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NAME |SYNOPSIS |DESCRIPTION |RETURN VALUE |EXAMPLE |FILES |SEE ALSO |AUTHOR |REPORTING BUGS |LICENSE |RESOURCES |NOTES |COLOPHON | |
LIBTRACEEVENT(3) libtraceevent ManualLIBTRACEEVENT(3)tep_set_function_resolver, tep_reset_function_resolver, tep_register_function, tep_register_print_string, tep_get_function_count - function related tep APIs
#include <event-parse.h> typedef char *(tep_func_resolver_t)(void *priv, unsigned long long *addrp, char **modp); inttep_set_function_resolver(struct tep_handle *tep, tep_func_resolver_t *func, void *priv); voidtep_reset_function_resolver(struct tep_handle *tep); inttep_register_function(struct tep_handle *tep, char *name, unsigned long longaddr, char *mod); inttep_register_print_string(struct tep_handle *tep, const char *fmt, unsigned long longaddr); inttep_get_function_count(struct tep_handle *tep)
Some tools may have already a way to resolve the kernel functions. These APIs allow them to keep using it instead of duplicating all the entries inside. Thetep_func_resolver_t type is the prototype of the alternative kernel functions resolver. This function receives a pointer to its custom context (set with thetep_set_function_resolver()call ) and the address of a kernel function, which has to be resolved. In case of success, it should return the name of the function and its module (if any) inmodp. Thetep_set_function_resolver()function registersfunc as an alternative kernel functions resolver. Thetep argument is trace event parser context. Thepriv argument is a custom context of thefunc function. The function resolver is used by the APIstep_find_function(3),tep_find_function_address(3), andtep_print_func_field()to resolve a function address to a function name. Thetep_reset_function_resolver()function resets the kernel functions resolver to the default function. Thetep argument is trace event parser context. These APIs can be used to find function name and start address, by given address. The given address does not have to be exact, it will select the function that would contain it. Thetep_register_function()function registers a function name mapped to an address and (optional) module. This mapping is used in case the function tracer or events have "%pS" parameter in its format string. It is common to pass in the kallsyms function names with their corresponding addresses with this function. Thetep argument is the trace event parser context. Thename is the name of the function, the string is copied internally. Theaddr is the start address of the function. Themod is the kernel module the function may be in (NULL for none). Thetep_register_print_string()function registers a string by the address it was stored in the kernel. Some strings internal to the kernel with static address are passed to certain events. The "%s" in the event’s format field which has an address needs to know what string would be at that address. The tep_register_print_string() supplies the parsing with the mapping between kernel addresses and those strings. Thetep argument is the trace event parser context. Thefmt is the string to register, it is copied internally. Theaddr is the address the string was located at.tep_get_function_count() returns the number of registered functions in a tep handler.
Thetep_set_function_resolver()function returns 0 in case of success, or -1 in case of an error. Thetep_register_function()function returns 0 in case of success. In case of an error -1 is returned, and errno is set to the appropriate error number. Thetep_register_print_string()function returns 0 in case of success. In case of an error -1 is returned, and errno is set to the appropriate error number.
#include <event-parse.h> ... struct tep_handle *tep = tep_alloc(); ... char *my_resolve_kernel_addr(void *context, unsigned long long *addrp, char **modp) { struct db *function_database = context; struct symbol *sym = sql_lookup(function_database, *addrp); if (!sym) return NULL; *modp = sym->module_name; return sym->name; } void show_function( unsigned long long addr) { unsigned long long fstart; const char *fname; if (tep_set_function_resolver(tep, my_resolve_kernel_addr, function_database) != 0) { /* failed to register my_resolve_kernel_addr */ } /* These APIs use my_resolve_kernel_addr() to resolve the addr */ fname = tep_find_function(tep, addr); fstart = tep_find_function_address(tep, addr); /* addr is in function named fname, starting at fstart address, at offset (addr - fstart) */ tep_reset_function_resolver(tep); } ... if (tep_register_function(tep, "kvm_exit", (unsigned long long) 0x12345678, "kvm") != 0) { /* Failed to register kvm_exit address mapping */ } ... if (tep_register_print_string(tep, "print string", (unsigned long long) 0x87654321, NULL) != 0) { /* Failed to register "print string" address mapping */ } ...event-parse.h Header file to include in order to have access to the library APIs.-ltraceevent Linker switch to add when building a program that uses the library.
libtraceevent(3),trace-cmd(1)
Steven Rostedt<rostedt@goodmis.org[1]>, author oflibtraceevent.Tzvetomir Stoyanov<tz.stoyanov@gmail.com[2]>, author of this man page.
Report bugs to <linux-trace-devel@vger.kernel.org[3]>
libtraceevent is Free Software licensed under the GNU LGPL 2.1
https://git.kernel.org/pub/scm/libs/libtrace/libtraceevent.git/
1. rostedt@goodmis.org mailto:rostedt@goodmis.org 2. tz.stoyanov@gmail.com mailto:tz.stoyanov@gmail.com 3. linux-trace-devel@vger.kernel.org mailto:linux-trace-devel@vger.kernel.org
This page is part of thelibtraceevent (Linux kernel trace event library) project. Information about the project can be found at ⟨https://www.trace-cmd.org/⟩. If you have a bug report for this manual page, see ⟨https://www.trace-cmd.org/⟩. This page was obtained from the project's upstream Git repository ⟨https://git.kernel.org/pub/scm/libs/libtrace/libtraceevent.git⟩ on 2025-08-11. (At that time, the date of the most recent commit that was found in the repository was 2025-05-30.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which isnot part of the original manual page), send a mail to man-pages@man7.orglibtraceevent 1.7.3 09/24/2023LIBTRACEEVENT(3)Pages that refer to this page:tep_parse_saved_cmdlines(3)
HTML rendering created 2025-09-06 byMichael Kerrisk, author ofThe Linux Programming Interface. For details of in-depthLinux/UNIX system programming training courses that I teach, lookhere. Hosting byjambit GmbH. | |