ftrace_lookup_symbols(9)

💅 ftrace_lookup_symbols(9) — a Kernel API Manual moment

okay so bestie, welcome to the glow-up of ftrace_lookup_symbols(9), straight out of the Kernel API Manual ✨ this one's a little resolver function and honestly? she's kind of iconic 👑

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🌸 NAME 🌸

ftrace_lookup_symbols — Lookup addresses for array of symbols 🎀

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✨ SYNOPSIS ✨

int ftrace_lookup_symbols (const char **sorted_syms , size_t cnt ,
unsigned long *addrs );

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🦋 ARGUMENTS 🦋

• sorted_syms — array of symbols pointers, aka the symbols you want resolved. and listen, they must be alphabetically sorted, no cap 🔤
• cnt — number of symbols/addresses in the syms/addrs arrays 🔢
• addrs — array for storing the resulting addresses, that's her whole job 💖

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💜 DESCRIPTION 💜

so what she does is: this function looks up addresses for the array of symbols you hand her in the syms array (and yes, it must be alphabetically sorted, i'm serious 🙈) and then stores them all in the addrs array — which needs to be big enough to hold at least cnt addresses. big enough bestie, don't skimp 🫶

for a single symbol (cnt == 1), she uses kallsyms_lookup_name, which performs an O(log N) binary search via the sorted kallsyms index. that's the fast lane, no full O(N) linear scan over all kernel symbols like the multi-symbol path has to do. she's efficient and she knows it 💅

for multiple symbols, she uses a single-pass linear scan via kallsyms_on_each_symbol with binary search into the sorted input array. slay, one pass, we love to see it ⭐

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🔥 RETURN 🔥

0 if all provided symbols are found 💖 — -ESRCH otherwise 😭

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🌈 SEE ALSO 🌈

Kernel file ./kernel/trace/ftrace.c, plus the whole friend group:

• ftrace_lookup_ip(9), ftrace_free_filter(9), ftrace_hash_move(9), ftrace_location_range(9), ftrace_location(9), ftrace_text_reserved(9), ftrace_bug(9), ftrace_update_record(9), ftrace_test_record(9), ftrace_get_addr_new(9), ftrace_get_addr_curr(9), ftrace_rec_iter_start(9), ftrace_rec_iter_next(9), ftrace_rec_iter_record(9), ftrace_run_stop_machine(9), arch_ftrace_update_code(9), ftrace_startup_subops(9), ftrace_shutdown_subops(9), ftrace_regex_open(9), allocate_ftrace_func_mapper(9), ftrace_func_mapper_find_ip(9), ftrace_func_mapper_add_ip(9), ftrace_func_mapper_remove_ip(9), free_ftrace_func_mapper(9), register_ftrace_direct(9), unregister_ftrace_direct(9), modify_ftrace_direct_nolock(9), modify_ftrace_direct(9), hash_add(9), update_ftrace_direct_add(9), hash_sub(9), update_ftrace_direct_del(9), update_ftrace_direct_mod(9), ftrace_set_filter_ip(9), ftrace_set_filter_ips(9), ftrace_ops_set_global_filter(9), ftrace_set_filter(9), ftrace_set_notrace(9), ftrace_set_global_filter(9), ftrace_set_global_notrace(9), ftrace_ops_get_func(9), ftrace_kill(9), ftrace_is_dead(9), register_ftrace_function(9), unregister_ftrace_function(9)

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and that's the whole page, bestie 🧚💜 she lives in ./kernel/trace, this edition is dated October 2026, and she goes by ftrace_lookup_symbols(9) — periodt 💅🎀