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Fri, 12 Apr 2019 06:38:23 -0700 (PDT) Received: from oberon.eng.vmware.com ([146.247.46.5]) by smtp.gmail.com with ESMTPSA id x205sm11594682wmg.9.2019.04.12.06.38.22 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Fri, 12 Apr 2019 06:38:23 -0700 (PDT) From: Tzvetomir Stoyanov To: rostedt@goodmis.org Cc: linux-trace-devel@vger.kernel.org Subject: [PATCH v5 12/30] tools/lib/traceevent: Man pages for function related libtraceevent APIs Date: Fri, 12 Apr 2019 16:37:53 +0300 Message-Id: <20190412133811.15878-13-tstoyanov@vmware.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190412133811.15878-1-tstoyanov@vmware.com> References: <20190412133811.15878-1-tstoyanov@vmware.com> MIME-Version: 1.0 Sender: linux-trace-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Added new man pages, describing function related libtraceevent APIs: tep_register_function(), tep_register_print_string(), tep_find_function(), tep_find_function_address(), tep_set_function_resolver(), tep_reset_function_resolver() Signed-off-by: Tzvetomir Stoyanov --- .../Documentation/libtraceevent-func_apis.txt | 175 ++++++++++++++++++ .../Documentation/libtraceevent-func_find.txt | 88 +++++++++ 2 files changed, 263 insertions(+) create mode 100644 tools/lib/traceevent/Documentation/libtraceevent-func_apis.txt create mode 100644 tools/lib/traceevent/Documentation/libtraceevent-func_find.txt diff --git a/tools/lib/traceevent/Documentation/libtraceevent-func_apis.txt b/tools/lib/traceevent/Documentation/libtraceevent-func_apis.txt new file mode 100644 index 000000000000..1f69b472602e --- /dev/null +++ b/tools/lib/traceevent/Documentation/libtraceevent-func_apis.txt @@ -0,0 +1,175 @@ +libtraceevent(3) +================ + +NAME +---- +tep_find_function, tep_find_function_address, tep_set_function_resolver, +tep_reset_function_resolver, tep_register_function, tep_register_print_string - +function related tep APIs + +SYNOPSIS +-------- +[verse] +-- +*#include * + +typedef char pass:[*](*tep_func_resolver_t*)(void pass:[*]_priv_, unsigned long long pass:[*]_addrp_, char pass:[**]_modp_); +int *tep_set_function_resolver*(struct tep_handle pass:[*]_tep_, tep_func_resolver_t pass:[*]_func_, void pass:[*]_priv_); +void *tep_reset_function_resolver*(struct tep_handle pass:[*]_tep_); +const char pass:[*]*tep_find_function*(struct tep_handle pass:[*]_tep_, unsigned long long _addr_); +unsigned long long *tep_find_function_address*(struct tep_handle pass:[*]_tep_, unsigned long long _addr_); +int *tep_register_function*(struct tep_handle pass:[*]_tep_, char pass:[*]_name_, unsigned long long _addr_, char pass:[*]_mod_); +int *tep_register_print_string*(struct tep_handle pass:[*]_tep_, const char pass:[*]_fmt_, unsigned long long _addr_); +-- + +DESCRIPTION +----------- +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. + +The _tep_func_resolver_t_ type is the prototype of the alternative kernel +functions resolver. This function receives a pointer to its custom context +(set with the _tep_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) in _modp_. + +The _tep_set_function_resolver()_ function registers _func_ as an alternative +kernel functions resolver. The _tep_ argument is trace event parser context. +The _priv_ argument is a custom context of the _func_ function. The function +resolver is used by the APIs _tep_find_function()_, +_tep_find_function_address()_, and _tep_print_func_field()_ to resolve +a function address to a function name. + +The _tep_reset_function_resolver()_ function resets the kernel functions +resolver to the default function. The _tep_ 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. + +The _tep_find_function()_ function returns the function name, which contains the +given address _addr_. The _tep_ argument is the trace event parser context. + +The _tep_find_function_address()_ function returns the function start address, +by given address _addr_. The _addr_ does not have to be exact, it will select +the function that would contain it. The _tep_ argument is the trace event +parser context. + +The _tep_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 "%pF" or "%pS" parameter in its format string. It is common to +pass in the kallsyms function names with their corresponding addresses with this +function. The _tep_ argument is the trace event parser context. The _name_ is +the name of the function, the string is copied internally. The _addr_ is +the start address of the function. The _mod_ is the kernel module +the function may be in (NULL for none). + +The _tep_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. The _tep_ argument is the trace event parser +context. The _fmt_ is the string to register, it is copied internally. +The _addr_ is the address the string was located at. + + +RETURN VALUE +------------ +The _tep_set_function_resolver()_ function returns 0 in case of success, or -1 +in case of an error. + +The _tep_find_function()_ function returns the function name, or NULL in case +it cannot be found. + +The _tep_find_function_address()_ function returns the function start address, +or 0 in case it cannot be found. + +The _tep_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. + +The _tep_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. + +EXAMPLE +------- +[source,c] +-- +#include +... +struct tep_handle *tep = tep_alloc(); +... +char *my_resolve_kernel_addr(void *context, + unsigned long long *addrp, char **modp) +{ + return NULL; +} + +void show_function( unsigned long long addr) +{ + unsigned long long fstart; + const char *fname; + + if (tep_set_function_resolver(tep, my_resolve_kernel_addr, NULL) != 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, "kernel_function_foo", + (unsigned long long) 0x12345678, NULL) != 0) { + /* Failed to register kernel_function_foo address mapping */ + } +... + if (tep_register_print_string(tep, "print string", + (unsigned long long) 0x87654321, NULL) != 0) { + /* Failed to register "print string" address mapping */ + } +... +-- + +FILES +----- +[verse] +-- +*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. +-- + +SEE ALSO +-------- +_libtraceevent(3)_, _trace-cmd(1)_ + +AUTHOR +------ +[verse] +-- +*Steven Rostedt* , author of *libtraceevent*. +*Tzvetomir Stoyanov* , author of this man page. +-- +REPORTING BUGS +-------------- +Report bugs to + +LICENSE +------- +libtraceevent is Free Software licensed under the GNU LGPL 2.1 + +RESOURCES +--------- +https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git diff --git a/tools/lib/traceevent/Documentation/libtraceevent-func_find.txt b/tools/lib/traceevent/Documentation/libtraceevent-func_find.txt new file mode 100644 index 000000000000..04840e244445 --- /dev/null +++ b/tools/lib/traceevent/Documentation/libtraceevent-func_find.txt @@ -0,0 +1,88 @@ +libtraceevent(3) +================ + +NAME +---- +tep_find_function,tep_find_function_address - Find function name / start address. + +SYNOPSIS +-------- +[verse] +-- +*#include * + +const char pass:[*]*tep_find_function*(struct tep_handle pass:[*]_tep_, unsigned long long _addr_); +unsigned long long *tep_find_function_address*(struct tep_handle pass:[*]_tep_, unsigned long long _addr_); +-- + +DESCRIPTION +----------- +These functions 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. + +The _tep_find_function()_ function returns the function name, which contains the +given address _addr_. The _tep_ argument is the trace event parser context. + +The _tep_find_function_address()_ function returns the function start address, +by given address _addr_. The _addr_ does not have to be exact, it will select the +function that would contain it. The _tep_ argument is the trace event parser context. + +RETURN VALUE +------------ +The _tep_find_function()_ function returns the function name, or NULL in case +it cannot be found. + +The _tep_find_function_address()_ function returns the function start address, +or 0 in case it cannot be found. + +EXAMPLE +------- +[source,c] +-- +#include +... +struct tep_handle *tep = tep_alloc(); +... +void show_function( unsigned long long addr) +{ + const char *fname = tep_find_function(tep, addr); + unsigned long long fstart = tep_find_function_address(tep, addr); + + /* addr is in function named fname, starting at fstart address, at offset (addr - fstart) */ +} +... +-- + +FILES +----- +[verse] +-- +*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. +-- + +SEE ALSO +-------- +_libtraceevent(3)_, _trace-cmd(1)_ + +AUTHOR +------ +[verse] +-- +*Steven Rostedt* , author of *libtraceevent*. +*Tzvetomir Stoyanov* , author of this man page. +-- +REPORTING BUGS +-------------- +Report bugs to + +LICENSE +------- +libtraceevent is Free Software licensed under the GNU LGPL 2.1 + +RESOURCES +--------- +https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git