct timespec> get_boottime()
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if (!get_bool_env_var("BPFTRACE_VERIFY_LLVM_IR", verify_llvm_ir))
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return false;
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if (const char* stack_mode = std::getenv("BPFTRACE_STACK_MODE"))
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{
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auto found = STACK_MODE_MAP.find(stack_mode);
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if (found != STACK_MODE_MAP.end())
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{
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bpftrace.stack_mode_ = found->second;
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}
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else
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{
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LOG(ERROR) << "Env var 'BPFTRACE_STACK_MODE' did not contain a valid "
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"StackMode: "
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<< stack_mode;
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}
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}
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return true;
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}
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‎src/types.h

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@@ -69,6 +69,12 @@ enum class StackMode
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raw,
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};
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const std::map<std::string, StackMode> STACK_MODE_MAP = {
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{ "bpftrace", StackMode::bpftrace },
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{ "perf", StackMode::perf },
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{ "raw", StackMode::raw },
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};
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struct StackType
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{
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size_t limit = DEFAULT_STACK_SIZE;

‎tests/runtime/call

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@@ -207,13 +207,40 @@ EXPECT Attaching 1 probe
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TIMEOUT 5
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AFTER ./testprogs/syscall nanosleep 1e8
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NAME ustack
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PROG k:do_nanosleep { printf("%s\n%s\n", ustack(), ustack(1)); exit(); }
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EXPECT Attaching 1 probe
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TIMEOUT 5
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AFTER ./testprogs/syscall nanosleep 1e8
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NAME ustack_stack_mode_env_bpftrace
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PROG k:do_nanosleep { printf("%s", ustack(1)); exit(); }
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ENV BPFTRACE_STACK_MODE=bpftrace
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EXPECT ^\s+[a-zA-Z0-9_]+\+[0-9]+
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TIMEOUT 5
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AFTER ./testprogs/syscall nanosleep 1e8
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NAME ustack_stack_mode_env_perf
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PROG k:do_nanosleep { printf("%s", ustack(1)); exit(); }
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ENV BPFTRACE_STACK_MODE=perf
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EXPECT ^\s+[0-9a-f]+ [a-zA-Z0-9_]+\+[0-9]+
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TIMEOUT 5
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AFTER ./testprogs/syscall nanosleep 1e8
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NAME ustack_stack_mode_env_raw
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PROG k:do_nanosleep { printf("%s", ustack(1)); exit(); }
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ENV BPFTRACE_STACK_MODE=raw
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EXPECT ^\s+[0-9a-f]+$
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TIMEOUT 5
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AFTER ./testprogs/syscall nanosleep 1e8
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NAME ustack_stack_mode_env_override
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PROG k:do_nanosleep { printf("%s", ustack(raw, 1)); exit(); }
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ENV BPFTRACE_STACK_MODE=perf
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EXPECT ^\s+[0-9a-f]+$
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TIMEOUT 5
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AFTER ./testprogs/syscall nanosleep 1e8
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NAME cat
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PROG i:ms:1 { cat("/proc/uptime"); exit();}
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EXPECT [0-9]*.[0-9]* [0-9]*.[0-9]*

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