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cdacdce8e549fa142352125293fbf6d4e006f522
pstrace/src/dwarf/dwarf_function.c
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/*
* dwarf_function.cpp
*
* Created on: Feb 1, 2020
* Author: nnosov
*/
#include <dwarf.h>
#include <stdlib.h>
#include <libiberty/demangle.h>
#include <stdio.h>
#include "dwarf_stack.h"
#include "dwarf_utils.h"
#include "dwarf_function.h"
// -----------------------------------------------------------------------------------
// pst_function
// -----------------------------------------------------------------------------------
static bool get_frame(pst_function* fn)
{
// get CFI (Call Frame Information) for current module
// from handle_cfi()
Dwarf_Addr mod_bias = 0;
Dwarf_CFI* cfi = dwfl_module_eh_cfi(fn->ctx->module, &mod_bias); // rty .eh_cfi first
if(!cfi) { // then try .debug_fame second
cfi = dwfl_module_dwarf_cfi(fn->ctx->module, &mod_bias);
}
if(!cfi) {
pst_log(SEVERITY_ERROR, "Cannot find CFI for module");
return false;
}
// get frame of CFI for address
int result = dwarf_cfi_addrframe (cfi, fn->pc - mod_bias, &fn->frame);
if (result != 0) {
pst_log(SEVERITY_ERROR, "Failed to find CFI frame for module");
return false;
}
// setup context to match frame
fn->ctx->frame = fn->frame;
// get return register and PC range for function
Dwarf_Addr start = fn->pc;
Dwarf_Addr end = fn->pc;
bool signalp;
int ra_regno = dwarf_frame_info (fn->frame, &start, &end, &signalp);
if(ra_regno >= 0) {
start += mod_bias;
end += mod_bias;
reginfo info; info.regno = ra_regno;
dwfl_module_register_names(fn->ctx->module, regname_callback, &info);
pst_log(SEVERITY_INFO, "Function %s(...): '.eh/debug frame' info: PC range: => [%#" PRIx64 ", %#" PRIx64 "], return register: %s, in_signal = %s",
fn->name, start, end, info.regname, signalp ? "true" : "false");
} else {
pst_log(SEVERITY_WARNING, "Return address register info unavailable (%s)", dwarf_errmsg(0));
}
// finally get CFA (Canonical Frame Address)
// Point cfa_ops to dummy to match print_detail expectations.
// (nops == 0 && cfa_ops != NULL => "undefined")
Dwarf_Op dummy;
Dwarf_Op *cfa_ops = &dummy;
size_t cfa_nops;
if(dwarf_frame_cfa(fn->frame, &cfa_ops, &cfa_nops)) {
pst_log(SEVERITY_ERROR, "Failed to get CFA for frame");
return false;
}
fn->ctx->print_expr(fn->ctx, cfa_ops, cfa_nops, NULL);
pst_decl(pst_dwarf_stack, stack, fn->ctx);
if(pst_dwarf_stack_calc(&stack, cfa_ops, cfa_nops, NULL, NULL) && pst_dwarf_stack_get_value(&stack, &fn->cfa)) {
pst_log(SEVERITY_INFO, "Function %s(...): CFA expression: %s ==> %#lX", fn->name, fn->ctx->buff, fn->cfa);
// setup context to match CFA for frame
fn->ctx->cfa = fn->cfa;
} else {
pst_log(SEVERITY_ERROR, "Failed to calculate CFA expression");
}
pst_dwarf_stack_fini(&stack);
return true;
}
static pst_parameter* add_param(pst_function* fn)
{
pst_new(pst_parameter, p, fn->ctx);
list_add_bottom(&fn->params, &p->node);
return p;
}
static void del_param(pst_parameter* p)
{
list_del(&p->node);
pst_free(p);
}
static void clear(pst_function* fn)
{
pst_parameter* param = NULL;
struct list_node *pos, *tn;
list_for_each_entry_safe(param, pos, tn, &fn->params, node) {
list_del(&param->node);
pst_parameter_fini(param);
}
pst_call_site_storage_fini(&fn->call_sites);
}
static pst_parameter* next_param(pst_function* fn, pst_parameter* p)
{
struct list_node* n = (p == NULL) ? list_first(&fn->params) : list_next(&p->node);
pst_parameter* ret = NULL;
if(n) {
ret = list_entry(n, pst_parameter, node);
}
return ret;
}
bool handle_lexical_block(pst_function* fn, Dwarf_Die* result)
{
uint64_t lowpc = 0, highpc = 0; const char* origin_name = "";
dwarf_lowpc(result, &lowpc);
dwarf_highpc(result, &lowpc);
Dwarf_Attribute attr_mem;
Dwarf_Die origin;
if(dwarf_hasattr (result, DW_AT_abstract_origin) && dwarf_formref_die (dwarf_attr (result, DW_AT_abstract_origin, &attr_mem), &origin) != NULL) {
origin_name = dwarf_diename(&origin);
Dwarf_Die child;
if(dwarf_child (&origin, &child) == 0) {
do {
switch (dwarf_tag (&child))
{
case DW_TAG_variable:
case DW_TAG_formal_parameter:
pst_log(SEVERITY_DEBUG, "Abstract origin: %s('%s')", dwarf_diename(&origin), dwarf_diename (&child));
break;
// Also handle DW_TAG_unspecified_parameters (unknown number of arguments i.e. fun(arg1, ...);
default:
break;
}
} while (dwarf_siblingof (&child, &child) == 0);
}
}
const char* die_name = "";
if(dwarf_diename(result)) {
die_name = dwarf_diename(result);
}
pst_log(SEVERITY_DEBUG, "Lexical block with name '%s', tag 0x%X and origin '%s' found. lowpc = 0x%lX, highpc = 0x%lX", die_name, dwarf_tag (result), origin_name, lowpc, highpc);
Dwarf_Die child;
if(dwarf_child (result, &child) == 0) {
do {
switch (dwarf_tag (&child)) {
case DW_TAG_lexical_block:
handle_lexical_block(fn, &child);
break;
case DW_TAG_variable: {
pst_parameter* param = add_param(fn);
if(!pst_parameter_handle_dwarf(param, &child, fn)) {
del_param(param);
}
break;
}
case DW_TAG_GNU_call_site:
pst_call_site_storage_handle_dwarf(&fn->call_sites, &child, fn);
break;
case DW_TAG_inlined_subroutine:
pst_log(SEVERITY_DEBUG, "Skipping Lexical block tag 'DW_TAG_inlined_subroutine'");
break;
default:
pst_log(SEVERITY_DEBUG, "Unknown Lexical block tag 0x%X", dwarf_tag(&child));
break;
}
}while (dwarf_siblingof (&child, &child) == 0);
}
return true;
}
bool pst_function_print_dwarf(pst_function* fn)
{
char* at = NULL;
if(!asprintf(&at, " at %s:%d, %p", fn->file, fn->line, (void*)fn->pc)) {
return false;
}
if(at[4] == ':' && at[5] == '-') {
free(at);
if(!asprintf(&at, " at %p", (void*)fn->pc)) {
return false;
}
}
//ctx->print(ctx, "%s:%d: ", file.c_str(), line);
// handle return parameter and be safe if function haven't parameters (for example, dwar info for function is absent)
pst_parameter* param = next_param(fn, NULL);
if(param && param->is_return) {
// print return value type, function name and start list of parameters
pst_parameter_print_dwarf(param);
fn->ctx->print(fn->ctx, " %s(", fn->name);
param = next_param(fn, param);
} else {
fn->ctx->print(fn->ctx, "%s(", fn->name);
}
bool first = true; bool start_variable = false;
for(; param; param = next_param(fn, param)) {
if(param->is_return) {
// print return value type, function name and start list of parameters
pst_parameter_print_dwarf(param);
fn->ctx->print(fn->ctx, " %s(", fn->name);
continue;
}
if(param->is_variable) {
if(!start_variable) {
fn->ctx->print(fn->ctx, ")%s\n", at);
fn->ctx->print(fn->ctx, "{\n");
start_variable = true;
}
if(param->line) {
fn->ctx->print(fn->ctx, "%04u: ", param->line);
} else {
fn->ctx->print(fn->ctx, " ");
}
pst_parameter_print_dwarf(param);
fn->ctx->print(fn->ctx, ";\n");
} else {
if(first) {
first = false;
} else {
fn->ctx->print(fn->ctx, ", ");
}
pst_parameter_print_dwarf(param);
}
}
if(!start_variable) {
fn->ctx->print(fn->ctx, ");%s\n", at);
} else {
fn->ctx->print(fn->ctx, "}\n");
}
free(at);
return true;
}
bool pst_function_handle_dwarf(pst_function * fn, Dwarf_Die* d)
{
fn->die = d;
get_frame(fn);
Dwarf_Attribute attr_mem;
Dwarf_Attribute* attr;
// get list of offsets from process base address of continuous memory ranges where function's code resides
// if(dwarf_haspc(d, pc)) {
dwarf_lowpc(d, &fn->lowpc);
dwarf_highpc(d, &fn->highpc);
// } else {
// pst_log(SEVERITY_ERROR, "Function's '%s' DIE hasn't definitions of memory offsets of function's code", dwarf_diename(d));
// return false;
// }
unw_proc_info_t info;
unw_get_proc_info(&fn->cursor, &info);
fn->ctx->clean_print(fn->ctx);
pst_log(SEVERITY_INFO, "Function %s(...): LOW_PC = %#lX, HIGH_PC = %#lX, offset from base address: 0x%lX, START_PC = 0x%lX, offset from start of function: 0x%lX",
dwarf_diename(d), fn->lowpc, fn->highpc, fn->pc - fn->ctx->base_addr, info.start_ip, info.start_ip - fn->ctx->base_addr);
fn->ctx->print_registers(fn->ctx, 0x0, 0x10);
pst_log(SEVERITY_INFO, "Function %s(...): CFA: %#lX %s", dwarf_diename(d), fn->parent ? fn->parent->sp : 0, fn->ctx->buff);
pst_log(SEVERITY_INFO, "Function %s(...): %s", dwarf_diename(d), fn->ctx->buff);
// determine function's stack frame base
attr = dwarf_attr(fn->die, DW_AT_frame_base, &attr_mem);
if(attr) {
if(dwarf_hasform(attr, DW_FORM_exprloc)) {
Dwarf_Op *expr;
size_t exprlen;
if (dwarf_getlocation (attr, &expr, &exprlen) == 0) {
fn->ctx->print_expr(fn->ctx, expr, exprlen, attr);
pst_decl(pst_dwarf_stack, stack, fn->ctx);
if(pst_dwarf_stack_calc(&stack, expr, exprlen, attr, fn)) {
uint64_t value;
if(pst_dwarf_stack_get_value(&stack, &value)) {
pst_log(SEVERITY_DEBUG, "DW_AT_framebase expression: \"%s\" ==> 0x%lX", fn->ctx->buff, value);
} else {
pst_log(SEVERITY_ERROR, "Failed to get value of calculated DW_AT_framebase expression: %s", fn->ctx->buff);
}
} else {
pst_log(SEVERITY_ERROR, "Failed to calculate DW_AT_framebase expression: %s", fn->ctx->buff);
}
pst_dwarf_stack_fini(&stack);
} else {
pst_log(SEVERITY_WARNING, "Unknown attribute form = 0x%X, code = 0x%X", attr->form, attr->code);
}
}
}
// Get reference to return attribute type of the function
// may be to use dwfl_module_return_value_location() instead
pst_parameter* ret_p = add_param(fn); ret_p->is_return = true;
attr = dwarf_attr(fn->die, DW_AT_type, &attr_mem);
if(attr) {
if(!pst_parameter_handle_type(ret_p, attr)) {
pst_log(SEVERITY_ERROR, "Failed to handle return parameter type for function %s(...)", fn->name);
del_param(ret_p);
}
} else {
pst_parameter_add_type(ret_p, "void", 0);
}
// handle and save additionally these attributes:
// 1. string of DW_AT_linkage_name (mangled name of program if any)
// A debugging information entry may have a DW_AT_linkage_name attribute
// whose value is a null-terminated string containing the object file linkage name
// associated with the corresponding entity.
// 2. flag DW_AT_external attribute
// A DW_AT_external attribute, which is a flag, if the name of a variable is
// visible outside of its enclosing compilation unit.
// 3. A subroutine entry may contain a DW_AT_main_subprogram attribute which is
// a flag whose presence indicates that the subroutine has been identified as the
// starting function of the program. If more than one subprogram contains this flag,
// any one of them may be the starting subroutine of the program.
Dwarf_Die result;
if(dwarf_child(fn->die, &result) != 0)
return false;
// went through parameters and local variables of the function
do {
switch (dwarf_tag(&result)) {
case DW_TAG_formal_parameter:
case DW_TAG_variable: {
pst_parameter* param = add_param(fn);
if(!pst_parameter_handle_dwarf(param, &result, fn)) {
del_param(param);
}
break;
}
case DW_TAG_GNU_call_site:
pst_call_site_storage_handle_dwarf(&fn->call_sites, &result, fn);
break;
// case DW_TAG_inlined_subroutine:
// /* Recurse further down */
// HandleFunction(&result);
// break;
case DW_TAG_lexical_block: {
handle_lexical_block(fn, &result);
break;
}
// Also handle:
// DW_TAG_unspecified_parameters (unknown number of arguments i.e. fun(arg1, ...);
// DW_AT_inline
default:
pst_log(SEVERITY_DEBUG, "Unknown TAG of function: 0x%X", dwarf_tag(&result));
break;
}
} while(dwarf_siblingof(&result, &result) == 0);
return true;
}
bool pst_function_unwind(pst_function* fn, Dwarf_Addr addr)
{
fn->pc = addr;
Dwfl_Line *dwline = dwfl_getsrc(fn->ctx->dwfl, addr);
if(dwline != NULL) {
Dwarf_Addr addr;
const char* filename = dwfl_lineinfo (dwline, &addr, &fn->line, NULL, NULL, NULL);
if(filename) {
const char* str = strrchr(filename, '/');
if(str && *str != 0) {
str++;
} else {
str = filename;
}
fn->file = pst_strdup(str);
fn->ctx->print(fn->ctx, "%s:%d", str, fn->line);
} else {
fn->ctx->print(fn->ctx, "%p", (void*)addr);
}
} else {
fn->ctx->print(fn->ctx, "%p", (void*)addr);
}
const char* addrname = dwfl_module_addrname(fn->ctx->module, addr);
char* demangle_name = NULL;
if(addrname) {
demangle_name = cplus_demangle(addrname, 0);
char* function_name = NULL;
if(asprintf(&function_name, "%s%s", demangle_name ? demangle_name : addrname, demangle_name ? "" : "()") == -1) {
pst_log(SEVERITY_ERROR, "Failed to allocate memory");
return false;
}
fn->ctx->print(fn->ctx, " --> %s", function_name);
char* str = strchr(function_name, '(');
if(str) {
*str = 0;
}
fn->name = pst_strdup(function_name);
free(function_name);
}
if(demangle_name) {
free(demangle_name);
}
return true;
}
void pst_function_init(pst_function* fn, pst_context* _ctx, pst_function* _parent)
{
list_node_init(&fn->node);
// fields
fn->lowpc = 0;
fn->highpc = 0;
fn->pc = 0;
fn->die = NULL;
fn->name = NULL;
list_head_init(&fn->params);
pst_call_site_storage_init(&fn->call_sites, _ctx);
fn->sp = 0;
fn->cfa = 0;
memcpy(&fn->cursor, _ctx->curr_frame, sizeof(fn->cursor));
fn->line = -1;
fn->file = NULL;
fn->parent = _parent;
fn->frame = NULL;
fn->ctx = _ctx;
fn->allocated = false;
}
pst_function* pst_function_new(pst_context* _ctx, pst_function* _parent)
{
pst_function* fn = pst_alloc(pst_function);
if(fn) {
pst_function_init(fn, _ctx, _parent);
fn->allocated = true;
}
return fn;
}
void pst_function_fini(pst_function* fn)
{
clear(fn);
if(fn->frame) {
// use free here because it was allocate out of our control by libdw
free(fn->frame);
}
if(fn->name) {
pst_free(fn->name);
}
if(fn->file) {
pst_free(fn->file);
}
if(fn->allocated) {
pst_free(fn);
}
}
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